Long-term monitoring of fisheries in the Virgin Islands Biosphere Reserve

Boulon, Ralf; Beets, James; Zullo, Evonne

Long- term monitoring methods of species of demersal fin fish, conch, and whelk that are commercially important were developed and used at selected sites in the VIBR. The techniques used proved objective, repeatable, fast, easy and subject to a minimum of observer bias. A random-point, visual-census technique was used at habitats with a high fish-species count of demersal fin fish. Of the four bays selected. three (Trunk. Hawksnest. and Fish) have potential for tourist or land-based-sedimentation impact. The fourth, Lamesbur Bay, has low impact potential. Baseline data was collected for seven habitat types found in these bays. A visual. swimming. strip-transect method was used at three sites in two bays (a shallow [inner] and deep [outer] grass bed in Fish Bay and a shallow grass bed in a small bay east of Leinster Bay) to estimate conch densities and populations structure. Over a four-month period, the inner site at Fish Bay was compos~d of juvenile conch in densities ranging from .09-.28 conch/sq.m.; the outer of 99.9% mature conch in densities ranging from .08-.18 conch/sq.m. Sampled twice, the bay east of Leinster Bay was composed of 19% mature conch the first time. and 99% juvenile conch the second time. Densities ranged from .21-.26 conch/sq.m. The shift in population structure may be seasonal (migration). A random-point. strip-transect method was used for estimating density and population structure of whelk along a rocky coastland between Peter Bay and Windswept Beach (selected due to known low harvest). All whelks within a one-meter-wide strip from dry land to a one-meter depth were collected. The largest population size class is whelks under 1 cm., with 82% of all whelks being less than 4 cm. (approximate average size for maturity). This may indicate that periodic harvesting does occur. The density of whelks is estimated to be 36.7 whelks/m. of shoreline. Recommendations are made to monitor lobster using a systematic canvassing technique to ensure total coverage and no overlap of a selected. discrete lower fore-reef or bank pavement area. Data on sex (if female. whether berried or not) and size should be gathered. Handling lobster may effect the study and should be avoided.