Growth of Underyearling Sockeye Salmon (Oncorhynchus nerka) under Constant and Cyclic Temperatures in Relation to Live Zooplankton Ration Size

Abstract

Growth rates of Babine Lake underyearling sockeye salmon (Oncorhynchus nerka) fed rations of zooplankton of 14–84 cal/kcal sockeye∙d−1 (1 cal = 4.1868 J; 1.3–7.8% of dry body wt) were determined at constant temperatures of 6.2, 11.3, 15.3, and 15.9 °C, and under a cyclic temperature regime similar to that encountered during their diel vertical migrations. Growth of fish fed rations of 43–76 cal/kcal∙d−1 (4.0–6.9% of dry body wt) was equal or greater under cyclic temperatures than constant temperatures. At the lowest and highest rations growth was greater, respectively, under the constant low temperature and the constant high temperature than under cyclic temperatures. Gross growth efficiency, ranging from < 1 to 31%, was affected by temperature and ration in much the same way as growth. Young sockeye ingesting moderate rations comparable to those probably available in the relatively warm surface layers of Babine Lake, and undergoing diel migrations from deep cold waters to the surface, and return, are likely to grow more rapidly and efficiently than fish maintained at constant temperatures. The selective value of vertical migrations in thermally stratified waters may have an energetic basis as suggested by some other workers.Key words: sockeye salmon, growth rate, conversion efficiency, diel vertical migration, temperature, zooplankton ration, diel cyclic temperature

Growth, growth efficiency, and assimilation efficiency of the Tahoe sucker in cyclic and constant temperature

“…Under cyclic conditions, growth rates were shown to be enhanced (Brett 1971, Hokanson et al 1977, Biette & Geen 1980, Diana 1984 or not affected (Wurtsbaugh 1973, Medvick 1979, Cox & Coutant 1981. In those studies where growth was enhanced in cyclic regimes, the fishes exhibited faster growth rates only under certain conditions (Hokanson et al 1977, Biette & Geen 1980, Diana 1984. We suggest that Tahoe sucker do not exhibit faster growth rates in the cycling temperature reglme because they are unable to behav~orally thermoregulate in their temporally isothermal environments.…”

“…Specific growth rate (SG = G x 100) was calculated (Biette & Geen 1980), where G = instantaneous growth calculated as the difference between the natural logarithms of the final and initial wet weights divided by the number of days in the experiment (Ricker 1975). Gross growth efficiency is the ratio of growth to total food ingested (BIC x loo), where B is the change in biomass in grams and C is the ration in grams (Biette & Geen 1980).…”

“…Gross growth efficiency is the ratio of growth to total food ingested (BIC x loo), where B is the change in biomass in grams and C is the ration in grams (Biette & Geen 1980). We report gross growth efficiency only for the temperature-ration conditions at which the fish exhibited positive growth.…”

“…McLaren (1963) proposed that marine invertebrates could partition more energy to growth by feeding in the surface waters and assimilating the food in the cooler deeper waters. Brett (1971), Swift (1976), Enright (1977), and Biette & Geen (1980) have modified McLaren's hypothesis and have assumed that feeding rates are stimulated at higher temperatures and that although total metabolic rate and assimilation vary directly with temperature, the decline in assimilation is less responsive to temperature. These investigators focused on species that behaviorally thermoregulate (by vertical migration).…”

Lake Roosevelt Fisheries Evaluation Program, Part C; Lake Roosevelt Pelagic Fish Study: Washington Department of Fish and Wildlife, 1998 Annual Report.

“…Temperatures above the growth and/or consumption optimum may have forced fish into deeper water, but we were not able to identify negative impacts of this change in distribution. In fact, salmonids can increase their growth rate by moving between optimal and sub-optimal temperature regimes, depending on the availability of forage (Biette and Geen 1980). If growth rates or available forage decrease in the future we may want to reconsider temperature and other abiotic environmental conditions as possible limiting factors to pelagic fish production.…”