Human and natural predators combine to alter behavior and reduce survival of Caribbean spiny lobster

Abstract

Fishing disturbance can have indirect negative effects on animal behavior and survival, but receives little attention compared to measures of direct fisheries extraction. We quantified changes in the density of Caribbean spiny lobster Panulirus argus when exposed to experimental human disturbance and injury typical of sport-diver harvest attempts in the field. A complementary study in a large seawater arena quantified lobster sheltering behavior and survival when exposed to the single and combined effects of human disturbance and triggerfish Balistes capriscus predators. Human disturbance and injury of lobsters in the field caused lobsters to emigrate from shelters that had been typically occupied over successive days. Similarly, both the presence of triggerfish predators and human disturbance promoted decreased lobster shelter fidelity to individual shelters in the arena. Overall shelter use and gregariousness increased in the presence of natural triggerfish predators but not as a function of human disturbance. Decreased shelter use and gregariousness by lobsters when exposed to human disturbance may have contributed to their decreased survival when exposed simultaneously to triggerfish. These results highlight how human disturbance and injury of lobsters can alter their behavior and reduce subsequent survival in the presence of their natural predators, and illustrate the need to incorporate the negative effects of sport-divers into models that estimate population demographic rates.