Relationships between postlarval settlement and commercial landings of Caribbean spiny lobster (Panulirus argus) in Florida (USA)

Abstract

Commercial catch of Caribbean spiny lobsters (Panulirus argus) in Florida was highly correlated with the abundance of pueruli on artificial collectors. Each lunar month from 1994–2023, we counted postlarvae on artificial collectors at two locations in the Florida Keys (USA). We compared various indices of puerulus settlement and commercial landings. Significant correlations between postlarval indices and the sum of August and September commercial landings were identified at one sampling location. Commercial landings in these first two months of the fishing season likely represent a better index because, as the fishing season progresses, fishing effort and landings are influenced more by non-recruitment factors such as tropical disturbances, catch levels, and the price of lobster. The postlarval index with the highest correlation to landings included the months with peak settlement between January and June in the year prior to the fishing season (p < 0.001). The timing of the postlarval index and range of months indicates that it takes between 14- and 20-months post-settlement for a lobster to enter the fishery and that these peak settlement pulses drive landings in the commercial fishery. The correlation between postlarval settlement and fishery landings suggests that the quantity of postlarvae — and not post-settlement processes — is the primary driver of the spiny lobster population in Florida. Results from this study also indicate that postlarval settlement levels have declined over the past 30 years. As a population that relies heavily on postlarval supply from outside of Florida, this highlights the need for future research into the cause of the decline and any potential link to spawning stock biomass, particularly considering declining landings Caribbean-wide.