Redside Dace (Clinostomus elongatus): COSEWIC assessment and status reports 2017

Official title: COSEWIC Assessment and Status Report on the Redside Dace (Clinostomus elongatus) in Canada 2017

Committee on the status of Endangered Wildlife in Canada (COSEWIC)
Endangered 2017

COSEWIC assessment summary

Assessment summary – November 2017

Common name: Redside Dace

Scientific name: Clinostomus elongatus

Status: Endangered

Reason for designation: This small, colourful minnow is highly susceptible to changes in stream flow and declines in water quality, such as occur in urban and agricultural watersheds. The Canadian range of this species largely overlaps with the Greater Toronto Area (GTA), where urban land use is widespread and projected to increase in the future. The continued expansion of the GTA has led to ongoing habitat degradation, causing serious declines in range and number of individuals and populations.

Occurrence: Ontario

Status history: Designated Special Concern in April 1987. Status re-examined and designated Endangered in April 2007 and November 2017.

COSEWIC executive summary

Redside Dace
Clinostomus elongatus

Wildlife species description and significance

Redside Dace is a colourful minnow that features a yellow lateral stripe extending the length of the body and a bright red stripe below the yellow. The back is a variable shade of green and the ventral surface is silvery white. The body is slender and laterally compressed. Maximum size is 120 mm. Redside Dace has a long snout with a projecting lower jaw. Pectoral fins are longer in males than females. The species is an indicator of habitat quality.

Distribution

Redside Dace has a discontinuous distribution that includes tributaries of the five Great Lakes, Ohio River, upper Mississippi River, and the Susquehanna River. The heart of the distribution includes much of New York, Pennsylvania, and Ohio. The western portion of the range includes parts of Wisconsin and an area in southeastern Minnesota. Small disjunct patches of range are also present in West Virginia, Kentucky, Iowa, and Michigan. In Canada, most populations occupy streams flowing through the Greater Toronto Area into Lake Ontario. Populations are also known from the Lake Erie watershed (Grand River), a few rivers in the Lake Huron watershed (Saugeen River, Gully Creek, South Gully Creek, Two Tree River), and two Lake Simcoe tributaries (Kettleby Creek, Sharon Creek).

Habitat

Redside Dace currently occupy small tributaries 5-10 m in width. During most of the year, including the winter, they are found in pools ranging in depth from 11 to 100 cm. Substrate is highly variable, ranging from silt to boulders. Redside Dace habitat usually has riparian vegetation consisting of overhanging grasses and shrubs considered important for production of terrestrial insects. Streams running through relatively open areas appear to be superior to those in forested areas. Redside Dace is a coolwater fish with a preference for clear water. Spawning occurs in riffle habitat with fine gravel substrate.

Biology

Spawning occurs in late May at temperatures of 16-18°C. Eggs are normally deposited in nest depressions constructed by associate species such as Common Shiner or Creek Chub. The maximum age reported for Redside Dace in Ontario is three years (although a five-year-old individual has been identified; Drake pers. comm. 2017) and four years in New York and Pennsylvania. Most individuals mature after their second winter. Growth in Ontario populations is comparable to those in New York, Pennsylvania, and Wisconsin. First-year fish grow very rapidly; most individuals mature following their second winter. Dietary studies have revealed that Redside Dace are predominantly surface and supra-surface feeders. Gut content analyses are consistent in finding a very large proportion of terrestrial insects, particularly dipterans, in the diet.

Population size and trends

Population sizes are unknown for most catchments. Quantitative estimates of abundance have been made on one occasion for five Ontario populations. Estimates range from 462-741 individuals in the Gully Creek to 21,530-38,582 individuals in the Humber River. Trends in abundance are usually based on presence/absence information determined in general fish surveys and, in recent years, in surveys targeting Redside Dace. Surveys suggest declining population sizes in several systems including Lynde Creek (east branch), Rouge River (east branch, Morningside tributary), Don River, Humber River, Credit River, Sixteen Mile Creek, Grand River (Irvine Creek), Spencer Creek, Saugeen River (main branch and Meux Creek), and Holland River (Kettleby Creek). Populations in Bronte Creek, Don River, and Sharon Creek are likely extirpated.

Threats and limiting factors

The overall threat impact is very high. The greatest threats are natural system alterations that degrade habitat in both urban and rural settings. These include factors that alter flow regimes, including streambed alterations, surface hardening of watersheds, agricultural drain maintenance, reservoir development, and disruption of headwater features. Urban and rural habitat is frequently altered by removal of riparian vegetation, leading to warmer thermal regimes and reduced availability of terrestrial insects. Invasive predatory fishes, including centrarchids, salmonids, and Northern Pike, also threaten Redside Dace populations. Pollution from several sources is a threat across the range. Pollutants include chloride, leachate from landfill sites, and storm-water inputs in urban settings. In rural areas, siltation and nutrient inputs from agricultural runoff and manure mismanagement are especially relevant. Low-level and potential threats include incidental catch in the bait fishery and negative impacts from scientific monitoring.

Protection, status, and ranks

Redside Dace receives some protection from provisions of the Fisheries Act. Ontario statutes, including the Endangered Species Act and the Planning Act, also protect the species and its habitat. Redside Dace was assessed as Endangered by COSEWIC in 2007 and listed as such under the Species at Risk Act in May 2017 (Schedule 1). It is classified as Endangered under the Ontario Endangered Species Act. General status ranks are Global 3, National (N) 2 (Canada), N3/N4 (U.S.), and Subnational 2 in Ontario.

Technical summary

Scientific name: Clinostomus elongatus

English name: Redside Dace

French name: Méné long

Range of occurrence in Canada (province/territory/ocean): Ontario

Demographic information

Generation time (usually average age of parents in the population; indicate if another method of estimating generation time indicated in the IUCN guidelines (2011) is being used):

2-3 yrs
Most mature at 2 y, all mature by 3 y.

Is there an [observed, inferred, or projected] continuing decline in number of mature individuals?

Yes
Inferred from continuing declines in quality of habitat, particularly in the Greater Toronto Area.

Estimated percent of continuing decline in total number of mature individuals within [5 years or 2 generations]:

>50%
Based on overall threat impact of very high and an index of abundance appropriate to the taxon (area of occupancy based on 1 km x 1 km grids).

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over the last [10 years, or 3 generations]:

81% reduction
Inferred from a decline in an index of abundance appropriate to the taxon (area of occupancy based on 1 km x 1 km grids).

[Projected or suspected] percent [reduction or increase] in total number of mature individuals over the next [10 years, or 3 generations]:

>50% decrease
Suspected based on ongoing habitat loss in the Greater Toronto Area.

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over any [10 years, or 3 generations] period, over a time period including both the past and the future:

>50% reduction
Inferred from a decline in an index of abundance appropriate to the taxon (area of occupancy based on 1 km x 1 km grids) and ongoing habitat loss in the Greater Toronto Area.

Are the causes of the decline a) clearly reversible and b) understood and c) ceased?

a. Yes
b. Yes
c. No

Are there extreme fluctuations in number of mature individuals?

No

Extent and occupancy information

Estimated extent of occurrence (EOO):

44,842 km²

Index of area of occupancy (IAO) (Always report 2x2 grid value):

332 km²

Is the population “severely fragmented” i.e., is >50% of its total area of occupancy in habitat patches that are (a) smaller than would be required to support a viable population, and (b) separated from other habitat patches by a distance larger than the species can be expected to disperse?:

a. Yes
b. Yes

Number of “locations” (use plausible range to reflect uncertainty if appropriate):

6-15

Is there an [observed, inferred, or projected] decline in extent of occurrence?

Yes, observed 4.4% decline (46,900 km² in 2007; 44,842 km² currently)

Is there an [observed, inferred, or projected] decline in index of area of occupancy?

Yes, observed 47% decline (628 km² in 2007; 332 km² currently)

Is there an [observed, inferred, or projected] decline in number of subpopulations?

Yes, observed.
Likely extirpation from Grand River and Don River since last report.

Is there an [observed, inferred, or projected] decline in number of “locations”*?

Yes, observed.
Likely loss of Grand River location since last report. Likely loss of Don River location if Greater Toronto Area watersheds are considered separate locations (i.e., there are 15 extant locations).

Is there an [observed, inferred, or projected] decline in [area, extent and/or quality] of habitat?

Yes, observed

Are there extreme fluctuations in number of subpopulations?

No

Are there extreme fluctuations in number of “locations”?

No

Are there extreme fluctuations in extent of occurrence?

No

Are there extreme fluctuations in index of area of occupancy?

No

* Number of locations (Note: See Definitions and abbreviations on COSEWIC website and IUCN (Feb 2014) for more information on this term.)

Quantitative analysis

Probability of extinction in the wild is at least [20% within 20 years or 5 generations, or 10% within 100 years]: Unknown

Threats (direct, from highest impact to least, as per IUCN Threats Calculator)

Was a threats calculator completed for this species? Yes. Overall, the threat impact score was very high.

1. Natural system modifications (streambed alteration, agricultural drain maintenance, reservoir development, altered flow regimes, dewatering, riparian vegetation removal)
2. Invasive predators (Northern Pike, Largemouth Bass, Black Crappie, Brown Trout, Rainbow Trout)
3. Pollution (inputs resulting from poor storm-water management, chloride, leaching from landfill sites, nutrient inputs, siltation)

What additional limiting factors are relevant?

Redside Dace has limited environmental tolerance and very limited dispersal capability.

Rescue effect (immigration from outside Canada)

Status of outside population(s)?

Declining
Michigan (S1S2); New York (S3)

 

Is immigration known or possible?

No

Would immigrants be adapted to survive in Canada?

Probably

Is there sufficient habitat for immigrants in Canada?

No

Are conditions deteriorating in Canada?⁺

Yes

Are conditions for the source population deteriorating?⁺

Yes

Is the Canadian population considered to be a sink?⁺

No

Is rescue from outside populations likely?

No

⁺ See Table 3 (Guidelines for modifying status assessment based on rescue effect).

Data-sensitive species

Is this a data sensitive species? No

Status history

COSEWIC Status History: Designated Special Concern in April 1987. Status re-examined and designated Endangered in April 2007 and November 2017.

Status and reasons for designation:

Status: Endangered

Alpha-numeric codes: A2b+3bc+ 4bc; B2ab(i,ii,ii,iv,v)

Reasons for designation: This small, colourful minnow is highly susceptible to changes in stream flow and declines in water quality, such as occur in urban and agricultural watersheds. The Canadian range of this species largely overlaps with the Greater Toronto Area (GTA), where urban land use is widespread and projected to increase in the future. The continued expansion of the GTA has led to ongoing habitat degradation, causing serious declines in range and number of individuals and populations.

Applicability of criteria

Criterion A (Decline in Total Number of Mature Individuals): Meets Endangered: A2b, since there is an inferred reduction in total number of mature individuals greater than 50% over the last 10 years based on (b) an index of abundance appropriate to the taxon (1km² area of occupancy grids); A3bc, since there is a projected reduction in total number of mature individuals greater than 50% over the next 10 years based on (b) an index of abundance appropriate to the taxon and (c) a decline in the index of area of occupancy and quality of habitat; and, A4bc, since there is an observed and projected reduction in total number of mature individuals greater than 50% over a 10-year period spanning the past and future based on (b) an index of abundance appropriate to the taxon and (c) a decline in the index of area of occupancy and quality of habitat.

Criterion B (Small Distribution Range and Decline or Fluctuation): Meets Endangered. Greater than 50% of its total area of occupancy is in habitat patches that are smaller than required to support a viable population and separated by distances larger than the known dispersal capability of the species. It fulfills B2ab(i,ii,iii,iv,v), since the IAO is below the threshold and there is a decline in i) EOO, ii) IAO, iii) area, extent and quality of habitat, iv) number of subpopulations, v) and number of mature individuals.

Criterion C (Small and Declining Number of Mature Individuals): Not applicable. Exceeds thresholds.

Criterion D (Very Small or Restricted Population): Not applicable. Exceeds thresholds.

Criterion E (Quantitative Analysis): Not available.

Preface

The status of Redside Dace was last assessed by COSEWIC in 2007. The assessed status was Endangered due to continuing declines, sensitivity to habitat alterations, and the likelihood of further development in the remaining areas of relatively undisturbed habitat. Since then, important information about the species has become available, including quantitative estimates of population size in five watersheds (Poos et al. 2012), dispersal patterns in the Rouge River (Poos and Jackson 2012), and the distribution of population genetic variation across the range (Serrao 2016). New methods for detection and, potentially, estimating population size have also been developed, including deployment of underwater video cameras (Castaneda pers. comm. 2016) and amplification of environmental DNA (Serrao 2016; Reid et al. 2017). The status of Redside Dace has not improved since 2007 and continued declines, including likely extirpation in Don River and Grand River, are anticipated unless factors threatening the species are mitigated.

COSEWIC history

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions (2017)

Wildlife species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)

A wildlife species that no longer exists.

Extirpated (XT)

A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A wildlife species facing imminent extirpation or extinction.

Threatened (T)

A wildlife species likely to become endangered if limiting factors are not reversed.

Special concern (SC)
(Note: Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.)

A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at risk (NAR)
(Note: Formerly described as “Not In Any Category”, or “No Designation Required.”)

A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data deficient (DD)
(Note: Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” [insufficient scientific information on which to base a designation] prior to 1994. Definition of the [DD] category revised in 2006.)

A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.

The Canadian Wildlife Service, Environment and Climate Change Canada, provides full administrative and financial support to the COSEWIC Secretariat.

Wildlife species description and significance

Name and classification

Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Genus/Species: Clinostomus elongatus
English Common Name: Redside Dace
French Common Name: Méné long

Redside Dace is one of two species in the genus Clinostomus (Page et al. 2013). The other member of the genus, Rosyside Dace (C. funduloides) occupies upland Atlantic slope drainages from southern Pennsylvania to the Savannah River. It is also present in the Ohio and northeast Mississippi drainages (Page and Burr 2011). No subspecies of Redside Dace are recognized. Phylogenetic analysis of mitochondrial DNA sequences (control region and cytochrome-b) and an intron of a nuclear gene (ribosomal protein S7) suggest that Clinostomus is the sister group of a lineage containing the genera Richardsonius and Iotichthys (Houston et al. 2010).

Morphological description

Redside Dace is a colourful minnow that features a yellow lateral stripe, above the lateral line, extending from the head to the caudal peduncle (Figure 1). A bright red stripe situated below the yellow stripe extends, above and below the lateral line, from just posterior to the operculum to a point below the dorsal fin where it is replaced by a black line that extends to the caudal peduncle. The back is a variable shade of green and the ventral surface is silvery white. Colours are brightest during the spawning season (Scott and Crossman 1973; Page and Burr 2011).

The body is slender and laterally compressed. Maximum size is 120 mm (COSEWIC 2007), but average size is 75 mm (Holm et al. 2009). Redside Dace has a long snout and a large mouth with a projecting lower jaw. Pectoral fins are longer in males than females. Lateral-line scales number 63-75 (Holm et al. 2009). As in many other minnows, reproductive male and female Redside Dace develop nuptial tubercules, particularly on the top of the head and pectoral fins (Scott and Crossman 1973; Holm et al. 2009; Page and Burr 2011).

Population spatial structure and variability

Range-wide population genetic structure has been described based on analysis of variation of mitochondrial DNA (ATPase 6 and 8) and 10 microsatellite loci across 28 populations in Ontario and the United States (Serrao 2016; Serrao et al. 2017). Globally, the species displays strong phylogeographic structure. Three principal mitochondrial DNA lineages were identified that are strongly concordant in distribution with three population clusters revealed by microsatellite loci. The likely basal lineage (haplogroup 3) is distributed in the eastern Ohio River drainage (Allegheny and Monongahela rivers). Haplogroup 1 is present in the lower Ohio River drainage and tributaries of the lower Great Lakes. It also co-occurs with haplogroup 3 variants at sampling sites in the Allegheny drainage. Haplogroup 2 is present in the western portion of the species’ range, specifically in the upper Mississippi drainage and at sites along the south shore of Lake Superior. Analysis of molecular variance (AMOVA) revealed that differences among haplogroups accounted for the largest fraction of mitochondrial DNA variation (71.1%). Smaller fractions of variation were accounted for by differences among populations within haplogroups (21.9%) and differences within populations (7.0%). Thus, most of the variation is revealed among higher-level groupings, i.e., across regional comparisons.

Microsatellite variation revealed three population clusters that largely overlap geographically with the distribution of mitochondrial DNA haplogroups. Microsatellites also revealed more fine-scale population structuring. Genetic assignment testing showed virtually every sample site to be differentiated from all other sites, even within regional population clusters. Pairwise FST estimates ranged from 0.08 to 0.62 and all were statistically significant. AMOVA showed, in contrast to the mitochondrial DNA, the largest proportion of variation to be within populations (59.2% p) with less variation partitioned among populations within regional clusters (21.1%) and among regional clusters (19.7%; Serrao 2016). In summary, the information revealed by nuclear microsatellite loci is largely consistent with information derived from mitochondrial DNA. Microsatellites revealed additional information about fine-scale genetic structure of Redside Dace populations, specifically, that populations are unique at local, as well as, regional levels.

Designatable units

Designatable units (DUs) must be both distinct and evolutionarily significant (COSEWIC 2016). Canadian populations of Redside Dace can be considered distinct because all are genetically unique (Serrao 2016; Serrao et al. 2017). However, it is unclear whether they meet the significance criterion. All populations occur within tributaries of the Great Lakes, and hence all occupy the Great Lakes – Upper St. Lawrence freshwater biogeographic zone. The genetic uniqueness of each population is likely the result of small population effects rather than local adaption to stream-specific environmental conditions. Redside Dace has limited dispersal capability (see Dispersal and Migration section), so the homogenizing effects of gene flow among watersheds is almost certainly very limited. Furthermore, the species typically occupies relatively small waterways that, in many cases, support small populations. The latter are particularly subject to population bottlenecks, founder events, and/or genetic drift, all of which could result in non-adaptive genetic differentiation.

One Canadian population is a geographic outlier. The Two Tree River population near Sault Ste. Marie is geographically removed from the southern Ontario populations and is genetically allied to Upper Mississippi River/Lake Superior populations (Serrao 2016; Serrao et al. 2017). While this population likely has a different history in terms of glacial refugia and postglacial dispersal than southern Ontario populations, it does occupy the same biogeographic zone (see Figure 2 in COSEWIC 2016) as all other populations, and there is no compelling evidence of adaptive differentiation. For these reasons, all Canadian populations are considered to be within a single DU.

Special significance

In Canada, much of the habitat historically occupied by Redside Dace has become urbanized as Ontario’s Greater Toronto Area (GTA) has been developed. The usual association of Redside Dace with cool, clear waters suggests the species is an indicator of good habitat quality. The large component of flying insects, particularly dipterans that are caught on-the-wing, in the diet is unique among Canadian cyprinids and represents a conduit for transfer of energy from terrestrial to aquatic habitats.

Distribution

Global range

Redside Dace has a patchy distribution that includes tributaries of the five Great Lakes, Ohio River, upper Mississippi River, and the Susquehanna River (Figure 2). The heart of the distribution includes much of New York, western Pennsylvania, and northeastern Ohio. The western portion of the range includes parts of Wisconsin and an area in southeastern Minnesota. Small, disjunct range patches are also present in West Virginia, Kentucky, and Michigan. The species is thought to be extirpated in Iowa (Iowa Fish Atlas 2004 to 2006). A single record exists for Maryland from the Monongahela drainage, but this may represent a human-mediated introduction (Fuller 2016).

Canadian range

Most Canadian populations occupy streams flowing through the Greater Toronto Area into Lake Ontario (Figure 3). This series of streams is bounded on the east by Pringle Creek (Whitby) and on the west by Spencer Creek (Hamilton). Populations are also known from the Lake Erie drainage (Grand River), Lake Huron drainage (Saugeen River, Gully Creeks, Two Tree River), and Lake Simcoe drainage (Holland River).

Extent of occurrence and area of occupancy

Since the last status update (COSEWIC 2007), the extent of occurrence has declined slightly (4.4%; 46,900 km² versus 44,842 km² currently), whereas IAO has declined substantially (53%; 628 km² versus 332 km² currently) (Figure 4).

Search effort

An account of historical sampling effort for Redside Dace in Ontario is given in COSEWIC (2007). Until the late 1970s, Canadian records were derived from general watershed surveys rather than from searches specifically targeting Redside Dace.

Sampling effort varies over time and among watersheds. For many watersheds, the baseline information was collected over a 10-year period (1949 through 1959) in wide-ranging surveys by the Ontario Department of Planning and Development (ODPD). Subsequent sampling was done mostly by the Ministry of Natural Resources and Forestry (MNRF), Fisheries and Oceans Canada, Royal Ontario Museum, local Conservation Authorities, and academic institutions. Sampling has not always been done systematically through time, although many sites sampled by ODPD, as well as additional sites, were resampled by subsequent workers from other agencies. In recent years systematic sampling rotations have been established in some watersheds. Fisheries sampling occurs in systems under jurisdiction of the Toronto Regional Conservation Authority on a three-year rotation (150 fixed sites across nine watersheds; (Lawrie pers. comm. 2017). Redside Dace is not specifically targeted under this regime and many sampling stations cannot be considered optimal Redside Dace habitat. The Lake Simcoe Region Conservation Authority surveys fish communities annually, although Redside Dace has not been specifically targeted in its monitoring for the last five years (Wilson pers. comm. 2017). Watersheds under the Central Lake Ontario Conservation Authority are also monitored regularly (five-year rotation since approximately 1999; Kelsey pers. comm. 2017). Similarly, Credit Valley Conservation has established approximately 100 stations, 50 of which are sampled annually (Morris pers. comm. 2016) and Conservation Halton monitors approximately 100 sampling stations in catchments under its authority (Dunn pers. comm. 2016). In contrast, routine sampling does not occur in several other watersheds in which Redside Dace is present currently or historically. This is the case in the Grand River (Barnucz pers. comm. 2016), and Saugeen River (Scheifley pers. comm. 2016). A summary of sampling effort is presented in Table 1.

University researchers have been sampling several watersheds in recent years using conventional detection methods as well as novel approaches including eDNA detection in water samples (Serrao 2016) and deployment of underwater video cameras (Castaneda pers. comm. 2016). Poos and Jackson (2012) surveyed selected reaches of five streams using depletion sampling (seining) and extrapolated their results to produce stream-wide population estimates (see Fluctuations and Trends). Appendix Tables 1-26 summarize information contained in a database of catch records maintained by MNRF and the Redside Dace Recovery Team.

Habitat

Habitat requirements

Redside Dace occupy small tributaries 5-10 m in width with pool and riffle areas (McKee and Parker 1982; Meade et al. 1986). During most of the year, including the winter, they are found in midwater positions of pools (Novinger and Coon 2000; Zimmerman 2009; Poos et al. 2012; Villard and Heaton 2016) 11-100 cm deep (Coon 1993). Substrate of occupied stream reaches is highly variable, ranging from silt to boulders (Koster 1939; Trautman 1957; McKee and Parker 1982). Redside Dace habitat usually has riparian vegetation consisting of overhanging grasses and shrubs such as alder (Koster 1939). Production of its principal food supply, largely dipterans (Daniels and Wisniewski 1994), depends on presence of this vegetation. Streams running through relatively open areas are considered superior to those in forested areas provided riparian vegetation is present (Andersen 2002; Parish 2004).

Redside Dace is considered to be a cool-water fish. McKee and Parker (1982) reported the maximum temperature experienced by the species during August/September in Ontario to be 23°C, although usually below 20°C. Maintaining these conditions depends on the presence of intact headwater features and groundwater seepage (Redside Dace Recovery Team 2010). Dissolved oxygen concentration is usually greater than 7 mg/L. Streams are usually clear; those with significant amounts of organic material on the substrate are sometimes brown tinged. Despite these habitat preferences, Redside Dace were found by McKee and Parker (1982) at two sites with elevated turbidity (i.e., 0.3 m Secchi disc transparency). by Holm (pers. comm. 2016) in turbid water in Fourteen Mile Creek, and by Castaneda (pers. comm. 2017) in very turbid water (10-20 NTU) in Two Tree River. Records from turbid waters in the GTA are more likely the result of temporary high flow events than tolerance of poor water quality.

Spawning has been observed in riffle, run, and the tail-end of pool habitats (Koster 1939; Zimmerman 2009; Lawrie pers. comm. 2017). McKee and Parker (1982) noted the absence of Redside Dace in pools of the East Humber River in early May and suggested the pre-spawning fish had relocated to riffle areas. Koster (1939) noted adults moving from pool to gravelly riffle areas to spawn in late May when water temperature was 18°C or higher.

Habitat trends

Most of the waterways containing Redside Dace flow through the GTA, one of the most highly developed, and developing, regions in Canada. Habitat degradation associated with urbanization is considered the most important cause of decline in the species (COSEWIC 2007). In general, as development has proceeded inland from the Lake Ontario shoreline, most populations of Redside Dace have been lost from higher-order stream reaches, relegating the remaining populations to ever-decreasing stretches of headwater habitat (Figure 5; Reid and Parna 2017). While Redside Dace is sometimes considered to be a headwater specialist, this perception is likely an artifact of the loss of the species from previously suitable downstream habitat (Redside Dace Recovery Team 2010). In addition to urbanization, habitat degradation has been associated with other causes such as agriculture and aggregate and water extraction. Specific factors that have been implicated in the decline of Redside Dace throughout its range include, elimination or alteration of riparian vegetation, siltation, elevated turbidity, channel alteration, increased variation in water flow regimes, altered temperature regimes, instream barriers, pollutant inputs, and exotic species introductions (Daniels and Wisniewski 1994; COSEWIC 2007; Redside Dace Recovery Team 2010).

The most immediate concerns about habitat trends apply to catchments in the GTA, several of which are expected to undergo additional development, or are adjacent to areas where development is planned (COSEWIC 2007). One particularly notable project planned in Pickering is the Seaton Community, to be situated in the headwaters of Duffins Creek. The community will house up to 70,000 residents in an area of 2785 hectares. Some 53% of the area, including forest, wetlands, valley, and floodplains, has been designated as a Natural Heritage System and a monitoring program has been established to evaluate the impact of the development and the water management measures to be implemented (TRCA 2016). The ultimate impact on Redside Dace in Duffins Creek remains to be determined. Additional future development is also expected in the headwater region of Fourteen Mile Creek, although details are not available (Dunn pers. comm. 2016). Population projections by the Government of Ontario suggest an increase of 42.3% (from 6.7 to 9.6 million) in the GTA between 2016 and 2041 (Ontario Ministry of Finance 2017), with growth likely occurring into the remaining range of Redside Dace in the GTA.

Water-quality parameters in the Credit River are deteriorating (Morris pers. comm. 2016). Elevated levels of bacteria and contaminants, including nutrients and chlorides, were reported in Fletcher’s Creek and Silver Creek (CVC 2002). Declines in Redside Dace in these tributaries have been attributed to poor water quality. Water quality in Lynde Creek, based on phosphorus loading, is rated fair (CLOCA 2016).

The range of Redside Dace in Canada is severely fragmented as greater than 50% of the populations likely occur in habitat patches that are smaller than required to support a viable population and are separated from other habitat patches by a distance greater than the species can disperse (<500 m; Poos and Jackson 2012) and, in most cases, by physical watersheds. In 2007, DFO conducted a recovery potential workshop for Redside Dace (DFO 2009; Mandrak pers. comm. 2017). In that workshop, 14 participants evaluated among other things, the population status of Redside Dace by watershed. Population status was evaluated by assessing spatial extent, abundance, and trajectory. Population size was assessed as small (<100 individuals), medium (100-1,000 individuals), and large (>1,000 individuals). Of the 24 populations considered, five were considered extirpated and four were not assessed. Of the 15 populations assessed, 10 were assessed as small populations, three as medium populations, and two as large populations (Table 4). Velez-Espino and Koops (2009), recommended a recovery target of 4,711. Based on this recovery target, at least 13 of 15 assessed populations are not viable. As Redside Dace is a habitat specialist, and habitat degradation and loss is the greatest threat to the species, it can be inferred that the habitat patches for at least 13 of the populations are smaller than required to support a viable population.

Biology

Life cycle, demographic parameters and reproduction

Spawning was observed in Danby Creek, a headwater stream of the Susquehanna River, in late May when water temperature reached 18°C (Koster 1939). Similar timing of spawning in the East Humber River was reported by Parker and McKee (1982) and in Fourteen Mile Creek (COSEWIC 2007; Holm pers. comm. 2016). Males, followed soon after by females, leave pool habitat and enter shallow areas with fine gravel substrate just prior to spawning. Males establish small territories just downstream of nest depressions constructed by Common Shiner (Luxilus cornutus) or Creek Chub (Semotilus atromaculatus). Ripe females, accompanied by one to several males, enter the depression and deposit non-adhesive eggs in the gravel (Koster 1939). Host species may enhance survivorship of Redside Dace eggs by providing some protection from predators and by removing debris from the nest.

The maximum age reported for Redside Dace in New York (Koster 1939) and Pennsylvania (Schwartz and Norvell 1958) is four years. In Ontario, the maximum age observed is five years (Drake pers. comm. 2017) although most do not survive beyond three years (McKee and Parker 1982). Growth in Ontario populations is comparable to those in New York, Pennsylvania, and Wisconsin (Becker 1983). First-year fish grow very rapidly, followed by annual decrease in growth increments of approximately 5% (Schwartz and Norvell 1958). Most individuals mature following their second winter and all are mature after three winters (Koster 1939; McKee and Parker 1982); therefore, the generation time is 2-3 years.

Physiology and adaptability

Little information is available about physiology of Redside Dace. Novinger and Coon (2000) reported that metabolic rate increases with temperature and that critical thermal maximum increases with acclimation temperature. McKee and Parker (1982) found Redside Dace at oxygen concentrations as low as 4.0 mg/L although, at most sites, oxygen concentration was greater than 7.0 mg/L.

Redside Dace is not generally considered to be tolerant of habitat disturbance. The species has disappeared from many streams in which conditions have been altered. For example, the species has disappeared from some Ohio streams that have been affected by domestic, agricultural, and industrial pollution (Trautman 1957). Water-quality requirements have been described as “stringent” and the species is usually found in clear streams (McKee and Parker 1982).

Dietary studies have revealed that Redside Dace is predominantly a surface feeder. Gut-content analyses are consistent in finding a large proportion of terrestrial insects, particularly Dance Flies (Empididae), in the diet (Schwartz and Norvell 1958; McKee and Parker 1982; Daniels and Wisniewski 1994).

Dispersal and migration

Redside Dace spend most of their time in pools. Until specific studies were conducted, dispersal was thought to be restricted to springtime movement between pool habitat and adjoining riffle spawning habitat (Koster 1939; McKee and Parker 1982). Using mark-recapture methods, Poos and Jackson (2012) determined that movement of Redside Dace in two tributaries of the Rouge River is generally restricted. By tracking movements of 2141 individuals over a one-year period, they reported that dispersal does appear to be limited, but more extensive than previously thought. In Berczy Creek, 41% of recaptures were in the same pool, while 31% of recaptures in the Leslie tributary were in the same pool. Individuals dispersing among pools usually moved less than 100 m, and an average of only 3.8% of inter-pool movement involved displacement greater than 300 m. However, dispersal models suggest that the probability of moving >500 m is 0.4-5%, and varies seasonally, while the probability of moving >1000m varies between very rare and 1%. Unpublished results from this study indicate that the magnitude of movement (both dispersal distance and frequency) differed seasonally in the two creeks. Substantial movement was observed during July/August in Berczy Creek, and during September/October in Leslie tributary. Movements were correlated with high catch-per-unit-effort of cyprinid and catostomid species in the destination pool (Creek Chub, Bluntnose Minnow Pimephales notatus, White Sucker Catostomus commersonii, Common Shiner), suggesting that Redside Dace may be responding directly to the presence of these species (i.e., signifying a schooling effect or capitalizing on nest-building potential), or may be responding to habitat conditions that benefit the set of species (Drake pers. comm. 2017).

Schwartz and Norvell (1958) found that the sex ratio of Redside Dace sampled in a Pennsylvania stream changed seasonally. Specifically, the proportion of males decreased in samples taken during the spring and was extremely low after June. This observation suggests the possibility of sex-specific movement, but other workers have not reported this phenomenon.

Interspecific interactions

Redside Dace usually lives in mixed-species groups, often schooling with Creek Chub, Eastern Blacknose Dace (Rhinichthys atratulus), White Sucker, Bluntnose Minnow, and Common Shiner (Koster 1932; Poos and Jackson 2012; Drake pers. comm. 2016). This behaviour has been hypothesized to reduce predation risk (Poos and Jackson 2012) and extends to spawning behaviour as well. Redside Dace has been observed to deposit eggs in redds constructed by other species, specifically Creek Chub and Common Shiner. Hybridization has been documented among these species, probably facilitated by their associations on the spawning grounds (Koster 1939). Redside Dace is a small-bodied fish that is subject to predation by a variety of larger fishes and other animals. The nature of interactions between native Brook Trout (Salvelinus fontinalis) and Redside Dace is not known, but the two species naturally co-occur in some watersheds (e.g., Duffins Creek). Introduced predatory species are considered to have contributed to the decline of the species in some catchments (see Threats section).

Population sizes and trends

Sampling effort and methods

Most survey work was done using seine nets and/or backpack electrofishers. Some records are based on visual observations rather than physical captures. Very recently, underwater video cameras have been deployed to record occurrences (Davis et al. 2015; Castaneda pers. comm. 2016; Lawrie pers. comm 2017). Another recently developed method for detecting Redside Dace, and other species, is analysis of water samples for DNA using quantitative polymerase chain reaction (qPCR). When a species is present in a stream, DNA deposited into the water column (environmental DNA or eDNA) due to sloughing of skin and gut cells can be detectable using sensitive laboratory methods (Darling and Mahon 2011; Serrao 2016).

Abundance

The lack of consistent population sampling through time prevents quantitative estimates of abundance in most systems (Heaton pers. comm. 2016). Qualitative indications of abundance rely on presence/absence information determined through time from the various survey efforts outlined above. Systematic sampling in five Toronto area catchments has permitted quantitative estimates of abundance (Poos et al. 2012; details below). Because these estimates represent a snapshot in time, they are not informative regarding trends in abundance.

COSEWIC (2007) used 1 km x 1 km grids to measure area of occupancy. Although it is no longer acceptable to measure the index of area of occupancy at this scale, measuring area of occupancy at this scale represents an index of abundance appropriate to the taxon. It is appropriate because the species occurs in habitat patches in streams typically less than 10 m wide. COSEWIC (2007) reported area of occupancy to be 441 km². Using the same grid scale on 2007 to 2016data, the area of occupancy is 83 km² and, as an index of abundance, represents a decline of >81%.

Fluctuations and trends

Redside Dace has been historically recorded from 62 Ontario streams (Redside Dace Recovery Team 2010) within 26 watersheds (Table 2). In general, there has been a lack of repeated sampling of the same sites using the same gear type; therefore, there is little information regarding population trends. Few of the original Ontario Department of Planning and Development (ODPD) sites, sampled in the 1950s, are included among sites sampled on a regular basis by several Conservation Authorities. Almost all ODPD sites included in ongoing sampling rotations have yielded no Redside Dace since regular rotations began. Similarly, catch records at other sites in the rotations (i.e., those not sampled by ODPD) are not informative. Redside Dace have never been recorded at most of these sites. The species has been recorded at a few other sites consistently (e.g., sites on the Leslie and Berczy tributaries of Rouge River and Mitchell’s Creek tributary of Duffins Creek) while other sites have yielded records on single occasions.

Population trends across watersheds, based on presence/absence data, are indicated in Table 2. There is strong evidence indicating the species has been extirpated from eight watersheds (Pringle Creek, Petticoat Creek, Highland Creek, Don River, Mimico Creek, Etobicoke Creek, Clarkson Creek, Sharon Creek). Two records from an unidentified creek on Niagara Peninsula are unconfirmed. If Redside Dace did occur there historically, the species has almost certainly been extirpated from that catchment as well. Redside Dace may have been extirpated from three additional watersheds (Morrison Creek, Bronte Creek, Grand River (Irvine Creek, Snow Drain)). Surveys suggest continuing decline in population sizes in several systems including Lynde Creek, Duffins Creek, Rouge River (east branch, Morningside Tributary), Credit River, Sixteen Mile Creek, and possibly Spencer Creek, Kettleby Creek, and Saugeen River (main branch, Meux Creek). At present, the largest populations are believed to occur in Rouge River and Humber River (Poos et al. 2012). Stable populations appear to be present in three small Lake Huron watersheds (Two Tree River, Gully Creek, and South Gully Creek). Populations in Carruther’s Creek, Humber River, and Fourteen Mile Creek may be stable.

Pringle creek

The most recent record is from 1959. The Central Lake Ontario Conservation Authority has sporadically surveyed 13 sites (electrofishing and seining) over the period 2008 – 2016. Redside Dace is likely extirpated from Pringle Creek (Andersen 2002; Kelsey pers. comm. 2017).

Lynde creek

Many sites in Lynde Creek have been sampled since the last COSEWIC assessment (COSEWIC 2007); all live specimens recorded over that period have come from the west branch, in and near Heber Down Conservation Area. Seven specimens were collected in a small area south of Lyndebrook Road in 2009. The presence of Redside Dace in the same area was confirmed in at least two sampling events in 2010 (number of individuals not recorded). In 2012, eDNA was detected at a nearby site. Two specimens were collected in 2009 at a site in the northern portion of Heber Down Conservation Area and Redside Dace were observed (number not recorded) in 2010 at another site just upstream. A site just downstream of Highway 7 yielded a single specimen in 2009 and 3 specimens in 2014. An unknown number was observed at this site in 2010. A single specimen was captured just north of Highway 7 in 2014. The few specimens captured and eDNA detections noted above were the result of considerable effort. OMNRF and Central Lake Ontario Conservation Authority sampled 75 sites throughout the watershed using backpack electrofishing in 2009 and 2014 (Moore 2017).

A major agricultural spill occurred in the west branch of Lynde Creek just upstream of Watson’s Glen Golf Course in July 2014. A mixture of manure and acidic material caused severe reduction of dissolved oxygen and pH along approximately 21 km of stream, including much of the Heber Down Conservation Area (Moore 2017). Much of the affected area was surveyed on foot and dead fishes were noted. Although Redside Dace was not observed among the dead fish, it was determined that the spill eliminated almost all fishes in the affected area. Following the spill, 20 sites were electrofished in 2014, 2016, and 2017 by OMNRF (Reid 2016), but Redside Dace was not found. The extent of the fish kill is indicated by severely reduced species diversity and density downstream of the spill site determined in the 2014 sampling. Prior to the spill, densities at surveyed sites averaged 1.65/m² versus 0.02/m² after the spill (Moore 2017). Finally, a major effort to detect eDNA was completed in 2013 and 2014 by OMNRF (Reid et al. 2017). Water samples from 72 sites resulted in eDNA detections at four sites, three on west branch and one site on the east branch. These recent survey results indicate that Redside Dace is present in very low numbers in both branches of Lynde Creek.

Carruthers creek

No records from the lower reaches of Carruthers Creek are known since 1978 (Natural Heritage Information Centre). All subsequent records are from Highway 407 southward to Deer Creek Golf Course, including 90 individuals captured in 2001 (Ruthven pers. comm. 2001). Since the previous COSEWIC assessment (COSEWIC 2007), specimens were reported from eight sites in this area in 2009 (two specimens), 2011(two specimens), 2013 (two live specimens and eDNA), 2014 (56 specimens), and 2015 (47 specimens). Serrao (2016) collected 50 specimens just north of Deer Creek Golf Course in 2012/2013. In 2016, seven specimens were captured in a 30 m stream corridor upstream of Highway 7 that was re-aligned in 2005 (Villard and Heaton 2016).

Duffins creek

Redside Dace was known to be present in three areas of Duffins Creek at the time of the previous COSEWIC status report (COSEWIC 2007), including the east branch headwater tributary Mitchell Creek, downstream tributaries of East Duffins Creek, and Ganatsekiagon Creek. Specimens have been captured at sites in all of these areas since 2007. In Mitchell Creek, three sites yielded specimens or eDNA detections. Redside Dace were recorded in 2009 (specimens from two sites), 2012 (specimens at one site, eDNA detected at one site), 2014 (specimens at one site), and 2015 (specimens at one site). Two sites farther downstream on the east branch produced records; one specimen in Brougham Creek in 2009 and one eDNA detection in the east branch in 2012. In Ganatsekiagon Creek, Redside Dace was reported from nine sites including two sites in 2009 (eight live specimens), one site in 2010 (two specimens), one site in 2012 (one specimen and eDNA detection), one site in 2013 (eDNA detection), and six sites in 2015 (46 specimens).

Intensive sampling of 2105 m of stream length (including 10 pools) in 2008 resulted in an estimated basin-wide population size of 1207 to 2398individuals (Poos et al. 2012).

Petticoat creek

Redside Dace was likely extirpated from Petticoat Creek prior to the most recent status update (COSEWIC 2007). No specimens have been reported since 1954 despite regular surveys (Lawrie pers. comm. 2017).

Rouge river

Although the Rouge River populations were considered to be among the healthiest in Ontario in 2007, with specimens captured at many sampling sites, significant declines were noted in preceding years, particularly in Morningside Creek (COSEWIC 2007). All recent records are from tributaries of the west branch and were reported by MNRF and University of Toronto personnel. Extensive sampling in Berczy Creek and the Leslie tributary in 2008 yielded 2141 specimens (Poos and Jackson 2012). A quantitative estimate of population size for the Rouge River was 4499-9180 individuals (Poos et al. 2012). A single individual from Morningside Creek was reported in 2009. Another single individual was captured in Bruce Creek in 2012. In Berczy Creek, additional specimens were captured in 2009 (three sites), 2012 (three sites), 2013 (one site), 2014 (two sites), and 2015 (two sites). Additional specimens from Leslie tributary were reported from 2009 (five sites), 2010 (one site), 2012 (two sites), 2014 (one site), and 2015 (one site). The Robinson Creek tributary, which enters the west branch of the Rouge River at Milne Dam Conservation Park is believed to support Redside Dace, although specimens have not been reported since the previous COSEWIC assessment. The lack of recent records from the east branch (Little Rouge) suggests the possibility the species has been extirpated from that part of the watershed.

Highland creek

Redside Dace was considered likely extirpated from Highland Creek by COSEWIC (2007) because no specimens had been reported since 1952. Highland Creek is surveyed regularly as part of the Toronto Region Conservation Authority monitoring program.

Don river

Considerable effort has been expended searching for Redside Dace in the Don River over the last 30 years. The decline of Redside Dace from both east and west branches of the Don River is documented by COSEWIC (2007). The species was widespread into the 1980s and 1990s. There are no recent records for the west branch and the species may now be extirpated there (Lawrie pers. comm. 2017). Only four recent records exist for the east branch; all from a small area in Richmond Hill. In 2011, a single individual was captured in Little Don Park. In 2013, the species was captured on video at two sites, both upstream from the 2011 record. One site was near the Bathurst/Major MacKenzie intersection; the second was approximately one kilometre upstream, just below Mill St. eDNA was also detected in 2013 at one site (Serrao 2016). Intensive sampling in the east branch in 2008 revealed Redside Dace in only two of 27 pools (Poos et al. 2012; Lawrie pers. comm. 2017). However, high densities were observed in those two pools (99.2 individuals/pool). The basin-wide population estimate was 402-1607 individuals (Poos et al. 2012). Substantial seine and video sampling of the two pools in 2016 and 2017 failed to detect any Redside Dace (Lawrie pers. comm. 2017). It is likely that the species is now extirpated in the Don River.

Humber river

The Humber River appears to contain one of the healthier populations of Redside Dace in Canada. It is unusual among Canadian watersheds regarding historical patterns of Redside Dace occurrence. As described in COSEWIC (2007), extensive survey effort during the 1940s across the system revealed the species to be present only in a limited portion of the east branch and a single site in Black Creek. Subsequent sampling revealed the species to be present in the main branch (near Bolton) in 1959. Surveys conducted during the 1970s, 1980s, 1990s, and early 2000s found Redside Dace in the east, west, and central Humber branches. Fieldwork since 2007 has found Redside Dace only in the tributaries of the west Humber and the east Humber upstream of the Kortright Centre for Conservation. In the east Humber, Toronto Region Conservation Authority (TRCA) personnel found a single specimen at the mouth of Marigold Creek in 2009 and MNRF reported another specimen upstream in the same year. Three sites on Purpleville Creek (east Humber) yielded specimens in 2011 and 2014 while two sites near Hwy 11 (between Hwy. 400 and Hwy. 27) yielded a total of 5 specimens in 2010 and 2014.

On the west Humber, MNRF reported Redside Dace in Kilmanagh Creek at one site in 2009, two sites in 2010, one site in 2011, one site in 2013, and two sites in 2015. Redside Dace was also captured in a west Humber tributary below Healy Bridge in 2011 (two specimens) and at a site approximately 2km upstream in 2013 (four specimens).

The largest population estimates determined by Poos et al. (2012) are in the Humber River (21530-38582 individuals).

Mimico creek and Etobicoke creek

Despite some survey effort over the past 30 years, including recent sampling as part of the TRCA monitoring program, Redside Dace has not been reported from these systems since the 1940s. The species is likely extirpated from these systems, although there is a small possibility the species persists in the headwaters of Etobicoke Creek, which flow through unsurveyed privately owned land (Lawrie pers. comm. 2017).

Credit river

Redside Dace persist in localized areas of the Credit River. Over the past decade, the Credit Valley Conservation Authority has established approximately 100 sampling sites throughout the watershed, approximately 50 of which are surveyed annually (Morris pers. comm. 2016). Recent records exist from Fletcher’s Creek (two sites in 2010, two sites in 2011, two sites in 2014), Huttonville Creek (one site in 2008), Silver Creek (two sites in 2014, one site in 2016), Springbrook Creek (one site in 2011), and an unspecified tributary near Eldorado Park. Sites that have yielded Redside Dace historically, but not recently, include Rogers Creek, Levi’s Creek, and Caledon Creek.

Morrison creek

The most recently caught specimens of Redside Dace in Morrison Creek were electrofished in 2000 in a 1.7 km section of stream. COSEWIC (2007) considered the species to be extirpated or nearly extirpated from this system; however, an eDNA detection was made in 2015 at one of nine sites sampled. An extensive search in 2016 by MNRF staff did not locate live specimens (Dunn pers. comm. 2016).

Sixteen Mile creek

Catch records suggest a contraction in Sixteen Mile Creek prior to 2007, particularly in the most upstream reaches, although the species appears to persist throughout much of the system. McKee and Parker (1982) were unable to find the species despite “intensive effort” in 1979 and 1980. Recent MNRF records include two sites on the west branch from 2008, and one nearby site from 2009 (all three sites approximately 700 m upstream of Highway 401 near Kelso Conservation Centre), two sites from 2010 on the middle east branch (upstream of #5 Sideroad east of 5th Line), one site from 2011 on the middle east branch (approximately 2 km upstream of 2010 sites), one site from 2013 on the middle east branch (one of the sites from 2010), and two sites from 2015 (both on middle east branch near #5 Sideroad and 5th Line). Targeted sampling by University of Toronto personnel at five sites in 2016 (west branch downstream of Kelso Conservation Centre) did not capture Redside Dace (Castaneda pers. comm. 2016).

Fourteen Mile creek

Survey work from 1998 to 2003 returned significant numbers of Redside Dace and indicated that the population in Fourteen Mile Creek was reasonably healthy. Recent sampling (2010, 2012, 2013, 2015, and 2016) has continued to locate significant numbers of fish. This sampling has been concentrated around the upper Fourteen Mile Creek Lands and just upstream of Upper Middle Road, but also included sites farther upstream and downstream, on both east and west branches. One site on the east branch near Dundas St. West yielded 148 specimens on 20 September 2012.

Early surveys revealed Redside Dace to be widely distributed in Fourteen Mile Creek. Records from 1985 suggested that the species had disappeared from the lower portion of the system, i.e., downstream from the Queen Elizabeth Way highway (COSEWIC 2007). The capture of specimens in this area and a small tributary entering from the east in 2000 and 2016 (Castaneda pers. comm. 2016) suggests either an expansion from upstream reaches or that the species survived in very low numbers since the 1950s.

Fourteen Mile Creek is a relatively small waterway in which catches of Redside Dace appear to have increased in recent years. Whether this is due to population growth, or simply increased sampling effort, is not known (Dunn 2016).

Bronte creek

Surveys from the 1970s indicated that Redside Dace was common throughout Bronte Creek including downstream portions of the drainage. From 1970 to 1979, Redside Dace was observed at all 20 sites surveyed (COSEWIC 2007). After that time, the species seems to have largely disappeared from the system. Between 1995 and 2004, three specimens were collected in 1998 at three sites, all a short distance south of the intersection of Highway 6 and Concession Road 10E. The species has not been reported since then in Bronte Creek despite intensive sampling since 2008 (60 sites; Dunn pers. comm. 2016).

Spencer creek

A rapid decline in Redside Dace abundance was noted during the 1990s. Sampling during the 1970s indicated that the species was widely distributed in the upper main branch of Spencer Creek and in a tributary, Flamborough Creek. Staton et al.(1993) and Thompson et al. (1995) found specimens only in a 1-2 km portion of habitat (downstream of Safari Road and east of Westover Road) where the species was noted in the 1970s. The most recent record is a single specimen captured in this area in 1998 (Redside Dace Recovery Team; RSD database). Unsuccessful searches at three sites previously occupied by Redside Dace were made in 1998, 2001, and 2004. Water samples collected in 2015 from 11 sites were negative for eDNA (Reid et al. (2017). Current population trends are unknown due to insufficient sampling.

Niagara peninsula

There are no records from the Niagara Peninsula since 1960. As noted previously, if historical records of Redside Dace on Niagara Peninsula are reliable, the species has probably been extirpated from this area.

Grand river

The decline in the Grand River described in COSEWIC (2007) appears to have continued. Sampling in 1997 to 2005 revealed apparent disappearance from several historically occupied sites on Irvine Creek and Snow Drain and strong declines at other sites more recently found to support Redside Dace. The last specimen was collected at Irvine Creek by DFO personnel in 2003. There has been no sampling from 2005 through 2015 (Barnucz pers. comm. 2016). In 2016, University of Toronto personnel surveyed 8 headwater sites on Irvine Creek and Snow Drain specifically for Redside Dace, but found none (Castaneda pers. comm. 2016). All of these sites had either yielded Redside Dace in previous sampling events, or are situated very near to sites that historically supported the species. The species may be extirpated from the Grand River; however, additional sampling is needed for confirmation.

Saugeen river

Little sampling effort has been expended in the Saugeen watershed since the previous COSEWIC status update (Scheifley pers. comm. 2016). In 1953/1954, five sites along a 13 km stretch of Meux Creek (approximately between Neustadt and Alsfeldt) yielded Redside Dace. In 2001, Redside Dace were found at two additional sites in the headwaters of Meux Creek. Sampling in 2004 found only a single specimen in the original five sites (COSEWIC 2007). In 2016, Redside Dace was not found at five sites spanning the combined length of stream sampled in 1953/1954 and 2001 (Castaneda pers. comm. 2016), suggesting that Meux Creek may no longer support Redside Dace.

In the South Saugeen River, one site yielded Redside Dace in 1953. There are no more recent records and no reported search effort since the previous COSEWIC status assessment.

The only part of the Saugeen system to have recent records of Redside Dace is the headwater area near Flesherton. In 1953/1954, 20 sites along a 40 km segment of river yielded Redside Dace. Subsequent sampling of subsets of these sites occurred in 1985 (10 sites), 2000 (nine sites), 2001 (two sites), 2004 (10 sites; COSEWIC 2007), 2005 (six sites), 2013 (one site; Serrao 2016) and 2016 (five sites; Castaneda pers. comm. 2016). Redside Dace were found in 2000 (three sites), 2005 (six sites), 2013 (1site) and 2016 (three sites; targeted sampling). All sites yielding Redside Dace are just downstream of the Osprey Wetland Conservation Lands. The species appears to have been eliminated from most of its historical distribution in the Saugeen River.

Gully creeks

Gully Creek, a small stream entering Lake Huron approximately 15 km south of Goderich, was found to contain Redside Dace in 1980 when eight individuals were captured at two sites. The species was subsequently reported in 1999 from one site (one individual), 2001 from one site (six individuals), 2003 from one site (four individuals). One site yielded 282 individuals from five seine hauls in 2007. Fish may have been concentrated at this site due to low water levels during the summer of 2007 (Drake pers. comm. 2017). In 2009, four sites yielded Redside Dace (at least 24 individuals) and, in 2010, an unknown number of individuals was observed at one site. A single site yielded 36 specimens in 2013 (Serrao 2016) and four sites yielded 17 individuals in 2016 (targeted sampling; Castaneda pers. comm. 2016). A quantitative population size estimate of 462-741 individuals was reported by Poos et al. (2012). Unlike the distribution of fish in the Don River, which were found to be concentrated in just two pools, the Gully Creek population was found to be scattered at low density throughout the system, except for the large catch from one site in 2007.

A second small stream, South Gully Creek, located approximately 20 km south of Gully Creek, contains a population of Redside Dace. Sampling in 2008 and 2011 was conducted by MNRF and Ausable Bayfield Conservation Authority. A single fish was captured in June 2008 at one site; the same site yielded four fish in August of 2008. Forty-two individuals were captured at four sites in 2011. In 2016, 60 individuals were sampled at one site (targeted sampling; Castaneda pers. comm. 2016).

Holland river system

Redside Dace was first detected in Kettleby Creek, a tributary of the Holland River, in 1976 when an unspecified number of fish were observed at one site. In 1980, two sites were sampled, resulting in two individuals recorded at one site and an unspecified number at the other site. Redside Dace was recorded on subsequent sampling attempts at single sites in 1987 (two individuals), 1988 (five individuals), 2003 (one individual), 2005 (one individual), and 2006 (10 individuals). Serrao (2016) collected 35 specimens in 2012 to 2013 as part of a study of genetic variation in Redside Dace. eDNA was not detected in any of 11 sampling stations in Kettleby Creek in 2014 (Reid et al. 2017). Although regular sampling in Kettleby Creek is conducted by Lake Simcoe Conservation Authority, Redside Dace is not specifically targeted (Wilson pers. comm. 2017).

One individual was caught in 1991 in a different tributary of Holland River at the intersection of Hwy 400 and Hwy 9. Subsequent sampling at this site has not been reported. The species was also found in Sharon Creek (one site, four individuals) in 1994. Since that date, repeated recent sampling has not yielded Redside Dace in Sharon Creek (Wilson pers. comm. 2017). Water samples from nine stations in 2014/2015 did not reveal eDNA for Redside Dace (Reid et al. 2017).

Redside Dace appears to persist in the Holland River drainage but likely at low abundance. Population trends are unclear from catch records.

Two tree river

Two Tree River is a small waterway on St. Joseph Island near Sault Ste. Marie, Ontario. Redside Dace was first reported in 1997 at the culvert of A Line Road (one specimen). Four specimens were reported from the same site in 2002. Between 2009 and 2011, specimens were reported from 20 sites, with numbers of fish per site ranging from one to 63. Serrao (2016) collected 40 specimens in 2013 and a single individual was captured in a small tributary of Two Tree River in 2015. Redside Dace appear to be widely distributed throughout the system.

Rescue effect

There is virtually no prospect for rescue effect. Redside Dace is a poor disperser based on dispersal models constructed from tagging data from Rouge River (Poos and Jackson 2012; Drake pers. comm. 2017) and the very low levels of gene flow among watersheds (Serrao 2016; Serrao et al. 2017). The species is a habitat specialist now generally limited to headwater areas. Rescue from American populations would require dispersal through vast areas of inhospitable habitat including the lower reaches of American and Canadian tributaries to the Great Lakes, many of which have barriers, and the Great Lakes proper and/or major connecting waterbodies such as the Detroit River.

Threats and limiting factors

To identify the nature and magnitude of threats to the Redside Dace, a threats calculator was completed based on the IUCN-CMP (World Conservation Union-Conservation Measures Partnership) unified threats classification system (IUCN and CMP 2006; Salafsky et al. 2008). Based on the threats calculator, the overall threat impact is very high, which indicates a potential population decline of 50-1-00% over the next 10 years (Appendix 2).

Physical habitat alteration

Natural system alterations is ranked very high threat impact and is the greatest threat to Redside Dace (Appendix 2). Some of these threats, which operate in both urban and rural settings, result in altered water flow regimes. Many streams are highly modified. Frequently, channels have been widened, resulting in reduction of preferred pool habitat. Prior to enactment of the Ontario Endangered Species Act in 2007, the biological needs of Redside Dace, or any other fish species, were not generally considered when stream beds were moved or otherwise altered. A common feature in urban settings is general surface hardening of watersheds caused by road paving and construction of housing and other buildings (Redside Dace Recovery Team 2010). This increases surface imperviousness and, when combined with destruction of headwater features that affect groundwater discharge, can alter base flow and/or dramatically change stream discharge during extreme weather events, especially if combined with poor storm-water management. Poos et al. (2012) conducted extensive sampling in five Toronto area watersheds to develop quantitative estimates of Redside Dace population sizes. They reported a highly significant negative relationship between population size and impervious land-use at pool and sub-catchment scales.

Water flow regimes have also been affected by stream bed alterations associated with reservoir development and establishment of barriers to fish movement. For example, reservoirs installed in the headwaters of Mountsberg Creek (Bronte Creek tributary) and Spencer Creek have altered flow regimes and increased water temperatures (Featherstone 2000). The tributary of the Two Tree River noted above has largely been diverted into a drain that flows beside L Line Road in St. Joseph Island. Stream flow is also disrupted by extraction of surface/subsurface water, although the magnitude of this threat cannot be quantified. Many watersheds occupied by Redside Dace flow through agricultural areas and near golf courses. Water extraction for irrigation reduces flow volumes, potentially to levels insufficient to support Redside Dace and other species. Agricultural drain maintenance also affects fish populations. Snow Drain is a tributary of Irvine Creek (Grand River watershed) that has historically contained Redside Dace. The apparent disappearance of Redside Dace from Irvine Creek in recent years may be associated with clean-out of the drain (Staton pers. comm. 2017).

Redside Dace is also affected by habitat alterations that are not directly connected to stream flow. Removal of riparian vegetation, particularly grasses, forbs, and shrubs, has a negative impact on terrestrial insects which constitute a large fraction of the species’ diet. The practice also reduces cover and, along with some physical stream bed alterations such as channelization, results in elevated water temperatures due to reduced shading. The widespread use of broad-spectrum insecticides may also reduce insect forage available to Redside Dace.

Invasive species

Invasive species is ranked as a very high-medium threat impact (Appendix 2). Introduced predatory species also threaten Redside Dace, although study is required to better characterize the nature of this threat. Northern Pike (Esox lucius), Largemouth Bass (Micropterus salmoides), and Black Crappie (Pomoxis nigromaculatus) are now present in Bronte Creek (COSEWIC 2007; Redside Dace Recovery Team 2010), a system in which Redside Dace has not been observed for more than a decade. The marked reduction in Redside Dace abundance in Spencer Creek may also be associated with predatory species. Salmonids are another potential problem. Redside Dace has disappeared from several streams in Wisconsin, including Deer Creek and Fries Feeder Creek, wherein the distribution of piscivorous Brown Trout (Salmo trutta) has expanded (Lyons et al. 2000). Brown Trout and Rainbow Trout (Oncorhynchus mykiss) are present in some Toronto-area streams and are stocked in the Credit River (Silver Creek; Morris pers. comm. 2016). Brown Trout, in particular, may be a serious threat. Examination of the stomach contents of one individual revealed that it had consumed a large number of Redside Dace (Drake pers. comm. 2017). The impact of Rainbow Trout is more uncertain; an experimental study on Rosyside Dace, the congener of Redside Dace, revealed little interaction with Rainbow Trout when the species were held together in an artificial stream (Rincon and Grossman 1998). 

Pollution

Pollution is ranked a high threat impact (Appendix 2). Inputs of toxic materials from numerous sources also threaten Redside Dace. Agricultural activities, particularly cultivation, can accelerate sedimentation and raise turbidity in otherwise clear-water streams. Chronic nutrient inputs, especially nitrogen and phosphorus, are often associated with use of tile beds to rapidly drain farm fields. Redside Dace are also affected by acute episodes of nutrient pollution. For example, a manure spill in Lynde Creek in 2014 resulted in a large fish-kill (Moore pers. comm. 2017). Other sources of pollution include leachate from landfill sites, storm-water inputs, and chloride from roadway salting.

Low level/potential threats

The harvest and sale of bait fishes is a significant component of the Ontario recreational fishery; some 100 million fish are collected annually (OMNR and BAO 2006), mostly from lower reaches of Great Lakes tributaries and nearshore areas of lakes (Drake, pers. comm. 2017). In addition, bait fishes collected by anglers for their own use is a potential source of mortality (Drake pers. comm. 2017). Although Redside Dace is not targeted and collection is illegal, there is some risk of capture through bycatch because the species is susceptible to capture by seining (Reid et al. 2008; Drake and Mandrak 2014a). Bait fishers have been observed capturing Redside Dace while seining for other species in Spencer Creek and, in some instances, may be responsible for transfer of fishes (and potentially other organisms) among watersheds (Staton pers. comm. 2017). A study of species composition in live bait fish sales did not report Redside Dace (Drake and Mandrak 2014b), suggesting that the probability of incidental catch in the bait fishery is low, but greater than zero. Drake and Mandrak (2014a) estimated the probability of incidental capture of Redside Dace based on a generic harvest model. Results suggest an average of 358 harvest events would lead to a 95% chance of capturing Redside Dace during harvest operations, but this value could be lower (156) or higher (failure to capture entirely) based on uncertainty in harvest site selection and detection. Licence stipulations for bait harvesting in waters containing Redside Dace typically prohibit collection of bait animals during 1 May and 30 June as a means of protecting spawning fish (Gibson pers. comm. 2017). Currently, the bait fishery is not viewed as a serious threat to Redside Dace.

Scientific monitoring may have some negative impact. Although lethal sampling in Ontario is generally no longer permitted, there may be delayed or unobserved negative effects resulting from capture for population monitoring (e.g., Bohl et al. 2009). These potential effects have not been examined specifically in Redside Dace.

Climate change and severe weather

Climate change looms as a significant future threat. Although the timeframe of full impact is not immediate (i.e., it is longer than 10 years or three generations), some effects of climate change are currently evident. The impact on specific Redside Dace populations cannot be predicted with confidence. Two important determinants of stream water temperature, air temperature and groundwater discharge (Power et al. 1999; Poole and Berman 2001), are both expected to be affected by climate change. As average air temperature increases in coming years, stream water temperatures will likely increase. Redside Dace, a cool-water species, will likely be negatively affected by higher average temperatures. In addition to contributing to warmer stream temperatures, reduced groundwater discharge is expected to contribute to higher variation in stream flows resulting from more frequent extreme weather events (Redside Dace Recovery Team 2010). The degree of stream warming as a result of climate change is expected to vary in southern Ontario watersheds due to variation in groundwater discharge. Chu et al. (2008) reported that watersheds in the Nottawasaga region and eastern Lake Ontario basin will probably experience relatively small impacts from climate change due to high rates of groundwater discharge. Watersheds containing Redside Dace are situated outside these areas, hence are expected to be impacted more significantly. Although Chu et al. (2008) were unable to predict the impact of climate change on cool-water fish distributions in southern Ontario, their models suggested that most watersheds currently containing Redside Dace have a mid-to-high probability of retaining cold-water fishes. Impacts on cool-water species inhabiting these systems will presumably be lower.

Limiting factors

Several factors limit the potential for recovery of Redside Dace. Low dispersal ability has been shown by direct observation (Poos and Jackson 2012) and indirectly by modelling (Drake pers. comm. 2017) and by the observation of genetic uniqueness of each population (Serrao 2016). The retraction of the species to headwater areas also limits inter-watershed dispersal. The preference for clear, cool water limits the species’ ability to expand out of headwater streams. Redside Dace are also known to spawn in the nests of other cyprinid species, specifically Creek Chub and Common Shiner (Koster 1939). The degree to which this behaviour is obligatory is not known; therefore, the degree of dependence on these species remains to be determined. Furthermore, the observation of Redside Dace movement into reaches of Rouge River with high catch per unit effort of other cyprinids and White Sucker suggests the possibility of some uncharacterized ecological association among these species that could be undermined if their populations are reduced. Finally, an additional limiting factor affecting Redside Dace is suggested by modelling data indicating that population abundance is quite sensitive to juvenile mortality (Velez-Espino and Koops 2008).

Number of locations

Accurately quantifying the number of locations is difficult owing to uncertainty about the number of watersheds, and tributaries within watersheds, that still support Redside Dace. Redside Dace is known to have been present in 26 watersheds in Ontario (Table 2). The historical distribution in those watersheds was likely continuous, and the subsequent threats largely watershed-wide, which would suggest a maximum of 26 locations. Of these 26 locations, Redside Dace is thought to still occur in 15. However, fragmentation of those watersheds by threats gives the appearance of more locations. Conversely, the system alteration threat related to urbanization is the single most plausible threat for those populations in the 18 watersheds in the Golden Horseshoe (including 10 watersheds in the Greater Toronto Area) – this would suggest a maximum of nine locations, of which three have been lost, leaving six extant locations. Therefore, depending on how they are defined, there are six to 15 extant locations.

Protection, status and ranks

Non-legal status and ranks

Redside Dace was assessed as Endangered by COSEWIC in 2007, and was listed under the federal Species at Risk Act in May 2017. It is also classified as Endangered under the Ontario Endangered Species Act. Conservation status ranks are provided in Table 3 (NatureServe 2015).

Note: Current Occurrence: Limited (<50 km); Wide (>50 km). Size: Small (<100 individuals); Medium (100-1000); Large (>1000); Trajectory: Stable; Declining; Increasing; Unknown; Status: Extirpated; Critical; Cautious; Healthy. Numbers represent certainty ranks: 1=best guess; 2=CPUE or standardized sampling; 3=quantitative analysis. n/a – not applicable. na – not assessed

Habitat protection and ownership

Redside Dace habitat receives protection under the harm provisions of the Species at Risk Act and will receive additional protection once critical habitat is identified. Redside Dace habitat receives some protection by provisions of the federal Fisheries Act. Ontario statutes also protect habitat, including the Endangered Species Act and the Planning Act. A habitat regulation under the Endangered Species Act provides protection to identified occupied and recovery habitat (previously occupied habitat) as well as supporting habitat such as riparian zone, meander belt, wetlands, and groundwater supply. The Planning Act is implemented by local Conservation Authorities which control flood plain development.

The Crown owns the beds of navigable rivers. Most land, urban and rural, adjacent to waterways is privately owned. These lands are usually surrendered to the municipality in housing developments (Redside Dace Recovery Strategy 2010).

The Rouge National Urban Park, established in 2015, encompasses much of the east branch of the Rouge River. Policy directions for this new class of park regarding future development are presently unclear. The Park’s impact on the species remains to be determined.

Acknowledgements and authorities contacted

Many individuals provided information (often answering repeated inquiries) and/or facilitated preparation of this report in various ways. Data, published and unpublished, were provided by Emily Funnell and Scott Reid (Ontario Ministry of Natural Resources and Forestry), Rowshyra Castaneda and Nicholas Mandrak (University of Toronto), Andrea Dunn (Halton Conservation), David Lawrie (Toronto and Region Conservation Authority), Dan Moore (Central Lake Ontario Conservation Authority), Paul Villard (GEO Morphix Ltd.), and Lynn Bouvier (Fisheries and Oceans Canada). The following were especially helpful for discussions pertaining to various aspects of the report: Cynthia Lee (Toronto Zoo); Andrew Drake, Shawn Staton, and Jason Barnucz (Fisheries and Oceans Canada); Jodie Scheifley, Art Timmerman and Scott Gibson (Ontario Ministry of Natural Resources and Forestry); Bob Morris and Jennifer Dougherty (Credit Valley Conservation Authority); Ian Kelsey (Central Lake Ontario Conservation Authority), and Rob Wilson (Lake Simcoe Region Conservation Authority). Erling Holm (Royal Ontario Museum), co-author of the 2007 COSEWIC status update, cheerfully answered numerous requests for information. Brian Zimmerman (Ohio State University) provided the image shown in Figure 1 and on the cover. Staff of the COSEWIC Secretariat, including Angèle Cyr, Jenny Wu, Julie Beaulieu, and Alan Filion provided mapping and other services, and, as usual, were a pleasure to work with. Numerous reviewers provided valuable comments of draft versions of the report.

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Biographical summary of report writers

Tim Birt is an adjunct professor at Queen’s University. His research activities have focused mainly on population genetics and evolution of seabirds and fishes. He has authored or co-authored five COSEWIC status reports.

Collections examined

None

Appendix 1. Results of early and recent sampling in Canadian watersheds (Tables 1 - 26)

The information presented in the following 26 tables is summarized from data in the Redside Dace database (Holm and Andersen 2005) (cited in COSEWIC 2007) annotated with more recent records form various sources. It consists of a table for each watershed in Canada where there is information on success of capture of Redside Dace at both historical and more recent sampling sites. Where known, the following information is summarized: gear (S-seine, E=electrofisher), number of sampling attempts, electrofisher seconds (Total e-secs), length of stream sampled (Total Run Length), and number of seine hauls (Total # hauls). In many cases, there is no information on the number of Redside Dace captured in a sampling event. In these cases, the number of individuals given is preceded by ≥. For example, if 29 sites were sampled, but there is no information on the number captured at any of the sites, the number of individuals is given as ≥ 29. In many cases, an historical site was visited more than once at different times, often by different individuals. Thus, if the number of sites sampled is 13 and the number of sampling events is 22, some of the sites were visited more than once.

^*Gear S = seine, E = electrofisher, n/a = not available
⁺SAPO = Stream Assessment Protocol of Ontario

Redside Dace was not found at any additional sites in Pringle Creek since the 1959 survey.

^*Gear S = seine, E = electrofisher
⁺SAPO = Stream Assessment Protocol of Ontario

^*eDNA positive detections
^**electrofishing

Sources for Table 1a and 2a
1959 Ontario Department of Planning and Development surveys
1985 ROM Accession 4910
2000 Andersen 2002

^*also positive eDNA detection at one site (Serrao 2016)

^*Gear, S = seine, E = electrofisher, n/a = not available

Sources for Table 4a
1954 Ontario Department of Planning and Development surveys
1978 ROM Accession 3752 (Ministry of Natural Resources stream surveys)
1979 CMN79-1077, 79-1079 (Parker and McKee 1980)
1985 ROM Accession 4910 (Holm and Crossman 1986), ROM Accession 5267 (R. Steedman)
1999 ROM Accession 6771 (Ecotec)
2003 Forder 2003, Toronto Region Conservation Authority database (2003)

^* live specimens collected at three sites; eDNA detected at 3 sites

Sources for Table 5
1928 UMMZ 85643
1952 ROM 15637
1976 ROM Accession 3074 (Ministry of Natural Resources)
1981 ROM Accession 4415 (Metro Toronto Region Conservation Authority)
1984 to 1985ROM Accession 5267 (R. Steedman)

There are no additional sites where Redside Dace were found since the 1952 survey.

Sources for Table 6a
1954 Ontario Department of Planning and Development surveys
1982 ROM Accession 4556
1984 to 1985 ROM Accession 5267 (R. Steedman), ROM Accession 4830, ROM Accession 4749
1987 Ministry of Natural Resources, Aurora, files (Rouge.171)
1992 ROM Accession 6386 (G. Wichert)
1994 Ministry of Natural Resources, Aurora files (Rouge. 80)
1999 ROM Accession 6750 (Sir Sanford Fleming Student)
2000 ROM Accession 6797, 6807 (Holm et al.), Toronto Region Conservation Authority database (2003)
2001 J. Andersen (pers. comm.). W. King (pers. comm.)
2002 Andersen et al. 2002 (Aurora MNR files), M. Cece and R. Roth (Marshall Macklin Monaghan), OMNR Aurora files
2003 Toronto Region Conservation Authority database (2003), W. King (pers. comm.)
2005 Comments from a reviewer (Andersen?) of the Redside Dace status update 2006

^*specimens not counted at one site

^*Gear, S = seine, E = electrofisher, n/a = not available

Sources for Table 7a
1949 Ontario Department of Planning and Development surveys
1970s ROM Accession 2094, Martin (1986)
1995 to 2003TRCA database (2003); Ministry of Natural Resources, Aurora, files (Dillon Consulting); ROM Accessions 6542, 6768, 6783, 6876, 7268,
1981 to 1985Martin 1986, ROM Accessions 4497 (Martin/Whillans) and 5267 (R. Steedman)
1991 to 1992ROM Accession 6386 (G. Wichert), 6768

^* eDNA detected at one site; video detection at other site

^*Gear, S = seine, E = electrofisher, n/a = not available

Sources for Table 8a
1949 Ontario Department of Planning and Development surveys
1970s ROM Accession 2094, Martin (1986)
1995 to 2003TRCA database (2003); Ministry of Natural Resources, Aurora, files (Dillon Consulting); ROM Accessions 6542, 6768, 6783, 6876, 7268,
1981 to 1985 Martin 1986, ROM Accessions 4497 (Martin/Whillans) and 5267 (R. Steedman)
1991 to 1992 ROM Accession 6386 (G. Wichert), 6768

Sources for Table 9a
1946 Ontario Department of Planning and Development surveys
1972 Toronto Region Conservation Authority database
1979 CMN79-1015, 79-1016, 79-1020, 79-1021
1981 ROM Accession 4415
1984 to 1985ROM Accession 5267 (R. Steedman)
1987 Toronto Region Conservation Authority database
1992 ROM Accession 6386 (G. Wichert)
1996 ROM Accession 6767 (OMNR), ROM Accession 6709 (TRCA)

^* eDNA detections

Table 11. Results of sampling in Mimico Creek at sites where Redside Dace were captured prior to 1950

Results time period	Results number of sites sampled	Results number of sites with Redside Dace	Results percentage of sites with Redside Dace	Results number of specimens	No. of Sampling Events 8	Effort number of sampling events	Effort total E-secs	Total run length	Effort total number hauls
1935 to 1949	4	4	100	≥4	S	4	n/a	n/a	n/a
1984 to 1985	4	0	0	0	S/E	7	≥2556	≥21	n/a
1992 to 2002	3	0	0	0	S/E	3	7986	≥1	n/a

*S=seine, E=backpack electrofisher

Sources for Table 11
1935 ROM 11712 (1 site)
1949 Ontario Department of Planning and Development surveys (3 sites)
1984 to 1985ROM Accessions 49?? (4 sites), 5267 (R. Steedman 3 sites)
1992 to 2002Toronto Region Conservation Authority database (2 sites), ROM Accession 6386 (G. Wichert, 1 site)

There are no additional sites in Mimico Creek where Redside Dace were found since the 1949 survey.

Sources for Table 12a
1928 to 1935ROM and UMMZ records
1984 to 1985ROM Accession 4923
1995 to 2004ROM Accession 6645 and TRCA Watershed Monitoring database, 2003 and 2005

There are no additional sites in Mimico Creek where Redside Dace were found since the 1949 survey.

^* Gear S = seine; E = electrofisher

Sources for Table 13a
1954 Ontario Department of Planning and Development surveys
1965 Reed 1968 in Martin 1984
1982 to 1985Martin 1984, ROM Accession 5267 (Steedman surveys), M Ruthven (pers. comm. 2001)
1992 to 1999Credit Valley Conservation records; ROM Accessions 6386 (G. Wichert), 6567, 6765, and 6769
2000 to 2003Credit Valley Conservation; Ministry of Natural Resources, Aurora files; Forder 2003

^* visual observations; numbers of individuals not reported

Sources for Table 14a
1957 Ontario Department of Planning and Development surveys
1985 ROM Accession 4964 (Holm and Crossman 1986)
1991 A.Timmerman
1993, 1995 Ministry of Natural Resources, Aurora, files
2000 ROM Accession 6822 (Holm et al.)
2001 Conservation Halton
2002 Ministry of Natural Resources, Aurora, files
2003 Ministry of Natural Resources, Aurora, files (M. Heaton)

^*eDNA detection

^*Gear, E = electrofisher, S = seine, n/a = not available

Sources for Table 15a
1957 Ontario Department of Planning and Development surveys
1972 to 1979Halton Conservation, Ministry of Natural Resources, Parker & McKee 1980
1994 to 2003Halton Conservation; Ministry of Natural Resources, Aurora; ROM Accessions 6621, 6960; Forder 2003
2010 to 2015Redside Dace Recovery Team (RSD database); Halton Conservation (Dunn 2016)

Table 16a. Results of sampling in Fourteen Mile Creek at 1957 Ontario department of planning and development sites.

Results time period	Results number of sites sampled	Results number of sites with Redside Dace	Results percentage of sites with Redside Dace	Results number of specimens	Effort gear*	Effort number of sampling events	Effort total E-secs	Total run length	Total number seine hauls
1957	3	3	100	≥ 3	S ?	n/a	n/a	n/a	n/a
1985	3	1	33	8	S/E	3	351	4	>50
1990	1	1	100	≥6	?	2	n/a	n/a	n/a
1998 to 2003	1	1	100	65	S/E	4	?	≥1	≥150
2010	1	1	100	2	n/a	n/a	n/a	n/a	n/a
2012	1	1	100	Unspecified**	n/a	n/a	n/a	n/a	n/a

^*Gear, E = electrofisher, S = seine, n/a = not available

Sources for Table 16a
1957 Ontario Department of Planning and Development surveys
1985 ROM Accession 4964 (Holm and Crossman 1986.)
1990 ROM 60209
1998 ROM 71696
2000 ROM Accession 6825
2001 ROM Accession 6956
2003 Ministry of Natural Resources (M. Heaton)
2010 Redside Dace Recovery Team (RSD database); Halton Conservation (Dunn 2016)
2012 Redside Dace Recovery Team (RSD database); Halton Conservation (Dunn 2016)

^* 2 specimens from one site; visual observation only from the other site, number of individuals not reported

Sources for Table 17a
1972, 1978 McIlwrick 1996, Halton Conservation watershed reports, B. Edmondson and A. Sorenson
1974 Ministry of Natural Resources Stream surveys
1979 Canadian Museum of Nature records, Paton and Sharp 1979
1995 ROM Accession 6770 (A Timmerman, Ministry of Natural Resources); Conservation Halton
1998 ROM Accession 6771 (Ecotec ); Conservation Halton
2000 ROM Accession 6797 (ROM and Halton Conservation); Conservation Halton

^*Gear, E = electrofisher, S = seine

Sources for Table 18a
1970 Ministry of Natural Resources stream surveys, ROM records
1972 ROM 28384, 28387, 28388
1973 Ministry of Natural Resources stream surveys, ROM Accession 2448
1979 CMN 79-1085, 79-1087
1984 Holm 1986 (Fig 6, Table 17)
1993 Staton et al. 1993
1998 ROM Accession 6597, 6622
2004 Hamilton Region Conservation Authority (S. Wiseman, email and attachment 25 April 2005)

Sources for Table 19
1976 Ministry of Natural Resources Stream survey
1980 ROM 41411, ROM Accessions 4413, 4402
1987 to 1988ROM Accession 6988
1991 Gamsby & Mannerow Limited, 1995
2000 ROM Accession 6797 (Holm et al.)
2002 to 2003 ROM Accession 7280 (J. Andersen)
2005 Redside Dace Recovery Team (RSD database); ROM Accession7377
2006 Redside Dace Recovery Team (RSD database); Anderson 2006 (unpublished)
2012 to 2013 Serrao 2016
2014 eDNA survey; Reid et al. 2017

There are no additional sites where redside dace were found since 1976 to 1980 surveys

Sources for Table 20
1994 Ministry of Natural Resources, Aurora, files (Holland River 155)
2003 ROM Accession 7280 (J. Andersen)
2014 to 2015 Reid et al. 2017

There are no additional sites where redside dace were found since 1994 survey.

^*Gear: E=electrofisher, S=seine n/a = not available

Sources for Table 21a
1974 ROM Accession 2701 (Grand River Conservation Authority surveys)
1979 CMN79-1064
1997 ROM Accession 6534 (Holm & Boehm 1998)
1998 ROM Accession 6601 (Holm et al.)
2000 ROM Accession 6797 (Holm et al.)
2001 ROM Accession 6924 (Holm et al.)
2003 N. Mandrak, pers. comm.
2016 R. Castaneda 2016

Sources for Table 22a
1951 Ontario Department of Planning and Development surveys
1985 Holm and Crossman 1986
2000 ROM records
2001 Gibson 2001
2004 Forder 2005
2016 Castaneda 2016

^*Gear: S= seine, E=backpack electrofisher
⁺OSAP = Ontario Stream Assessment Protocol
n/a = not available

Sources for Table 23a
1953 Ontario Department of Planning and Development surveys
1985 ROM Accession 4901
1990 C. Portt & Associates (ROM Accession 6873)
1992 to 1993ROM Accession 7131 (BAR Environmental and Ministry of Natural Resources)
2001 S. Gibson, MSc thesis, University of Toronto
2004 ROM Accession 7236 (Forder 2005)
2016 Castaneda 2016

Sources for Table 24a
1980 Ministry of Natural Resources stream surveys
1999 ROM Accession 6750 (Sir Sanford Fleming Student)
2001 S. Gibson
2009 Redside Dace Recovery Team (RSD database)
2016 Castaneda 2016

Appendix 2. IUCN threats calculation for Redside Dace

Species or ecosystem scientific name

Redside Dace - Clinostomus elongatus

Element ID

n/a

Elcode

n/a

Date:

04/12/2016

Assessor(s)

Dwayne Lepitzki (moderator and Mollusc SSC co-chair), Nick Mandrak (FWF SSC co-chair), Tim Birt (author), Tim Haxton, Mark Poesch and Jim Grant (SSC members), Rebecca Dolson (OMNR), Andrew Drake, Bill Glass, Shawn Staton and Lynn Bouvier (DFO), Angele Cyr (COSEWIC Secretariat).

References

draft calculator from writer, draft report

Assigned overall threat impact:

A = Very high

Impact adjustment reasons:

n/a

Overall threat comments

Residential/commercial development impact was rated "high" because these threats affect at least 10 of 17 catchments supporting RSD, i.e. those catchments in the most urbanized settings. Generation time 2-3 years, therefore, score severity and timing for 10 years; 30 "subpopulations" / "locations" (creeks and rivers), but most in Rouge (< 20%) and Humber (~80%) rivers (have pop estimates). RPA in development by DFO that should be reviewed before COSEWIC reassessment (December 2017 update - RPA not completed before assessment). There may be a DU split (December 2017 update - assessed as one DU). Population decline outcome = 50 -100% over the next 10 years. Currently Endangered under B criteria. 50% decline over the next 10 years is not unrealistic.