Channel darter (Percina copelandi) COSEWIC assessment and status report: chapter 7

Population Sizes and Trends

Biologists have returned to the original locations and several of the new locations of capture in Ontario and Quebec in an attempt to determine the status of the channel darter in Canada (Appendix 1). In the westernmost part of the channel darter’s range, individuals had been observed from Lake Erie around Port Dover in 1946-47, at the mouth of Pike Creek in 1980, and at Pelee Island in 1984 (Goodchild 1994). While no recent data exist for these sites, two specimens were captured in Lake Erie at Holiday Beach Provincial Park in 1997 [Royal Ontario Museum (ROM) 70951], indicating that this species still occurs in this area. In 1940, one specimen was collected in the Detroit River one mile south of Amherstburg, Essex County; a single specimen was again captured in the Detroit River near Bois Blanc Island in 1997 [ROM 70916].

Following up on the specimens collected in eastern Ontario, two specimens were collected in 1948 from an unnamed creek near Moira Lake; none were observed when the area was re-examined in 1997 and the population is thought to be extirpated (Appendix 1) (Alan Dextrase, Ontario Ministry of Natural Resources (OMNR), personal communication). Nine individuals were observed in the Trent River in 1976 [OMNRS64]; two specimens were found at the same location in 1997 [ROM 70990] and two more specimens were captured in 2001 (Alan Dextrase, OMNR, personal communication). A new population of channel darter was discovered near the mouth of the Trent River in 1998, four specimens were captured (Alan Dextrase, OMNR, personal communication). Eleven more were collected in 2001 and biologists discovered a new collection site further upstream where two more specimens were collected (Alan Dextrase, OMNR, personal communication). Channel darters are extant at all three of these sites along the Trent River, which are separated by dams.

Biologists from the OMNR reported captures of the channel darter in the Skootamatta River in 1974. During 1991, biologists returned to this river and captured 21 specimens [ROM 70537]. Twelve additional specimens were captured when the area was sampled in June 2001 (Jason Lean, Trent University, personal communication).

In Quebec, Percina copelandi is still found in a number of sites in the Montérégie region. In the Rivière aux Outardes-Est, the Rivière aux Anglais and the Rivière à la Truite, channel darter had been previously captured in 1976. Channel darter was captured in all three of these rivers as recently as 1996. Thirteen specimens were collected from Rivière aux Outardes-Est, four from Rivière aux Anglais and 20 were collected from Rivière à la Truite (Desrochers et al. 1996). Also the Rivière Noire, previously searched in 1987, was still home to channel darter in 1995, when two specimens were captured (LaViolette 1998).

In Papineau County, a channel darter was captured in the Ottawa River near Quyon as reported by McAllister and Coad (1974). Chabot and Caron (1996) reported the capture of three additional specimens in the Ottawa River between Hull and Quyon in 1996.

In the Chaudière-Appalaches region, channel darters were captured in the Rivière aux Bleuets in 1977 but subsequent searches in 1992 and 1996 failed to find any further specimens. Also, in the Rivière du Sud near Montmagny, channel darters were captured in 1941 and again in 1964; however, none were found when the area was searched in 1996 (Desroches et al. 1996). The channel darter is sensitive to sedimentation and poor water quality. It is likely that recent agricultural and urban development along these rivers has caused an increase in the suspended sediment levels and has led to the extirpation of this species at these locations (Lapointe 1997). Percina copelandi was still found in the Rivière Bras Saint-Nicolas in 1997 (exact number unknown), after initially being found there in 1980 (Lapointe 1997).

In the Estrie region, the channel darter was captured in the Rivière Niger near Ayer's Cliff in 1931 but was not found when the area was searched in 1996. In the Rivière Maskinongé, channel darter specimens were captured in 1934 but a search in 1996 failed to find any specimens. Field notes collected by Desrochers et al. (1996) for Rivière Maskinongé indicated that significant shoreline erosion occurred at this site, a result of increased boat traffic. Specimens of Percina copelandi were originally found at several sites along the Rivière Yamaska in 1969; one specimen was found in the southeast portion of the river in 1995 (LaViolette 1998). Other sites along the Yamaska have not yet been re-examined.

In the Lanaudière region, channel darters had been captured in the Rivière du Chicot in 1941 and in 1971 but a more recent search in 1996 with a variety of sampling gear types found no specimens (R. Dumas, Société de la faune et des parcs du Québec (MEF), personal communication). Elsewhere in the region, five specimens of Percina copelandi were found in the Rivière Bayonne in 1996, after last being captured there in 1971 (Lapointe 1997).

In the Mauricie–Bois Francs region, specimens of Percina copelandi have been captured at several sites along the St. Lawrence River. Channel darters were captured in the Rivière Gentilly and in the Rivière Bécancour, tributaries to the St. Lawrence, in 1941 and 1964 respectively. In 1996, Fournier et al. (1997) reported that three specimens were captured in the Gentilly–Bastican reach of the St. Lawrence River. Specimens were last found near Port St-François in 1972 as none were captured when the area was re-examined in 1995 (Fournier 1996).

There has been little information available on the population sizes of channel darter, which make it difficult to evaluate population trends. Optimal habitat conditions for channel darter survival may not occur every year. This may result in variation in reproductive success and changes in abundance from year to year. Goodchild (1994) suggested that channel darters might be able to repopulate areas when water quality improves. In Quebec, one of the objectives of the channel darter recovery team is to study the possibility of restoring channel darter habitats in order to re-establish the species (Équipe de rétablissement du fouille-roche gris 2001).

There are nine sites in Quebec for which no recent data exist because they have not been re-examined since the previous status report. These include Rivière Châteauguay, Rivière Richelieu and Point-du-Buisson from the Montérégie region, Ruisseau Salmon from the Estrie region, Rivière aux Ormes, Rivière du Chêne, Rivière Henri from the Chaudière–Appalaches region, Rivière Bécancour from the Mauricie–Bois Francs region and Rivière L’Assomption from the Lanaudière region.

Areas where channel darters were collected were generally located in undisturbed rivers along forested or agricultural areas with natural shorelines and good water quality (Lapointe 1997). The six waterbodies in Quebec where biologists returned in unsuccessful attempts to collect channel darter were areas that have undergone habitat changes such as agricultural and urban development causing increased sedimentation (Lapointe 1997). These sites include rivières Niger and Maskinongé in the Estrie region, Rivière du Sud and Rivière aux Bleuets in the Chaudière–Appalaches region, Port St. François in the St. Lawrence River, and Rivière du Chicot in Lanaudière (Appendix 1). Lapointe (1997) suggested that in the St. Lawrence drainage, agricultural and urban development has caused increased sedimentation. In the St. Lawrence valley, 70% of forested habitats have disappeared and 40 000 km of water have been drained essentially eliminating optimal channel darter habitat (Équipe de rétablissement du fouille-roche gris 2001).

The distribution of the channel darter is more widespread than previously thought, particularly throughout Quebec, considering its rarity throughout North America. Since the original status report, 127+ specimens of Percina copelandi were captured from four new waterbodies in Ontario and 102 specimens were captured from six new waterbodies in Quebec. At the majority of these new sites fewer than ten specimens were captured. Although in Ontario 65 specimens were captured in the St. Clair River and 58+ specimens were captured in the Moira River. In Quebec, 76 specimens were captured in the Gatineau River and 16 specimens were captured from Rivière Kinonge (Appendix 1). It is likely that the new records of capture are the result of increased sampling efforts and not increasing population sizes. The St. Lawrence and its tributaries have been more thoroughly sampled.

Fewer than 100 specimens of channel darter were captured in Ontario prior to 1993 (Goodchild 1994). Since this report, 184+ specimens have been captured in Ontario in the tributaries to Lake Ontario and along the shores and tributaries of Lake Erie and Lake St. Clair. In Quebec, 700+ specimens of channel darter were captured prior to 1993. Since 1993, 154+ specimens were captured in the tributaries of the St. Lawrence River in the regions of ChaudièreAppalaches, Estrie, Lanaudière, MauriceBois Francs, Montérégie and the Outaouais.

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