MEPS 564:127-143 (2017)  -  DOI: https://doi.org/10.3354/meps11987

ABSTRACT: Fisheries typically truncate target species’ size distributions through an increase in mortality, especially if harvest is size-selective. Such truncation can push a harvested species’ size distribution into classes most vulnerable to gape-limited predation, such that predator-prey dynamics might affect the rate of recovery from fishing. Understanding this rate of recovery is crucial to adaptive management of no-take reserves and fisheries closures. We used a 2-species size-structured model to examine how gape-limited predation alters post-harvest recovery for 3 example prey species, viz. cod, haddock, and whiting. We found little difference in recovery patterns of prey abundance and size structure between systems with gape-limited generalist predation and those with no size-dependent predation. However, gape-limited obligate predation can lead to fluctuations, with transient declines, that delay recovery to the pre-harvest equilibrium for both biomass and mean size due to a time lag in predator recovery. Fluctuating recovery dynamics under obligate predation were most likely for predators that experienced greater declines due to prey loss during harvest and for slow-growing prey with an adult size refuge. We conclude that through these delays, the presence of a strong dynamically linked predator can alter the expectations of the time scale for different recovery metrics used in adaptive management.

KEY WORDS: Size-selective harvest · Species interactions · Gape-limited predation · Size structure · Multi-species fisheries models · Ecosystem-based fisheries management · Marine reserves · Monitoring