05/12/2024 – 13:38
Researcher Marcelo Reis developed, during his doctorate in oceanography at the University of Sydney, Australia, a mathematical formula and a new technique capable of carrying out ecological risk analysis focused on fisheries management. The technique prevents accidental fishing of sharks and rays, in order to preserve the species, reducing the risk of extinction of some of them, such as the hammerhead shark, for example. Reis completed his master’s degree at the Federal University of Alagoas (Ufal).
The work was carried out based on fishery and species occurrence data from the Australian Fisheries Management Authority’ (AFMA)
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According to the researcher, AFMA data has the advantage of being of good quality, as the fishing authority determines the obligation, in commercial fishing, for fishermen to describe the geographical location, the species seized and the total weight of the animals. “By correlating these practical occurrences with the probability made in the literature and, mainly, through the source of AquaMaps – a platform created by German institutes – I was able to cross-reference the data”, said Marcelo Reis.
Based on the average catch per geographic unit and the possibility of occurrence, weighted by the total area, Reis took a value for each species. “In other words, an index of fishing interaction between the occurrence of species and the occurrence of fishing. We divided it by type, compared it with the target species of fisheries and basically used this for by-catch of sharks and rays, which are threatened animals in general, within the extinction categories of the International Union for Conservation of Nature (IUCN )”. Many species are of minor conservation concern, but others are globally threatened, although locally, in Australia, there are well-protected species, such as the hammerhead shark, because there are very specific rules for capturing these animals. “They have catch limits.” This is one of the most threatened species worldwide.
Advantage
In terms of cost-benefit, Reis highlighted that the advantage is that it is an easy method, because it does not require a large amount of data. “We basically have a qualitative method that doesn’t need a lot of quality data. Because, for you to manage any species, you need to make a huge effort to collect information about the species to create a more complex and detailed plan. And the idea of this metric that we created is to create a quick access system to take the species that are most threatened or that have a higher rate of interaction and select them first.” The tests carried out in Australia validated the method developed by the Brazilian researcher.
Reis’ formula seeks to give more precision to fishing activity, helping to preserve endangered species and helping to delimit preferred areas for carrying out this economic activity. The work was published in the international journal Diversity.
According to Marcelo Reis, there is currently a global trend that ecology has been based, for many years, on a more preventive attitude, towards correction. Nowadays, this type of study, called ecological risk analysis, uses modeling to predict which species may be more vulnerable in the future.
Taboo
Reis explained that, worldwide, the conservation of sharks and rays is still taboo, largely because of the 1975 film Jaws, directed by Steven Spielberg, which had a huge impact by showing that sharks are an aggressive species. Marcelo Reis stated that sharks are less killers than other animals. Data from 2023 shows that, across the world, eight people died from shark attacks, while in Africa there were 500 people attacked by hippos. “And nobody talks about it. One million people died from mosquito bites and associated diseases,” he recalled. For the researcher, there is this mythification of sharks in general, because they are large predators, they are in an environment that is not the natural environment of humans. “But worldwide, the conservation of sharks and rays, as a rule, ends up becoming taboo because people think that sharks are monsters that are eating people.”
Leading researchers are working around the world to reduce the number of shark attacks. In Brazil, there are several species that fit into the red list of most threatened species in the world. Among them, Reis mentioned the blue shark, the tiger shark, a flat-headed shark, which is responsible for several attacks in Recife (PE), as well as three or four species of hammerhead shark, as well as smaller species. In Australia, there are more than 400 species of sharks and rays.
Reis stated that the method he developed does not need to be applied exclusively to fishing activities, but can be used for other extractive studies, including vegetable studies. “It’s all a question of anthropic pressure, that is, anthropic extractivism, and area. Among the advantages of the method, he recalled that it can be adjusted according to the reality and location of the search intention. Marcelo Reis’ work is also signed by professor William Figueira, from the University of Sydney.
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