Fate of juvenile school prawns, Metapenaeus macleayi, after simulated capture and escape from trawls

Two laboratory experiments were done to assess the fate of juvenile school prawns, Metapenaeus macleayi, after simulated multiple capture and escape from trawls. In the first experiment, prawns that were trawled and escaped one, five or 10 times, sustained some physical damage (mostly limited to the loss of antennae), but this was not significantly different from that sustained by control prawns that had not been trawled. Similarly, there were no significant differences between the different treatments and control prawns in their stress levels (as measured by changes in concentrations of L-lactate). Levels of L-lactate were greatest in all prawns immediately after the experiment started and then significantly reduced after 24 and 48 h. In the second experiment, treated prawns were trawled and escaped 10 times and then monitored for mortalities over 2 weeks. Compared with control prawns (that were not trawled), significantly more treated prawns died at the end of the 2 weeks, but the overall post-trawl survival rate was >89%. It is concluded that the multiple contact and escape of juvenile school prawns from trawls had minimal effect on their overall condition.