Behavior of juvenile bluefish Pomatomus saltatrix in vertical thermal gradients: influence of season, temperature acclimation and food

Abstract

Behavioral responses of juvenile bluefish Pomatomus saltatrixl. exposed to cold water in a vertical thermal gradient were measured under controlled laboratory conditions. The temperature regime was similar to conditions that these fish encounter in their inshore and estuarine habitats along the Middle Atlantic coast. Measures included activity, schooling, position with respect to depth and temperature, and feeding. Bluefish, acclimated to 20 or 14 'C, avoided cold water as it was introduced into the experimental aquarium by initially increasing swimming speed and shifting their distribution upward in the water column. Fish with a similar thermal history were distributed into progressively colder water from August through November, reflecting a predisposition for lower temperatures. This change in behavioral response to temperature coincided with this species' southerly fall migration. When food was presented at potentially debilitating temperatures which were normally avoided, motivation to feed modified their avoidance response, with the fish entering these temperatures and successfully feeding. Results are discussed in relation to natural patterns of migration and distribution.

External and internal grouping characteristics of juvenile walleye pollock in the Eastern Bering Sea

“…Laboratory studies have demonstrated that older juveniles swam into cold water to feed and/or avoid predation, whereas younger fish did not (Olla and Davis, 1990;Sogard and Olla, 1993). Avoidance of colder water by age-1 juveniles is likely related to their lower tolerance to thermal change as a function of body size (Olla et al, 1985;Olla and Davis, 1990;Sogard and Olla, 1993). Ressler et al (2014) found that euphausiid density was higher in areas of the Bering Sea with cooler bottom temperatures, which were corroborated by our study results.…”

Interaction between the vertical distribution of juvenile walleye pollock Theragra chalcogramma in the eastern Bering Sea, and cannibalism

“…Several experimental studies have indicated an interaction between food deprivation and temperature preference in fishes (Ehrlich et al 1979, Olla et al 1985. In general, vertical migration is efficient energetically if the cost of migration is less than the energy saved from being in waters of lower temperature where their metabolic demands are less (Brett & Groves 1974).…”

Temperature magnified postcapture mortality in adult sablefish after simulated trawling

“…While there is a plethora of information on the effects of temperature on a number of fish species (e.g. Fry, 1967;Brett, 1970;Olla et al, 1985) little is known about how this factor may interact with capture stressors. Sablefish Anoplopoma fimbria Pallas is a highly valued species that is the subject of an intense commercial fishery off the Pacific Coast of North America.…”