DOI: 10.5061/dryad.c866t1gdx
title: Data for: Coherent long-term body-size responses across all Northwest Atlantic herring populations to warming and environmental change despite contrasting harvest and ecological factors

description: Body size is a key component of individual fitness and an important factor
 in the structure and functioning of populations and ecosystems.
 Disentangling the effects of environmental change, harvest, and intra- and
 inter-specific trophic effects on body size remains challenging for
 populations in the wild. Herring in the Northwest Atlantic provide a
 strong basis for evaluating hypotheses related to these drivers given that
 they have experienced significant warming and harvest over the past
 century, while also having been exposed to a wide range of other selective
 constraints across their range. Using data on mean length-at-age 4 for the
 sixteen principal populations over a period of 53 cohorts (1962-2014), we
 fitted a series of empirical models for temporal and between-population
 variation in the response to changes in sea surface temperature. We find
 evidence for a unified cross-population response in the form of a
 parabolic function according to which populations in naturally warmer
 environments have responded more negatively to increasing temperature
 compared with those in colder locations. Temporal variation in residuals
 from this function was highly coherent among populations, further
 suggesting a common response to a large-scale environmental driver. The
 synchrony observed in this study system, despite strong differences in
 harvest and ecological histories among populations and over time, clearly
 indicates a dominant role of environmental change on size-at-age in wild
 populations, in contrast to commonly reported effects of fishing. This
 finding has important implications for the management of fisheries as it
 indicates that a key trait associated with population productivity may be
 under considerably less short-term management control than currently
 assumed. Our study, overall, illustrates the need for a comparative
 approach within species for inferences concerning the many possible
 effects on body size of natural and anthropogenic drivers in the wild.
description: See Methods section in: <strong>Coherent long-term
 body-size responses across all Northwest Atlantic herring populations to
 warming and environmental change despite contrasting harvest and
 ecological factors</strong>.
description: # Data for Coherent long-term body-size responses across all Northwest
 Atlantic herring populations to warming and environmental change despite
 contrasting harvest and ecological factors
 This Dryad data submission
 includes datasets needed for the analysis in Coherent long-term body-size
 responses across all Northwest Atlantic herring populations to warming and
 environmental change despite contrasting harvest and ecological factors.
 The information needed to reproduce the analysis is given in the
 article's main text as well as in the Supplementary Information file.
 ## Description of the data and file structure laa4.tmean.df: * stock:
 population identity (see names in Figure 2) * cohort: birth year (here,
 corresponding to year-age = year-4 years old) * year: year of capture *
 location: location for temperature series (see Figure 2a) * mlen: mean
 length-at-age (mm) * mean_temp: mean temperature in the year of capture *
 tmean: corresponds to lifetime SST (see Methods) * colgrad: hexacode for
 figures which include a fill gradient by cohort combined.full.plus: as in
 laa4.tmean.df nls.params.24: * model: corresponds to the model variant in
 Table 2 * mt: corresponds to the mean lifetime SST over the 1962-2014
 period (see x-axis in Figure 4) * k, ymax, topt: estimated model
 parameters (obtained from R's nls function) * k.se,ymax.se,topt.se:
 estimated standard errors for model parameters (obtained from R's nls
 function) resdat4: * rows: each of the 16 stocks * cols: each of the 53
 cohorts * values: standardized residuals (see Methods subsection 2.4)
 dfa4_mod1_fits, dfa4_mod2_fits: * rows, cols: as in resdat4 * values:
 model fits from the one-trend and two-trend DFA analyses SSB.df2: * stock,
 cohort: as in laa4.tmean.df * age: corresponds to the age classes
 accounted for by mean.ssb * year: corresponds to the year of SSB (as
 reported in the reference variable) * SSB: spawning stock biomass (t) for
 the stock in the year of assessment * reference: origin of the data values
 * location: location of data within the specified reference * mean.ssb:
 mean SSB since birth (corresponds to lifetime SSB_agegroups in Figure 6)
 ## Sharing/Access information The DOI of the article to which these data
 are related is: 10.1111/gcb.17187