Science report on the Ecosystem Effects of Fishing

Published on November 6, 2006

According to a report published in the current edition of Science, there is a risk of collapse of the world’s seafood populations by 2048 if current trends in destruction and overfishing continue.

Scientific data going back to the 1960s and historical records of over thousand years reveal that marine biodiversity has declined dramatically, with 29% of commercial fish-species already in collapse.

By 2048 the researchers predict that catches will decrease by 90% from the maximum catch. This applies to all species, from mussels and clams to tuna and swordfish, as well as ocean mammals, including seals, killer whales and dolphins according to Boris Worm, the lead author of the study “Impacts of Biodiversity Loss on Ocean Ecosystem Services”, recently published in Science Magazine.

The report includes a vast amount of research, including scientists from many institutions in Europe and the Americas. It draws conclusions from four different kinds of data; open sea catch records, historical records from coastal zones in North America, Europe and Australia, Experiments performed in small, relatively contained ecosystems, and studies on Marine Protected Areas (MPA:s).

“Whether we looked at tide pools or studies over the entire world’s ocean, we saw the same picture emerging,” says Worm “In losing species we lose the productivity and stability of entire ecosystems. I was shocked and disturbed by how consistent these trends are – beyond anything we suspected.”

Worm believes that the decline in marine biodiversity is caused by overfishing and destruction of seabed habitats, which in turn result in feedback effects on the ecosystem. “When ocean species collapse, it makes the ocean itself weaker and less able to recover from shocks like global climate change, pollution and over-exploitation”, says Worm.

The report argues that current ways of exploiting fish-stocks assumes that there will always be another species to exploit after one has been depleted. Worm et al highlights that there is a finite number of stocks that we have already gone through one-third, and we will soon get through the last one. “Unless we fundamentally change the way we manage all the ocean species together, as working ecosystems, then this century is the last century of wild seafood.”, says Steve Palumbi, from Stanford University in California, one of the other scientists on the project.

The findings of the study suggests that the elimination of locally adapted populations and species does not only damage the ability of marine ecosystems to feed a growing world population, but also sabotages their stability and recovery potential in a rapidly changing marine environment.

The main conclusion of the study is that business as usual would cause serious threats to global food security, costal water quality, and ecosystem stability, affecting current and future generations. It suggests that marine biodiversity can be restored through sustainable fisheries management, pollution control, maintenance of essential habitats, and the creation of marine reserves.

“The benefits of marine-protected areas are quite clear in a few cases; there’s no doubt that protecting areas leads to a lot more fish and larger fish, and less vulnerability,” says Carl Gustav Lundin, head of the IUCN global marine programme.