Forty Years of Field and Laboratory Experiments with Hatchery-Reared Queen Conch: The Case for Conserving Natural Stocks

Abstract

Rehabilitating overfished species through releases of cultured juveniles depends upon growth and survival of those animals in the field. Releasing cultured queen conch (Strombus gigas) was proposed 40 years ago to rebuild over-harvested populations. Hatchery culture has been perfected and thousands of juveniles can be produced with meticulous husbandry. Many field experiments have been conducted with hatchery-raised queen conch since the early 1980s, but the results cast doubt regarding stock enhancement. Queen conch demonstrates high natural mortality rates, and cultured conch can have morphological and behavioral deficiencies that diminish survival. Deficiencies can be reduced with perfect culture conditions and prerelease field conditioning; and survival can be improved by releasing large juveniles, but all of these measures add to cost of seed stock. Also, release requirements are problematic. Habitat selection, release timing, and release patterns are all critical for reducing predation losses. While all of these challenges have been considered, no field release has resulted in survival rates that are encouraging. The cost of stock restoration through release of cultured queen conch will be enormously expensive, if successful at all, and every effort should be made to conserve wild populations. Hatchery production for stock restoration should be considered a last resort.