Skip booklet index and go to page content

Recovery Strategy for the Eastern Sand Darter

1.5 Threats

1.5.1  Threat Classification

  Table 3.  Summary of threats to eastern sand darter populations in Canada.

Ontario:

SystemStatusDistributionThreats (severity rank*)
Ausable Riverextirpatedsingle collection record from Ailsa Craig (1929)

·         siltation (HIGH)

·         high nutrient levels (HIGH)

·         toxic chemicals (MEDIUM)

·         altered flow regime(MEDIUM)

Big Creekextirpated 

·         siltation (HIGH)

·         agricultural nutrient loading (HIGH)

·         water-taking associated with agriculture (MEDIUM)

Big Otter Creekextirpated 

·         siltation (HIGH)

·         agricultural nutrient loading (HIGH)

·         water-taking associated with agriculture (MEDIUM)

Catfish Creekextirpated ·         turbidity and siltation(HIGH)
Grand Riverpossibly declininglower Grand River (Brantford to Cayuga)

·         siltation (HIGH)

·         nutrient loading (LOW)

·         dams (UNKNOWN)

·         urban-based toxins (UKNOWN)

Lake Erie stable?InnerLong Point Bay, Rondeau Bay, Pelee Island·         invasive species (i.e. round goby, tubenose goby (Proterorhinus marmoratus) (UNKNOWN)
Lake St. Clairdeclining?Mitchell's Bay, Pike Creek to Thames River outflow·         invasive species (i.e. round goby, tubenose goby)(UNKNOWN)
Sydenham RiverdecliningEast Branch

·         siltation (HIGH)

·         high nutrient levels (HIGH)

·         toxic chemicals(MEDIUM)

·         land-use practices and/or dams that interfere with channel forming processes (MEDIUM)

·         invasive species (i.e. round goby) (UNKNOWN)

ThamesRiverstableLowerThames River (Komoka to Kent Bridge)

·         siltation (HIGH)

·         land-use practices and/or dams that interfere with channel forming processes (HIGH)

·         invasive species (i.e. round goby) (UNKNOWN)

·         urban-based toxins  (UNKNOWN)

 

Quebec:  

SystemStatusDistributionThreats (severity rank*)
St. Lawrence River:   
Montréal-Sorel ReachStable?Saint-Sulpice

·         Agricultural pollution (HIGH)

·         Urban pollution (HIGH)

·         Loss of riparian cover (HIGH)

·         Dams (HIGH)

·         Commercial bait fishing (UNKNOWN)

Lake St. Pierre archipelagoStable?Sainte-Anne-de-Sorel, Saint-Ignace-de-Loyola, Du Moine Island.

·         Agricultural pollution (HIGH)

·         Wave action from boats (MODERATE)

·         Decrease in water levels (MODERATE)

·         Commercial bait fishing (UNKNOWN, PRESUMED LOW)

Lake St. PierreStable?North and south shores of the lake.

·         Agricultural pollution (HIGH)

·         Wave action from boats (MODERATE)

·         Decrease in water levels (MODERATE)

·         Commercial bait fishing (UNKNOWN, PRESUMED LOW)

Other Waterbodies:   
Lake of Two MountainsExtirpated?Anse à l’Orme and Sainte-Marthe-sur-le Lac.

·         Agricultural pollution (LOW)

·         Urban pollution (MEDIUM)

·         Loss of riparian cover (LOW)

·         Dams (LOW)

·         Wave action from boats (MEDIUM)

·         Exotic or invasive species (UNKNOWN)

·         Commercial bait fishing (UNKNOWN)

Châteauguay RiverStable?Near Mercier and between Châteauguay and Athelstan.

·         Agricultural pollution (HIGH)

·         Urban pollution (HIGH)

·         Loss of riparian cover (HIGH)

·         Dams (HIGH)

·         Modification of hydrology (HIGH)

·         Agricultural land use (MEDIUM)

·         Wave action from boats (NULL)

·         Decrease in water levels (HIGH)

·         Exotic or invasive species (UNKNOWN)

·         Commercial bait fishing (UNKNOWN, PRESUMED MODERATE)

Trout RiverStable? 

·         Agricultural pollution (HIGH)

·         Urban pollution (LOW)

·         Loss of riparian cover (HIGH)

·         Dams (MEDIUM)

·         Modification of hydrology (HIGH)

·         Agricultural land use (MEDIUM)

·         Wave action from boats (NULL)

·         Decrease in water levels (LOW)

·         Exotic or invasive species (UNKNOWN)

·         Commercial bait fishing (UNKNOWN)

 

Table 3 (Con’t.)

 

SystemStatusDistributionThreats (severity rank*)
Richelieu RiverStable?Between McMasterville and the mouth of the Saint-Marc River; in the Chambly Basin; and in Missisquoi Bay.

·         Agricultural pollution (HIGH)

·         Urban pollution (HIGH)

·         Loss of riparian cover (HIGH)

·         Dams (LOW)

·         Modification of hydrology (LOW)

·         Wave action from boats (MODERATE)

·         Decrease in water levels (NULL)

·         Exotic or invasive species (UNKNOWN)

·         Commercial bait fishing (UNKNOWN, PRESUMED MODERATE)

Yamaska RiverExtirpated?Between the mouth and Hugues Rapids.

·         Agricultural pollution (HIGH)

·         Urban pollution (HIGH)

·         Loss of riparian cover (HIGH)

·         Dams (NUL)

·         Modification of hydrology (HIGH)

·         Agricultural land use (pâturages) (HIGH)

·         Exotic or invasive species (UNKNOWN)

·         Commercial bait fishing (UNKNOWN, PRESUMED MODERATE)

L’Assomption RiverStable?L’Assomption and Joliette.

·         Agricultural pollution (HIGH)

·         Loss of riparian cover (HIGH)

·         Modification of hydrology (HIGH)

·         Commercial bait fishing (UNKNOWN)

Ouareau RiverStable?Crabetree

·         Agricultural pollution (LOW)

·         Dams (HIGH)

·         Commercial bait fishing (UNKNOWN)

Saint-François RiverExtirpated?Notre-Dame-de-Pierreville

·         Agricultural pollution (HIGH)

·         Urban pollution (HIGH)

·         Loss of riparian cover (HIGH)

·         Commercial bait fishing (UNKNOWN)

Yamachiche RiverUnknown?Near the mouthThreats unknown in this river.
Bécancour RiverUnknown? 

·         Agricultural pollution (HIGH)

·         Loss of riparian cover (HIGH)

·         Commercial bait fishing (UNKNOWN)

Gentilly RiverUnknown?Bécancour

·         Agricultural pollution (HIGH)

·         Urban pollution (HIGH)

·         Loss of riparian cover (HIGH)

·         Commercial bait fishing (UNKNOWN)

Orignaux RiverUnknown?Rivière-aux-OrignauxThreats unknown in this river.
Du Chêne RiverUnknown? Threats unknown in this river.

1.5.2   Description of Threats

a) Agricultural pollution:

Nutrient loading (N, P) – In Quebec, the eastern sand darter is mostly found in the St. Lawrence River and its tributaries between Lake of Two Mountains and Leclercville.  The expanding hog industry in this region, both in terms of number of animals and in land size to meet its needs, represents one of the most significant threats to aquatic wildlife and its habitats.  The excessive use of fertilizers is the main consequence resulting from this industry, impacting fish habitats by the eutrophication of the streams.  The excessive growth of aquatic plants, algae, or periphyton reduces the amount of oxygen found in the water, which threatens benthic species such as the eastern sand darter (FAPAQ 2002).

Use of pesticides–Hog production is closely linked to corn farming since it is part of the hog diet.  Corn farming in Quebec has increased since 1970 and now covers over 436 000 ha, mostly in the Montérégie area.  This type of farming uses the largest proportion of commercial pesticides and herbicides in Quebec, a non-point source of pollution that alters water quality in the rivers in the southern part of the province where populations of eastern sand darter are found (FAPAQ 2002).

b) Urban and industrial pollution:

Untreated wastewater disposal Resource development and exploitation along with urbanization are at the heart of several sources of pollution.  The presence of urban and industrial pollutants in aquatic environments leads to decreased water quality and dissolved oxygen and can have a negative impact on different stages of a fish’s life cycle.  Wastewaters from cities, textile factories, pulp and paper mills and from mines contain several chemicals such as heavy metals (i.e. lead and mercury), chlorinated hydrocarbons (i.e. DDT and PCBs) and polycyclic aromatic hydrocarbons (i.e. benzopyrene).  Some of these chemicals harm the endocrine systems of organisms exposed to this wastewater and cause malformations, as well as reproductive and development problems in many fish species (i.e. white sucker (Catostomus commersonii), copper redhorse (Moxostoma hubbsi), whitefish (Coregonus clupeaformis) (Jobling and Tyler 2003; cited in de Lafontaine et al. 2002, Environment Canada 2006).

Thermal pollution – Urban activities also represent a source of thermal pollution.  This problem may be caused by factories (e.g. refineries, steel plants) using water circuits to cool certain installations and dispose of this water, which is sometimes high in temperature, into the rivers.  With higher temperatures, the metabolic reactions of the organisms present in the area are accelerated, as long as the water remains within the organism’s zone of tolerance.  If the temperature rises above the critical threshold, metabolic reactions slow down.  Although the specific critical threshold for eastern sand darter is not known, in most percid species, it is relatively low and usually varies between 30°C and 38°C (Lydy and Wissing 1988, Smith and Fausch 1997, Beitinger et al. 2000).  Thermal effects on fishes can be lethal but are also likely to impact their behaviour (i.e. migration), their metabolism (i.e. oxygen consumption), reproduction (i.e. reproductive success), their embryonic and larval development, feeding (i.e. deterioration of food sources) and their growth (Beitinger et al. 2000).

The eastern sand darter is considered to be intolerant to pollution (Barbour et al. 1999).  It has possibly been extirpated from two highly polluted rivers, the St. François and Yamaska rivers, and it’s status is not definitively known in two other polluted rivers (Assomption and Richelieu).  As with most other percid species, urban or industrial pollutants could affect eastern sand darter populations (Holm and Mandrak 2000, Grandmaison et al. 2004, Gaudreau 2005, NatureServe 2006).  Scott and Crossman (1973) mentioned that it is unlikely that the eastern sand darter will survive very long due to the environmental assaults from highly industrialized areas such as Montreal.

c) Loss of riparian cover: Riparian strips play a significant role in protecting the quality of water in agricultural areas.  These strips slow and catch particles running off on the ground surface as well as keeping the soil in place while protecting the banks from surface erosion.  Deforestation and the disappearance of riparian strips in order to increase crop acreage and corn farming lead to higher water temperatures but also increased runoff, sedimentation and nutrient enrichment in streams and rivers likely to effect eastern sand darter habitats (FAPAQ 2002, Vachon 2003).  Excessive siltation can smother deposited eggs, reduce available substrate oxygen and adversely affect prey abundance (Holm and Mandrak 1996).  Eastern sand darter populations in Vermont and New York have benefited from decreased silt loads as a result of reforestation of stream slopes (Daniels 1993).

  d) Dam construction: The construction of a dam changes the stream flow by transforming a lotic environment into a lentic environment.  When the current’s speed is slowed or eliminated, sedimentation increases.  In addition, dams increase sedimentation by mitigating spring freshets.  In Quebec, certain rivers harbouring eastern sand darter populations are harnessed, such as the Ouareau, Richelieu and Yamaska rivers (Holm and Mandrak 2000, Grandmaison et al. 2004, Gaudreau 2005, NatureServe 2006).  The presence of dams could also lead to the fragmentation of eastern sand darter populations.  Small, increasingly isolated populations may suffer inbreeding effects and a loss of genetic variability that could impair their ability to respond to changing environmental conditions.

e) Stream channelization and changes to natural flow regimes:In Quebec, nearly 40,000 km of streams have been straightened to increase agriculture production.  These interventions involve uniformity and commonality of streams as well as changing their hydrologic regime.  After a rainfall or during the spring snowmelt, flow velocity increases and can cause banks to collapse and shores to erode more rapidly (FAPAQ 2002).  Shore erosion combined with eroding fields (i.e. ploughed land) or from tile drainage brings fine particles to the streams that choke the bottoms of streams and rivers.  Furthermore, the straightening of streams changes the physical process leading to the formation of sand banks, often associated with the occurrence of eastern sand darter (FAPAQ 2002, Gaudreau 2005).  Tile drainage is a serious threat to eastern sand darter in southwestern Ontario, as it speeds up the surface and subsurface water flow into drains, causing even greater erosion of drains or channels created under the Drainage Act.  The Drainage Act itself is a major impediment to restoration as it is a very powerful but archaic piece of legislation, designed to remove water at the expense of soil and water quality throughout a watershed.  Activities that alter channel structure and flow conditions, as to interfere with sand deposition and erosion, are likely associated with the decline of the eastern sand darter (Dextrase et al. 2003). 

In lakes Erie and St. Clair, eastern sand darter have been collected from nearshore habitats such as wave-protected sandy beaches, sandy shores and shallow bays (van Meter and Trautman 1970, Thomas and Haas 2004). Shoreline hardening has affected natural erosion processes and, thereby, altered nearshore sediment transport (Edsall and Charlton 1997).  Disruption of sediment transport and deposition processes may reduce the availability of nearshore habitats with suitably sized sand.  However, as nearshore Great Lakes ecosystems and associated impacts of shoreline alteration are poorly understood (Goforth and Carman 2003), it is difficult to assess the severity of this stressor.     

  f)  Riparian pastures: Some agricultural practices accelerate silting and increase turbidity in streams.  Grazing and treading of riparian vegetation by livestock destroy its buffering ability, increases bank erosion and the silting of streams while returning sediments to suspended matter (FAPAQ 2002, Vachon 2003).

g) Wave action from boats: Waves hitting the shores of a stream as a result of passing boats can cause bank erosion.  On the St. Lawrence River, high tonnage vessels erode the banks and accelerate silting (Gaudreau 2005).  In the St. Lawrence River freshwater reach, where the eastern sand darter lives, wave action from boats is estimated to push back banks up to 3 m per year.  The impact of smaller pleasure boats in smaller rivers and streams is also considerable.

h) Lower water levels in the St. Lawrence River:Fluctuating water levels in the St. Lawrence River stem from the combined action of several natural factors (e.g. climate and climatic variations), but also from human intervention.  The flow of the river is influenced by water control works used principally to limit spring flooding, facilitate commercial shipping and generating hydroelectric power.  The construction of the St. Lawrence Seaway also brought about considerable changes in flow.  Dredging of the shipping channel and shoals, which concentrates the flow in the main channel and reduces current speed in the shallows, has had an ongoing effect on water levels.

Species residing in the shallows such as the eastern sand darter could be considerably affected by the lower water level issue in the St. Lawrence River.  The loss of sand banks could result in reduced habitat area for this species (Gaudreau 2005).

i) Exotic or invading species: Round goby, an introduced species, can cause considerable harm in North American aquatic ecosystems.  Since its discovery in the St. Clair River in 1990, this species has quickly colonized the Great Lakes and spread to the St. Lawrence River (Bernatchez and Giroux 2000).  In 2000, the round goby had only been observed in a few locations in the St. Lawrence, particularly in the area of Quebec.  It is now very widespread in the river and even overlaps the distribution of eastern sand darter in some areas.  A single specimen was caught by a sport fisherman in the St. Lawrence River in the vicinity of Longueuil, close to Montreal, in 2004 (M. Bernard, MRNF, pers. comm.).  In Lake St. Pierre, sampling indicated that the round goby is very widespread in the lake, at depths greater than 2 m, but is not very abundant in shallower habitats.  It was associated with johnny darter (Etheostoma nigrum), with which it may compete as has been shown in the Great Lakes (French and Jude 2001, Baker 2005, Y. Mailhot, pers. comm.).  Round goby can supplant indigenous fishes through predation on eggs and young as well as through competition for habitat and food. The round goby also spawns several times throughout the summer and is tolerant of polluted waters; these characteristics may give it a competitive edge over native species.  This is a benthic species that, once established, could have a direct impact on darter species (Bernatchez and Giroux 2000).

 The ranges of the eastern sand darter and round goby overlap in Lake St. Clair (since 1993), the lower Thames River, and Lake Erie (since 1996). Since its introduction into the lower Great Lakes, the round goby has been implicated in the following declines of native benthic fish species: logperch (Percina caprodes) and mottled sculpin (Cottus bairdii) populations in the St. Clair River (French and Jude 2001); johnny darter, logperch and trout-perch (Percopsis omiscomaycus) in Lake St. Clair (Thomas and Haas 2004); and, channel darter (Percina copelandi), fantail darter (E. flabellare), greenside darter (E. blennioides), johnny darter, and logperch in the Bass Islands of western Lake Erie (Baker 2005).  Potential causes of these declines include goby predation on eggs and juveniles, competition for food and habitat, and interference competition for nests (French and Jude 2001, Janssen and Jude 2001).  The impacts of the round goby on eastern sand darter populations have not been studied.

NatureServe (2005) suggests that lampricide use for sea lamprey control could impact populations in Lake Erie and Lake Champlain.  However, the eastern sand darter has been shown to be moderately tolerant of stream lampricide treatments (3-trifluoromethyl-4-nitrophenol (TFM)) at routine treatment concentrations based on a series of TFM toxicity studies (Neuderfer 1987, 2000, MacKenzie 1991, 1995; cited in U.S. Fish and Wildlife Service 2001).

 j ) Commercial bait fishing:A study on the assessment of commercial bait fishing on five vulnerable fish species was conducted in the fall of 2005 in nine regions in Quebec (i.e. Centre-du-Québec, Chaudière-Appalaches, Lanaudière, Laurentians, Laval, Mauricie, Montérégie, Montreal and Outaouais) (Boucher et al., 2006).  There were no eastern sand darter in the fall catches during the sampling campaign.  The particular morphological characteristics of this species make it easily identifiable for fishermen.

Although the fishing sites, especially in the Richelieu River, cross over the species’ known distribution area, eastern sand darter was not caught by harvesters.  This was likely a result of the fishing practices used during this period, as well as the rarity of the species.  However, the spring and summer fishing seasons have not been monitored, consequently, it is difficult to assess the risk of capture for these two periods.  In spring and summer, harvest sites are much more varied, and the likelihood that they will cross over eastern sand darter habitats is probably high (Boucher et al., 2006) .

The eastern sand darter is not a legal baitfish in Ontario (Cudmore and Mandrak 2005) and its habitat is not suitable for bait harvesting.  The extent to which eastern sand darter are a by-catch of bait harvesting in Ontario is unknown; however, at an expert opinion workshop held in Ontario indicated that the probability of baitfish harvesting impacting Ontario eastern sand darter populations was low but the magnitude would be high (N. Mandrak, DFO, pers. comm.).

It has been suggested that native darter species are becoming increasingly popular in the international aquarium business, especially in New York (McKeown and Stegemann 1999); however, it is not known if this is a significant threat in Ontario.