Warning This Web page has been archived on the Web.

Archived Content

Information identified as archived on the Web is for reference, research or recordkeeping purposes. It has not been altered or updated after the date of archiving. Web pages that are archived on the Web are not subject to the Government of Canada Web Standards, as per the Policy on Communications and Federal Identity.

Skip booklet index and go to page content

Consultation Workbook on the River Redhorse and Deepwater Sculpin

PART 2:  Information about the species

Part 2:  Information About The Species

River Redhorse

Status: Special Concern

Last examined by COSEWIC:April 2006

Biology

It is a large sucker with a broad, flat head, a long snout and a mouth that faces down.  Generally, mature individuals are greater than 500 mm in length. The maximum age of River Redhorse reported in Canada is 28 years.

The River Redhorse is a late maturing and long-lived sucker that requires large interconnected river habitat to complete its life-cycle. Spawning occurs during late spring in areas with fast flowing water and gravel or cobble riverbed.

River redhorse feed primarily on mussels, insect larvae and crayfishes.

Where is this fish found?

In Canada, the River Redhorse has been captured in both river and lake environments. However, its survival depends on access to suitable riverine spawning habitat: moderate to swift current, riffle-run habitat and clean coarse riverbed. Outside of the spawning period, the River Redhorse are found in deeper run/pool habitats. In the Richelieu River, young-of-the-year are found along vegetated shores where average depth is 1.5 m (maximum ≤ 3.0 m), the bank slope is shallow (≤ 20º) with fine silt, clay and sand sediment.

In Ontario, it is found in the Mississippi, Ottawa, Grand, Thames and Trent rivers and the Bay of Quinte. In Quebec, river redhorse were reported from the Châteauguay, Richelieu, Yamaska, and Saint-François basins and in the Ottawa and St. Lawrence rivers. Additionally spawning-ready River Redhorse have recently been collected from the Gatineau River.

How many fish are there?

Population sizes are not available. However, large numbers of spawning adults (50+) have been identified in the Grand and Trent rivers in Ontario and in the Richelieu and Gatineau rivers in Quebec.

Threats to the population

The River Redhorse have restricted habitat preferences. They inhabit medium to large-sized rivers and are intolerant of high turbidity levels, siltation, and pollution. Rivers supporting River Redhorse are generally fragmented by hydroelectric, navigational and flood control dams. Dams can adversely affect populations by altering upstream and downstream habitat conditions, restricting the movements of individual fish, and limiting genetic variability between populations by preventing fish movement at spawning time. River Redhorse are also vulnerable to changes in the flow regime and siltation of their spawning habitats.

COSEWIC Reason for Designation:

This freshwater fish species occurs in Ontario and Quebec, and although it has been collected at new locations in both provinces, sometimes in large numbers, this is thought to reflect the use of more effective sampling techniques such as boat electrofishing. It has likely disappeared historically from the Ausable, Châteauguay and Yamaska rivers, since the use of boat electrofishing has failed to collect it recently. Threats to the species include habitat degradation (pollution, siltation), stream regulation that affects water flow (dams) and habitat fragmentation (dams). The Canadian range is highly fragmented and rescue effect is improbable because of the precarious conservation status in adjoining U.S. States.

What will happen if this fish is added to the SARA List?

A management plan must be prepared within three years of the River Redhorse being added to the SARA List.

The River Redhorse is included in the proposed Grand River recovery strategy which includes the following actions that are already underway or completed:

  • Investigations on the distribution of River Redhorse were conducted between 2002 and 2004 as part of the graduate research program from Trent University. Results included new locations for the species in the Grand River.
  • Develop a genetic diagnostic tool to verify the field identification of six similar redhorse species including the River Redhorse.
  • Additional investigations into different uses of resources by Grand River redhorses in 2002-04 were conducted as part of the graduate research program at the University of Guelph.
  • Fisheries and Oceans Canada and the Baitfish Association of Ontario have developed a baitfish brochure that will assist baitfish harvesters to identify species at risk such as River Redhorse in order to reduce the accidental catches of these species.
  • In 2003, the Grand River Fisheries Management Implementation Committee who endorses the Grand River recovery strategy, included information on the project in four presentations made to the public across the watershed. In addition, the Committee included an article on the recovery project in their 2004 newsletter update. A pamphlet, highlighting the six species at risk found in the watershed, has also been produced and distributed to the public.

Deepwater Sculpin (Great Lakes-Western St.Lawrencepopulations)

Status: Special Concern

Last examined by COSEWIC:April 2006

Biology

This is a lake-dwelling sculpin with an elongate body and reaches an average length of 51-76 mm and a maximum length of 235 mm

Little is known of its biology. A maximum age of seven has been reported. Age at maturity is three years for females and two years for males. Aquatic insects are the main diet. Deepwater Sculpin is an important component of the diet of fish, such as lake trout and burbot.

Where is this fish found?

The Deepwater Sculpin is a bottom-dwelling species found only in cold, highly oxygenated lakes. Adults in the Great Lakes are usually found between 60-150 m. They prefer water temperature of less than 5ºC.

This population is found in lakes Superior, Huron, Ontario, Nipigon, and Fairbank in Ontario. In Quebec it is found in Lac des Iles, Heney, Roddick and Thirty-One Mile lakes.

How many fish are there?

Estimates of population size are not available because most locations where Deepwater Sculpin are found have not been sampled extensively. Therefore population data are mostly limited to presence or absence information. However in the Great Lakes fairly intensive long-term index sampling programs provide quite good measures of relative abundance.

In Lake Superior, Deepwater Sculpin are fairly widely distributed and are caught consistently albeit at quite low densities.

In Lake Huron, Deepwater Sculpin were relatively widespread but in recent years (since 1999), catches appear to have declined and abundance reduced; the Lake Huron Fisheries Assessment Unit has not seen a Deepwater Sculpin in their assessment program since 1998.

In Lake Erie, reports of Deepwater Sculpin have been rare and have always been only larval individuals (young-of-the-year). The reproductive status of the populations in Lake Erie is unclear as no adults have ever been observed in that lake.

In Lake Ontario, Deepwater Sculpin was once very abundant in the deep waters of the main basin. They were rare and considered endangered throughout the 1950s, 1960s, 1970s and early 1990s. Since 1996, individuals of all ages have been caught suggesting that their current presence is due to increased reproductive success by a remnant population. Although continuous colonization cannot be conclusively ruled out, the appearance of gravid females, small young fish, and the increased appearance of recent year-classes provides strong circumstantial evidence that abundance is increasing and successful reproduction is occurring.

In Quebec, it is found in Lac des Iles, Roddick, Thirty-one Mile and Heney lakes.

Threats to the population

Threats may include predation from exotic species such as Alewife and Rainbow Smelt, competition for food with zebra mussels, pollution and lake eutrophication.

COSEWIC Reason for Designation:

This species occurs in the deeper parts of 10 coldwater lakes, including lakes Superior, Huron and Ontario, in Ontario and Quebec. Previously thought to be exterminated in Lake Ontario, it now appears to be re-established in that lake, albeit in small numbers. Populations have been exterminated in 2 lakes in Quebec due to eutrophication of these lakes, and may be in decline in Lake Huron, possibly in relation to the introduction of zebra mussel.

What will happen if this fish is added to the SARA List?

A management plan must be prepared within three years of the Deepwater Sculpin being added to the SARA List.