Effect of different types of shelter on growth and survival of Panulirus ornatus juveniles

摘要

At settlement, lobsters naturally choose cryptic shelters for protection, both from predators and from cannibalism at times of moulting. Some studies with other crustaceans have shown that providing shelters improves their growth and survival during culture. However, there is very little information on the effect of different shelter types on growth and survival of juvenile Panulirus ornatus (ornate spiny lobster). An experiment was carried out to determine whether shelter affects the growth and survival of P. ornatus juveniles, and which type of shelter is best. Four shelter types were examined during 40 days of nursery culture: 1. wood shelter with drilled holes; 2. coral shelter with drilled holes; 3. net shelter; and 4. no shelter (control). Each treatment had 6 replicate tanks each with 12 lobsters in a completely randomised design. Lobsters were fed trash fish once daily. Specific growth rate (carapace length and body weight) of lobsters was unaffected by shelter type. However, shelter type significantly (P < 0.05) affected survival: highest for the net shelter (80.6 ± 5.6%), with the no-shelter control (62.5 ± 4.2%) and the wood shelter (54.2 ± 2.4%) significantly lower, while the coral shelter (68.1 ± 6.9%) was not significantly different from all shelter types. These findings suggest that providing net shelters during the nursery phase may reduce cannibalism during moulting and lessen the competition between weak and more dominant lobsters.