Bruce F. Phillips

Testing collector designs for commercial harvesting of western rock lobster ( Panulirus cygnus ) puerulus

We have (i) tested modified western rock lobster sandwich collectors at different depths and distances offshore (ii) tested different collector designs (iii) examined the effect of collector size, and (iv) tested the effect of frequency of servicing the collectors. The only catches recorded in the onshore-offshore trials were on gear set at the inshore site (depths <5 m). Published data from the 1970s on the effect on catches of collector arrays and locations were reexamined with a general linear model. The analysis revealed marginally significant corner and layer effects, carry-over effects, and square-of-time effects. Five collector designs were therefore set in the shallows, two of which had replicates of three different sizes, and were checked over four lunar months during peak settlement. Sandwich collectors had significantly better catch rates than others (P <0.001), and settlement rates were highly correlated with collector dimensions (r = 0.72). Daily servicing for seven days around the time of new moon yielded catches 170% higher than those from a single monthly servicing (P <0.001). Results indicate that tests for collectors must take into account corner, carry-over, neighbour, and layer effects and that to do so they must be set out in an array and repositioned after each sampling.

Spiny lobster development: where does successful metamorphosis to the puerulus occur?: a review

This review re-addresses the question: Where does metamorphosis to the puerulus mainly take place among the shallow-water palinurids? A decade ago we reviewed this ecological question in a paper that focused on phyllosomal development of the western rock lobster, Panulirus cygnus. The main region of occurrence of its metamorphosis was found to be in the slope region beyond the shelf break. Because the puerulus of P. cygnus is a non-feeding stage, it was hypothesised that metamorphosis will not occur until the final phyllosoma has reached some critical, and specific, level of stored energy reserves. For late larval development and successful metamorphosis of P. cygnus, the richest food resources seem to be located in the slope waters adjoining the shelf break off Western Australia. This, like most shelf break areas, is a region of higher zooplankton and micronekton biomass than is usually found further offshore, and is dominated (in winter-spring months) by the warm south-flowing Leeuwin Current. In this new review, distribution and abundance data of final phyllosomas and pueruli are examined from, Panulirus argus, Panulirus cygnus, Panulirus japonicus, Panulirus ornatus and Jasus edwardsii, and where possible, related to features of the satellite imagery of the areas in which they occur. We hypothesise that metamorphosis will occur where the final stages have partaken of sufficient, appropriate nutrition to provide them with a reserve of bioenergetic resources, and this can occur where oceanographic fronts effect greater planktonic productivity and concentrations of food organisms. This may be near the shelf-break, or out to large distances offshore, because of large-scale oceanographic events such as the prevailing current system, its off-shoots, mesoscale eddy fronts, counter-currents, etc. However, we contend that, in terms of population recruitment, metamorphosis in most shallow-water palinurid species occurs mainly in the slope waters adjoining the shelf break of the region to which the species is endemic. Although some final phyllosomas may metamorphose much further offshore, it is unlikely that these pueruli will reach the shore, let alone settle and successfully moult to the juvenile stage. All of the data indicate that successful metamorphosis from the final-stage phyllosoma to the puerulus stage in all species occurs offshore but close to the continental shelf.

A REVIEW OF THE CONTRIBUTION OF J. STANLEY COBB TO THE FIELD OF LOBSTER RESEARCH

The interaction between behavior, ecology and fisheries management is complex. It is no less so in lobster fisheries than in any other fishery, and knowledge of the behavior of the American lobster, Homarus americanus, is critical to the successful management of this icon species. Stanley Cobb has spent a lifetime studying the American lobster. In addition to his own research, Stan has been the supervisor of 35 students who have obtained postgraduate qualifications to allow them to carry out further studies in this ever expanding field of research. The first papers published by Stan Cobb were, not surprisingly, all on the American lobster H. americanus (Cobb, 1968). The first study investigated whether there was a difference in time of molt of larval H. americanus to the juvenile stage if the bottom conditions varied between mud, sand, gravel and bare conditions. Larvae on a gravel substrate moulted significantly earlier than on all other substrates, supporting the hypotheses that bottom conditions are important in the time of molt to the epibenthic life of a juvenile lobster. The second study continued that of the first (Cobb, 1970). It was designed to discover what factor of the gravel substrate had affected the duration of the fourth stage larvae. However, the effects of being held singly or in pairs, and with two levels of illumination, were also tested in the experiment. In typical fashion the substrate type had no detectable effect on the larvae, and nor did the light. However, solitude did. This is how science progresses! The third of these studies was on adult lobsters, and investigated some of the relationships between a lobster and its shelter (Cobb, 1971). The method of excavating a shelter, its dimensions related to the size of the lobster, and the preferred level of darkness within the shelter, were all defined by this study. There was a positive relationship between lobster size and shelter size (Cobb, 1971). Larger lobsters choose, or construct, larger shelters by burrowing. They also may maintain a minimum distance between occupied shelters through aggression. These fundamental observations were used to determine the sizes of shelter

Morphological descriptions of laboratory reared larvae and post-larvae of the Australian shovel-nosed lobster Thenus australiensis Burton & Davie, 2007 (Decapoda, Scyllaridae)

Complete larval development from newly hatched larvae up to the juvenile stage was successfully achieved in the Australian shovel-nosed lobster Thenus australiensis under laboratory conditions. The larvae of this species passed through four phyllosoma stages (each stage has a single instar), and developed into the first juvenile stage via a post-larval, nisto stage. The shortest and mean durations from hatching to metamorphosis at a water temperature of 25°C were 32 and 38 days, respectively. Morphologies of body and appendages for all four phyllosoma stages and the nisto stage were described. The phyllosomas were fed exclusively on the jellyfish Aurelia aurita throughout their culture. Our results indicate that jellyfish may be a viable diet for T. australiensis phyllosoma’s in culture and may therefore be useful for commercial-scale lobster production.