Recruitment and survival of Northeast Pacific Ocean fish stocks: temporal trends, covariation, and regime shifts

Abstract

Two measures of productivity for fish stocks (recruitment and stock–recruit residuals) within two large marine ecosystems (Gulf of Alaska and eastern Bering Sea – Aleutian Islands) showed significant positive covariation within several groups of species and significant negative covariation between certain others. For example, stock–recruit residuals of gadids (Gadidae) in the Bering Sea were inversely related to those of shelf flatfishes (Pleuronectidae), suggesting that environmental forcing affects these groups in opposite ways. Salmon (Oncorhynchus spp.), Pacific herring (Clupea pallasii), and groundfish stocks each showed strong patterns of covariation within these taxonomic groups and within ecosystems, and both salmon and groundfish stocks showed positive covariation between the two ecosystems. However, we found little evidence of covariation between salmon and herring stocks or between these stocks and demersal stocks. Recruitment and stock–recruit residuals in individual stocks did not show a consistent response to known climatic regime shifts. However, combined indices of productivity across stocks showed decadal-scale variability (regime-like patterns), suggesting that both pelagic productivity (mostly salmon) and demersal productivity increased in response to the well-documented 1976–1977 climatic regime shift, whereas the 1988–1989 regime shift produced inconsistent or short-lived responses.

Temporal shifts in recruitment dynamics of North Atlantic fish stocks: effects of spawning stock and temperature

“…This is somewhat unexpected and seems to contradict earlier work by e.g. Mueter et al (2007), who pointed out that climate may induce persistent change in recruitment dynamics. Our results, in contrast, indicate that climate generally is not the main driver behind the long-term (as opposed to inter-annual) changes in juvenile survival or that the temperature measurements fail to capture the key climate changes.…”

“…The importance to recruitment of the different mechanisms may change over time, as a mortality factor operating at an early life stage may or may not be overshadowed by mortality factors operating at later life stages. Mueter et al (2007) emphasized that recruitment can be affected by predation; therefore, 'environmental'effects on productivity include changes in abundance of important predators, regardless of whether these were caused by environmental variability, fishing, or other factors. For instance, Stige et al (2013, this volume) found changing relevance of different environmental factors (including sea temperature and abundance of cod age 3 to 6 yr) for predicting recruitment of the Northeast Arctic cod and the North east Arctic haddock in the Barents Sea.…”

Synchrony of Marine Fish Catches and Climate and Ocean Regime Shifts in the North Pacific Ocean

“…However, for some stocks or species, there have also been dramatic increases in catch (or abundance) that cannot be easily attributed to changes in the management of these fisheries, and such increases may be related to climate change (Figure 1). There appears to be compelling evidence of a speciesspecific response to climate change (Spencer and Collie 1997;McFarlane et al 2000;Lehodey et al 2006;Mueter et al 2007;Osgood 2008), and this study provides a broader perspective of this important issue. In addition to the various socioeconomic effects, biological changes at the population level may well influence genetic diversity, interactions with other species, and a species' ability to adapt to future environmental stresses.…”

Evidence for harvest-induced maternal influences on the reproductive rates of fish populations

“…(a) Meta-analysis of marine fisheries data Although our model predicts MI on maximum reproductive rate that increases with RLS (figure 1), population dynamics in the wild are shaped by a suite of interacting physical and biological factors (Hilborn & Walters 1992;Trippel 1995;Mueter et al 2007) that could overwhelm MI and limit their relevance to management.…”

“…Third, long-term climatic conditions (regimes) can dominate the recruitment dynamics of many marine fish stocks by causing persistent and geographically pervasive changes in the carrying capacity of a marine environment (Mueter et al 2007). However, for climate regimes to explain the positive relationship between a g 0 =a d 0 and RLS, they must have closely coincided with periods of relatively high and low fishing mortality, and affected long-lived species more strongly than short-lived ones.…”