The Importance of Keeping the Big Ones: Harvest Slot Limits and Marine Protected Areas for the Management of the Caribbean Spiny Lobster

Fishing typically removes the oldest and/or largest individuals from populations undermining stability and reproductive success. Traditional fisheries management tools fail to protect these oldest and/or largest individuals, but two less conventional tools: marine protected areas (MPAs), and harvest slot limits have the potential to do so. Here I tested the possible use of these tools for the Caribbean spiny lobster, Panulirus argus, an iconic and economically valued species. After decades of intense fishing, the largest lobsters have largely been wiped out. The loss of the largest lobsters is significant as large lobsters have considerably greater reproductive potential than their smaller counterparts. I had four main objectives (1) developing a technique for directly ageing P. argus using banding in the gastric ossicles, (2) examining the possibility of reproductive senescence as it relates to body size in P. argus, (3) modeling the potential use of harvest slot limits and MPAs using a two-sex stage-structured matrix model, and (4) assessing the possible ecological consequences in terms of interactions with prey-species, of increasing the abundance and size of P. argus through a series of cafeteria trials. This work provides some necessary background information to support using MPAs and harvest slot limits in the management of P. argus in the Caribbean - calls for which has grown appreciably in recent years. Direct ageing of P. argus using bands in the gastric ossicles proved successful as it was possible to validate the ages of wild caught lobsters with lobsters of known age. The success of this technique opens up the potential for age based stock assessment and consideration of the relationship between size, age and reproduction. Lobsters were not found to exhibit reproductive senescence and for several of the metrics tested there was a positive relationship with parental size, confirming the biological value of retaining the largest lobsters in populations. The modeling demonstrated clearly the potential for MPAs and slot limits combined to increase the sizes and densities of P. argus in the marine environment, while the cafeteria trials demonstrated that larger lobsters did not have any appreciable preference for species of high ecological value