Our directory of things of interest

University Directory

Battle in the Baltic: Seals, birds and humans compete for food in the Baltic sea

A merciless eating machine that won't rest until all known fish have been devoured A merciless eating machine that won't rest until all known fish have been devoured Shutterstock
15 Dec
2017
Baltic seals and fish-eating bird populations are increasing and could be putting a strain on fish stocks

For the first time, ecologists have been able to quantify how important fish stock is shared among humans, seals and birds and their findings are raising difficult questions about how to manage food resources alongside growing wildlife populations.

‘We found that the impact of wildlife on fish stocks is real,’ says Sture Hannson, ecologist at Stockholm University who carried out the study with researchers from the Swedish University of Agricultural Sciences. Hannson estimates that humans consume 700,000 tonnes of fish, seals 100,000 tonnes and birds 100,000 tonnes. In other words, birds and seals are eating about one-fifth of the catch between them.

‘When it comes to coastal fish species such as whitefish, perch and pike, we can see a clear impact on these populations from seal and cormorant predation,’ says Hannson. 100 years ago there were 100,000 grey seals in the Baltic sea but industrial-scale hunting meant that by the 1940s this had dropped to 20,000 individuals and by the 1970s, a mere 4,000 individuals remained.

Since protections were introduced, their numbers have been able to grow to 50,000 and continue to increase by around eight per cent every year. Similarly, fish-eating birds such as cormorants have been allowed to flourish now that they are no longer persecuted. The flip side to this growth is that now both predator populations are stronger, they are coming into conflict with the fishing industry.

Related items

Subscribe to Geographical!

geo line break v3

Free eBooks - Geographical Newsletter

Sign up for our weekly newsletter today and get a FREE eBook collection!

geo line break v3

University of Winchester

geo line break v3

EDUCATION PARTNERS

Aberystwyth University University of Greenwich The University of Derby

TRAVEL PARTNERS

Ponant

Silversea

Travel the Unknown

DOSSIERS

Like longer reads? Try our in-depth dossiers that provide a comprehensive view of each topic

MORE DOSSIERS

NEVER MISS A STORY - Follow Geographical on Social

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...

Wildlife

A tightening of restrictions on the insecticides known as neonicotinoids…

Wildlife

Bonnethead sharks, the second smallest member of the hammerhead family,…

Nature

There’s more than enough plastic in the world. That’s why,…

Wildlife

The recent discovery of more than 200 million termite mounds…

Geophoto

The new year still remains a popular time to set…

Wildlife

After decades battling environmental crises that threaten to rob the…

Climate

As another new year beckons and the fight to protect…

Geophoto

A half century has passed since the ‘Earthrise’ photograph – widely believed to have…

Wildlife

Are howler monkeys being adversely affected by ingestion of pesticides containing…

Tectonics

Why unprepared tourists are putting themselves at risk in order…

Geophoto

The majestic and mighty polar bear is in danger of…

Wildlife

Exciting news for wildlife and photography enthusiasts alike – the…

Wildlife

A new system of robotic aerial vehicles is revolutionising the…

Wildlife

Technology used in creating safe urban environments is now being…

Climate

Brazil’s shift to the right of the political spectrum could…

Wildlife

Laura Cole travels to Orkney to find out why numbers…

Wildlife

The unprecedented frequency of winter tick epidemics have resulted in…

Oceans

Ocean debris, mostly composed of plastic, reaches remote Atlantic islands…

Geophoto

With motion detectors becoming ever more sophisticated, and clearer, crisper…

Nature

Natural capital is a way to quantify the value of…