Anchovy Explosion

They’re back. After a nearly half-century of rarity, big schools of anchovies – an important prey for both wildlife and humans — are again showing up in Europe’s North Sea. A new study tries to explain why, and finds climate shifts are probably playing a role.

The North Sea, which sits northeast of Scotland and west of Scandinavia, is at the northern range of the anchovy (Engraulis encrasicolus), a little fish prized for its oily, salty taste. Still, the area supported a healthy anchovy fishery in the 19th century and into the 1930s. “In the latter half of the 20th century,” however, “anchovy were only rarely found in the North Sea,” a research team reports in Marine Ecology Progress Series. Then, in the 1990s, there was a sudden and surprising rebound.

Researchers had several theories for the rebound. One was that more southern populations were moving north due to changing ocean conditions. Another was that climate shifts had enabled small remaining resident populations to boom – a homegrown population explosion that didn’t require immigrants.

To test those and other ideas, the researchers took a close look at everything from weather and catch data to anchovy genetics and life history. The most likely explanation, they concluded, is that warmer winters and other climate shifts have helped make the North Sea’s chilly waters more cozy for spawning anchovies and growing larva. As a result, the once small local populations have grown and expanded their range.

The shift may be good news for anything that likes to eat anchovies. But it is also a reminder of how climate change is reshuffling many ecosystems — and the full ecological impacts of the anchovy boom remain to be seen. David Malakoff | January 11, 2012

Source: Petitgas, P., Alheit, J., Peck, M., Raab, K., Irigoien, X., Huret, M., van der Kooij, J., Pohlmann, T., Wagner, C., Zarraonaindia, I…. (2012) Anchovy population expansion in the North Sea. Marine Ecology Progress Series, 1-13. DOI: 10.3354/meps09451 

Image © Le-thuy Do |