Dissertation Research

I conducted my doctoral research at the University of California Santa Cruz in the laboratory of Dr. Giacomo Bernardi. My dissertation work was both empirical and theoretical. The theoretical component involved a meta-analysis of population genetics studies focused on commercially important fish species, with the intention of using results from a large number of studies to develop a set of quantitative criteria for consistently and objectively implementing fisheries management strategies. The empirical component focused on population genetics and conservation genetics of commercial species targeted by small-scale fisheries in the Gulf of California and the Caribbean Sea.

Empirical studies investigated the role of oceanographic processes and aggregating behavior in structuring populations of Leopard grouper (Mycteroperca rosacea) in the Gulf of California and Nassau grouper (Epinephelus striatus) in the wider Caribbean.

Leopard grouper (Mycteroperca rosacea) Nassau grouper (Epinephelus striatus)

Both grouper species are known to form spawning aggregations. Spawning aggregations are reproductive gatherings of conspecific fish, consisting of anywhere from a few hundred to several thousand individuals. Fish may migrate anywhere from a few hundred meters to thousand of kilometers to reach aggregation sites. The spatial and temporal predictability of many aggregations make them easy targets for fishermen. High densities of fish found in aggregations guarantee fishermen high yields with minimal fishing effort. Leopard grouper are listed as Vulnerable by the International Union for the Conservation of Nature (IUCN). They form spawning aggregations of up to a few hundred individuals and have experienced a 50% reduction in biomass over the past 10 years. Nassau grouper are listed as Endangered by the IUCN and are currently under consideration for inclusion in the U.S. Endangered Species Act. They form spawning aggregations of up to several thousand individuals and have experienced a 60% decrease in population size over the past 30 years. At least one third of all known Nassau grouper aggregations have been eliminated by overfishing.

Increased knowledge of population structure and demography may facilitate more effective conservation and management strategies. I was interested in incorporating results of my dissertation into marine policy and fisheries management plans. In the Gulf of California I collaborated with researchers at both research institutions and non-governmental organizations as part of an ecosystem-based management project known as PANGAS. We plan to incorporate socioeconomic, genetic, oceanographic and fecundity data to generate management plans for six commercial species in the Gulf of California. Genetic results will also be used to inform to design a network of marine reserves in the northern Gulf of California being implemented by Comunidad y Biodiversidad, A.C. My work in the Caribbean was largely done in collaboration with two of my committee members, Dr. Brice Semmens and Dr. Yvonne Sadovy, as well as collaborators that I have met through the Gulf and Caribbean Fisheries Institute.

Click on the pictures below to see additional images from my fieldwork in the Gulf of California and the Caribbean Sea.

Fieldwork in Gulf of California PANGAS Subtidal Monitoring Cruise Fieldwork in Little Cayman