No abstract

Understanding how environmental productivity and resource competition influence somatic growth rates and plasticity in life-history traits is a critical component of population ecology. However, evolutionary effects often confound the relationship between plasticity in life-history characteristics and environmental productivity. We used a unique set of experimentally stocked populations of rainbow trout (Oncorhynchus mykiss) to empirically test predictions from life-history theory relating to patterns in immature growth rates, age- and size-at-maturity, and the energy allocated into reproduction across climatic and fish density gradients. Our results support theoretical predictions that plasticity in life-history characteristics is a function of environmental variables. In particular, we demonstrate that immature growth rates are best explained by climatic and density-dependent competition effects and that age-at-maturity and the energy allocated to reproduction depends on juvenile growth conditions. Empirical evidence of these relationships helps to improve our understanding of optimal life-history strategies of fish populations.

Effective management of socioecological systems requires an understanding of the complex interactions between people and the environment. In recreational fisheries, which are prime examples of socioecological systems, anglers are analogous to mobile predators in natural predator-prey systems, and individual fisheries in lakes across a region are analogous to a spatially structured landscape of prey patches. Hence, effective management of recreational fisheries across large spatial scales requires an understanding of the dynamic interactions among ecological density dependent processes, landscape-level characteristics, and angler behaviors. We focused on the stocked component of the open access rainbow trout (Oncorhynchus mykiss) fishery in British Columbia (BC), and we used an experimental approach wherein we manipulated stocking densities in a subset of 34 lakes in which we monitored angler effort, fish abundance, and fish size for up to seven consecutive years. We used an empirically derived relationship between fish abundance and fish size across rainbow trout populations in BC to provide a measure of catch-based fishing quality that accounts for the size-abundance trade off in this system. We replicated our experimental manipulation in two regions known to have different angler populations and broad-scale access costs. We hypothesized that angler effort would respond to variation in stocking density, resulting in spatial heterogeneity in angler effort but homogeneity in catch-based fishing quality within regions. We found that there is an intermediate stocking density for a given lake or region at which angler effort is maximized (i.e., an optimal stocking density), and that this stocking density depends on latent effort and lake accessibility. Furthermore, we found no clear effect of stocking density on our measure of catch-based fishing quality, suggesting that angler effort homogenizes catch-related attributes leading to an eroded relationship between stocking density and catch-based fishing quality at the timescale of annual surveys. We conclude that declines in fishing quality resulting from understocking (due to declines in catch rate with low fish abundance) and overstocking (due to suppressed growth and limited recruitment at high density) give an optimal stocking rate that depends on accessibility and latent effort.

Recreational fisheries are empirically tractable examples of social–ecological systems (SESs) that are characterized by complex interactions and feedbacks ranging from local to regional scales. The feedbacks among the three key compartments of the recreational fisheries SES—individual fish and populations, regionally mobile anglers, and regional and state‐level fisheries managers—are strongly driven by behavior, but they are poorly understood. We review and identify factors, antecedents to behaviors, and behaviors most important to the outcomes of the coupled SES of recreational fisheries, which emerge from a range of social–ecological interactions. Using this information, we identify data gaps, suggest how to reduce uncertainty, and improve management advice for recreational fisheries focusing on open‐access situations in inland fisheries. We argue that the seemingly micro‐scale and local feedbacks between individual fish, fish populations, anglers, and managers lead to the emergence of important macro‐scale patterns—some of which may be undesirable, such as regional overfishing. Hence, understanding the scale at which the behavior‐mediated mechanisms and processes identified in this article operate is critical for managing for the sustainability of spatially structured recreational fisheries. We conclude our study by providing relevant research stimuli for the future.

Management of recreational fisheries involves understanding how anglers interact with the fishery resource. Managers must understand the source (spatial distribution), efficiency, and behavior of angler effort in order to develop optimal management strategies in a social–ecological framework. We interviewed anglers (n = 1,956) and assessed fish populations in 21 lakes that are part of a multistock, spatially structured fishery for Rainbow Trout Oncorhynchus mykiss in the interior of British Columbia, Canada. Our objective was to assess the spatial behavior, harvest behavior, and catch efficiency of anglers and to understand the strengths of interactions between anglers and fish populations in three regions within this large fishery. Our results suggest a diverse angler population that varied in its behavior and its impact on the fishery. Using a hierarchical cluster analysis, we identified four distinct angler groups based on three variables that directly described how anglers interacted with the fishery (spatial distribution, catchability, and harvest behavior). Angler characteristics varied between groups, and the relative proportions of the four discrete angler groups varied among management regions. Substantial variation in angler characteristics across groups and variation in the relative distribution of the groups across regions imply that a “one size fits all” management approach is not optimal for this fishery. Instead, strategies that are attuned to angler characteristics would constitute a better approach for managing this large, spatially structured fishery.Received April 18, 2012; accepted March 10, 2013