How to translate text using browser tools
1 August 2016 Underwater Towed Video: A Novel Method to Estimate Densities of Queen Conch (Lobatus gigas; Strombidae) Across Its Depth Range
Erik Maitz Boman, Martin De Graaf, Leo A. J. Nagelkerke, Jimmy Van Rijn, Melanie Meijer Zu Schlochtern, Aad Smaal
Author Affiliations +
Abstract

Queen conch (Lobatus gigas) populations living deeper than 20 m are rarely studied, because of the limitations of conventional survey methods using divers [i.e., belt transect (BT), towed-diver]. Acrucial management goal for conch populations is to maintain adult densities at adequate levels to ensure reproduction, which is highly density dependent. Therefore, accurate estimates of adult conch densities, both in shallow and deep areas, are essential. The rapid technical progress of video systems has made it possible to develop new cost-effective ecological sampling tools, which can be used to survey areas previously hardly accessible. A lightweight towed video array was used, which was able to survey adult conch throughout the species entire depth range (ca. 0–60 m depth), in a safe and efficient manner. The towed video method (TVM) was compared with a conventional BT method using scuba divers, in its ability to identify adult live and dead conch. A series of intercalibration transects was conducted in a high-complexity (HC) and in a low-complexity (LC) habitat by having the towed video followed by a diver conducting a concurrent standard BT, covering the exact same surface area as the towed video. In both the HC and LC habitat, adult live queen conch had similar counts with both methods. Adult dead conch were not mistaken for live conch but were significantly underestimated with the towed video compared with the BT. The results validate the use of TVM as a reliable sampling tool to estimate densities of live adult conch in both HC and LC habitats throughout the species depth range.

Erik Maitz Boman, Martin De Graaf, Leo A. J. Nagelkerke, Jimmy Van Rijn, Melanie Meijer Zu Schlochtern, and Aad Smaal "Underwater Towed Video: A Novel Method to Estimate Densities of Queen Conch (Lobatus gigas; Strombidae) Across Its Depth Range," Journal of Shellfish Research 35(2), 493-498, (1 August 2016). https://doi.org/10.2983/035.035.0222
Published: 1 August 2016
KEYWORDS
deep-water populations
density estimate
video survey
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top