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

Abstract

Knowledge of the relationship between the number of offspring produced (recruitment) and adult abundance is fundamental to forecasting the dynamics of an exploited population. Although small-scale experiments have documented the importance of maternal quality to offspring survival in plants and animals, the effects of this association on the recruitment dynamics of exploited populations are largely unknown. Here, we present results from both a simple population model and a meta-analysis of time-series data from 25 species of exploited marine fishes that suggest that a population of older, larger individuals has a higher maximum reproductive rate than an equivalent population of younger, smaller individuals, and that this difference increases with the reproductive lifespan of the population. These findings (i) establish an empirical link between population age structure and reproductive rate that is consistent with strong effects of maternal quality on population dynamics and (ii) provide further evidence that extended age structure is essential to the sustainability of many exploited fish stocks.

Consequences of fisheries-induced evolution for population productivity and recovery potential

“…Although the estimation of population growth rates has comprised a fundamentally important component of some fisheries-related research [42,43], population growth rate has attracted comparatively little attention in studies of fisheries-induced evolution (but see earlier studies [44 -46] for closely related examples). In this respect, the analysis by Hutchings [16] was a rare attempt to estimate how life-history changes in an exploited fish stock affect the rate of population growth.…”

Maternal influences on offspring size variation and viability in wild European lobster Homarus gammarus

“…Maternal influences on offspring size could be an important source of variation in larval quality and, consequently, of variation in recruitment (Marshall & Keough 2008, Venturelli et al 2009). Therefore, maternal influences could also be an important source of error in fisheries science and management if they are assumed to be absent or unimportant.…”

“…It is increasingly recognised that the phenotype of mothers matters for population productivity and resilience to environmental change in the sea (Birkeland & Dayton 2005, Hsieh et al 2006, Venturelli et al 2009). Specifically, large and old females of many aquatic species are typically highly fecund and are known to produce larger, more robust offspring as compared to small and young spawners (Trippel 1998, Berkeley et al 2004a.…”

Red snapper management in the Gulf of Mexico: science- or faith-based?

“…Reproductive potential lost as biomass as the cohort grows older is offset for many years by increased egg production in older spawners because these larger females produce more eggs (Campbell 2008;Walters et al 2008a;Venturelli et al 2009). This also implies that fishing pressure on red snapper by the directed fishery is highest during the time when biomass production is highest and continues, but to a lesser degree on older age classes that are responsible for most of the egg production.…”