HOW DOES PHYSIOLOGICAL AND MORPHOLOGICAL TRAITS and social interaction EFFECT GROWTH PERFORMANCE OF SPINY LOBSTER IN CAPTIVITY?

Spiny lobsters can display large inter-individual differences in growth rate which have been reported as major drawbacks to the successful production in captivity. One explanation is that dominant lobsters use agonistic behaviours to controll a disproportional share of food resources benefiting individual growth performance. The ability of an animal to compete for and control resources is often determined by the combination of that individual's morphological and physiological traits such as body size, sex, metabolic physiology and prior experience or condition. Thus, understanding how intraspecific diversity affects growth performance is an important consideration. Relationship between metabolic phenotype, social behaviour and growth performance has not been previously investigated in any spiny lobster species. In a laboratory experiments, we examined the influence of individual variation of metabolic phenotype on growth performance of juvenile spiny lobster, Sagmariasus verreauxi (5.99±2.77g) that were reared either individually (n=17) or as a group of 20 communally for 90 days. Furthermore, we investigated the influence of metabolic phenotype, body size, sex, feeding contest experience and rearing history on the social behaviour (dominance and aggressiveness) status of individual lobsters by examining their ability to compete for food in a series of randomly paired feeding contest experiments. Growth performance, survival and feed intake were significantly greater in communal rearing demonstrating that social interaction has an important influence on growth of lobsters. We also found a direct link between metabolic phenotype and growth of lobsters in the absence of social interaction but not in the communal setting.  These results suggest that the effect of social interaction outweighs the influence of metabolic phenotype on lobster growth. Lobster social status was significantly linked with body size, metabolic phenotype and sex. Larger lobster are predicted to be dominant over smaller lobsters. Moreover, low metabolic rate lobsters displayed a greater ability to win over high metabolic rate lobsters. Female lobsters are also predicted to become more dominant than male lobsters irrespective of size and metabolic phenotype status. The combination of body size, metabolic phenotype and sex dependent responses of spiny lobsters dominance status and aggressiveness during feeding competition combine to determine the growth performance of individual lobsters. Hence, growth performance of spiny lobsters in captivity is determined by the link between individual lobster's morphological and physiological traits and social interaction.