Efficacy of isobutanol to reduce transport stress of juvenile ornate tropical rock lobster (TRL; Panulirus ornatus)

Abstract

The ornate tropical rock lobster (TRL; Panulirus ornatus) is a fast growing spiny lobster that is prized for its vivid colouration and excellent eating qualities. The TRL aquaculture industry is reliant on the successful transport of juveniles to often distant grow-out sites from where they are harvested in the wild or raised in hatcheries. There has been mixed success transporting TRL juveniles, with high mortality rates which are typically associated with metabolic stress. Isobutanol, a food safe alcohol, has been shown to act as a sedative in adult TRL, as well as several other commercially important lobster species. This study found that juvenile TRL were rapidly sedated with isobutanol treatments at 350 and 500 ppm (15.05 and 6.47 min, respectively) and sustained inactivity was observed (36.12 and 60.62 min, respectively). Pre-treatment with isobutanol at 25 and 50 ppm led to decreased CO2 production rates during a 2 h air exposure experiment compared to untreated individuals (∼55 and 28%, respectively). Glycogen stores were maintained (∼75 higher) while lactate and ammonia concentrations were lower (∼50% and 40%, respectively) compared to untreated individuals. Isobutanol treatments at 25 and 50 ppm prior to 20 h of simulated transport improved overall survival (87.5% without treatment; 100% at either isobutanol treatment), while maintaining glycogen stores (∼80% higher) and limiting the accumulation of lactate and ammonia (∼25% and ∼ 45% lower, respectively) compared with untreated individuals. The results indicate that isobutanol treatment prior to air exposure during transport has the potential to improve outcomes from the transport of live juvenile TRL by decreasing overall metabolic stress and increasing survival.