A surface plankton sampler for the larval stages of the western rock lobster.

Abstract

A net capable of catching the larval stages, including the puerulus of Panulirus longipes* (MilneEdwards) in the surface plankton is described. The sampler has a square 0.25 m2 mouth, an overall filtering length of 140 cm and a 10 cm diameter PVC cod-end bucket. Towed from a short boom from the side of a small boat or from a longer boom out from the side of a larger vessel, the sampler has a bridle attached to two opposite corners and a weight at the bottom corner so that in operation it presents a relatively unobstructed diamond shaped opening to the water.

A total of 112 puerulus stage larvae were caught with this sampler (fitted with a 2.5 mm mesh net) during five nights of sampling within the reef at Seven Mile Beach. The greatest number of larvae were found to be present in the surface plankton prior to midnight.

Modified versions of this sampler with either 2.5 mm or 1.0 mm mesh net have been successfully used to sample puerulus and phyllosoma stages of western rock lobster larvae in the surface waters off the west coast of Western Australia.