Assessing trade-offs to inform ecosystem-based fisheries management of forage fish

• Published in: Scientific reports Vol. 4; no. 1; p. 7110
• Main Authors: Shelton, Andrew Olaf, Samhouri, Jameal F., Stier, Adrian C., Levin, Philip S.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19-11-2014; Nature Publishing Group
• Subjects: 631/158/1745; 631/158/672; Animals; Computer Simulation; Conservation of Natural Resources; Ecology; Ecosystem; Ecosystems; Female; Fish conservation; Fish harvest; Fish populations; Fisheries; Fisheries - economics; Fisheries - ethics; Fisheries - statistics & numerical data; Fisheries management; Fishery management; Fishes - physiology; Food Chain; Food webs; Forage; Foraging behavior; Humanities and Social Sciences; Humans; Male; Marine ecosystems; Marine fish; Models, Statistical; multidisciplinary; Pacific Ocean; Population dynamics; Population Dynamics - statistics & numerical data; Predators; Reproduction - physiology; Science; Pacific Ocean
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep07110

Twenty-first century conservation is centered on negotiating trade-offs between the diverse needs of people and the needs of the other species constituting coupled human-natural ecosystems. Marine forage fishes, such as sardines, anchovies and herring, are a nexus for such trade-offs because they are both central nodes in marine food webs and targeted by fisheries. An important example is Pacific herring,
Clupea pallisii
in the Northeast Pacific. Herring populations are subject to two distinct fisheries: one that harvests adults and one that harvests spawned eggs. We develop stochastic, age-structured models to assess the interaction between fisheries, herring populations and the persistence of predators reliant on herring populations. We show that egg- and adult-fishing have asymmetric effects on herring population dynamics - herring stocks can withstand higher levels of egg harvest before becoming depleted. Second, ecosystem thresholds proposed to ensure the persistence of herring predators do not necessarily pose more stringent constraints on fisheries than conventional, fishery driven harvest guidelines. Our approach provides a general template to evaluate ecosystem trade-offs between stage-specific harvest practices in relation to environmental variability, the risk of fishery closures and the risk of exceeding ecosystem thresholds intended to ensure conservation goals are met.