No abstract

Growth in three species of spiny lobster-Panulirus cygnus in Western Australia, P. argus in Cuba, and P. ornatus in Torres Strait, Australia-was modelled by using nonlinear random-coefficient models. Approximate confidence intervals about the mean growth curve for carapace length, to include 95% of the population at any age, have been estimated for these models. For both P. ornatus and P. cygnus, similar estimates of growth rate were obtained from both laboratory and field studies. Growth of the two tropical species, P. ornatus and P. argus, was much faster than that of the temperate species P. cygnus. All three species showed high variability in the growth rates of individuals. Microtagging of first-moult post-puerulus juveniles of P. cygnus with 1 mm long × 0.25 mm stainless-steel tags provides the first published field data on the growth of spiny lobsters from the beginning of the benthic period. These data suggest that tagging or handling can decrease the growth rates of spiny lobsters.

Juvenile lobsters Panulirus ornatus in the Torres Strait emigrate once a year from the Torres Strait to the Gulf of Papua, several hundred kilometres to the northeast. They mature and spawn during this emigration. After spawning the lobsters disappear. It has been suggested that the combined stress of reproduction and emigration results in mass mortality. To test this hypothesis, lobsters were collected at several stages of the emigration and their condition defined by the water content and composition of the digestive gland and abdominal muscle. A cage experiment, with 2 feeding regimes, was conducted to examine the likelihood of post-reproductive mortality. Compared to lobsters in the Torres Strait, before emigration takes place, lobsters that had con~pleted the breeding emigration were in very poor condition. There were changes in the size and composition of both the digestive gland and abdominal muscle. Three stages of deterioration were recognised; in the final stage the digestive gland tissue was severely atrophied. The physiological characteristics identified in this study provide a quantitative basis for future work on the mortality rates of lobsters that have completed the emigration.

A small poeciliid fish thought to be G. a. holbrooki was identified anatomically as P. caudimaculatus. Gel electrophoresis confirmed the absence of hybrids between the two species. Reference to G. a. holbrooki in the literature suggests misidentification at other locations. It should be recognized that P. caudimaculatus is quite distinct from G. affinis.