Refining spiny lobster (Panulirus argus) escape and mortality estimates in Florida’s lobster trap fishery using long-term video

Abstract

The Caribbean spiny lobster (Panulirus argus) fishery in Florida, valued at millions of dollars annually, relies mostly on wooden-slat traps baited with live, sublegal-size lobsters to attract legal-size individuals. However, this practice leads to confinement-related mortality due to starvation and depredation. We investigated the escape rates and mortality of bait lobsters using long-term deployable cameras, documenting behavior of bait lobsters in traps. Although previous research found that long-term confinement of these bait lobsters results in their poor health and mortality, these estimates of mortality relied on periodic observations of traps that could not differentiate causes and timing of mortality. To identify how the long-term confinement of bait lobsters affects their likelihood for escape or mortality, we deployed traps with one lobster for each of the following treatments: healthy/fed or starved for 2, 4, or 6 weeks. Long-term deployable cameras and infrared lights mounted on traps were used to observe the fate (i.e., escape or mortality) of these lobsters over a 2-week trap soak period typical in the fishery. We conducted 12 deployments of 103 total traps over 1 year and found that escape varied with duration of lobster starvation. Our study confirmed escape rates from past studies (1.26 ± 0.43 % of lobsters per day) and revealed "serial confinement," where escaped lobsters re-entered traps, potentially prolonging their confinement and mortality risk. Starvation, caused by long-term confinement, resulted in increased mortality, with smaller lobsters (<68 mm carapace length) facing higher risk of mortality. Video documentation allowed for the first time to differentiate between starvation mortality and depredation within traps; depredation by octopuses (Octopus briareus) and triggerfish (Ballistes spp.) posed a substantial threat, reducing trap catch efficiency. Our video documentation showed that the presence of dead lobsters in traps further decreased catch rates for the duration (∼5d) the carcass remained in the trap, underscoring the negative impact on fishery yield. Our findings emphasize the need for the fishery to explore management strategies to mitigate mortality of sublegal-size lobsters in traps due to long-term confinement, including trap reduction, use of escape gaps, and shorter trap soak times, akin to successful practices in other spiny lobster fisheries. The study highlights the utility of long-term deployable cameras in assessing trap functioning and catch dynamics, offering insights for sustainable management of Florida's lobster fishery while preserving its cultural and economic significance.