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Data for: Size spectrum model reveals importance of considering species interactions in a freshwater fisheries management context

Citation

Benoit, David; Chu, Cindy; Giacomini, Henrique; Jackson, Donald (2022), Data for: Size spectrum model reveals importance of considering species interactions in a freshwater fisheries management context, Dryad, Dataset, https://doi.org/10.5061/dryad.rn8pk0pbw

Abstract

Inland fisheries have significant cultural and economic value around the globe, providing dietary protein, income, and recreation. Consequently, methods for monitoring and managing these important fisheries are continually being refined. In marine systems, multi-species size spectrum models have been increasingly used to explore management scenarios of important fish stocks within an ecosystem-based fisheries management framework; however, these models have not been applied in freshwater systems. In this study, we developed a multi-species size spectrum model for the fish community of Lake Nipissing, a large, productive lake in Ontario, Canada. To the best of our knowledge, this is the first fully calibrated multi-species size spectrum model for an inland fishery. Using this model, we explored the impacts of different management scenarios on fish community dynamics while taking species interactions into account. Specifically, we examined how changes in fishing mortality affect: (1) species biomass; (2) community size structure; and (3) stock recovery times. We found that community dynamics following changes in fishing mortality were driven by complex interactions among species, including competition and predation. The greatest changes in biomass and community size structure were observed following changes in fishing mortality to top predators, with community size structure most strongly influenced by changes in mortality to the largest species in the community. Counter to predictions based on generation time, the smallest species in our model exhibited the longest time to recovery due to strong competition and predation. Our results demonstrate the importance of taking an ecosystem-based approach and considering species interactions in the management of inland fisheries and highlight the potential of size spectrum model use in freshwater systems.

Methods

Parameters relating to growth (asymptotic weight, weight at maturity, and the von Bertalanffy growth coefficient) were estimated for all species, excluding forage fish, from Fall Walleye Index Netting (FWIN) data provided by the Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry (OMNDMNRF). As growth rates may vary from year to year, we estimated average growth parameters from FWIN data spanning two decades (1998 to 2016). To represent the forage fish, we used growth parameters for the most abundant forage species, Common Shiner. The interaction matrix, which is used to scale feeding interactions between all species pairs, was based on spatial overlap across depth strata in the lake. Average fishing mortality across time was calculated for each species from annual fishing mortality estimates provided by the OMNDMNRF spanning 1972 to 2020.

Funding