Seeking improvements for more sustainable fishing

Scientists are putting their all into the search for ways to reduce fisheries’ impacts on ecosystems and preserve fishing resources. 

The Common Fisheries Policy (CFP), a European policy, sets the conditions for fisheries resource conservation and for the management of fisheries and fleets that exploit these resources. What with continuing efforts to bolster resource sustainability, the impact of climate change, and the economic situation of the sector (affected by Brexit, COVID-19, and inflation), good fisheries management has more and more complexity to take into account. Scientists play an essential role in fisheries management by sharing knowledge and suggesting ideas for the future. Here are some examples.

Smart nets that combine video and artificial intelligence

The first idea is to fine-tune the selectivity of fishing vessels. The goal is to capture fewer juveniles, limit rejects and give species that grow slowly (cod, hake) the time they need to reproduce. Leaving younger fish in the water enables them to contribute to ecosystem functioning. Research is under way to optimize the minimum size of individuals caught and the network of fishing vessels. Digital technology also paves the way to smart nets, which can open or close based on which species are targeted, through the use of cameras and artificial intelligence

Other possibilities are being studied to reduce impacts on fish habitats, potentially by developing trawl nets that dig less deeply into sediment, or by rethinking ways of fishing that involve traps and pots.

The second idea is to analyze and compare different management practices (for example, reducing fishing activity or closing off certain zones) using complex bioeconomic models, which help fisheries managers evaluate the compromises between exploiting resources and conserving them. To do so, new indicators for ecological, economic and social sustainability must be developed to better measure impacts and better identify the most suitable fishing methods.

Integrating predator-prey relationships into the calculations

The third idea is to more fully account for the ecosystemic dimension in fisheries management objectives. This is, in fact, one of the guidelines suggested for the reform of the Common Fisheries Policy. Scientists’ appraisals of the situation today are based on a species-by-species approach, yielding figures for a single population in a specific area. The goal is to integrate more environmental parameters and the consequences that exploitation of that population would have on the ecosystem.

“In the Irish Sea, we were seeing a collapse in white fish populations.”

David Reid, Marine Institute (Ireland)

In the Irish Sea, the ICES-WKIRISH project is developing this type of ecosystem-based approach. One of the project leaders, David Reid, from Ireland's Marine Institute, explains, “In the Irish Sea, we were seeing a collapse in white fish populations, which spurred representatives of the fishing sector to seek help from scientists. We worked on a model that integrates environmental parameters like temperature and other parameters for the food chain interactions between different species in the Irish Sea, from plankton up to cod, haddock and sole. Other actors and stakeholders in the sector, fishermen and NGOs, also contributed to the project.” Fishermen’s knowledge especially helped to determine the diets of the main species commercialized. “No fewer than 50 predator-prey relationships were revealed. The model’s accuracy and its ability to track changes at fisheries over time have been improved.”

Population mortality rates due to fishing can be revised upward when the ecosystem’s status is good, and downward when the parameters show a less favorable situation, all while taking precautions to remain within the limits of the maximum sustainable yield.

Scientific models make it possible to better reflect the complexity of marine ecosystems. Their purpose is to improve understanding of populations’ dynamics in their environment and help determine the appropriate levels of fishing activity more granularly with a view to preserving marine resources. Little by little, new ecosystem-based fisheries management methods are emerging. Climate disruption, the biodiversity crisis, heightened pollution...Within the context of these worldwide changes, the criteria for sustainability itself are also up for redefinition.