The common octopus is among the species of fish and invertebrates what is disappearing faster on fishing grounds around the world. This is stated by a pioneering study carried out by researchers from the University of British Columbia (Canada), the University of Western Australia and the GEOMAR Helmholtz Center for Ocean Research in Kiel (Germany).
Experts from these three centers have been estimating the biomass -the weight of a certain population in the water- of 1,300 marine species. In this way, they have been able to observe global declines, severe in many cases, in the amount of shellfish and fish that are commonly consumed. Of all the creatures analyzed, 82% were already below the thresholds that would guarantee basic sustainability, which indicates that they are fished in quantities that prevent reproduction and lead to extinction.
What’s more, 87% of these species were in a “very serious” range of overexploitation, with biomass at only 20% of the required volume required to optimize sustainable fishing. This is also to the detriment of fishermen, who take longer and suffer greater difficulties to achieve catches which in turn are increasingly rare.
“This is the first study at a global level on the long-term trends for the biomass of the populations of fish and invertebrates exploited by fishing in all the coastal areas of the planet,” he explains. Maria “Deng” Palomares, study leader and initiative coordinator Sea Around Us of UBC Institute for Oceans and Fisheries. “When we look at how the populations of the most popular species in the last 60 years, we discovered that, as of today, most of its biomasses are well below the levels that allow optimized fishing ”.
To reach that conclusion, the researchers applied intensive computerized stock assessment methods called CMSY and BSMY to the accumulated volumes of fishing according to each marine ecosystem, a data work compiled to the period 1950-2014 for the initiative Sea Around Us. The greatest declines in fishing grounds were verified in the southern and northern fringes of the Indian Ocean, and in the southern polar region of the Atlantic Ocean, where the populations have contracted 50% since 1950.
Most of the globe is experiencing downward trends in the concentration of species, but the analysis has found some exceptions. One of them takes us to North Pacific Ocean, where the Population biomass has increased by 800% in the polar and subpolar regions, and approximately 150% in temperate areas. However, despite these sources of improvement, the global image is a reason for concern, alert Daniel Pauly, co-author and principal investigator of Sea Around Us.
“Exceptions aside, our findings are in line with the indications of systematic and widespread overfishing in coastal and inland waters of most of the world for the last 60 years, ”he explains. “For this, we need clear guidelines for improving fisheries management, which should not be based solely on annual catch limits, but also by the layout of protected and inviolable marine areas that allow stocks to recover ”.