The effects of transport density on cortisol levels in juvenile winter flounder, Pseudopleuronectes americanus.

摘要

The objective of this study is to determine which transport density produced the least amount of stress when juvenile winter flounder P. americanus were relocated to a given release site. Approximately 10 000 cultured juvenile flounder were used in this study. Tagged flounder were stocked at five different densities (100, 200, 300, 400 and 600% of the substrate area) and transported to the release site in Hampton, New Hampshire, USA. Transport to the release site at all stocking densities elicited a stress response in juvenile winter flounder when compared to the control fish, however, distinct differences in the amount and extent of the stress response existed between the densities. The initial transport of fishes from CML to the research vessel did not elicit an increase (P=0.91) in cortisol concentration in any of the stocking density. In contrast, after 45 mins of vessel transport, cortisol level for all densities statistically went higher as compared with the control. Although cortisol levels of fish stocked at each density were still elevated upon arrival at the release site (90 min vessel transport), all values except those for fish stocked at 600% begun to decrease. The reduction in cortisol levels continued after 48 h recovery, as levels of hormone returned to near baseline levels for all transport densities except for those stocked at 600%..