Spatial and Temporal Variations in Stock Abundance of Queen Conch, Strombus gigas, in the US Virgin Islands
Friedlander A, Appeldoorn RS, Beets J. 1994. Spatial and Temporal Variations in Stock Abundance of Queen Conch, Strombus gigas, in the US Virgin Islands. Pages 51-60. In Appeldoom RS and Rodriguez B. Quen Conch Biology, Fisheries and Mariculture. Fundacion Clientifica Los Roques, Caracas, Venuzuela
Study of conch populations around St. John and St. Thomas. Looked at abundance and habitat preference. Noted that the large degree of variation between transect readings limit the usefulness of comparison over a short period of time, but did reveal statistically significant trends over longer period of time (in this case a population decline). Estimates of conch abundance from transect surveys tend to have high variance. Obtaining statistical significance between two different estimates is often impossible. However, repeated sampling, particularly at the same sites, can detect trends in stock size over time, in spite of associated high variance. In 1990, a transect survey of adult queen conch abundance was conducted at 22 sites in St. Thomas and St. John, U.S.V.I. Stations and transects were identical to previous surveys conducted in 1981 and 1985 (St. John only). Conch showed an aggregated distribution. Densities were significantly different among habitat types. Coral rubble and algal plain areas had the highest density of conch. Average density in 1990 was similar between islands (12/ha) and lower than observed in 1981 or 1985. Temporal variations were examined in detail for the St. John data, using only those stations sampled in all three surveys. Average densities were 37,31 and 11 conch/ha, respectively, for similar transects conducted in 1981, 1985 and 1990. Differences between any two years were not statistically significant, despite the presence oflarge differences. However, a Jonckheere test for ordered alternatives showed that the continuous decline in abundance since 1981 was indeed significant. Currently there is a ban on conch fishing in St. Thomas/St. John. Verification of significant stock decline and low observed density support management implementation.
- Type
- Book Chapter
- Authors
- Friedlander, Alan; Appeldoorn, Richard; Beets, James
- Units
- VIIS
- Keywords
- Animal Studies, Habitats, Population, Population Decline, queen conch (Strombus gigas), St. John, US Virgin Islands