Interactive effects of fishing effort reduction and climate change in a central Mediterranean fishing area: Insights from bio-economic indices derived from a dynamic food-web model

Abstract

Disentangling the effects of mixed fisheries and climate change across entire food-webs requires a description of ecosystems using tools that can quantify interactive effects as well as bio-economic aspects. A calibrated dynamic model for the Sicily Channel food web, made up of 72 functional groups and including 13 fleet segments, was developed. A temporal simulation until 2050 was conducted to evaluate the bio-economic interactive effects of the reduction of bottom trawling fishing effort by exploring different scenarios that combine fishery and climate change. Our results indicate that direct and indirect effects produce a net increase in biomass of many functional groups with immediate decline of trawlers’ catches and economic incomes, followed by a long term increase mainly due to biomass rebuilding of commercial species which lasts 5-10 years after fishing reduction. Synergistic and antagonistic effects caused by changes in the fishing effort and in climate characterize a specific functional group’s response in biomass which, in turn, modulate also the catch and income of the other fleets, and especially of those sharing target resources. However, trawler’s intra-fleet competition is higher than the others fleet effects. In the medium term, the effects of fishing effort reduction are higher than those of climate change and seem to make exploitation of marine resources more sustainable over time and fishery processes more efficient by improving ecosystem health.

Exploring the feasibility of technological transfers of two by-catch reduction devices in the crustacean bottom trawling of the central Mediterranean

“…All these potential management rules should be carefully monitored to determine their effective application. In addition, as already shown by Vitale et al (2018b), in the near future, to simulate the effect of mounting the tested BRDs or the adoption of the abovementioned management rules, it would be worthwhile to incorporate the selectivity results in an ecosystem model (e.g., Ecopath With Ecosim) to assess the effects not only on commercial target species but also on the other components of the trophic web in the area (Agnetta et al, 2022).…”

Adding to the mix – Challenges of mixed‐fisheries management in the North Sea under climate change and technical interactions

“…We showed that management of mixed fisheries constituted both a great challenge for fishers in the short‐term, but also had the potential to offset negative climate change effects for demersal North Sea stocks in the mid‐ to long‐term future. In general, reductions in fishing effort have the potential of stock rebuilding in temperate regions (Cheung et al, 2022), allowing sustainable harvesting and increased profits in the mid‐ to long‐term (Agnetta et al, 2022). Still, overcoming losses in profit and yield in the transitional period is crucial and requires adaptive compensatory measures (Agnetta et al, 2022).…”

“…In general, reductions in fishing effort have the potential of stock rebuilding in temperate regions (Cheung et al, 2022), allowing sustainable harvesting and increased profits in the mid‐ to long‐term (Agnetta et al, 2022). Still, overcoming losses in profit and yield in the transitional period is crucial and requires adaptive compensatory measures (Agnetta et al, 2022). Management that allows for flexible advice within the F MSY range or limits year‐to‐year TAC variability could, in part, address this issue under the landing obligation, however with some trade‐offs.…”

Detecting, attributing, and projecting global marine ecosystem and fisheries change: FishMIP 2.0

“…We hypothesize that forcing FishMIP models with more realistic fishing and environmental drivers of change will improve models' skill in reproducing both the inter-annual to decadal variability and the long-term trends in catches and biomass (Capotondi, et al 2019;Jacox et al 2020). First, because the environmental variability at the inter-annual to decadal temporal scales is better captured by the observationally based climate forcing (Liu et al, 2019) and, second, because the variability and trend of fishing effort are major drivers of biomass and catch changes (Agnetta et al, 2022). The simulation experiment framework (Fig.…”