This project seeks to clarify the conditions under which predator-prey relationships and interspecies competition should be included in fisheries models. In the first year of the project, the fellow used a simplified, hypothetical three-species food-web model, consisting of two competing prey species and one predator. The model was then “run” to simulate the effects of fishing on nontarget species, under varying levels of bycatch, competition and predation. The goal was to determine thresholds at which the harvesting of one species would benefit the other two and cease to benefit them because of high incidental takes. Results suggest that when competition and predation are strong, a moderate intensity of fishing pressure increases abundances of nontarget species, even with moderate levels of bycatch. Preliminary results underscore the importance of including predator-prey relationships and interspecies competition in ecosystem-based fisheries models. In the coming year, the fellow will be studying the selective pressure (Darwinian sense) of fishing on the age of maturity and growth rates of the target species, as well as the implications for fish communities.
Modeling the Effects of Interspecies Facilitation on Recruitment Success and Population Stability in Dwarf Rockfishes (Sebastes spp.)