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Catch diversification provides multiple benefits in inland fisheries
- Matsuzaki, Shin‐Ichiro S., Shinohara, Ryuichiro, Uchida, Kei, Sasaki, Takehiro
- Journal of applied ecology 2019 v.56 no.4 pp. 843-854
- agroecosystems, fisheries statistics, freshwater fisheries, functional properties, income, lakes, markets, nitrogen, phosphorus, prices, species diversity
- 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.