Distribution of Jasus spp. (Decapoda: Palinuridae) phyllosomas in southern waters:: implications for larval recruitment

We sampled the distribution of mid- and late-stage (= advanced) Jasus group 'lalandii' rock lobster phyllosomas at 28 approximately equidistant stations across similar to 16 000 km of ocean between the west coast of Africa and the west coast of New Zealand to determine whether the larvae were mostly associated with the patchy allopatric distribution of the adults or were widespread. The Jasus phyllosomas (n = 210) occurred in greatest abundance in the general vicinity of adults. Nucleotide-sequencing and restriction-fragment length polymorphism (RFLP) techniques were used to identify 93 of these larvae from 18 stations to species level. Most of the larvae caught were J. lalandii and J, edwardsii, and a few were probably J. paulensis. Most of these larvae were taken near (within a few hundred kilometres) their respective adult habitat off southern Africa, Australia and New Zealand, and Amsterdam Island. The exceptions were small numbers of J. lalandii larvae in the southwest Indian Ocean as far east as Amsterdam Island, adjacent to the J. paulensis habitat, and J. edwardsii larvae across the south Tasman Sea. A single larva off southwest Africa could not be identified to any known Jasus species and may indicate the presence in the genus of an as yet undiscovered species or subspecies. No J. caveorum, J. frontalis, or J. verreauxi (and probably no J. tristani) were found. Our results suggest that Jasus spp. larvae which subsequently recruit to benthic populations use behavioural strategies and/or physical mechanisms to avoid being carried too far away from their parental ground. However, a proportion of larvae, small yet possibly not insignificant, occurs great distances from where adults of the species are known. These larvae are unlikely to recruit to benthic populations, but their occurrence invites further consideration of how Jasus spp. maintain allopatric populations.