DOI: 10.5061/dryad.79cnp5htj
title: An updated life history scheme for marine fishes predicts recruitment variability and sensitivity to exploitation

description: 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.
description: Life history trait data were collected from FishBase (Froese
 & Pauly 2000; accessed Sep 24 2019) on a stock-specific basis for
 244 exploited marine fish species. FishBase was accessed using the package
 <i>rfishbase</i> (version 3.0.4; Boettiger et al. 2015) for
 the software <i>R</i> (version 4.0.3; R Development Core Team,
 2016). All life history traits were the mean (if numeric) or most frequent
 (if categorical) value reported for each stock of each species.
 "tmax" is the maximum time to maturity in years.
 "Fecundity" is the logarithmic mean of minimum and maximum
 fecundity. "PCI" is the Parental Care Index that weighted
 quantitative and categorical data on the mode of fertilization, Balon’s
 (1990) reproductive guilds, the presence/absence of any kind of parental
 care, and the duration of the gestation period. Missing values of maturity
 and fecundity for a small fraction of stocks (6% and 19% respectively)
 were imputed using closely related traits belonging to that stock and
 traits from other stocks using additive regression and bootstrapping
 techniques implemented with the <i>aregImpute</i> function in
 the <i>Hmisc</i> package (Harrell et al., 2017) of the
 software <i>R</i>. Separate imputations were performed on the
 taxonomic groups: Elasmobranchii, Scorpaeniformes, and non-Scorpaeniform
 teleosts. Time series of recruitment (R), spawning
 stock biomass (SSB), fishing rate (F), and exploitation rate (ER) were
 retrieved from the RAM Legacy Stock Assessment Data (RAM SAD) version 4.44
 assessment data only (http://ramlegacy.org). Data gathered prior to 1950,
 stocks with less than 10 years of data, and stocks with an unknown
 assessment method were excluded. Exploitation rate was used to estimate
 the fishing rate for stocks where it was missing using the Baranov
 equation. Variance in the recruitment time series was calculated as
 normalized recruitment deviations from expectations based on (1) a simple
 density dependent survival model (R/SSB), (2) a normal compensation
 (Beverton-Holt) model, and (3) an over compensation (Ricker)
 model. RAM SAD stocks were matched to FishBase stocks
 using information on regional location from both databases. If a RAM SAD
 stock was not represented by one FishBase stock, then the mean of one or
 more FishBase stocks were used. These means are indicated with
 fractional FishBaseStockCodes.