Abstract

In Bahía de la Ascensión (Mexico), the fishery for spiny lobsters (Panulirus argus) relies on the extensive use of casitas, artificial shelters 1.5 – 2 m2 in surface area and 10 – 15 cm in height that can harbor the full size range of these highly gregarious lobsters. The emergence in 2000 of the disease caused by Panulirus argus Virus 1 (PaV1), which mostly affects juvenile lobsters and can be transmitted by contact, has raised concern about the potential effect of casitas on local prevalence levels of the PaV1 disease. To address this issue, we sampled thousands of lobsters from the commercial catch from Bahía de la Ascensión during three years, and from 530 casitas distributed over three different zones within the bay during two fishing and two closed seasons. In the commercial catch, disease prevalence (% lobsters patently infected with PaV1) was low (0.74 – 1.6%) but differed significantly with year. Among lobsters occupying casitas, disease prevalence was generally higher in juveniles than in subadults/adults, but varied with zone and season. In particular, levels of disease prevalence were consistently lower in one zone (0 – 2.9%) relative to the other two zones (5.3 – 9.6%). Regardless, the average prevalence (4.7%) was statistically similar to the average prevalence reported in Cuba (4.8%), where casitas are also used, and in Florida Bay (5%), where casitas are not used. These findings suggest that the dynamics of the PaV1 disease in lobster populations is driven more by local intrinsic and extrinsic factors than by the use of casitas.