Spotted gar (Lepisosteus oculatus) COSEWIC assessment and status report: chapter 5

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Habitat

Habitat requirements

Adult spotted gar prefer quiet, vegetated, shallow (0-5 m) clear waters of lakes and rivers (Carlander 1969, Scott and Crossman 1998, Lee et al. 1980, Lane et al. 1996b, Page and Burr 1991, Snedden et al. 1999, Coker et al. 2001, Cudmore-Vokey and Minns 2002). The adults are generally found over silt and clay (but often sand) substrates (Lane et al. 1996b).  Snedden et al. (1999) described in detail the spotted gar habitat in Louisiana, noting that submerged branches, fallen trees or log complexes provided diurnal resting cover. The structurally complex shallow water habitat preferred by the spotted gar is probably related to its foraging tactics. Vegetation around which spotted gar were found in Oklahoma included primarily Polygonum, Potamogeton, Myriophyllum, and Justicia (Tyler and Granger 1984).

Nursery habitat consists of the top meter of water in the spring (1-2 m in fall) over sand, silt, or clay substrate. Areas of dense submergent and emergent vegetation are preferred (Simon and Wallus 1989, Lane et al. 1996a, Cudmore-Vokey and Minns 2002).

Spawning habitat consists of shallow water (0-1 m) with aquatic vegetation, brush or debris (Scott and Crossman 1998, Lee et al. 1980, Lane et al. 1996c) in quiet areas (Simon and Wallus 1989) such as flooded riparian areas (Snedden et al. 1999).

Trends

As the result of the lack of historical data, there is little information on changes in habitat in areas where spotted gar have been recorded. Aquatic vegetation appears to vary with lake water levels. During the 1980s aquatic vegetation had declined significantly due to increased water levels; however, an increase in aquatic vegetation cover in Rondeau Bay has recently occurred following a decrease in water levels, and also as a result of increased water clarity due to the invasion of dreissenid mussels (S. Dobbyn, OMNR, pers. comm.). This may have resulted in an increase in the amount of habitat preferred by spotted gar. However, vegetation removal programs carried out in Rondeau Harbour may offset any positive effect in the harbour area (Dobbyn, pers. comm.). At Point Pelee, the period between breaching events (breaching of the barrier beaches) has increased as a result of declining lake water levels. As a result water quality (e.g. DO levels) has declined and turbidity increased (H. Surette, University of Guelph, pers. comm.). Increased turbidity may limit the ability of the spotted gar to sight feed.

Protection/ownership

In Canada, the spotted gar occurs in publicly owned waters, and all fish habitat within these waters is protected by the federal Fisheries Act. In addition, it is found in Point Pelee National Park, Rondeau Provincial Park, and Long Point Bay, which has both a provincial park and a national wildlife area. Therefore, its habitat receives additional protection afforded to national wildlife areas through the Canada Wildlife Act, and national and provincial parks through the Canada National Parks Act and Ontario Provincial Parks Act. As a Threatened species listed in Schedule 1 of the federal Species at Risk Act, the spotted gar and its residence are protected; however, its critical habitat is yet to be protected under the Act.