Examining the Movement of the Common Spider Conch Lambis lambis in Shallow Water of a Northeastern Indian Ocean Atoll Using Passive Acoustic Tracking

Abstract

Despite the commercial and cultural values of conch (family: Strombidae), there is a paucity of biological and ecological information to assist with the management of many conch fisheries. The common spider conch Lambis lambis, harvested throughout the Indo-Pacific for its meat and shell, is an example of such a data-deficient conch species. This study used passive acoustic tracking to estimate the spatial requirement and broad movement patterns of L. lambis over a 13-mo period in an extremely shallow (depth < 2 m) lagoonal environment of the Cocos (Keeling) Islands (CKI). The mean kernel utilization density home range for L. lambis during the study period was estimated at 18,059 ± 3,298 m2(n = 14). The mean home range was also estimated monthly and was found to be significantly larger in January (austral summer) than in the preceding October and November, likely a function of the reproductive cycle of L. lambis at CKI. Estimated home range size and animal size were not found to be correlated, and there were no observed differences between the sexes. The results show that, in an environment of preferable habitat with adequate resources, L. lambis have a home range that is relatively small when compared with studies of the Caribbean queen conch Lobatus gigas. The information on the spatial requirement and movement ecology for L. lambis at CKI from this study will assist with informing management techniques, not only for this fishery but also for other small conch fisheries worldwide.