TROUT-PERCH Percopsis omiscomaycus Walbaum 1792 (Percopsidae) Global rank G5 (20Sep1996) State rank S3 (20Sep1996, reviewed 02May2006) State rank reasons Distribution restricted to mainstream Yukon River; range extension from Porcupine River relatively new. Considered rare; population trend Photo credit: Ohio Dept. of Natural Resources unknown. Habitat is mostly pristine; threats are minimal and include water pollution and 1963). Large females and most males die after diversion. spawning, but some individuals live to spawn twice. Males begin to mature their second Taxonomic comments summer and can live to be three years; females The family Percopsidae, found only in North mature a year later and live up to four years America, contains two species: the trout-perch, (Magnuson and Smith 1963, McPhail and Percopsis omiscomaycus and the sand roller, P. Lindsey 1970, Scott and Crossman 1973, Muth transmontana. 1975, Morrow 1980). General description Ecology A small thick bodied fish with a large head, long An important prey item for lake trout (Salvelinus snout and small mouth. Generally silvery to namaycush), walleye (Stizostedion vitreum), transparent in color. Five distinct rows of dark northern pike (Esox lucius), sauger (Sander spots along the sides and back. Dorsal and anal canadensis), yellow perch (Perca flavescens) and fins have weak spines. Teeth are small and in others. Important nutrient transporters in brush-like bands (Scott and Crossman 1973). thermally stratified lakes due to their habit of feeding at night in the shallows and moving to Diagnostic characteristics deeper waters during the day where they are Trout-perch share characteristics with both trout eaten by larger fishes confined to cooler depths. and perch families. Individuals have an adipose This species hosts a wide variety of parasites fin like trout; however they have spines in some (forty-two species reported), including fins and superficially resemble members of the trematodes, cestodes, nematodes, perch family. Distinguished from all other acanthocephalans, and crustaceans; it is the Alaskan fish by the combination of ctenoid most important second intermediate host of the scales, weak spines in the dorsal and anal fins, cestode, Triaenophorus stizostedionis (McPhail long pectoral fins, and presence of an adipose and Lindsey 1970, Scott and Crossman 1973, fin. Alaskan fish are rarely more than 8 cm in Morrow 1980, Nelson and Dick 2002). length (Morrow 1980, Mecklenburg et al. 2002). Length (cm) 7.5 to 10.0 The only percopsid found in Alaska. This species Weight (g) 3-7 likely invaded the Yukon River relatively recently via the Peel and Porcupine rivers. Reproduction Usually spawns in spring, but spawning may Migration extend into late summer in some lakes. Most Moves from deep to shallow water to spawn spawners are age I or II (Scott and Crossman (Morrow 1980); lake populations often spawn in 1973, Becker 1983). Spawning generally takes streams in spring and return to lake after place at night, near the water surface, and near spawning (Scott and Crossman 1973). the edge of slow streams or along lake beaches. Several males cluster around and press close to Food the sides of the female. Eggs and milt are Young feed on zooplankton to a greater extent released simultaneously. A single female can lay than adults, which feed on insects, crustaceans, up to 700 eggs. Eggs are adhesive and hatch in and other invertebrates, which are mainly benthic about 6 days at 20 to 23˚C (Magnuson and Smith species. Larger individuals may feed on fishes in State trends winter (Scott and Crossman 1973, Becker 1983). Unknown. Habitat Global protection Typically occurs in lakes but also found in deep Unknown. However, species is too small to be flowing pools of creeks and small to prized by anglers; therefore, generally managed large rivers; usually over sand substrate (Page as a non-game species. Yellow listed in B.C. due and Burr 1991). Normally in deep waters by day, to restricted distribution, although not considered moves into shallows at night (Becker 1983). at risk (Trout-perch 1999). Spawns in shallow rocky or gravelly streams or over sand, gravel bars, or rocks in lakes. Often State protection spawns in streams in spring and returns to lake Habitat receives protection where species occurs after spawning. within Arctic, Nowitna, Koyukuk, Innoko, and Yukon Delta National Wildlife Refuges and in In Alaska, key habitats are slow moving portions Yukon-Charlie Rivers National Preserve (USFWS of the mainstream Yukon River (ADFG 2005). 1994, USFWS 2004 a, b, USFWS 2005a, b, c). Global range Global threats Atlantic and Arctic basins throughout most of Trout-perch are especially sensitive to aquatic Canada from Quebec to Yukon and British pollution and sedimentation associated with row Columbia and south to the Potomac River crop agriculture and channelization (Pflieger drainage, Virginia; Yukon River drainage, 1997). Fish exposed to pulp mill effluent on the Yukon and Alaska; Great Lakes and Mississippi Kapuskasing River, Ontario, showed a change in River basins south to West Virginia, age structure that was likely driven by an eastern Kentucky, southern Illinois, central increase in mortality (Gibbons et al. 1998). May Missouri, North Dakota, and northern also be temperature sensitive; summer die-offs in Montana; locally common in lakes, uncommon Minnesota lakes have been attributed to higher throughout most of range (Page and Burr 1991). than average temperatures (Eddy and Underhill 1974). A marked decline in the Red Deer River, State range Alberta trout-perch population was attributed to Mainstream Yukon River from the mouths of the the impacts of a dam built there (Nelson pers. Tatonduk, Kandik, and Charlie Rivers comm. in Bramblett 2005). downstream at Circle and Nulato, at the mouth of the Andeafsky River, and at the outer edge of the State threats Yukon Delta at the mouths of Apoon Pass, Habitat within Alaska is generally in good Elongozhik Pass, and Bugomowik Pass. Also condition, but water diversion, impoundment and occurs in the Porcupine River, just upstream from pollution are potential threats within the Yukon the Canadian border (Morrow 1965, McPhail and River drainage. May also be sensitive to rising Lindsey 1970, Scott and Crossman 1973, Morrow water temperatures as a result of climate change; 1980, Mecklenburg et al. 2002). summer die-offs in Minnesota have been attributed to higher than average water Global abundance temperatures (Eddy and Underhill 1974). Relatively abundant within its range in Canada Conversely, trout-perch could also be positively and the lower 48 states (Mecklenburg et al. affected by climate change and warming 2002). In Heming Lake, Manitoba, the adult fish temperatures since this species currently thrives population was estimated at 2,929 to 3,636 fish in milder climates. per hectare (Morrow 1980). State research needs State abundance Information needed on basic life history including Rare; captured intermittently (Morrow 1980, reproductive biology, population age structure 1965, Mecklenburg et al. 2002). This species is and habitat preferences. Migration patterns not probably still expanding its range in the Yukon well understood, needs study (ADFG 2005). River system (McPhail and Lindsey 1970). State inventory needs Global trends Distribution information is likely incomplete. Unknown. Monitor local populations at index sites to provide Trout-perch 2 information on population trends. Map current American Fisheries Society. Bethesda, MD. distribution and other similar habitats for future 1,037 pp. investigation (ADFG 2005). Morrow, J. E. 1965. First record of the trout- State conservation and management needs perch, Percopsis omiscomaycus, from Develop a network of biologists to establish Alaska. Copeia 1965 No. 2, p.232. unified protocols for sampling trout-perch and other fish species with similar habitat needs Morrow, J. E. 1980. Freshwater fishes of Alaska. (ADFG 2005). Alaska Northwest Publishing Company, Anchorage, AK. LITERATURE CITED Muth, S. E. 1975. Reproductive biology of the Alaska Department of Fish and Game (ADFG). Trout Perch, Percopsis omiscomaycus 2005. Trout-perch. In: Our wealth maintained: (Walbaum), in Beech Fork of Twelvepole a strategy for conserving Alaska’s diverse Creek, Wayne County, West Virginia. wildlife and fish resources, a Comprehensive American Midland Naturalist 93: 434-439. Wildlife Conservation Strategy emphasizing Alaska’s nongame Nelson, P. A. and T. A. Dick. 2002. Factors species. Anchorage, AK. shaping the parasite communities of trout- perch, Percopsis omiscomaycus Walbaum Becker, G. C. 1983. Fishes of Wisconsin. Univ. (Osteichthyes:Percopsidae), and the Wisconsin Press, Madison. 1,052 pp. importance of scale. Can J. Zool. 80: 1986- 1999. Bramblett, R.G. 2005. Trout-perch. Montana’s fish species of special concern. American Page, L. M., and B. M. Burr. 1991. A field guide Fisheries Montana Chapter. Available online to freshwater fishes: North America north of at: Mexico. Houghton Mifflin Company, Boston, http://www.fisheries.org/AFSmontana/SSCpa MA. 432 pp. ges/Trout-perch.htm. Accessed 9/23/05. Eddy, S., and J. C. Underhill. 1974. Northern Pflieger, W. L. 1997. The fishes of Missouri. fishes. University of Minnesota Press, Missouri Department of Conservation, Minneapolis, MN. Jefferson City, MO. Gibbons, W. N., K. R. Munkittrick, M. E. McMaster, and W. D .Taylor.1998. Monitoring Scott, W. B., and E. J. Crossman. 1973. aquatic environments receiving industrial Freshwater fishes of Canada. Fisheries Res. effluents using small fish species 2: Bd. Canada, Bull. 184. 966 pp. comparison between responses of trout- perch (Percopsis omiscomaycus) and white sucker (Catostomus commersoni) Trout-perch. 1999. B.C. Fish Facts. Conserv. downstream of a pulp mill. Environmental Sect., Fish. Manage. Branch, B.C. Minist. Toxicology and Chemistry 17: 2238-2245. Fish. 2 pp. Magnuson, J. J. and L. L. Smith. 1963. Some U. S. Fish and Wildlife Service (USFWS). 1994. phases of the life history of the trout-perch. Fisheries investigations on the Kandik, Ecology 44: 83-95. Charley, Nation, and Tatonduk Rivers, Yukon-Charley Rivers National Preserve, McPhail, J. D. and C. C. Lindsey. 1970.