Bay of Biscay and Celtic Sea depleted since 1970s, new study shows

Europeans have gotten used to managing a depleted sea, according to a long term study of the Celtic Sea and the Bay of Biscay. Fish have become much fewer, younger and smaller since the 1950s.

You may recognise the following structure of a news story about fish: A scientist says a fish stock is in a bad state. Then a fisherman says that’s nonsense because he can see himself that there is plenty of fish. The audience is led to believe that, well, it can’t be that bad if the fisher says that nothing has changed.

But, in fact, the sea has changed a lot. Generations of fishermen and managers have only known a state of degradation and have gotten used to scarcity as something normal, according to French researchers who this week published a study in the journal Ocean & Coastal Management in which they have studied the long term trends in the Celtic Sea and the Bay of Biscay.

A sharp decline in fish abundance in this area took place before the 1970s and this depleted state is what we have gotten used to, the study shows. The scientists at Université Européenne de Bretagne have analysed stock status and ecosystem indicators of the Celtic Sea and the Bay of Biscay from 1950 to 2008 based on landings, stocks assessments data and additional auxiliary observations.

Celtic Sea and the Bay of Biscay. Image: Eric Gaba, Wikimedia Commons.

Celtic Sea and the Bay of Biscay. Image: Eric Gaba, Wikimedia Commons.

Sharp decline between 1950s and 1970s
“While there has been a tenfold increase in fishing pressure since world war II, total fish abundance has been divided by six. All indices confirm a sharp decline in biomass between the 1950s and 1970s, and we have stayed at a low level since then. Even though the situation has improved slightly for some stocks the last few years, we must not forget where we have come from and the fact that the level of biomass is still very low,” Didier Gascuel, one of the researchers, said in a press release.

According to the study, the apparent stability in landings over the last 50 years masks the fact that the fisheries have been sustained at the cost of a dramatic increase in fishing pressure, and a change in species composition and fishing grounds.

This means that as soon as one resource has been overexploited, fishers have adopted by exploiting new areas and species and by improving their technology – in many cases aided by EU subsidies.

Caught fish is now younger and smaller
Over the studied period, the maximum size of fish has decreased by 32 cm on average for all the species. The large predatory fish are the most affected. For the most exploited species there has also been a change in age structure: the older fish have disappeared and the fishery is dependent on catching younger and younger fish.

“A more moderate fishing pressure would allow for an abundant resource and bigger catches, which would guarantee a better profitability of the industry. Looking back only 20 or 30 years may lead you to think that the ecosystem has not changed. The long term perspective, on the contrary, shows us how much it has deteriorated,” said Didier Gascuel.

Reduce fishing
The concept of “shifting baselines” – i.e. where scientists fail to identify the correct baseline for how abundant a fish species population was before human exploitation and thus work with scarcity as the normal state – has previously been demonstrated in other parts of the world, but this is the first long term study of the Celtic Sea and the Bay of Biscay which shows that the same syndrome applies to this area in Europe.

To reach sustainable levels, fishing pressure on most demersal (living near the bottom of the sea) stocks would need to be cut by at least half, the study concludes. But, Didier Gascuel notes, “achieving such a change seems to be a challenge in the context of the reform of the Common Fisheries Policy.”

Guénette, S., Gascuel, D., Shifting baselines in European fisheries: The case of the Celtic Sea and Bay of Biscay, Ocean & Coastal Management (2012),

Axel Naver

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