Interaction of ecological and angler processes: experimental stocking in an open access, spatially structured fishery

Abstract

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.

How ecological processes shape the outcomes of stock enhancement and harvest regulations in recreational fisheries

“…, Mee et al. ). That said, there is a need to inform and maybe even “educate” anglers about which forms of stocking are beneficial and which are unlikely to generate additive effects (Fujitani et al.…”

“…, Mee et al. ). It is important for managers to understand how changes in regulations will affect target‐species substitution and site substitution (Sutton and Ditton , Gentner and Sutton ) in multi‐species fisheries.…”

“…As a consequence, it has been found empirically that intermediate stocking rates attract the greatest fishing effort, because low stocking rates produce catch rates low enough to affect anglers’ behavior and high stocking rates reduce fish growth and affect anglers’ satisfaction with the size of fish caught, thereby attracting less fishing effort (Mee et al. ). We argue that a diminishing marginal return in utility from increasing catch rates is consistent with economic (Beardmore et al.…”

Synchrony — An emergent property of recreational fisheries

“…Outlining specific management goals and understanding the best way to implement a desirable change, while considering subsequent cascading consequences through space and time, will be necessary for successful management of these social‐ecological systems. Traditional recreational fisheries management techniques applied to the waterbody level, such as designated fishing seasons, species‐specific size and length limits, and fish stockings could also be balanced by taking a watershed‐scale approach (Mee et al., ; Nguyen et al., ; Wilson et al., ). We suggest that cross‐scale management that includes an understanding of how angler and resource heterogeneity interact through space and time will be most effective for maximizing ecosystem services within these recreational fisheries (Arlinghaus et al., ; Ward et al., ).…”

Ecological, angler and spatial heterogeneity drive social and ecological outcomes in an integrated landscape model of freshwater recreational fisheries

“…Our own pervious work, 156 however, has revealed that such expectations are not warranted . Instead, 157 deviations from a catch-based ideal free distribution (where at equilibrium all lakes 158 supposedly offer a regional average catch quality, Mee et al, 2016) should be the norm 1) 159 when angler's site choice is sub-optimal (by choosing the lake with the highest expected 160 11 utility probabilistically rather than deterministically), and 2) when multiple attributes in 161 addition to catch affect site choice. Both dimensionssuboptimal lake choice and multiple 162 non-catch attributes providing utilityshould foster a dynamic equilibrium that maintains 163 between-lake variation in catch rates and other measures of catch qualities 164 Matsumura et al, 2010), but this predictions remains to be fully explored in the present paper.…”