The importance of scientiﬁc research to achieve sustainable shark ﬁsheries in Mexico

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May 5, 2020
The Mexican seas are inhabited by 111 species of sharks (Del Moral-Flores and León, 2015), which represents 21.8% of those recorded worldwide (Weigmann, 2016). This is possible due to the great diversity of coastal and oceanic habitats on both coasts of the country. Of those species, at least 33 are of commercial interest ((de la Federación DOF, 2010) and (de la Federación DOF, 2018)) and are fished for the consumption of their meat and fins. The meat has great acceptance in the national market, whilst fins are exported to the Asian market.
In Mexico there are official records of shark catches since the late 1930's. In the 1970's, shark fishing increased exponentially due to the national demand for meat and the international demand for fins, reaching 35,000 tons per year by the 1990's (Castillo-Géniz J.L. and del Prado A., 1998). After a decrease in catches in the last decade, with less than 30,000 tons per year in the current decade, catches gradually increased to 42,704 tons in 2017 (SAGARPA, 2017). Therefore, research is necessary to achieve the sustainability of this fishery; it must be determined to decide if shark species can tolerate these levels of fishing without affecting their abundances. Worldwide, there is concern about the status of many shark species because declines in their populations put them at risk of extinction (Dulvy and White, 2014), and local extinctions have already been documented (Pérez-Jiménez, 2014). This is because, in general, sharks are very vulnerable to intense and prolonged periods of fishing due to their biological characteristics such as slow growth rates, late sexual maturity, low fertility and long reproductive cycles, which result in low population growth rates (Musick and Fordham, 2000).
However, despite the over-fishing of some shark species (i.e. fishing intensity exceeds the recovery potential capacity of their populations), it does not seem feasible to prohibit this fishery as coastal fishing communities depend on this marine resource, and due to the demand for shark meat in Mexico. Simpfendorfer and Dulvy (Simpfendorfer and Dulvy, 2016) indicate that prohibiting shark fishing is not a solution to the over-fishing problem faced by some shark populations in the world, as most of the species are caught incidentally (i.e. the species are not the objective of the fishery), and because they play an important role for worldwide food security. These researchers highlight that a feasible solution is to move towards sustainable fishing, because the current capturing of at least 33 species of shark is sustainable. In some regions of Mexico, research can make some shark fisheries sustainable, combining knowledge of the biology of the species and the dynamics of the fishing communities (Pérez-Jiménez and Méndez-Loeza, 2015).
Shiffman and Hueter (Shiffman and Hueter, 2017) indicate that some lessons, which guide shark fisheries towards sustainability, are to protect those species with the lowest biological productivity. In Mexico, NOM-029- PESC-2006(de la Federación DOF, 2007 establishes the protection of some of these species such as white, basking and whale sharks. Such international treaties contribute to the sustainability of fisheries, and Mexico meets the guidelines of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Meanwhile, developed countries support the transition towards the sustainability of fisheries in developing countries and in Mexico, researchers collaborate with different international institutions to receive training and improve the assessments of the status of shark species.

Contributions
• Dr. Juan Carlos Pérez Jiménez wrote the article. He is a researcher at El Colegio de la Frontera Sur in Campeche, Mexico. His work focus on shark biology and the management of their fisheries. (Twitter @jcarlosperez74). • Lauren Nelson edited the article. Lauren is a Ph.D. student at Newcastle University (UK), researching computational drug design alongside the Northern Institute for Cancer Research. Lauren also writes a scientific blog aiming make science understandable for the masses. (Twitter @ashortscientist; Instagram @ashortscientist; Blog: ashortscientist.wordpress.com). • Ernesto Llamas made the illustrations. He obtained his Ph.D. in Biotechnology from Universitat de Barcelona doing his research at the Centre for Research in Agricultural Genomics. Creator, editor and illustrator of Sketching Science. (Twitter @neto flames; Instagram @eellamas).