River Redhorse (Moxostoma Carinatum) Is One of Seven Species of the Genus Moxostoma in Canada
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COSEWIC Assessment and Update Status Report on the River Redhorse Moxostoma carinatum in Canada SPECIAL CONCERN 2006 COSEWIC COSEPAC COMMITTEE ON THE STATUS OF COMITÉ SUR LA SITUATION ENDANGERED WILDLIFE DES ESPÈCES EN PÉRIL IN CANADA AU CANADA COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows: COSEWIC 2006. COSEWIC assessment and update status report on the river redhorse Moxostoma carinatum in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 31 pp. (www.sararegistry.gc.ca/status/status_e.cfm). Previous report: Parker, B. 1987. COSEWIC update status report on the river redhorse Moxostoma carinatum in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-12 pp. Parker, B. and P. McKee. 1983. COSEWIC status report on the river redhorse Moxostoma carinatum in Canada. Committee on the Status of Endangered Wildlife in Canada.1-10 pp. Production note: COSEWIC would like to acknowledge Scott Reid and Hilary Gignac from the Watershed Science Centre, Nicholas E. Mandrak from the Department of Fisheries and Oceans, and Nathalie Vachon and Pierre Dumont from the Ministère des Ressources naturelles et de la faune du Québec for writing the update status report on the river redhorse Moxostoma carinatum. The report was contracted to the Watershed Science Centre by Environment Canada and was overseen and edited by Claude Renaud, Co-chair, COSEWIC Freshwater Fishes Species Specialist Subcommittee. For additional copies contact: COSEWIC Secretariat c/o Canadian Wildlife Service Environment Canada Ottawa, ON K1A 0H3 Tel.: (819) 997-4991 / (819) 953-3215 Fax: (819) 994-3684 E-mail: COSEWIC/[email protected] http://www.cosewic.gc.ca Également disponible en français sous le titre Évaluation et Rapport de situation du COSEPAC sur le chevalier de rivière (Moxostoma carinatum) au Canada – Mise à jour. Cover illustration: River redhorse – Illustration by Joe Tomelleri, under licence to Fisheries and Oceans Canada. Reproduced with permission. ©Her Majesty the Queen in Right of Canada 2006 Catalogue No. CW69-14/493-2006E-PDF ISBN 0-662-43297-5 Recycled paper COSEWIC Assessment Summary Assessment Summary – April 2006 Common name River redhorse Scientific name Moxostoma carinatum Status Special Concern 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. Occurrence Ontario and Quebec Status history Designated Special Concern in April 1983. Status re-examined and confirmed in April 1987 and in April 2006. Last assessment based on an update status report. iii COSEWIC Executive Summary River Redhorse Moxostoma carinatum Species information The river redhorse (Moxostoma carinatum) is one of seven species of the genus Moxostoma in Canada. It is similar in appearance to the shorthead redhorse (M. macrolepidotum) and greater redhorse (M. valenciennesi). It can be distinguished from other redhorse sucker species by its moderate-sized head, entirely plicate lips, and caudal peduncle scale count. Distribution The river redhorse is found throughout the central and eastern Mississippi River system and the Gulf Slope from Florida to Louisiana. Several disjunct populations of river redhorse are found in southcentral Ontario and southern Quebec. Since the previous status report, river redhorse populations have been reconfirmed at some historical locations. New populations have been identified in Ontario and Quebec. Habitat In Canada, the river redhorse has been captured in both river and lake environments. However, its persistence is dependent on access to suitable riverine spawning habitat: moderate to swift current, riffle-run habitat and clean coarse substrates. Outside of the spawning period, reduced abundance in these habitats suggests that deeper run/pool habitats are used during other periods of the year. 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) and the substrate is fine (silt, clay and sand). Biology The river redhorse is a late-maturing, long-lived species that requires large interconnected riverine habitat to fulfill the need of all life-stages. Generally, mature specimens are greater than 500 mm TL, and can exceed 700 mm TL. The maximum age reported for river redhorse in Canada is 28 years. Spawning occurs during late spring in areas with fast-flowing water and gravel or cobble substrate. Except for the few iv Quebec rivers supporting copper redhorse (M. hubbsi), the river redhorse is the last of the Moxostoma species to spawn. River redhorse feed primarily on benthic invertebrates including molluscs, insect larvae and crayfishes. Population sizes and trends Given the lack of baseline data, population size trends cannot be addressed directly. Populations in the Mississippi River, Ottawa River, and the Richelieu River identified in the last status update are still present. In some watersheds, the species has likely disappeared (Châteauguay and Yamaska) or suffered substantial declines (St. Lawrence River). Population sizes for the Gatineau River and Mississippi River have been estimated. However, low numbers of recaptured fish and violations of model assumptions (e.g. high immigration rates) indicate that these estimates have a high degree of error. Identification of population trends would benefit from continued standardized sampling. Limiting factors and threats Tolerance for a narrow range of habitat characteristics and a limited amount of suitable habitat restrict the distribution of river redhorse. It is an inhabitant of medium- to large-sized rivers and 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 gene flow between populations. Due to restrictive spawning habitat (water depth and substrate) preferences, river redhorse recruitment is vulnerable to changes in the flow regime and siltation of spawning habitats. Special significance of the species River redhorse was historically a food source for native people and first European settlers and a species of minor commercial importance near Montreal. This fishery no longer exists. It is one of the few freshwater fishes that feed extensively on molluscs, thereby performing a unique ecological function. Existing protection or other status designations The river redhorse was first designated as Special Concern (Rare) by COSEWIC in 1983 and was reconfirmed as such in 1987 and 2006. In Ontario, it has been ranked as Special Concern by the OMNR. The river redhorse will be designated Vulnerable in Quebec. v 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 5th 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 (2006) 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 it 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.