Evaluating the effect of a selective piscivore fishery on rockfish recovery within marine protected areas

Abstract

Oken, K. L., and Essington, T. E. Evaluating the effect of a selective piscivore fishery on rockfish recovery within marine protected areas. -ICES Journal of Marine Science, 73: 2267-2277. Received 14 January 2016; revised 28 March 2016; accepted 8 April 2016Although ecosystem-based fisheries management is often associated with trade-offs between conflicting demands for ecosystem services, the holistic ecological considerations the approach promotes may sometimes lead to novel solutions that benefit both conservation and fisheries. Directed fishing on large piscivorous fish can reduce predation on prey and thereby benefit those populations, but incidental take of prey species in these fisheries may negate or even reverse the benefit. Whether benefits from reduced predation outweigh the costs of increased fishing will depend on the relative strength of each mortality source and the sensitivity of the population to mortality at different life stages. In the California Current, predatory lingcod (Ophiodon elongatus) populations recovered rapidly from fishing exploitation over the past two decades, while recovery of some rockfish species (Sebastes spp.) has been slow, mainly because of low natural productivities. One management tool has been the adoption of rockfish conservation areas (RCAs) that prohibit bottom contact fishing gear. Because lingcod also inhabit RCAs, fishers have been unable to catch their sustainable lingcod quotas. Therefore, we explored the conditions under which opening RCAs to a selective lingcod fishery might permit rockfish recovery despite the potential bycatch. We developed a joint equilibrium model of the two populations and analysed scenarios to assess the sensitivity of the model's predictions to key uncertainties. The model suggests a wide range of fishery and ecological conditions under which a lingcod fishery may not harm rockfish populations. However, a sensitivity analysis indicated that the range of fishing scenarios where rockfish are not harmed is highly sensitive to assumptions regarding the nature of the trophic linkage between lingcod and rockfish. We conclude that consideration of trophic interactions may reveal new fishing opportunities that meet both ecological and human goals, but precise predictions of the outcomes will require more detailed models and adaptive management.

Expanded consumer niche widths may signal an early response to spatial protection

“…In fact, rockfish biomass consumed by lingcod in Washington State was 5–10 x higher in MPAs than adjacent fished areas [63]. Simulation models of lingcod and rockfish interactions within MPAs off the northeastern Pacific [64] highlight the generality of the community-level consequences of protecting apex predators on the recovery of their prey [1], although behavioral evidence would be needed to substantiate this hypothesis.…”

“…Rockfish species are long-lived, late-to-mature mid-trophic level predators that can exhibit slow responses to spatial protection. Lingcod on the other hand, are faster growing, higher trophic level predators that appear to respond more quickly to spatial protection [32–34]. Because RCAs are protecting rockfish and, indirectly, their predators, lingcod, previous theoretical and empirical research suggests that the dynamics of predator-prey interactions could be changing in multiple ways within these MPAs [14,32,35].…”

Out with the New And In With the Old: Reviving a Traditional Makah Halibut Hook for Modern Fisheries Management Challenges

“…Most rockfish have long life spans, late sexual maturation, and a closed swim bladder that causes them to experience barotrauma and low survival rates when brought up from depth (Parker et al 2000). Area closures, bag limits, and selective harvest of predators have been explored as tools for rockfish management in both the United States and Canada (Yamanaka and Logan 2010; Oken and Essington 2016). Considerable catches of rockfish still occur despite these spatial closures in Pacific Halibut longline fisheries.…”

Fisheries Volume 46 Number 7 July 2021

“…Most rockfi sh have long life spans, late sexual maturation, and a closed swim bladder that causes them to experience barotrauma and low survival rates when brought up from depth (Parker et al 2000 ). Area closures, bag limits, and selective harvest of predators have been explored as tools for rockfi sh management in both the United States and Canada (Yamanaka and Logan 2010 ;Oken and Essington 2016 ). Considerable catches of rockfi sh still occur despite these spatial closures in Pacifi c Halibut longline fi sheries.…”