05-06-2025
Seabirds in trouble due to fewer sand eel and sprat
The unassuming little sand-eel keeps a low profile. We haven't even got its name right — this is not an eel, nor is it closely related to eels. However, sand-eel and sprat are 'keystone species' which support a unique marine eco-system, as recent declines in their numbers show.
Even great whales, the largest animals ever to have lived, gorge themselves on these little creatures. Puffins, guillemots, and kittiwakes are not only partial to sand-eel and sprat, they rear their chicks on them.
We have several sand-eel species in Irish waters. Skinny plankton-feeders up to 30 centimetres long, they swim in great shoals from May to September, burrowing into sand when danger threatens.
Fishermen use sand-eels as bait, but we don't eat them. They were not, therefore, harvested traditionally. That has changed... they are now being fished on an industrial scale to supply the fish-meal, pet-food, and salmon-farming industries. Critics claim that the slaughter is altering the habits of whales and leading to food-shortages among seabirds. The seas, in some areas, are becoming 'marine deserts'.
Puffins and kittiwakes depend heavily on sandeels for food during the breeding season. Picture: RSPB
But there's a caveat; man-made global warming is the real villain of the piece. It is creating conditions unsuitable for the little fish. Sea temperatures, particularly off the West of Ireland, are now several degrees higher than 'normal'.
Even the great whales are moving elsewhere. Whale-watching excursions from Union Hall are being discontinued — most unwelcome news. Having encountered whales at locations from Iceland to South Africa, I can say from personal experience that Colin Barnes' West Cork operation was second to none.
Seabirds are also in trouble. Declines in their numbers off Norway and Scotland are being linked to reduced sand-eel and sprat abundance. In some areas, puffins are feeding their chicks on less nutritious pipe-fish. The colony on Norway's Røst archipelago used have over a million pairs of puffin, but numbers there have declined by more than 80% since the 1970s.
For our #puffin tracking project we combine GPS tags with cameras to identify the prey birds bring back to the nest - like this tagged bird on Grimsey (Iceland) bringing a beakful of tiny sandeels to its chick. #seabirdersaturday @SkyOceanRescue @NatGeo — Annette Fayet (@AnnetteFayet) July 14, 2018
Researchers from Oxford University found that puffins must now travel ever longer distances to harvest fish for their chicks. Being divers, they are heavy, with wings doubling as fins. Flying long distances, with fish held in the bill, is an additional burden on stressed parents. Chicks are undernourished and their survival rates fall.
However, in some locations, puffins seem to be holding their own. Skomer, a small uninhabited island less than two kilometres off the Pembrokeshire coast, is home to the Skomer vole, a distinct sub-species of rodent. It is claimed that around half the world's population of Manx shearwaters breed there. Shearwaters nest deeply in burrows. Visiting the island in daylight, you might not be aware of the multitude of birds in the ground beneath your feet.
But the island's most conspicuous summer resident is the in-your-face puffin. It's also a burrow nester, but active in daylight. More than 43,600 of these 'sea parrots', were counted on Skomer this summer by the Wildfowl Trust of South and West Wales. With puffins doing so well, sand-eels and sprat must also be holding their own in that part of the Irish Sea.
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