Catch diversification provides multiple benefits in inland fisheries

Abstract

Diversification of fisheries and agroecosystems can increase and stabilize production and revenue, despite unpredictable changes in ecosystems and markets. Recent work suggests that diversification can provide multiple benefits simultaneously, but empirical evidence of relationships between catch or crop diversification and the provision of multiple benefits is scarce. The effect of diversification on multiple benefits may vary temporally and among systems. Using long‐term (11–54 years) capture fishery statistics from five Japanese lakes, we examined whether catch diversity increased multiple benefits, including revenue, nitrogen and phosphorus removal, and seasonal commercial species diversity. We also assessed whether catch species diversity increased the stability of each benefit via a portfolio effect (PE). Our study revealed positive relationships between catch diversity and the bundle of benefits (the mean of all normalized benefits; i.e., the provisioning of multiple benefits) in all five lakes, even after controlling for the total catch. The effects of catch diversity on individual benefits were positive or insignificant and differed among the study lakes. These differences were likely caused by the range and variation of functional characteristics among catch species. The influence of the annual mean price on revenue suggested that market forces did have an effect. We also found that aggregated revenue as well as N and P removal were 1.6–2.1 times (four lakes), 1.5–2.2 times (four lakes), and 1.4–2.2 times (all five lakes) more stable, respectively, than would be expected if only a single species were harvested. This greater stability suggests that maintaining catch species diversity may increase the stability of multiple benefits through PEs. Synthesis and applications. Our analysis suggests that catch diversification has great potential to increase the magnitude and stability of multiple benefits. Although total catch alone was sufficient to provide multiple benefits, a goal of maximization with specialization may decrease stability and deplete resources. Under fluctuating environmental and economic conditions, diversification strategies promise to be a potential management option for achieving resilient and sustainable inland fisheries.

Biodiversity as insurance: from concept to measurement and application

“…The benefits of diversification have been documented for food production from fisheries across multiple spatial scales (Sethi, 2010), from regional (Sethi, Reimer & Knapp, 2014; Anderson et al ., 2017; Cline, Schindler & Hilborn, 2017) to global (Dee et al ., 2016), and in both marine (e.g. Sethi et al ., 2014; Anderson et al ., 2017) and freshwater (Matsuzaki et al ., 2019) systems. They have also been documented at different levels of biological organisation, from diversity within fish populations to metacommunities, and at different levels of social organisation, from individual fishers and their income variability (Anderson et al ., 2017; Holland et al ., 2017) to regional management units and aggregate yields (Schindler et al ., 2010; Dee et al ., 2016).…”

Four decades of climatic fluctuations and fish recruitment stability across a marine‐freshwater gradient

“…In a variable environment, biodiversity can stabilize whole communities when species with different biological traits fluctuate asynchronously in space, time, or both (Loreau et al, 2021). In fisheries, portfolio effects have been documented in marine and freshwater systems (Matsuzaki et al, 2019; Schindler et al, 2010; Thorson et al, 2018) and across biological levels of organization—from spatially structured populations (Carlson & Satterthwaite, 2011; Hilborn et al, 2003; Schindler et al, 2010) to communities (Anderson et al, 2017; Hammond et al, 2020). Mounting evidence suggests that portfolio effects can arise from biological structure (i.e., the combination of species with different biological traits) or spatial structure (i.e., heterogeneity in the environments they inhabit), which promote independent fluctuations and thus buffer the community from variability (Greene et al, 2010; Hilborn et al, 2003; Moore et al, 2014).…”

A social-ecological approach to estimate fisher resilience: a case study from Brazil

“…Furthermore, fishers do not use a lot of gear which, therefore, limits their ability to exploit other resources, makes them more vulnerable to resource fluctuations (Aguilera et al 2015), and simultaneously increases pressure on specific resources (Roos et al 2016). Even under fluctuating environmental and economic conditions, catch diversification can reduce economic risks and be a potential management option for achieving SER (Matsuzaki et al 2019). Management strategies should support sustainable diversification, whether it be of gear, fisheries, or alternative sources of income to improve fisher flexibility under vulnerable conditions.…”