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Recovery Strategy for the Copper Redhorse (Moxostoma hubbsi) in Canada

1. Background

1.1 Committee on the Status of Endangered Wildlife in Canada (COSEWIC) species assessment information

Below is the COSEWIC assessment summary as it appeared in the 2004 Update Status Report (COSEWIC, 2004):Footnote 1

Date of assessment: November 2004

Common name: Copper Redhorse

Scientific name: Moxostoma hubbsi

Status: Endangered

Reason for designation: This species is endemic to Canada where it is now known from only three locations in southwestern Quebec that possibly represent a single population. The distribution and abundance of the species have been severely reduced due to a number of anthropogenic factors (e.g., urban development, agricultural practices, and the construction of dams) that have contributed to a decrease in water quality and habitat availability. The recent introduction of exotic species such as zebra mussel may further impact habitat quality.

Occurrence: Quebec

Status history: Designated Threatened in April 1987. Status re-examined and designated Endangered in November 2004. Last assessment based on an update status report.

1.2 Description

The Copper Redhorse is a large-scaled catostomid fish of the genus Moxostoma, a group of relatively large fish, with an inferior,Footnote 2 protrusible mouth, lips with plicaeFootnote 3 and a pharyngeal apparatus with teeth arranged in an arch around the opening of the esophagus. It has 15 to 16 rows of scales around the caudal peduncle,Footnote 4 like its congener the greater redhorse (Moxostoma valenciennesi), whereas there are usually 12 or 13 in the other species with which it occurs in sympatry in southern Quebec, namely the silver redhorse (M. anisurum), shorthead redhorse (M. macrolepidotum) and river redhorse (M. carinatum). Its short, massive head, shaped like an equilateral triangle, with a moderately high arch rising sharply behind the head, creating a humpback appearance, its pharyngeal apparatus, exceptionally robust with 18 to 21 molariform teeth per arch (Figure 1) are the main characteristics by which it can be distinguished from the other species (Legendre, 1954; Scott and Crossman, 1974; Mongeau, 1984; Mongeau et al., 1986).


Figure 1. Pharyngeal apparatus of the adult Copper Redhorse.

Pharyngeal apparatus of the adult Copper Redhorse (see long description below).

Photo: Yves Chagnon, Ministère des Ressources naturelles et de la Faune du Québec.

Description of Figure 1

Figure 1 is a photograph by Yves Chagnon from the Ministère des Ressources naturelles et de la Faune du Québec of an adult Copper Redhorse's pharyngeal apparatus.

Certain characteristics of eggs and larvae have been described in various studies (Gendron and Branchaud, 1991; Beauchard, 1998; Grünbaum et al., 2003; Vachon, 2003a). In juvenile Copper Redhorse, the reduced number of pharyngeal teeth as well as their molariform appearance, widened base and more robust arches are already evident and can be used to distinguish them from other redhorse species (Vachon, 1999a, 2003a). Despite considerable efforts to develop other larval identification techniques, genetic analysis remains the most reliable method (Branchaud et al., 1996; Lippé et al., 2004).

The growth rate in length and weight is generally higher than that of its congeners. No difference in growth has been observed between the sexes. Total length and weight average over 500 mm and 5 kg respectively. Females are generally more corpulent than males (Mongeau et al., 1986; Mongeau et al., 1992).

1.3 Needs of the Copper Redhorse

1.3.1 Biology and ecology

The diet of the Copper Redhorse is based almost exclusively on small molluscs. Over 90% of the prey identified in the digestive tracts of adult Copper Redhorse are gastropods (snails) or bivalves (mussels) (Mongeau et al., 1986; Mongeau et al., 1992). In young-of-the-year, more than 50% (in number) of prey are microcrustaceans, the remainder being composed of worms, algae and insect larvae (Vachon, 1999a). Molluscs constitute part of the diet of several fish species in the streams of the St. Lawrence Plain. However, very few North American species are dependant upon this food source and none to the same extent as the Copper Redhorse. The particular configuration of the pharyngeal apparatus is well adapted to crushing shells and its level of specialization constitutes an evolutionary peak (Jenkins, 1970; Mongeau et al., 1986; Mongeau et al., 1992).

Compared to its congeners found in Quebec, this species reaches the largest size, is the most fecund, and has the longest lifespan, living for at least thirty years. The Copper Redhorse also takes the longest to reach sexual maturity, usually around the tenth year (Mongeau et al., 1986).

The reproduction period of the Copper Redhorse occurs later in the season than for its congeners in the St. Lawrence Plain. Spawning begins in mid-June and lasts until the first week in July at which time water temperatures vary between 18°C and 26°C. Fecundity ranges from 35 000 to 112 000 eggs (Mongeau et al., 1986; Mongeau et al., 1992). The eggs hatch after 4 to 7 days of incubation and the larvae emerge and begin swimming 12 to 16 days after fertilization (Branchaud and Gendron, 1993; Branchaud et al., 1995). Known spawning sites are located in white waters, at depths varying between 0.75 m and 2.0 m. The heterogeneous substrate is composed of rocks, fine and course gravel, and, at times, fragments of bedrock embedded in clay (La Haye et al., 1992; Mongeau et al., 1992; Boulet et al., 1995; Boulet et al., 1996; Dumont et al., 1997). During the reproduction period, the Copper Redhorse, especially the females, will travel between the spawning site and areas of calmer water (Gariépy, 2008). Spawning occurs mainly at night (La Haye et al., 1992; Gariépy, 2008). Spawners appear to be capable of spawning in more than one site during the same season (Gariépy, 2008).

The growth of young-of-the-year is closely linked to the number of degree-days above 10°C during the growing season, which ends at the latest around the end of September, even if the fall is late. Juvenile Copper Redhorse remain associated with grass beds near the shore, where the substrate is fine, during their first growing season and at the beginning of the second (Vachon, 1999a, b, 2002). It is not known what habitats juveniles frequent after two years of age. Capture of juveniles is very rare. Specialization of the pharyngeal apparatus occurs at an early stage in the life cycle, making it possible for juveniles to leave the nursery area early on and travel to the grass beds where molluscs are plentiful, making their capture problematic.

Adult Copper Redhorse are found in the habitats of the St. Lawrence River, the Richelieu River, the Rivière des Prairies and the Rivière des Mille Îles, especially in the shallow grass beds around the islands and archipelagos (Vachon and Chagnon, 2004; Gariépy, 2008). In spring, the main variables defining habitat selection are vegetation, current velocity, turbidity and sphaeriid abundance (D. Hatin, Ministère des Ressources naturelles et de la Faune du Québec (MRNF), unpublished data). In summer, the Copper Redhorse chooses sites characterized by the presence of gastropods, a relatively fine substrate (clay, silt, and sand), low current velocity (<0.5 m/s) and presence of dreissenids (Gariépy, 2008). The grass beds of the St. Lawrence constitute a highly productive habitat with high density mollusc populations (Nilo et al., 2006). The gastropod-rich habitat zones preferred by the Copper Redhorse are generally less than 5 m in depth and have a slow moving current (Ferraris, 1984; Gariépy, 2008). In the winter, adult habitat is essentially characterized by shallow depths (< 4 m), slow water current (<0.3 m/s), relatively fine substrate, little or no vegetation density and little or no gastropod density (Comité ZIP des Seigneuries, 2006; Gariépy, 2008; Fisheries and Oceans Canada (DFO), 2010a; D. Hatin, MRNF, unpublished data).

Copper Redhorse movements vary according to season. Average distance travelled daily is low in the summer (0.13 km/d) and the winter (0.17 km/d), moderate in the fall (0.55 km/d) and highest in the spring (0.93 km/d), nearing the reproduction period (Comité ZIP des Seigneuries, 2006; Gariépy, 2008; D. Hatin, MRNF, unpublished data). Adults living in the St. Lawrence River migrate from 40 to 100 km over a time range of 4 to 40 days to reach the spawning grounds in Saint-Ours and Chambly. Adults living in the Richelieu River will migrate over a much shorter distance (average of 28 km) and time range (7 days on average) to reach the same spawning sites (D. Hatin, MRNF, unpublished data). Males of the Catostomidae family generally travel to the spawning grounds before the females (Page and Johnston, 1990). However, individuals of both sexes have been observed at spawning sites at Chambly and Saint-Ours several days before spawning (Gariépy, 2008; D. Hatin, MRNF, unpublished data). Size of territories also varies according to season. It is small in the summer (0.3 km2) and winter (<0.7 km2), medium in the fall (2.3 km2) and largest in spring, nearing the reproduction period (Comité ZIP des Seigneuries, 2006; Gariépy, 2008; D. Hatin, MRNF, unpublished data). In summer, adults each intensively occupy a relatively confined area within their territory, corresponding approximately to the size of the grass bed in the area (Gariépy, 2008). The home ranges of individuals do not seem to overlap, but this may be due to the low population density.

1.4 Population and distribution

The Copper Redhorse is the only fish endemic to Quebec. Its discovery has been attributed to Vianney Legendre in 1942 (Legendre, 1942), but it appears to have been first described by Pierre Étienne Fortin in 1866 under the name of an already known species of the genus Moxostoma (Branchaud and Jenkins, 1999).

Telemetric monitoring, genetic analysis of specimens, and studies conducted on contaminant levels present in the Copper Redhorse all indicate that the species now forms one single population (de Lafontaine et al., 2002; Lippé et al., 2006; Gariépy, 2008). Since 1942, specimens have been found in certain sections of the Richelieu River, the Yamaska River, Noire River, Rivière L’Acadie, Rivière des Prairies and Rivière des Mille Îles, at the mouth of the Maskinongé and Saint-François rivers, and in a few stretches of the St. Lawrence River, between Vaudreuil and the downstream sector of Lake Saint-Pierre (Figure 2). Telemetric monitoring has shown that the distribution of the Copper Redhorse has not changed since it was first discovered, except for the Yamaska River and Noire River where the species has likely disappeared (Mongeau et al., 1986; Boulet et al., 1995; Gariépy, 2008). The extirpation of the populations in the Yamaska and Noire rivers, feared by Mongeau et al. (1986), owing to the significant degradation and fragmentation of habitat in this basin, seems to be confirmed (Boulet et al., 1995).


Figure 2. Distribution area of the Copper Redhorse

Distribution area of the Copper Redhorse (see long description below).

Description of Figure 2

Distribution area of the copper redhorse. It ranges in the Richelieu River, Rivière Yamaska, Rivière Noire, Rivière L’Acadie, Rivière des Prairies and Rivière des Mille Îles, at the mouth of the Rivière Maskinongé and Rivière Saint-François, and in a few stretches of the St. Lawrence River, between Vaudreuil and the downstream sector of Lac Saint-Pierre.

To date, two spawning grounds have been identified in the Richelieu River: the main one in the Chambly rapids archipelago and another in the channel downstream from the Saint-Ours dam (Figure 3). Potential spawning grounds have been identified in the Lavaltrie-Contrecoeur (Île Hervieux) sector of the St. Lawrence River, though the use by Copper Redhorse of this stretch of river could not be determined (Vachon and Chagnon, 2004). Other areas within the distribution range of the species may offer suitable conditions for reproduction. These include the Lachine rapids, the channel downstream from the Rivière-des-Prairies hydroelectric facility, the Grand Moulin and Terrebonne rapids in the Rivière des Mille Îles, and the Dorion and Sainte-Anne-de-Bellevue channels at the head of Lake Saint-Louis (Mongeau et al., 1986; Comité ZIP des Seigneuries, 2006). The first reported Copper Redhorse observation was that of mature individuals ready to spawn at the head of Lake Saint-Louis (Legendre, 1942). Reproduction activity has, however, never been observed outside of the Richelieu River spawning grounds (Jenkins, 1970; Massé et al., 1981; Mongeau et al., 1986; Vachon and Chagnon, 2004). An important nursery area has been located along the banks of the Richelieu River, downstream of Chambly, in the Île Jeannotte and Île aux Cerfs sectors (Vachon, 1999a, b, 2002).


Figure 3. Potential and known used spawning sites

Potential and known used spawning sites (see long description below).

Description of Figure 3

Potential and known used spawning sites. The two known spawning sites are in the Richelieu River in the Chambly basin and the Saint-Ours dam. Île Hervieux, Lachine rapids, the channel downstream from the Rivière-des-Prairies hydroelectric facility, the Grand Moulin and Terrebonne rapids in the Rivière des Mille Îles, and the Dorion and Sainte-Anne-de-Bellevue channels at the head of Lac Saint-Louis are potential spawning sites.

 

Examination of archeological remains dating from the 19th century from the banks of the Richelieu and St. Lawrence rivers indicates the existence of a historically more abundant population, representing respectively 16.7% and 9.1% of all redhorse species (Osthéothèque de Montréal, 1984; Courtemanche and Elliot, 1985). More recently, in ichthyological inventories conducted in the Montreal area between 1965 and 1983, the abundance of Copper Redhorse was estimated at between 2 and 3% compared to its congeners (Mongeau et al., 1986). The proportion dropped to 0.04% during the monitoring of the Vianney-Legendre fish ladder in 2003 (Fleury and Desrochers, 2004). Present population size is difficult to estimate given the rarity of the species and the accidental mortality risk associated with handling individuals captured to estimate population size. A preliminary estimate, based on an assessment conducted with recaptured specimens made by a commercial fisherman in 2000, in the Lavaltrie-Contrecoeur sector of the St. Lawrence River, provides a maximum abundance estimate of a few hundreds (Vachon and Chagnon, 2004).


1.4.1 Limiting factors

Several characteristics of the species’ biology and ecology constitute factors that increase its vulnerability. The Copper Redhorse reaches sexual maturity at a relatively late age (around 10 years) which, when compared to other species, delays the contribution of recruits to the reproductive effort. Furthermore, spawning takes place late in the season, end of June to early July, exposing the Copper Redhorse to lower water levels and a shorter growing season for fry which are consequently smaller in size when confronting their first winter. The hypothesis of selective winter mortality according to size has not been clearly proven, but remains plausible (Vachon, 1999a, b, 2002). The spawning period of the Copper Redhorse coincides with the peak period of pesticide concentrations in rivers (see section 1.5.5 Contaminants) and with a period of increased human activity associated with the Quebec and Canada national holidays (see sections section1.5.4 Recreational activities and section1.5.6 Fisheries).

The specialized diet of the species also contributes to its vulnerability because it reduces its adaptability in its choice of possible prey. Finally, the limited distribution range of the Copper Redhorse, even historically, adds to its vulnerability when confronted with changes to its habitat.

Nevertheless, the great longevity of the Copper Redhorse, which can extend to over thirty years, has until recently allowed the residual population to maintain a high level of genetic heterogeneity (Lippé et al., 2006).

1.5 Threat: classification and description

The numerous studies conducted since the beginning of the 1990s indicate that the species is having difficulty reproducing in its natural environment and that the population is aging (Branchaud and Gendron, 1993; Vachon, 2002; Vachon and Chagnon, 2004).

There is no doubt that anthropogenic activities are endangering the Copper Redhorse. Agricultural activities, urban development and recreational activities exert considerable pressure on the environment inhabited by this species. The 2004 COSEWIC Status Report identified several threats to the recovery of the species. The majority of threats were associated with habitat degradation, including the acceleration of erosion and increased turbidity resulting from agricultural activities, deforestation and urbanization, contamination of water by potential endocrine disruptors, and the eutrophication of watercourses. Other threats include the construction of dams which fragment the habitat and obstruct the passage of fish, lower water levels, invasive exotic species, and the intensive use of the Chambly rapids by recreational boaters in summer, the main spawning ground of the Copper Redhorse. Incidental catch by sport and commercial fishermen and pathogens introduction were added to the list of threats identified by COSEWIC and presented in this Section. Each threat has been assessed using six parameters (Table 1). It is important to mention that the severity of impact and level of concern associated with certain threats facing the species can vary locally depending on factors such as habitat type and threat intensity.

Table 1. Summary table of Copper Redhorse threats
ThreatsRangeOccurrenceFrequencyCausal certaintySeverity of impactLevel of concern
Habitat Degradation - ErosionGeneralCurrentOngoingHighHighHigh
Habitat Degradation - Shoreline HardeningGeneralCurrentOngoingHighHighHigh
Habitat Degradation - EutrophicationLocalCurrentOngoingHighHighHigh
Introduction of Organisms - Species IntroductionsLocalAnticipatedOngoingLowUnknownModerate
Introduction of Organisms - Pathogen IntroductionsGeneralAnticipatedSeasonalHighLowHigh
ContaminantsGeneralCurrentOngoingModerateModerateHigh
DamsLocalCurrentOngoingHighHighHigh
Recreational activitiesLocalCurrentSeasonalModerateModerateModerate
Sport FishingLocalCurrentSeasonalLowModerateModerate
Commercial FisheryLocalCurrentRecurringLowModerateLow
Flow AlterationGeneralAnticipatedSeasonalLowLowLow

Legend: Range: indicates whether threat is general throughout the distribution range or just present locally. Occurrence: indicates whether threat is historic, current, imminent or anticipated. Frequency: indicates whether threat occurrence is one-time, seasonal, ongoing or recurrent (not annual or seasonal). Causal certainty: indicates whether available knowledge about the threat and its impact on the viability of the population is of high, moderate or low quality. Severity of impact: indicates whether the severity of the threat is high, moderate or low. Level of concern: indicates whether threat management is, on the whole, of high, moderate or low concern. This may take into account the capacity to mitigate or eliminate the threat.


1.5.1 Habitat degradation

The waterways that are used by the Copper Redhorse are located in the most densely populated areas of Quebec and the concomitant intensive agriculture and urban development are the main causes of habitat degradation.

1.5.1.1 Erosion

Though soil erosion is a naturally occurring phenomenon, it is significantly accelerated by human activity. The intensive agriculture carried out in the lowlands of the St. Lawrence River contributes noticeably to soil and bank erosion (for a review, see Roy, 2002). Increases in drainage capacity, the channelling of watercourses, intensive agricultural techniques, and the loss of riparian vegetation have accelerated sedimentation in the watersheds inhabited by the Copper Redhorse. It is estimated that 50 000 km of watercourses were modified in Quebec between 1944 and 1986, an average of more than 1 000 km per year (MEQ, 2003). Wide row monoculture,Footnote 5 for crops such as corn and soybeans, requires yearly soil tillage and the cropping practices associated with it are believed to contribute most to water erosion. In the Richelieu River basin, where 70% of the territory is devoted to agriculture, 78% of that agricultural land is used for wide row cultures (Simoneau and Thibault, 2009). Despite policies and regulations currently in use, the trampling of banks by livestock and the absence of wind-breaks and adequate riparian vegetation contribute to soil erosion.

Along the St. Lawrence River, between Montreal and Lake Saint-Pierre, the banks have been receding 80 cm each year since the early 1980s and as much as 3 m in certain sectors such as the islands of Boucherville and Berthier-Sorel (State of the St. Lawrence Monitoring Committee, 2008). When water levels are sufficiently high to reach the banks, wave action from passing commercial vessels and recreational boats accelerates bank erosion. Wave action from commercial vessels using the St. Lawrence shipping channel can have an impact on banks at distances up to 800 m, especially between Montreal and Sorel (Dauphin, 2000). Massé and Mongeau (1976) demonstrated the negative impact of wave action from passing commercial vessels on the ichthyological fauna of the St. Lawrence, between Montreal and Sorel, especially through disruption of aquatic grass beds and exposed spawning grounds. During the summer, the Richelieu River is also becoming a busy waterway, used by recreational boaters. Another source of sedimentation and turbidity is the dredging of waterways and the release of sediments in the water.

Climate change is likely to impact on the ecosystems of the St. Lawrence Plain. From 1960 to 2003, the central and western portion of southern Quebec recorded a mean annual temperature increase between 0.5°C and 2.0°C (Yagouti et al., 2006). Climate forecast models predict warmer summers in southern Quebec with an accompanying increase in evaporation without, however, being able to establish whether precipitation will increase or decrease (Bourque and Simonet, 2008). Increases in frequency and scale of extreme weather events are also foreseeable, impacting directly on soil and bank erosion. Increases in precipitation or in severe rainfall events will create more runoff and accelerate the slumping of banks.

Soil and bank erosion lead to the acceleration of siltation and increases in turbidity. Siltation and increases in turbidity in watercourses lead to habitat loss and disrupt the entire food chain (reviewed in Vachon, 2003b). Sediments settle in the interstices in the gravel and rocks that form the substrate and can cover a spawning ground. Increased turbidity prevents penetration of sunlight into the water and impedes photosynthesis in plants while also reducing visibility for animal species that are visual predators. Fine sediments block the respiratory and digestive system of planktonic organisms that young Copper Redhorse feed on. Most fish in the family Catostomidae, specifically those in the genus Moxostoma, are extremely sensitive to turbidity, as are molluscs which constitute the principal prey of the Copper Redhorse (Vachon, 2003b).

1.5.1.2 Shoreline hardening

Urbanization, industrialization and real estate development have brought significant changes in the riparian morphology and vegetation of the St. Lawrence River and its tributaries. Backfilling, deforestation, the installation of riprap,Footnote 6 and the construction of walls and other infrastructure such as harbours, bridges and marinas have contributed to shoreline hardening and degradation of riparian and aquatic environments. A shoreline inventory conducted in 1995 revealed that 45% of the shoreline between Cornwall and l’Île d’Orléans was covered by a protective structure, be it a wall or riprap (Lehoux, 1996). A shoreline study of the municipality of Saint-Jean-sur-Richelieu showed that 75% of the shoreline was covered by a protective structure (CNC, 2008). It is estimated that over 75% of the north shore of Montreal has been developed, along with more than 65% of the Laval shoreline (Boutin and Lepage, 2009).

Mechanical stabilization activities on banks and littoral zones modify the physical characteristics of a watercourse (flow, current velocity, temperature) necessary for the maintenance of habitats such as aquatic grass beds. Moreover, hardened shorelines, devoid of vegetation, do not retain rainwater runoff as efficiently, contributing to increased sediment transport into the watercourses. Direct impacts on the Copper Redhorse are difficult to quantify, but since the young and the adults depend so heavily on the aquatic grass beds, degradation of the riparian environment is considered a threat to the species.

1.5.1.3 Eutrophication

Nitrogen and phosphorus are essential nutrients for the growth of living beings. The introduction of massive quantities of these elements into the rivers, through human activities, leads to the proliferation of algae and aquatic vegetation which may become excessive, invading aquatic environments and causing their premature aging.Footnote 7

Since the early 1960s, with the change from a pasture-based agriculture to intensive cereal crops, phosphorus has been applied in progressively greater quantities to agricultural land in order to increase crop production. The level of nutrient input has, at times, been greater than the actual crop requirements and, in certain regions, the phosphorus level in agricultural land is consequently very high, and even critical (Gangbazo et al., 2005). Agricultural practices that contribute to erosion lead to the transport of phosphorus-laden soil into local watercourses. Degradation and loss of riparian environments and vegetation deprive watercourses of adequate buffer zones that can act as natural filters for sediments and fertilizers. The Ministère du Développement durable, de l’Environnement et des Parcs du Québec (MDDEP) has set the limit for maximum total phosphorus concentration in rivers to prevent eutrophication at 0.030 mg/l [Ministère de l'environnement du Québec (MEQ), 2001]. Between 2001 and 2003, the MDDEP calculated that average phosphorus concentration at the mouth of the Richelieu River was 0.037 mg/l, while the Rivière des Hurons, a tributary of the Richelieu, revealed a phosphorus concentration of 0.182 mg/l (Gangbazo et al., 2005). Simoneau and Thibault (2009) estimate that 50% of the total phosphorus load transported into the Richelieu River annually comes from agricultural sources.

Residential and industrial wastewater also contributes to the eutrophication of surface water. Wastewater produced by approximately 60% of people living in Quebec is eventually dumped into the St. Lawrence River, after treatment. This wastewater is rich in organic matter, nitrogen and phosphorus. The organic matter requires high levels of oxygen in order to decompose, thus contributing to the reduction of dissolved oxygen. The sewage treatment facilities in Montreal, Longueuil, Laval and Saint-Jean-sur-Richelieu are physico-chemical treatment plants that filter organic matter using coagulation and settling techniques that do not involve bacteriological decomposition. The resulting effluent has a high biological demand for oxygenFootnote 8. Many Quebec municipalities have dual-purpose sewage systems in which rainwater is combined with residential and industrial wastewater. During periods of high rainfall or snowmelt, untreated wastewater is regularly released into both the St. Lawrence and Richelieu rivers.

Eutrophication leads to changes in the habitat. Biologically, this can signify a change in the resident species, and physicochemically this translates into reductions in dissolved oxygen. The enrichment of watercourses has created habitats which are beneficial to species that are more tolerant to eutrophication, such as pumpkinseed (Lepomis gibbosus), brown bullhead (Ameiurus nebulosus) and yellow perch (Perca flavescens). A water quality assessment of the Richelieu River basin, conducted in accordance with the Bacteriological and Physicochemical Quality Index of the Government of Quebec, has shown increasingly noticeable degradation in water quality, progressing downstream along the Richelieu River, and very poor water quality in two of its tributaries, the Rivière L’Acadie and Rivière des Hurons (Simoneau and Thibault, 2009).


1.5.2 Introduced organisms

1.5.2.1 Invasive exotic species

The St. Lawrence River is a busy shipping channel used by vessels from all the continents of the world. Ballast waterFootnote 9 has been identified as a probable factor in the introduction of numerous species into shipping channels. Studies have shown that the ballasts, hulls and side tanks of ships coming from abroad and entering the St. Lawrence River contain various assemblages of living organisms from all over the world (including non-indigenous taxa, toxic or harmful taxa, and taxa that constitute a potential risk) (Gauthier and Steel, 1996; Bourgeois et al., 2001). The sale and distribution of ornamental plants is also responsible for introducing several non-indigenous plant species into the aquatic ecosystems of Quebec (White et al., 1993; de Lafontaine and Constan, 2002). The Richelieu River, connected to Lake Champlain and the Hudson River, is another known route of entry for several exotic species (de Lafontaine and Constan, 2002). Lack of public awareness and certain legal ambiguities contribute to the introduction of invasive and exotic species in the aquatic environment (Dumont et al., 2002). The establishment of exotic species can modify the species composition of ecosystems and alter the food chain. The widespread presence of highly competitive non-indigenous species presents a threat to the Copper Redhorse.

Several aquatic species recently established in the Copper Redhorse distribution range, including the tench (Tinca tinca), the round goby (Neogobius melanostomus), and the zebra and quagga mussels (Dreissena polymorpha and D. bugensis), constitute potential threats to the recovery of the Copper Redhorse. Other species, such as Asian carp species introduced to North America and considered very invasive, also need to be monitored (Vanderploeg et al., 2002; DFO, 2005). Climate change, too, could spur the northern migration of species which could compete with the Copper Redhorse (reviewed in Rahel et al., 2008). Climate change could contribute to the impact that invasive species have on the habitat and on the Copper Redhorse by leading to increases in water temperatures, changes in competition and predation relationships, and an increase in disease severity (Rahel et al., 2008; Rahel and Olden, 2008).

1.5.2.2 Introduction of pathogens

The introduction of pathogens can also constitute a serious threat to various fish species. For example, Viral Hemorrhagic Septicemia (VHS) is a contagious viral disease which, to varying degrees, affects at least 65 species of fish, including two redhorse species. First identified in the Great Lakes in 2005, this disease is linked to massive mortalities in several fish species in that region (Canadian Cooperative Wildlife Health Centre, 2005). A screening program was implemented for the St. Lawrence River and some of its tributaries in 2007 by the MRNF and the Canadian Food Inspection Agency and, as of spring 2012, no cases of VHS have been detected in Quebec. There is no known treatment for this disease. The Canadian Food Inspection Agency has implemented a biennial strategy to monitor the presence of the VHS virus in Canadian wild fish (CFIA, 2009). Given the present precarious status of the Copper Redhorse, massive mortality associated with this disease, or other pathogens and parasites, could significantly impede the survival and recovery of the species.


1.5.3 Dams

Numerous hydroelectric dams and flow regulation structures have been constructed on the St. Lawrence River and its tributaries (Figure 2). These structures in the distribution area of the Cooper Redhorse present a threat to its recovery because they impede migration and fragment species habitat when they are impassable. For more than thirty years, the dam at Saint-Ours obstructed the free passage of the Copper Redhorse to the spawning grounds in Chambly. Until the construction of the Vianney-Legendre multispecies fish ladder in 2001, the possibility for a fish to cross the dam was limited to a short period of time of 2 to 3 weeks on average, from early April to mid May. Since 1967, the majority of Copper Redhorse was forced to spawn in the afterbay of the dam, which is not an optimum habitat (La Haye et al., 1992; Boulet et al., 1995; Branchaud et al., 1996; Dumont et al., 1997). Hydroelectric projects, new or existing, on flow regulation dams within the Copper Redhorse distribution range, constitute a threat not only by posing obstacles to the free passage of fish, but also because their turbines could be a cause of mortality. Dams can also destroy spawning habitat by affecting water flow patterns. A mini-hydroelectric facility project on the Chambly rapids was abandoned in 1994 because of the threat it posed to the reproduction of the Copper Redhorse.


1.5.4 Recreational activities

The popularity of the Chambly archipelago among swimmers and recreational boaters (jet-skis, kayaks, motor boats), especially during the Copper Redhorse spawning period, increases stress on the spawners and can lead to the destruction of eggs (Gendron and Branchaud, 2001; Laporte and Maurice, 2008). Mooring and the use of propeller engines in shallow waters can considerably disturb the grass beds. The area around the Île Jeannotte and Île aux Cerfs, a productive fry rearing ground, is also popular with boaters in the summer. The St. Lawrence River, particularly around the Boucherville and Lake Saint-Pierre archipelagos, is another regular destination for recreational boaters. Noise, the crushing of eggs, and damage caused by boat motors (water turbulence, uprooting of vegetation) can prevent the Copper Redhorse from feeding and carrying out other vital activities. Disturbances caused by recreational activities in the strategic habitats of this species such as the aquatic grass beds and the spawning grounds constitute a threat to the recovery of the Copper Redhorse.


1.5.5 Contaminants

The rotation of corn and soybean crops is constantly evolving in southern Quebec (Statistics Canada, 2006). These crops have undergone profound changes in the last few years with the advent of genetically modified seeds resistant to glyphosate herbicide. Though pesticides are used on many crops, most are employed on corn and soybean (MEQ, 2003; Giroux, 2010). More than 30 pesticides, especially herbicides, can be used on corn crops in Quebec. Their widespread use, their application on bare soil in the spring, and the need for two or three applications during a growing season, make herbicides all the more likely to make their way into watercourses. The risk increases if herbicide application is followed closely by rain because these products are easily transported by runoff. Because of the Copper Redhorse’s late spawning period, the presence of adults in the Richelieu spawning grounds coincides with periods of lowering water levels and peak pesticide application (Gendron and Branchaud, 1997). Significant quantities of pesticides are used throughout the Richelieu River watershed on almost all (96%) of the row crops grown there (Simoneau and Thibault, 2009). Up to 29 pesticides, including atrazine, metolachlor, and glyphosate, have been detected at the mouth of the Rivière des Hurons, a tributary of the Richelieu. They were found regularly to be at levels exceeding established limits for the protection of aquatic life (Giroux, 2010).

Industry, waste disposal sites, and municipal effluent are also an important source of contaminants such as heavy metals, dioxins, furans, polycyclic aromatic hydrocarbons (PAH), and residues from domestic products such as detergents and medications. These contaminants have been detected in the St. Lawrence River, especially in sediments. The Copper Redhorse occupies habitats located in the plume created by the effluent from the water treatment plants of Montreal, Longueuil and Laval and, consequently, is exposed to the various contaminants contained in this wastewater. A decrease in certain contaminant levels (metals, for example) has been observed in the sediments of Lake Saint-Pierre, although those in Lake Saint-Louis reveal little or no decrease in twenty years (State of the St. Lawrence Monitoring Committee, 2008). Though levels of certain contaminants, such as organochlorinesFootnote 10, tend to decrease in the fluvial ecosystem, emerging compounds such as organobromidesFootnote 11 are increasing exponentially (De Wit, 2002; State of the St. Lawrence Monitoring Committee, 2008). Concentrations of PAH, PCB, furans and dioxins exceeding Quebec’s water quality guidelines have been detected at the mouth of the Richelieu River and several fish in this river have been found to contain levels of mercury and PCB exceeding guidelines for the protection of wildlife (MDDEP, 1998; Laliberté and Mercier, 2006). Several contaminants have also been found near the spawning grounds in the Richelieu River (Giroux, 2000). Permits have been granted for the exploration of natural gas along the St. Lawrence valley and in the Richelieu River basin, using a new method, the extraction of shale gas by hydraulic fracturing and horizontal drilling. This method uses great quantities of water and a wide array of chemical additives. The environmental impacts of this industry, particularly on the water table, and air and soil quality, are still largely unknown.

The effects of herbicides in the environment include a decrease in the abundance of herbivorous zooplankton, a reduction in growth, chlorophyll content and photosynthesis in phytoplankton, and reduced levels of primary productivity and oxygen production in water. The Copper Redhorse is exposed to contaminants through its prey and the water and sediments in its environment. Persistent contaminants have been found in the flesh and viscera of several Copper Redhorse at levels comparable to those identified in other Catostomidae in the Richelieu and Yamaska river basins (de Lafontaine et al., 2002).

The Copper Redhorse is exposed to non-persistent contaminants in aquatic environments which may be responsible for the reproductive difficulties experienced by the species. Some pesticides may act as olfactory disruptors reducing the ability of spawners to sense pheromones, substances involved in behavioral synchronization and in gamete maturation in both sexes (Gendron and Branchaud, 1997). Certain industrial, agricultural, pharmaceutical and personal hygiene products can also act as hormone disruptors in many fish species and disrupt the reproductive system (Donohoe and Curtis, 1996; Aravindakshan et al., 2004). For example, close to a third of male spottail shiners (Notropis hudsonius) presented both male and female anatomical and biochemical characteristics downstream of the Montreal wastewater effluent, in the St. Lawrence River. The combination and interaction of these compounds may affect Copper Redhorse health and reproduction in ways not yet identified.

Climate change may also affect the impact of contaminants on the Copper Redhorse. The predicted increase in the frequency and intensity of severe weather events increases the risk of toxic discharges, while a change in rainfall patterns could increase pesticide runoff into watercourses (Schiedek et al., 2007; Bourque and Simonet, 2008). A rise in water temperature could also affect the toxicity of contaminants (reviewed in Schiedek et al., 2007). A decrease in water flow in rivers would result in a lower dilution effect and thus greater concentrations of contaminants in the habitat.


1.5.6 Fisheries

1.5.6.1 Commercial fishery

It is possible that the commercial fishery of the 19th century, which targeted mainly the larger individuals, weakened the Copper Redhorse population. At the time, the species was valued as a food source and was popular on the market (Branchaud and Jenkins, 1999). Today, there is no longer a Copper Redhorse commercial fishery. The species can, however, be incidentally caught by fishermen in the bait-fish and other commercial fisheries. There are between 70 and 75 fishermen involved in the bait-fish fishery in zones 7 and 8 along the St. Lawrence River, including Lake Saint-Pierre. In accordance with the fishing permits issued by the MRNF, these fishermen work primarily outside the Copper Redhorse distribution range, in the Upper Richelieu, Lake Saint-François and the smaller streams, but do have access to the St. Lawrence River. There are 25 commercial fishermen licensed to fish sturgeon using gillnets, 6 of whom are also authorized to use fyke nets, which increases the possibility of incidental catches of Copper Redhorse in Lake Saint Pierre. An outreach project aimed at these commercial fishermen was carried out by the Committee for the Lake Saint-Pierre Priority Intervention Zone (PIZ) in 2008 and 2009, to assess bycatch of Copper Redhorse. None were caught incidentally by fishermen in Lake St. Pierre during that period. Incidental catches remain marginal in this lake because this species is rare in the lake, there are few commercial fishermen, and there is limited overlap between habitats of Copper Redhorse and the main fishing areas. The risk for incidental catches is greater in the St. Lawrence River, where fyke net fishing areas overlap with the main Copper Redhorse habitats. To date, the risk has been managed through close collaboration between the one fisherman operating in the Contrecoeur sector and the MRNF personnel (Vachon and Chagnon, 2004). However, the situation could change if, for example, this fisherman were to sell his fishing rights to a less vigilant person. Though constant vigilance is required to assess the impact of commercial fisheries on the species, the buy-back of yellow perch permits in Lake Saint-Pierre and the relatively low number of commercial fishermen operating within the Copper Redhorse distribution range makes this threat of lesser concern.

1.5.6.2 Sport fishing

During the summer months, the Richelieu River, the islands of Sorel and of Boucherville, and the fluvial lakes are areas of high recreational activity, including sport fishing. In 2004, the region of Montérégie alone accounted for close to 140,000 sport fishermen (MRNF, 2004). The spawning period of the Copper Redhorse coincides with the Quebec and Canadian national holidays, a very busy period on the Richelieu River. Copper Redhorse can be caught with a fish hook, but they are not popular with fishermen who have to release them back into the water according to the Quebec Fisheries Regulations (1990) (SOR/90-214). However, certain ethnic communities in the metropolitan area are fond of carp, chub and redhorse and do not release these species when caught (Y. Labonté, MRNF, pers. comm.). These fishermen are often less informed about regulations and the presence of endangered species (Laporte and Maurice, 2008).


1.5.7 Water levels

The ecology of fish is significantly affected by water flow rates that determine habitat availability throughout the spring freshets and yearly cycles. The quantity and quality of aquatic grass beds necessary to the growth and nutrition of the Copper Redhorse depend in part on the water levels in the St. Lawrence River and the tributaries where the species is found. The St. Lawrence River exhibits high interannual variability in water levels, with cycles of alternating high and low water flow. The rivers of southern Quebec, especially the Ottawa River which is the main tributary of the St. Lawrence, are highly regulated by a series of dams (Figure 2). The flow of water issuing from Lake Ontario is also regulated by the Iroquois dam in the international section of the St. Lawrence River. In accordance with the Regulation Plan 1958-D of the International Joint Commission, the regulation of water flow is aimed at optimizing hydroelectric production and commercial navigation, while ensuring flood prevention.

A study was conducted on the potential adult summer habitat in watercourses with a wide range of flow rates, from very low to very high, in order to determine the relationship between the available potential habitat and the hydrological regime of the St. Lawrence (D. Hatin, MRNF, unpub. data). This study demonstrated that variations in flow rates, caused by climate change or the regulation of the St. Lawrence River water levels, have a notable effect on the availability of summer habitat for the Copper Redhorse. The area of available habitat may be reduced by half or doubled depending on whether flow rates are low or high.

Hydrology of the St. Lawrence River is also partly affected by dredging operations in the shipping channel and harbour facilities. Dredging of the shipping channel in the river has increased the flow depth in Lake Saint-Pierre from 4.3 m in 1847 to 11.3 m in 1998 (Morin and Côté, 2003). This activity has modified in quality and in quantity shallow-water shoreline habitats in the river corridor downstream of Montreal, particularly around Lake Saint-Pierre.

Changes in the rainfall regime brought on by climate change will affect water levels in the St. Lawrence River basin. These could result in a modification in the St. Lawrence River flow. According to Morstch and Quinn (1996), a temperature increase in the order of 4°C could reduce annual water flow by 40%. McBean and Motiee (2008), however, forecast a medium-term increase in precipitation and consequently in water flows in the Great Lakes and St. Lawrence River. Changes in the rainfall regime and subsequent water levels in the St. Lawrence River could also influence the frequency and intensity of dredging operations in the shipping channel and harbour facilities.

Footnotes

Footnote 1

Available on the Species at Risk Public Registry

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Footnote 2

A fish is said to have an inferior mouth when the lower jaw is shorter than the upper jaw.

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Footnote 3

Folds located on the lips.

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Footnote 4

The part of the body located between the anal region and the caudal fin (tail).

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Footnote 5

Cultures where rows of crops are far apart to allow machinery to operate. Primarily corn, potato, soy and other vegetables.

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Footnote 6

Riprap is rock or other material used to armor shoreline, streambeds, bridge abutments, pilings and other shoreline structures against scour, water or ice erosion.

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Footnote 7

Plant growth and the enrichment of watercourses is known as eutrophication. The phenomenon is generally accompanied by a reduction in dissolved oxygen in the water.

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Footnote 8

Biological or biochemical oxygen demand is a measure of the amount of oxygen required to allow micro-organisms to decompose the organic matter present in water, usually over a period of five days. The higher the measurement, the more organic matter there is in the water.

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Footnote 9

To ensure ship stability, reservoirs known as ballasts are filled with water at one port and emptied at another.

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Footnote 10

For example, dichloro-diphenyl-trichloroethane (DDT), mirex, polychlorinated biphenyls (PCBs)

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Footnote 11

Polybrominated diphenyl ethers (PBDEs)

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