Warming seas bring new marine species to Jersey waters

Rising sea temperatures around Jersey are changing the island’s marine environment, with new species appearing and some traditional wildlife moving further north, according to a local marine expert.

Francis Binney, head of Jersey’s Marine Resources, said the waters around the island are closely linked to temperatures on land, meaning hot weather can quickly influence the sea.

“When the land is hot in Jersey, the sea gets hot,” he said.

Binney explained that seawater temperatures have already reached close to their usual summer peak, with the normal maximum temperature around 18C. However, recent recordings have shown waters reaching 21C, with occasional spikes of up to 24C.

The warmer conditions have led to more sightings of sharks around Jersey, while tuna are also “making a resurgence”. Other species, including trigger fish and gilthead bream, are becoming more common in local waters.

However, Binney warned the changing climate is creating difficulties for marine life that depends on cooler conditions.

“We’re seeing the loss of a lot of those cold-adapted species, which, if they can, are moving north,” he said.

One example is the edible crab, traditionally popular in Jersey’s crab sandwiches. Binney said the species has largely disappeared from local waters and is now becoming more common further north, including around the coasts of Sweden and Norway.

As edible crabs decline, spider crabs are increasingly moving into Jersey waters, highlighting the wider changes taking place beneath the surface as the sea continues to warm.