By James M. Haynes, David C. Nettles, Kevin M. Parnell, Michael P. Voiland, Robert A. Olson, Jimmy D. Winter
Journal of Great Lakes Research, Volume 12, Issue 4, 1986, Pages 304-313, ISSN 0380-1330, DOI: 10.1016/S0380-1330(86)71730-9.

To examine movements of rainbow/steelhead trout (Salmo gairdneri) and associated environmental influences, 28 fish were radiotagged in and near a tributary of Lake Ontario during spring spawning runs in 1981 and 1982. Trout initially entering the lake from the tributary generally exhibited east-west reversals of movement along the southern shore of Lake Ontario before dispersing off shore. Seasonal movement rates averaged 3.2 +/- 1.6km/d over periods of 6-94 d; mean short term rates were 0.50 +/- 0.46 km/h. Temperatures occupied in the lake were 9.1 +/- 1.5[degree sign]C; temperatures at which fish were last observed were 9.8 +/- 3.8[degree sign] C. Movements offshore and ultimate disappearances occurred from April to July, but were most pronounced when temperatures near shore exceeded 10[degree sign] C. By linking trout movements to seasonal thermal structure in Lake Ontario, a testable hypothesis was established to explain the distribution of rainbow trout in spring and early summer. Based on tracking data, information provided by south shore anglers, and literature on the physical limnology of Lake Ontario, we hypothesize that rainbow trout disperse off shore in spring with thermal fronts, particularly the 6-8[degree sign] C zone known as the spring thermocline.
Keywords: Fish migration; fish behavior; thermal bar; thermal stratification

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