Apex predators (sharks, groupers, marine mammals) are hypothesized to play a central role-in some marine communities-on their structure and function. Understanding the dynamics of these individuals within the ecosystem is the basis for an ecosystem approach to fisheries management. Using a number of methods, we are performing research on the ecological interactions and processes of shark populations and the ecosystems in which they reside. In particular, we have conducted or are proposing research on shark predator/prey and trophic dynamics, bioenergetics, essential fish habitat, and the application of ecosystem models that may provide some insight into the function of marine ecosystems and their potential responses to the removal of apex predators.
Field and laboratory work involve novel approaches (e.g., biotelemetry, underwater acoustic arrays, satellite pop-up tags) to testing hypotheses regarding conventional nursery ground theory. At this time, shark essential fish habitat is classified based purely on presence/absence data. Opportunities exist to examine why different habitats may be of varying importance for sharks, if competition exists, and which species prefer which habitats.
Ecosystem modeling, focusing on the role of sharks as predators, is being conducted using ECOPATH/ECOSIM models, although opportunities are available to develop new modeling techniques. In addition, a number of hypotheses related to the effectiveness of the current size and design marine reserves are being evaluated.
Keystone predator; Predator-prey; Trophic dynamics; Essential fish habitat; Ecosystem modeling; Sharks;