Abundance of Veligers of the Queen Conch in North
Sound: An Executive Summary
By Gene Parsons, Bradley Johnson, and John Bothwell. Research and Assessment Section, Department of Environment, Cayman Islands Government. April 2001.
Summary
To determine the abundance of queen conch (Strombus gigas) veligers at 3 locations in the North Sound, an 18-month sampling program that collected 76 plankton samples on an average frequency of about once every 2 to 3 weeks was conducted from July 1997 through December 1998. Near-surface, horizontal plankton tows of 20-minutes duration were undertaken at each location using a bongo-net frame equipped with 2 conical nets of 0.5-meter diameter and 202-micron mesh. Of the 2,077 queen conch veligers collected through tow 36, 10 had broken shells that could not be measured; therefore, 2,067 were analysed for maximum shell length (SL). Of these 1,992 (96.4%) corresponded to Stage 1 (< 500 microns SL), 75 (3.64%) to presumptive Stage 2 (500-900 microns SL), and none to Stage 3 (settlement stage). In the 6 samples containing veligers, density varied from 0.06 to 34.86 per 10m³. The preliminary results indicate that the back-reef areas of the replenishment zones of Barkers and North Sound might be larval source areas owing to these zones partially functioning as refugia for queen-conch breeders.
