The ornate tropical lobster (Panulirus ornatus; TRL) is in high demand, especially in live seafood markets throughout many parts of Asia where it is prized for its flavour and vivid colouration. Adult TRL are harvested from the wild and shipped live to market, and juvenile TRL captured from the wild or raised from eggs in hatcheries are transported live to provide seed stock for grow out locations. With the growth in TRL aquaculture there is a need to develop more effective methods for the live shipping of juveniles, that eliminate any mortalities. The live transport of juvenile lobsters results in stress that is primarily metabolic; i.e., elevated CO2 and ammonia. Approaches to minimize this stress through alterations to metabolic rates has the potential to decrease mortality. Isobutanol is a low cost, naturally occurring food additive that is safe for human consumption and has shown efficacy as a transport sedative for adult TRL. This study investigated the effect of isobutanol on juvenile TRL physiology during immersion, air exposure and simulated transport to determine its efficacy for the transport of juvenile TRL.
Anaesthetic induction and subsequent recovery times were determined for 5 concentrations (25, 50, 250, 350 & 500 ppm). We found that induction time was dose dependent with the highest concentration (500 ppm) inducing the deep sedative state the fastest. Four deaths occurred following re-acclimation, 2 each at 350 and 500 ppm. CO2 production during air exposure was monitored after exposure to isobutanol. Individuals were assigned to one of four treatment groups (control, 25, 50 or 500 ppm). After exposure to treatment for 20 minutes, animals were emersed and CO2 production was tracked for 2 hours. CO2 production was significantly lower with 25ppm isobutanol compared to controls at all times points (Figure 1). All individuals survived except for 2 at 500ppm.
During 20 hours of simulated transport pre-treatment with isobutanol at 25 and 50 ppm resulted in lowered haemolymph ammonia and lactate compared with untreated individuals while tissue glycogen content was defended.