Temperature Requirements of Some Percids and Adaptations to the Seasonal Temperature Cycle
Authors: Hokanson Kenneth E. F. 
Published: April 2011

Temperature requirements are reviewed for three North American percids (walleye, Stizostedion vitreum vitreum; sauger, S. canadense; and yellow perch, Perca flavescens), three Eurasian percids (perch, P. fluviatilis; pikeperch, S. lucioperca; and ruffe, Gymnocephalus cernua), and nine cohabitant fish species for comparison. Whole-organism responses are described for each species — primarily concerning reproduction, growth, survival, and activity. The percids are classified as temperature mesotherms and they are arranged in order of their thermal requirements as follows: pikeperch > perches and ruffe > sauger > walleye. Perca and Stizostedion spp. are annual spawners with synchronous oocyte growth during fall through winter, culminating in spring spawning. Maturation occurs below 12 °C. Spawning occurs from late February through early July at 2–26 °C over their geographic ranges. Oocyte growth of ruffe is asynchronous, accelerated by warm temperatures; batch spawning occurs over a prolonged period, from mid-April through July at 11–18 °C. Physiological optima range from 22 °C for sauger and walleye to 25 °C for perch and 27 °C for pikeperch. The ultimate upper incipient lethal temperatures of percids range from 29 to 35 °C, depending on species and experimental conditions.Percid life phases are uniquely adapted to the seasonal temperature cycle of a temperate climate. The maturation limit (10 °C) for Perca spp. approaches the minimum winter temperature in lowermost latitudes of their distribution. Increasing temperature requirements of successive early life phases show how percids adapt to the spring spawning period. Spawning begins in a temperature range that optimizes gamete viability. Temperature has little effect on duration of the phases of gonad maturity in Perca and Stizostedion spp. These fishes adapt to different temperature regimens by shifting spawning temperatures, while spawning time changes only slightly, sometimes at the expense of gamete viability. Greater differences in spawning time observed at geographical extremities of their range are believed to be due to longer term adaptations that determine time of first maturity rather than adaptations of the adult maturation cycle. Ruffe are more adaptable, spawning several batches of ova under favorable environmental conditions. Summer distributions of Perca spp. lie between the 16 and 31 °C isotherms. These values represent the lower limit to normal maturation of adults and growth of young and the upper temperature for zero net biomass gain, respectively. Only maximal temperatures in lower latitudes approach the ultimate upper incipient lethal temperature of a species. Fish adapt to different thermal characteristics by changes in their avoidance/preference response, diel activity cycles, and seasonal migrations. No uniform mechanism of population regulation or resiliency is apparent for different acclimatization conditions. Therefore, management regulations for a given species should not be universally applied throughout its geographic range. Key words: Percidae, temperature requirements, adaptations, seasonal temperature cycles, Perca, Stizostedion, Gymnocephalus, temperature classification, literature synthesis