Abstract

The queen conch, Lobatus gigas, is an iconic gastropod, traditionally a significant dietary protein source for the Carib-bean. L. gigas is now commercially threatened, but little is known regarding diseases which may put depleted populations at further risk. To assess disease status of L. gigas in our region, we aim to describe a systematic technique for post-mortem examination. A variety of approaches for euthanasia, viscera extraction, dissection, and tissue preservation were explored using 32 conchs collected from St. Kitts and procedures were selected which provided optimal exposure of anatomy while requiring the least dissection. Conch are initially sedated by immersion in magnesium sulphate (3g/4L seawater) in order to facilitate removal from the shell without tearing of viscera. A hole in the shell is made to allow visualisation of the col-umnellar muscle which must be carefully severed while avoiding adjacent viscera. Subsequently, the body is extracted from the shell by placing steady traction on the operculum. Euthanasia is achieved by making a 1 cm sagittal incision through ganglia located immediately posterior to the eye stalks. Four incisions are then required for full visualization of tissues: the first opens the mantle cavity; a second ‘V’ cut accesses the pericardium; the third reveals the intestinal loop, kidney and nephridial gland; lastly the gastrointestinal lumina are opened. Tissue fixation with Davidson’s solution was found to have lessor post-sampling mucous production than with 10% neutral-buffered formalin. A necropsy guide was developed which will facilitate disease diagnosis in L. gigas.

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