Can We Have Our Fish and Eat Them, Too? Evaluating Whether a Selective Piscivore Fishery Can Foster Recovery of Rockfish

Predation and fishing are two size-structured processes that influence mortality, but predation generally targets small fish while fisheries select mature adults. Therefore, the effect on populations of simultaneously varying predation and fishing is often unclear. In the California Current, lingcod (Ophiodon elongatus) populations have recovered rapidly over the past two decades, and this recovery may be slowing recovery of overfished rockfish (Sebastes spp.) populations within rockfish conservation areas (RCAs) through increased predation. However, due to RCA restrictions, most lingcod quota is not met. We examined whether opening RCAs to a selective lingcod fishery could enhance rockfish productivity, despite the potential rockfish bycatch that would occur. Using linked density-dependent deterministic age-structured models for rockfish and lingcod, we calculated the change in rockfish spawning biomass occurring under a continuum of lingcod fishing intensities and incidental rockfish mortality rates. We show that opening RCAs to a lingcod fishery could enhance rockfish populations, making this case an example where an ecosystem-based approach to fisheries management leads to a win-win situation for conservationists and fisheries alike. However, the model is highly sensitive to assumptions regarding lingcod diets; before making major changes to existing fisheries management, better information on lingcod feeding habits is necessary.