A Witham post-larval collector

The Caribbean Marine Research Center has examined post-larval settlement of spiny lobster (Panulirus argus) and fish around Lee Stocking Island, Bahamas, since 2001 to determine fluctuations of lobster populations over space and time in mangrove nursery areas.

For 2003-2004, the recruitment study has been expanded to include nursery areas throughout the Bahamas, including 4 sites around Bimini, to determine the variability of recruitment of lobsters and fish over a large spatial scale.

Using "Witham Collectors" that mimic the natural habitat that lobster settle into when they make the transition from their planktonic life stage to the sea bed, the surveys record numbers of post-larval lobster & fish recruits through the seasons.

Post-larval lobster in the collector

A Witham Collector consists of a rectangular framework of PVC pipe, with six cross supports from which 6 sheets of "hogs-hair" air conditioner filter material hang. The hog-hair filters successfully mimic the structure and consistency of the macro-algae Laurencia, which is the preferred natural settlement habitat. The collectors are moored in 1-3 m of water, with the frame floating at the surface, and the hogs-hair hanging vertically down. This design presents the maximum possible surface area to attract the post-larval lobsters & fish.

Collectors are sampled 3 times per months around the new moon. This time period coincides with and influx of post-larval recruitment into shore during the first quarter of every new moon.

Each lobster or fish found is recorded onto a datasheet. The stage of development and the pigmentation of the post-larvae are recorded as well.

The Bimini Biological Field Station will be expanding this project around Bimini in the beginning of 2004. Quantifying the natural variability of lobster and fish stocks over time will provide useful information about the state of spiny lobster and fish populations, and consequentially, for fisheries management in the Bahamas.

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