Maternal influences on population dynamics: evidence from an exploited freshwater fish

Abstract

We used a field experiment, population modeling, and an analysis of 30 years of data from walleye (Sander vitreus; a freshwater fish) in Lake Erie to show that maternal influences on offspring survival can affect population dynamics. We first demonstrate experimentally that the survival of juvenile walleye increases with egg size (and, to a lesser degree, female energy reserves). Because egg size in this species tends to increase with maternal age, we then model these maternal influences on offspring survival as a function of maternal age to show that adult age structure can affect the maximum rate at which a population can produce new adults. Consistent with this hypothesis, we present empirical evidence that the maximum reproductive rate of an exploited population of walleye was approximately twice as high when older females were abundant as compared to when they were relatively scarce. Taken together, these results indicate that age- or size-based maternal influences on offspring survival can be an important mechanism driving population dynamics and that exploited populations could benefit from management strategies that protect, rather than target, reproductively valuable individuals.

Maternal and stock effects on egg-size variation among walleye Sander vitreus stocks from the Great Lakes region

“…Other studies have also documented a stock effect on walleye egg size (Johnston, 1997;Johnston and Leggett, 2002;Moles et al, 2008) and egg quality (Czesny et al, 2005). However, previous studies investigating linear relationships between walleye maternal traits and egg size point to inconsistent relationships, with some studies indicating that larger females produce larger eggs (e.g., Johnston, 1997;Wiegend et al 2007;Moles et al, 2008;Venturelli et al, 2010), while studies of other stocks suggest no such relationship (Czesny et al, 2005;Moles et al, 2008;present study).…”

“…Because of the relationships between maternal characteristics and egg size, changes in average maternal characteristics within a stock may affect mean egg size and have consequences for population dynamics. For example, size-selective harvesting may truncate female age and length distributions, leading to a decrease in mean egg size and quality Bobko and Berkeley, 2004), which could ultimately compromise recruitment potential and thereby affect population dynamics (e.g., Venturelli et al, 2010).…”

“…For example, larger walleye eggs tend to have greater yolk and oil volumes (Moodie et al, 1989), and even though proportional lipid content may be independent of egg size (Czesny et al, 2005), total lipid content will increase with egg size. In turn, walleye hatching from relatively large eggs are initially larger , may express greater early life survival (Venturelli et al, 2010), and are therefore more likely to survive to maturity. While relationships among fecundity, offspring size and offspring quality may vary among stocks, it is generally accepted that larger offspring experience some form of size-related advantage (e.g., Bernardo, 1996; but see, for example, Kaplan, 1992).…”

Fatty acids in an iteroparous fish: variable complexity, identity, and phenotypic correlates

“…In most fish species, larger eggs and larvae with increased lipid reserves are considered higher quality (Brooks et al 1997;Venturelli et al 2009;Fuiman and Ojanguren 2011;Olin et al 2012;Andree et al 2015). We observed positive correlations between fatty acid complexity of individual females and the quality eggs they produced, as determined by egg size, lipid content, and egg size variability, suggesting that females with more complex fatty acid profiles produced higher-quality eggs.…”

Reproductive allocation in exploited lake whitefish (Coregonus clupeaformis) and walleye (Sander vitreus) populations

“…However, spawning stock biomass alone is often a poor predictor of reproductive potential for many fish species (Leggett and Frank, 2008), and recent research has suggested that the composition of the spawning stock probably plays a role. Incorporating the size and/or age composition of the spawning stock into recruitment models appears to improve their predictive power (Forbes and Peterman, 1994;Marteinsdottir and Thorarinsson, 1998;Murawski et al, 2001) possibly because various aspects of reproductive effort (e.g., quantity and quality of gametes, spawning time and location) are related to adult age and body size (Mousseau and Fox, 1998;Berkeley et al, 2004;Green, 2008;Venturelli et al, 2010).…”