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COSEWIC Assessment and Update Status Report on the Copper Redhorse in Canada

Habitat

Habitat Requirements

Adult copper redhorse inhabit medium-sized rivers, with steep banks, a maximum depth of 4 to 7 m, a hard bottom, generally composed of clay, sand and gravel, in places where dense grass beds are usually absent or reduced to a thin strip along the shore. The summer water temperature exceeds 20ºC. These rivers are located in a region of Quebec of very limited area characterized by a growing season of at least 1790 degree-days above 5.6ºC. Although the current is slow, usually less than 0.3 m/s, certain segments have short stretches of fast-flowing water where the species finds conditions favourable to reproduction. Adults are absent from shallow sections with dense vegetation as well as from locations where the water is heavily polluted and turbid (Mongeau et al. 1986, 1988, 1992).

There are currently two known copper redhorse reproduction sites, namely the archipelago of the Chambly rapids and the tailrace of the Saint-Ours dam. The spawning grounds are in riffle areas, with a moderate to slow current and depths ranging from 0.75 to 2 m. The heterogeneous substrate is composed of fine to coarse gravel, rocks and sometimes even fragments of bedrock partly submerged in the clay (Boulet et al. 1995, 1996, Dumont et al. 1997, La Haye et al. 1992, La Haye and Clermont 1997, Mongeau et al. 1986, 1992). Other sites such as the Grand Moulin rapids in Rivière des Mille Îles and the Dorion and Saint-Anne-de-Bellevue channels at the head of Lake Saint-Louis could potentially meet the spawning requirements of the copper redhorse, but the presence of a spawning area there has never been demonstrated (Jenkins 1970, Massé et al. 1981).

Like their congeners, young-of-the-year copper redhorse frequent shallow littoral areas during their first growing season. These areas are less than or equal to 1.5 m deep, gently sloped (£20º) and vegetated. The current is very slow and the substrate is relatively fine (mix of clay-silt and sand) (Vachon 1999a). The section of the Richelieu River that includes Jeannotte Island and Île aux Cerfs at Saint-Marc-sur-Richelieu is an important nursery area for juvenile redhorse, especially the copper redhorse, since several specimens have been collected there (Vachon 1999ab, 2002). This sector is also inhabited by three other species that have already received COSEWIC status (Massé and Bilodeau 2003, Vachon 1999a, 1999b, 2002): the river redhorse, designated a species of special concern (Parker and McKee 1984, Parker 1988, status again under review), and the Channel darter (Percina copelandi) (Goodchild 1994) and Eastern sand darter (Ammocrypta pellucida) (Holm and Mandrak 1996), two threatened species.

Little is still known about the adults’ summer and winter habitat. The possibility that certain sectors of the St. Lawrence River may be used as an over-wintering area cannot be ruled out (Vachon and Chagnon 2004).


Trends

High quality copper redhorse habitats are in decline. Moreover, its feared disappearance in the Yamaska and Noire rivers is closely linked to environmental degradation. These rivers are located in the most heavily agricultural region of Quebec. Farms occupy 63% of the area of the Yamaska River watershed. In total, 200 000 hectares are intensively cultivated and more than a quarter of the hogs and poultry raised in Quebec come from this region (Primeau et al. 1999). The situation in the Richelieu River watershed is scarcely any better, where the total area under cultivation is 141 176 ha (56.3%) (Piché and Simoneau 1998). From 1979 to 1991, the human population in this watershed grew by 20% and the area of cultivated land increased by 10%. During that period, major changes occurred in the composition of livestock and poultry, including a decline in the number of cows and an increase in the number of pigs and poultry. These changes had an impact on crop type at the watershed scale: the area devoted to widely spaced bare soil crops (primarily corn) increased by 150%, whereas the area devoted to other cereals and forages fell by 28% and 38%, respectively (Simoneau 1993). In the Richelieu River, as in several sectors of the Yamaska, the situation in terms of contamination by toxic substances is considered worrisome (Berryman and Nadeau 1998, 1999).

The assessment of ecosystem integrity by the composition of the benthic (IBGN) and fish (IBI) communities shows that the Richelieu River is rated fair or poor over nearly three-quarters of its length. A significant reduction in the IBGN as well as a notable decline in pollution-sensitive benthic species have been recorded at the outlet of the Chambly Basin downstream of the Rivière des Hurons and the Rivière l’Acadie (agricultural tributaries). The IBI shows that the sector between Saint-Marc-sur-Richelieu and Saint-Ours is one of the most degraded of the whole river, owing to the increase in urban, industrial and agricultural pressures (Piché 1998, Saint-Jacques 1998).

In the Yamaska River, the lower ratings (fair and poor) which describe the integrity of the benthic (IBGN) and fish (IBI) communities were obtained in the section historically inhabited by the copper redhorse. The situation is slightly less precarious in the Noire River, where ecosystem integrity, as shown by these two indices, is deemed fair to excellent at the stations located in the sector where the species has previously been found (La Violette 1999, Saint-Onge 1999).

In the St. Lawrence River, agricultural pressures, although present, are less significant. However, urbanization and the associated practices, as well as industrial activities, are having considerable impacts on the ecosystems of the St. Lawrence. In Quebec, urban sprawl has been continuing for several decades and the St. Lawrence Lowlands and Great Lakes region is the most industrialized in Canada (Bernier et al.1998). An initial assessment of the biotic integrity of the St. Lawrence River based on the IBI shows that the ecosystem is fairly degraded (La Violette et al. 2003).

It should be stressed that the intensification of agricultural activities and urbanization often has a detrimental impact on forested areas. The negative impact of deforestation on aquatic ecosystems is well known. In Montérégie, this phenomenon is worrisome. Wooded areas covered approximately 26% of the territory of Montérégie in 2002. Compared to 1999, this represents a loss of 3.88% or 12 511 ha. Most of the major tree-cutting has been carried out for agricultural purposes (Soucy-Gonthier et al. 2003). The intensification of agricultural activities has cancelled out some of the efforts that have been made to clean up discharges of industrial and household waste.

The downward trends in St. Lawrence River water levels, as well as the acceleration of erosion of the banks by wave action from passing vessels, resulting from increased traffic by commercial ships and pleasure craft, are also disturbing aquatic ecosystems. Over the past 20 years, the water levels of the St. Lawrence River have been falling and low-water problems are becoming increasingly severe, compromising the quantity and quality of fish habitat (spawning, feeding and nursery areas). Several biological processes of fish fauna depend on subtle synchronisms between water levels, temperature and flow (Robichaud and Drolet 1998). The impacts on the copper redhorse are not known. The copper redhorse telemetry project currently under way will provide new data concerning the essential habitats of this species in the St. Lawrence River.


Protection/Ownership

The habitats of the copper redhorse are mainly under public ownership. However, some small tributaries may be privately owned. At the present time, only 63 ha, which constitute the Pierre-Étienne-Fortin wildlife refuge, are the subject of special protection measures (Figure 5). This refuge is partly under private ownership. The river bed is owned by Conservation de la Nature and certain islands (Saint-Jean archipelago) are owned by the municipality of Richelieu.