Interactions among adult demography, spawning date, growth rate, predation, overwinter mortality, and the recruitment of largemouth bass in a northern lake

Abstract

Using 12 years of data, we evaluated the mechanisms controlling largemouth bass, Micropterus salmoides, recruitment in a lake near the northern extent of the largemouth bass range. We found that complex interactions among adult demographics, size-selective predation, and overwinter mortality regulate the number of largemouth bass surviving the first year of life. The largest recruitment events required at least a moderate number of adults, but a large number of adults was not sufficient to produce a large cohort of largemouth bass. Predation was controlled by the number of both adult and juvenile bass and was not strongly correlated with reproductive output. Overwinter mortality was size dependent, strongly affecting bass entering the winter at <50-60 mm in length, and likely the result of starvation. Predation and overwinter mortality interacted with spawning date and growth rate to produce variable but predictable patterns of first year survival. At high adult and juvenile densities, predation regulates first year survival. At low adult and juvenile densities, first year survival was regulated by adult demographics and interactions among spawning date, growth rates, and overwinter mortality. Although we can forecast coarse patterns of cohort survival, the survival of individual fish was more difficult to predict because length and age were not highly correlated.Résumé : À partir de données s'étalant sur 12 ans, nous avons évalué les mécanismes régissant le recrutement de l'achigan à grande bouche, Micropterus salmoides, dans un lac situé près de la partie septentrionale de l'aire de répartition de ce poisson. Nous avons observé que des interactions complexes entre les paramètres démographiques des adultes, la prédation selon la taille et la mortalité hivernale déterminent le nombre d'achigans qui survivent plus d'un an. Les recrutements les plus importants étaient obtenus quand il y avait au moins un nombre modéré d'adultes, mais la présence d'un grand nombre d'adultes n'était pas suffisant pour produire une cohorte importante d'achigans. La prédation était régie par le nombre d'adultes et de juvéniles et n'était pas fortement corrélée avec la production génésique. La mortalité hivernale était fonction de la taille et touchait fortement les achigans dont la longueur au début de l'hiver était de moins de 50 à 60 mm; elle était probablement attribuable à l'inanition. La prédation et la mortalité hivernale étaient reliées à la date de fraye et au taux de croissance, d'où des profils de survie durant la première année variables mais prévisibles. Quand les densités des adultes et des juvéniles étaient élevées, la prédation déterminait la survie durant la première année. Quand ces densités étaient basses, la survie durant la première année était déterminée par les caractéristiques démographiques des adultes et les interactions entre la date de fraye, les taux de croissance et la mortalité hivernale. Bien que nous ayons pu prévoir les caractéristiques générales de la survie des cohortes, la survie des individus était ...

Predicting Crappie Recruitment in Ohio Reservoirs with Spawning Stock Size, Larval Density, and Chlorophyll Concentrations

“…Larval density was correlated with the number of spawning adults (Post et al 1998), a result similar to our study. Different from our study, however, the number of recruits was unrelated to larval density (Post et al 1998); rather, spawning date and growth rate influ- enced the probability of predation and overwinter mortality, and these processes interacted to regulate first-year survival (Post et al 1998). Another study sampled several life history stages of brown trout Salmo trutta and found egg density to be a strong predictor of the number of survivors in five subsequent life history stages (Elliott 1985).…”

“…Sampling multiple life history stages allows for determination and confirmation of when year-class strength is set and, in turn, allows for hypothesis generation of the important mechanisms. For largemouth bass Micropterus salmoides, the number of spawning adults, nests, newly hatched larvae, juveniles, and recruits were sampled for 12 years in Paul Lake, Michigan (Post et al 1998). Larval density was correlated with the number of spawning adults (Post et al 1998), a result similar to our study.…”

“…For largemouth bass Micropterus salmoides, the number of spawning adults, nests, newly hatched larvae, juveniles, and recruits were sampled for 12 years in Paul Lake, Michigan (Post et al 1998). Larval density was correlated with the number of spawning adults (Post et al 1998), a result similar to our study. Different from our study, however, the number of recruits was unrelated to larval density (Post et al 1998); rather, spawning date and growth rate influ- enced the probability of predation and overwinter mortality, and these processes interacted to regulate first-year survival (Post et al 1998).…”

“…Studies that have applied the stock-recruit relationship to multiple life history stages (e.g., adult stock, larvae, and recruits; for examples, see Elliott 1985;Post et al 1998) have several advantages over those that use only two life history stages (e.g., adult stock and recruits). First, including an intermediate life history stage, such as larvae, between adult stock and recruits can serve as a validation of the stock-recruit relationship.…”

Gigantic cannibals driving a whole-lake trophic cascade

“…In contrast, there is hardly any evidence for dynamic trophic cascades, in which major shifts in overall food-web structure are intrinsically driven by population dynamics. Only a few studies on recruitment variation have considered this aspect (10)(11)(12).…”