An updated life history scheme for marine fishes predicts recruitment variability and sensitivity to exploitation

Aim: Patterns of population renewal in marine fishes are often irregular and lead to volatile fluctuations in abundance that challenge management and conservation efforts. Here, we examine the relationship between life history strategies and recruitment variability in exploited marine fish species using a macroecological approach. Location: Global ocean. Time period: 1950-2018. Major taxa studied: Bony and cartilaginous fish. Methods: Based on trait data for 244 marine fish species, we objectively extend the established Equilibrium-Periodic-Opportunistic (E-P-O) life history classification scheme to include two additional emergent life history strategies: "Bet-hedgers" (B) and Salmonic (S) strategists. B strategists include Rockfishes and other species inhabiting patchy benthic habitats with life histories that blend characteristics of E and P species; they combine very long lifespans with elevated investments in both parental care and fecundity. S strategists are comprised of mostly salmonids that share life history characteristics with E and O species: elevated investments in parental care reminiscent of E strategists, but with reduced fecundity and short lifespans characteristic of O species. We analyzed how the E-B-P-O-S life history classification mapped onto patterns of recruitment variability observed in population time series data (n = 156 species). Results: Generalized linear models suggest that life history strategy explains a modest, yet significant amount of recruitment variability across species. Greater predictive power arose after controlling for increased recruitment variance associated with variable fishing pressure, with O strategists showing the strongest sensitivity. B strategists were similarly susceptible to exploitation as P stocks, but their longer times to maturity make them particularly vulnerable to overfishing. Main conclusions: A broader recognition of the distinct ecology of Salmonic and Bet-hedger groups is important when studying life history strategies in marine fish. More generally, our results stress the importance of considering life history strategies for understanding patterns of recruitment variability across fish stocks.