Lily Carter reports
Jersey’s native marine life could be at risk as rising sea temperatures attract invasive species from further south.
Some fish populations have declined or disappeared altogether, according to research by Jersey Marine Conservation.
The group's chairman, Kevin McIllwee said: "High temperatures lead fish to move to deeper water or move northward. Therefore we are observing a rising population of southern species and a decline in those species that need cold water for breeding."
Local researchers placed small temperature loggers around the island's coastline in 2020 and the data - now ready for analysis - provides evidence of Jersey's warming waters.
Jersey's Head of Marine Resources, Paul Chambers - who was leading the project - said: "We found an amazing number of things.
"One of the key things is that our seabed temperatures offshore is almost identical to the sea surface. That's quite unusual in oceanographic terms."
This phenomenon occurs due to Jersey's huge tidal range, which stirs up the water.
It means that when it is a hot day on land, it will also be hot on the seabed - meaning our marine life is particularly susceptible to heat waves and warmer weather.
The trend of rising sea temperatures is also exaggerated in the autumn and winter months.
This means fish which used to just be summer migrants can now stay here all year round.
Local fishers say the warmer waters are affecting their catches.
Gabby Mason, the co-founder of Jade's Fisheries, said octopuses are showing up in greater numbers and said "it isn't a positive sign."
Gabby said: "They're a huge predator and they don't really have any natural predators in Jersey's waters. So we are seeing issues with scallops and crabs and lobsters that are completely empty: they've just been eaten."
Meanwhile, other local catches are down - and it's proving difficult for the industry.
Gabby added: "We need the seasonality we need the colder waters for some of our species like lobster and shanker crab.
"Our fishing boats are set up for the historic fishing we’ve had say in the last 30 years. Not these rapid changes we’ve been seeing say for the last four."
She is calling for changes to legislation so the industry can adapt and change what they are allowed to fish.
Gabby said: "We’re not catching the same numbers of what we are designed to catch and what we have been. So there is a real fundamental shift and this is really making the fishing industry in Jersey suffer. We have fishermen leaving at an exponential rate, that is unheard of."
Meanwhile, conservationists are calling for more research - which could prove useful at a national level.
Kevin McIlwee said local waters are particularly important because they can provide a strong indicator of changes that will subsequently affect the UK.
He said: "We need to increase research, enabling us to more accurately predict these northbound trends in habitat shift and identify causes."