Survival and Cheliped Loss of Juvenile Lobsters Homarus gammarus during Simulated Out-of-Water Transport

Abstract

Juvenile lobsters Homarus gamrnarus reared for stock enhancement programs are frequently packed in Styrofoam boxes between layers of wet newspaper and shellsand and transported out of water from hatcheries to release sites. A single layer of frozen newspaper acts as a cooling element. The physical disturbance experienced by individuals while being transported was simulated under controlled conditions. Juveniles were sent on “journeys” lasting 0, 6, 9, 12, 15, 18, 21, and 24 h and were physically disturbed for 15 min of each hour. Mortality was low (2–7%) within the first 12 h of simulated transport but increased significantly (12–22%) after 15 h of exposure. This increase was primarily a result of high mortality (21–45%) in individuals packed in the layer nearest the cooling element. Air temperature recordings revealed a temperature gradient between layers throughout the test period. In all, 68.5% of all observed mortality occurred within 6 h of juveniles being returned to ambient seawater. Overall, 41 of the 80 animals identified as newly molted had died 72 h after the simulation. Cheliped loss was low (4.3%), but it did increase significantly with increased length of the simulated transport period. The results indicate that out-of-water transport is cost-effective for journey durations up to 15 h, but for longer periods the use of frozen newspaper as a cooling element requires careful examination. It is suggested that damp tissue paper is more suitable for the purpose. Out-of-water transportation of newly molted animals is not advised.