Estem matant el Mediterrani
Segles de sobreexplotació dels peixos i altres recursos marins, així com la invasió dels peixos des del mar Roig, han convertit en llocs àrids alguns ecosistemes de la mar Mediterrània, abans saludables.
Un equip del National Geographic, liderat pel biòleg català Enric Sala, ha fet un estudi per tal de valorar l’impacte de les reserves marines. L’estudi va trobar malgrat haver-hi zones ‘protegides’ del mar, on només s’hi permet algun tipus de pesca, la situació no és molt millor a la de llocs que no tenen cap protecció. Això suggereix, segons l’estudi, que la recuperació completa de la vida marina de la Mediterrània requereix reserves totalment (i no només parcialment) protegides.
La recerca es va publicar el 29 de febrer a la publicació PLoS ONE amb el titol de: The Structure of Mediterranean Rocky Reef Ecosystems Across Environmental and Human Gradients, and Conservation Implications.
Segons Sala: “Hem trobat un gradient enorme, un enorme contrast. Els majors nivells de biomassa de peixos el vàrem trobar en les reserves de fora d’Espanya i Itàlia. Desafortunadament, al voltant de Turquia i Grècia, les aigües estaven buides.
Interessant i oportuna també la reflexió que fa Miquel Sacanell, pescador artesanal: ‘Sense reserves marines, la pesca no té futur’.
Segons la nota publicada per National Geographic:
“…the researchers made hundreds of dives over three years off Morocco, Spain, Italy, Greece and Turkey, setting up transects to count fish and take samples of plants and animals living on the seafloor in 14 marine protected areas and 18 open-access sites. “The result is information on the Mediterranean at an unprecedented scale,” National Geographic said.
“While the level of protection was the most important factor in determining the biomass of fish, the health of the algal forests that support the fish depended on other factors, the authors write. Recovery of formerly abundant algal forests takes longer than recovery of fish. ‘It’s like protecting a piece of land where the birds come back faster than the old trees,’” Sala said.
The study provides the first baseline that allows evaluation of the health of any Mediterranean site at the ecosystem level — not only its fish but the entire ecological community, National Geographic said. “The trajectory of degradation and recovery found by the authors allows for evaluation of the efficacy of conservation at the ecosystem level for the first time.”
Sala believes the results about fully protected marine reserves give reason for hope in waters well beyond the Mediterranean. “If marine reserves have worked so well in the Mediterranean, they can work anywhere,” he said.
Often called the “cradle of civilization,” the Mediterranean is home to nearly 130 million people living on its shores, and its resources support countless millions more, National Geographic added. “A variety of pressures keep the organisms that live in the sea in a permanent state of stress.”
Death by a Thousand Cuts
“It’s death by a thousand cuts,” said Enric Ballesteros of Spain’s National Research Council and coauthor of the study. Among them are overexploitation, destruction of habitat, contamination, a rise in sea surface temperatures due to climate change and more than 600 invasive species. On the southwest coast of Turkey, for example, an invasive fish from the Red Sea called the dusky spinefoot has left Gokova Bay’s rock reefs empty.
A series of marine reserves that shelter slivers of the sea allows certain ecosystems to recover and their all-important predators to eventually reappear. “The protection of the marine ecosystems is a necessity as well as a ‘business’ in which everyone wins,” Sala said. “The reserves act as savings accounts, with capital that is not yet spent and an interest yield we can live off. In Spain’s Medes Islands Marine Reserve, for example, a reserve of barely one square kilometer can generate jobs and a tourism revenue of 10 million euros, a sum 20 times larger than earnings from fishing.”
“Without marine reserves, fishing has no future,” said fisherman Miquel Sacanell, who fishes near the Medes reserve.
The research was supported by Spain’s National Research Council, the Pew Charitable Trusts, the Oak Foundation, the Lenfest Ocean Program and the National Geographic Society.