Canadian biologists from the University of British Columbia, together with German colleagues from the GEOMAR Helmholtz Center for Ocean Research in Keele and scientists from the University of Western Australia, conducted a global analysis of the biomass of commercial fish and marine invertebrates in various marine basins, ecoregions and climatic zones and concluded that there the number is decreasing. The research results are published in the journal Estuarine, Coastal, and Shelf Science.
According to the results of work in the world, there is a global decrease in the biomass of commercial species. 82% of species are already below the level of recovery required to maintain sustainable prey.
The reason is that these species are caught at a faster rate than recovery – 87 populations with biomass levels less than 20% of what is needed to maximize sustainable yield were categorized as “very poor” by the authors.
This is the world’s first global study of how populations of exploited marine fish and invertebrates will change quantitatively across all coastal regions of the planet. We analyzed the populations of the main species over the past 60 years and found that the biomass of most of them is currently well below the level that can provide optimal catches.
Marie Dan Palomares, lead study author at the Institute of Oceans and Fisheries, University of British Columbia
According to scientists, the current volumes of caught fish will decrease, respectively, fishermen will try to compensate for the lack of catch volumes by expanding fishing areas, extending the fishing period or using less gentle technologies. This will lead to an even greater reduction in the number.
The trend is not unambiguously negative everywhere, for example, the largest reduction in reserves – more than 50% since 1950 – was noted for the southern and polar parts of the Indian and Atlantic oceans. However, in the Pacific Ocean biomass has increased: in the temperate zone by 150%, and in the polar and subpolar zones – by 800%.
According to the authors, the results of the study require immediate action: it is necessary to designate special marine protected areas in which fishing is completely prohibited, where biological species could recover.