Basin characteristics and temperature improve abundance estimates from standard index netting of rainbow trout (Oncorhynchus mykiss) in small lakes

Ward, Hillary G. M.; Askey, Paul J.; Varkey, Divya; McAllister, Murdoch K.

doi:10.1016/j.fishres.2012.07.011

Cited by 12 publications

(10 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For Rainbow Trout Oncorhynchus mykiss , Ward et al. () found that catchability was a function of surface water temperature at the time of gill netting and proportion of littoral area within each lake. Walleye CPE varies by season, water temperature, site effects, dissolved oxygen, and feeding behavior (Grant et al.…”

Section: Discussionmentioning

confidence: 99%

An Assessment Model for a Standard Gill Net Incorporating Direct and Indirect Selectivity Applied to Walleye

Radomski

Anderson

Bruesewitz

et al. 2019

N American J Fish Manag

View full text Add to dashboard Cite

Fisheries managers regularly use catch‐per‐effort (CPE) statistics and length‐frequency distributions from standard gill‐net surveys to inform future management activities. The data from these surveys is implicitly tied to the net's selectivity, and caution should be used when not accounting for selectivity. We combined indirect and direct methods for estimating the parameters of absolute selectivity by using data from Minnesota's standard gill‐net surveys for Walleye Sander vitreus, enabling the estimation of density from CPE. The indirect piece used a state‐wide gill‐net database and generalized linear modeling to identify a set of possible shapes for the selectivity curves. The direct piece added information based on 94 mark–recapture experiments that were paired with standard gill‐net surveys. The resulting statistical assessment model used a bi‐lognormal‐shaped selectivity curve that was geometrically similar for each mesh, and it estimated fishing intensity that differed substantially with mesh size. Applications of the selectivity model allow the estimation of Walleye density as CPE divided by absolute selectivity by length‐bin. The estimated absolute selectivity for the Minnesota standard gill net increased with increasing Walleye length to a peak of 0.76 ha/net at 535 mm and then decreased to about 0.26 at about 800 mm (1.0 and 0.34 relative selectivities, respectively). Fishing intensity increased with mesh size, so the selectivity curves for the individual meshes and that for the standard gill net (5 meshes in series) differed substantially from the curves that have resulted from indirect selectivity models that have ignored size‐dependent encounter probabilities and assumed equal contact probabilities for all meshes. We caution investigators that adjusting gill‐net catch data with indirect selectivity models that assume equal contact probabilities for each mesh may introduce considerable bias to estimates of population abundance and length distributions.

show abstract

Section: Discussionmentioning

confidence: 99%

An Assessment Model for a Standard Gill Net Incorporating Direct and Indirect Selectivity Applied to Walleye

Radomski

Anderson

Bruesewitz

et al. 2019

N American J Fish Manag

View full text Add to dashboard Cite

show abstract

“…The fish population data collected consist of autumn gillnet samples that follow BC's provincial guidelines (Ward et al. ), gillnet catch (number of fish per two net set) is used as a proxy for fish density in the lake and the asymptotic length ( L ∞ ) is estimated by fitting the VBGF (Eq. ) to the size at age data obtained from gillnet fork length measurements and otolith aging.…”

Section: Methodsmentioning

confidence: 99%

Habitat availability and ontogenetic shifts alter bottlenecks in size‐structured fish populations

Cantin

2018

Ecology

Self Cite

View full text Add to dashboard Cite

For species that utilize different habitats throughout their life cycle, the habitat limitation at a given stage can act as a bottleneck on population abundance, impacting density-dependent processes such as individual growth and survival. We explore the influence of habitat limitation on population dynamics by developing a multi-stage population model based on lake-dwelling rainbow trout (Oncorhynchus mykiss) populations where adults occupy the lake habitat but use tributaries for spawning and juvenile rearing. The model details density-dependent ecological processes and ontogenetic habitat shifts, harvest mortality, and the impact of climate on growth. We ran model simulations using a range of early life stage habitat availabilities and climatic conditions representative of the native range of rainbow trout in Canada and compared the results to empirical data. The results suggest that (1) increases in early life stage habitat leads to increases in population abundance but, due to density-dependent processes, also results in slower growing stunted populations; (2) population bottlenecks can occur at any life stage, even at the adult stage if spawning and rearing habitats are abundant; (3) when the level of competition for early life stages is increased, inter-cohort competition can lead to population cycles. The model's conclusions are further reinforced by empirical data showing a similar trend in the relationship between fish density and maximum size and providing evidence that limited early life stage habitat leads to lower fish densities and larger fish size. We provide a model that links environmental conditions to population dynamics and is useful for fisheries management and habitat conservation decisions.

show abstract

“…Fish density in each lake was estimated using the sampling methodology outlined in Ward et al. (), and this estimate of fish density was used to calculate the catch per unit effort (CPUE) that would be experienced by anglers based on the Ward et al. () catchability model.…”

Section: Methodsmentioning

confidence: 99%

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

Mee

Post

Ward

et al. 2016

Ecological Applications

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Basin characteristics and temperature improve abundance estimates from standard index netting of rainbow trout (Oncorhynchus mykiss) in small lakes

Cited by 12 publications

References 38 publications

An Assessment Model for a Standard Gill Net Incorporating Direct and Indirect Selectivity Applied to Walleye

An Assessment Model for a Standard Gill Net Incorporating Direct and Indirect Selectivity Applied to Walleye

Habitat availability and ontogenetic shifts alter bottlenecks in size‐structured fish populations

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

Contact Info

Product

Resources

About