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Video methodologies for deep water surveying of queen conch (Strombus gigas): a comparison study in Turks & Caicos Islands
van Rijn1, J., Austin, R.2, Henry, T.3, Littlewood, A.2 and Lockhart, K.3
Wild Conscience1; Joint National Conservation Committee (JNCC)2; Department of Fisheries & Marine Resource Management (FMRM), Turks & Caicos Islands3
ABSTRACT
Queen conch (Strombus gigas) remains one of the most important fishery resources in the Wider Caribbean Region, but growing demand has led to problems of over-fishing, illegal landings, and declines. In Turks and Caicos Islands (TCI), queen conch is the second most important commercial fishery, supporting a large export trade (>$3.5m USD per year) as well as a domestic market. Deep-water adult populations of queen conch are considered critical spawning stock refugia but have proved challenging to study using dive surveys due to safety considerations and practical limitations. Previous underwater visual surveys (UVS) in TCI have relied on scuba divers that have not been able to survey deeper waters where adult populations of queen conch may be present, resulting in incomplete stock assessments. This study compares two novel UVS methodologies that could provide a safer, more time and cost-effective way to survey queen conch at deeper depths: the established towed video array method (TVM) and more novel underwater drone (ROV).
The study, which outlines the specifications and operation of the two methods, also provides a qualitative analysis of the costs and benefits encountered which can be used to inform queen conch density and abundance survey planning and future monitoring efforts in the wider Caribbean. Despite the potential benefits offered by the underwater ROV, such as the ability to survey a wider range of habitats without risk of environmental damage, and reduced personnel required for transport and operation, the current high costs, maintenance, and functionality required to perform transect surveys, suggests the TVM offers a more time and cost-effective method for surveying queen conch at greater depths. The study formed part of a wider project focussing on sustainable management of the queen conch fishery in TCI and informed the completion of abundance surveys on the Caicos Bank: an expansive underwater plateau south of the Caicos Islands.
HOW TO CITE: van Rijn, J., R. Austin, T. Henry, A. Littlewood, and K. Lockhart, 2026. Video methodologies for deep water surveying of queen conch (Strombus gigas): a comparison study in Turks & Caicos Islands. Contribution 3.7, p172-183 IN CRFM, 2026. Volume I: Technical Papers. Presented at the CRFM 20th Anniversary Scientific Conference, 28-31 August 2023. CRFM Special Publication No. 37, CRFM Secretariat https://www.crfm.int/index.php?option=com_k2&view=item&id=912
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