Meeting Abstract

P2.41  Friday, Jan. 4  Effects of Exercise on Endocrinology in Three Different Swim Styles: California Yellowtail, California Sheephead, and White Seabass PETERS, C.J.*; LOWERY, M.S.; KELLEY, K.M.; DRAWBRIDGE, M.A; University of San Diego; University of San Diego; California State University, Long Beach; Hubbs Sea World Research Institute cpeters-07@sandiego.edu

We examined the effect of long-term continuous exercise on the growth endocrine axis of three California coastal fish species with a wide range of natural swimming behaviors and different capacities for sustained swimming. We monitored plasma insulin like growth factor I (IGF-I), plasma cortisol concentrations and somatic growth throughout the exercise conditioning in California yellowtail, California sheephead, and white seabass. Each species was subjected to a Fast, Moderate, or Slow exercise treatment with current velocities chosen to simulate 60%, 40% and 20% of maximum aerobic swimming speed (Ucrit) of each species. Transfer to the raceway system generally caused a large increase in cortisol. Swimming, particularly at higher velocity, accelerated the return to basal cortisol levels and often yielded cortisol lower than that seen in fish reared under normal aquaculture conditions. IGF-I concentration declined in response to the cortisol spike, but did not appear to be strongly affected by exercise even in species where exercise stimulated somatic growth. Only the yellowtail exhibited a substantial increase of plasma IGF-I associated with growth. Differences in swim styles and perhaps in regulatory IGF-I binding proteins may account for variations seen among species.