Abstract

The marine gastropod Queen conch (Lobatus gigas) is one of the most economically important and heavily exploited species in the Caribbean region (Brownell and Stevely 1981). Queen conch stocks have been heavily fished in many areas, predominantly in relatively shallow depths (< 15 m) easily accessible to free diving fishermen (Tewfik 2002). As conch densities in the shallow areas decrease, fishers must venture deeper to find conch. Other authors suggest that these deep water populations are a primary source of larvae for the shallow water populations (Stoner et al. 1992). As fishers are now targeting these deep populations it is important to accurately, safely, and economically make stock estimations. In order to properly manage conch fisheries, accurate estimates for shallow as well as deep water populations are need. Conventional dive surveys are currently the most common method used to survey conch populations. This method has limitations; as depth increases bottom time is restricted, and the dangers associated with increased depth also make deep dives more dangerous. Using technical divers to survey deep water conch populations, which can be found to a depth of 60 m (Randall 1964), is not cost-effective and the technical expertise is beyond most Caribbean nation’s capacity. Therefore, we have developed a safe and efficient towed video system which is able to survey deep water conch populations. The system has been used in the waters of St Eustatius, located in the northeastern Caribbean, to determine if the local conch population could support a small-scale commercial fishery. The adult Queen conch population was assessed using a towed video system in combination with scuba diving. To validate the video system and compare it to diving, a series of calibration transect covered by both a diver and the towed video array was conducted.

PDF Preview