Will fisheries be able to make up for the loss of production in the agricultural sector on our plates, or should we expect the same evolution of food resources provided by the sea? This is the meaning of the question asked by Audrey Boly to the oceanologist Philippe Curie, her guest today.
The data of the latter are hardly encouraging: world fish consumption is constantly increasing, from 6 to 9 kg per inhabitant and per year in 1950 for 3 billion earthlings to 21 kg today for a population close to 10 billion. In order to meet this demand, industrial fishing, carried out by very large groups, is putting increasing pressure on the resources as a whole.
strengthening technological means (GPS, radar or sonar, stronger nets) that allow more and more fish to be driven into the nets, faster, deeper, by fishing gear that destroys marine habitats, such as trawls that scrape up funds. Between the 1950s and 1990s, the amount of fish caught increased from 25 million tons per year in the 1950s to 100 million tons in the 1990s, and today the loss is one million tons per year. About 500 species of fish live in the Mediterranean, and 10% of these species are endangered. These data should be interpreted as indications of resource depletion due to overfishing.
Another sign of the overexploitation of our coasts is the origin of the fish we find on our shelves: 90% comes from other countries, which in turn are overexploited. Philippe Curie reports his African experience: in Senegal and Guinea, the fishery, which is entirely artisanal, is provided by a flotilla of canoes, the main catch of which consists of thiophea, a type of white sea bass. In the 1980s, 3,000 canoes brought between 3,000 and 5,000 tons of theft annually. Today, the number of canoes has increased tenfold, but only returns 50 tons. Thus, overexploitation has done its damage here as well. And these 50 tons go to foreign markets, as well as the production of sardinella, which replaced sea bass, in the form of fish meal intended for animal feed. Overfishing also has a direct impact on the balance between species: if we eliminate species A, the predator of species B, the latter will multiply out of control. Such is the case in Namibia, where ten million tons of sardines have been fished out of the sea, resulting not only in the decline of bird and marine mammal populations that feed on them, but also in the explosion of two species of jellyfish. Thus, the uncontrolled spread of some species (octopus on the coast of France) is a sign of ecosystem disturbance.
But overfishing is not the only reason: under the influence of climate change, the oceans are warming, causing fish to migrate to higher latitudes. To take the example of Senegal, this phenomenon also contributes to species scarcity and the enormous food security problems it causes. This warming of the water, as well as the increase in CO2 in the atmosphere, contribute respectively to a decrease in the oxygen content in the waters and acidification of the oceans. The ecological imbalance caused by these chemical modifications is significant: the size of the fish is decreasing, as has been observed in the sardine population in the Mediterranean Sea, which suffer from chronic malnutrition due to the qualitative and quantitative modification of the shellfish and plankton on which they feed. innings; Under the influence of heat peaks experienced by corals, from 15 to 20% of them have already disappeared, and the rest are on the way to extinction. This excess coral mortality is leading to the loss of habitat for many species.
There is also pollution: the marine space is a real garbage dump, which sooner or later gets all kinds of pollutants scattered over land (hydrocarbons, chemicals, plastic waste). Along with the “plastic continent” of the Pacific, several times the size of France, there is the problem of microplastics – insidious because less visible – that affects plankton and populations of turtles and marine mammals. And one day we will have to decide – and the sooner the better – to ban the use of plastic packaging and containers.
Consequently, it is these three factors – overfishing, global warming and pollution – that are synchronized to cause deep degradation of marine ecosystems, accumulating their impacts and creating positive feedback loops. Reversible or not? the journalist asks. Weakly reversible, the oceanologist answers, and at extremely long times. However, we have an example of bluefin tuna in the Mediterranean, where the establishment and enforcement of catch quotas allowed stocks to recover within three years. Thus, good management, based on an accurate assessment of marine stocks and prompt adaptation of fishing allowances, allows for rapid replenishment of resources. It is necessary to conserve marine stocks, because fish farming can in no way replace marine fishing: in the European market, in contrast to the Asian market, the share of farmed fish remains very low. But, above all, this fish farming activity competes with fishing rather than compensates for its shortcomings: farms are fattened with flour from anchovies, sardines, mackerel, herring, and their processing, rather than using them directly for food, represents a great waste of energy. .
The conclusion of the interview concerns the solution formulated by Philippe Curie: “Sustainable fisheries with respect for ecosystems“. By defining this concept, the oceanologist gives some concrete ideas: return to artisanal fishing by banning large units engaged in industrial fishing and redirect 35 billion euros of subsidies at the global level to create real local dynamics, return to fishing gear that do not destroy marine habitats manage marine resources in a manner similar to what has been described above with regard to the success of bluefin tuna conservation. productivity in favor of conservation of the environment.A specific example given by Philippe Curie is the management of the sardine fishery, which must leave the necessary quantity in the sea so that all its predators (birds, marine mammals) can feed on the tools and scientific data to be able to manage this resource in such a way that to save the ecosystem.
Thus, the podcast ends on an optimistic note, which, however, is recommended to be tempered on a personal level: the extraction of the oceans, which is only briefly mentioned in the podcast when the question of the usefulness of marine reserves is mentioned, is not excluded the “One Ocean Summit”, this eco -white masquerade, which took place in Brest a few weeks ago. You don’t have to be an ocean scientist to understand the environmental damage that cleaning up the ocean floor can cause. And this practice would undermine every ocean management effort that the experts have to offer.
Podcast link: https://podcasts-francais.fr/podcast/dernieres-limites
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