THE EFFECTS OF EXERCISE ON GROWTH, SURVIVAL AND BURST-ESCAPE PERFORMANCES OFHE EUROPEAN LOBSTER (HOMARUS GAMMARUS) REARED IN A ROTATIONAL CULTURE SYSTEM

Abstract

The present study examines the effects of varying levels of exercise on the growth, survival and burst-escape responses of 8 months-old juvenile lobsters. For this purpose, lobsters were cultured in custom-built rotating cylindrical compartments at 2 rpm. The diameter of each cylindrical compartment was 5.20 cm corresponding to a circumference of 21.20 cm. A non-moving conventional, rectangular container (5x7 cm) for juvenile lobster grow-out was also used as a control. Four different treatments were established to determine the effects of exercise duration: 0, 6, 12, and 24h. The daily distance covered by 6, 12 and 24h treatments were 15.26, 30.53 and 61.01 meters respectively. The mean initial weight of juvenile lobsters was 0.557 g. All lobsters were fed a frozen crustacean-based diet at 30% of body weight once a day. The trial lasted for 90 days. Burst-escape response of juvenile lobsters was determined using a custom-build rectangular flume incorporating a dummy lobster as a threat stimulus and response duration was recorded as an indicator of burst-escape capacity. The final mean wet weight for 0, 6, 12, and 24h treatments were 3.166, 3.046, 3.084 and 3.170 g, respectively, with no significant differences between treatments. The final mean wet weight of the rectangular control group was 2.107 g, which was significantly lower than those of treatments carried out in cylindrical compartments. Survival did not change among treatments and was 100%. In contrast, burst escape response of juvenile lobsters declined progressively with increasing exercise duration. Mean burst-escape response durations decreased from 22.5 s in the static cylindrical group to 21.4 s, 19.5 s, and 17.6 s in the 6 h, 12 h, and 24 h rotation treatments, respectively. Juvenile lobsters exposed to prolonged daily rotation exhibited reduced capacity to sustain repeated escape responses when challenged with a simulated predator stimulus, suggesting that rotational activity may compromise anaerobic escape performance. Overall, the results indicate that cylindrical rearing systems significantly improve juvenile lobster growth performance relative to conventional compartment designs, while prolonged rotational conditioning may negatively affect burst-escape capacity. The study highlights a potential trade-off between culture-system hydrodynamics and escape-related locomotor performance in juvenile lobsters.