溫暖的水域引發鯊魚大洗牌：北方海域新物種巡遊！

Sharks are changing where they live because the ocean is getting warmer. Scientists have noticed that some shark species, like porbeagle sharks, are moving north into warmer waters to follow their prey. As the water temperature rises, the fish that sharks eat are also moving, so the sharks follow them. This is happening around the Channel Islands and the South West of England. Recently, lifeguards asked people to leave the sea after a large shark, about 10 to 12 feet long, was seen off a beach in Jersey. Alex Plaster, from Jersey's marine resources team, explained that there have been rare sightings of bigger sharks, such as shortfin mako, porbeagle, and blue sharks, in the waters off the Channel Islands. However, he reassured people that the chance of anyone being bitten or attacked by a shark is almost zero. Plaster also said that there has never been a report of anyone being bitten by a shark in the English Channel area, including Jersey. He mentioned that the sharks people read about online, like bull sharks and great white sharks, have caused incidents in other parts of the world, but there has never been a confirmed sighting of these species in Jersey. Bryce Stewart, a scientist from the Marine Biological Association, said that one-off sightings of other sharks are relatively common. For example, a smalltooth sand tiger shark was washed up in the Channel Islands, and there have been sightings of large sharks that could be basking sharks, blue sharks, or porbeagle sharks. These sightings happen because large sharks can swim long distances and sometimes end up in new places due to currents or weather.

Plaster said that 14 different shark species have been recorded in Jersey over the last 100 years. Most of these sharks are small, measuring between 1 to 2 feet long, but some are larger, between 5 to 6 feet long. He added that Jersey and the surrounding Channel Island waters have a diverse group of sharks. Dr Bryce Stewart noted that most of the blue sharks seen off south-west England are pregnant females. He explained that warmer sea temperatures in winter are having a huge effect on marine life. Recently, new species like gill-head breams, stingrays, and bluefin tuna have been seen in greater numbers. These changes are linked to warming waters and shifting predator-prey relationships. Stewart said that the increase in bluefin tuna and shark species in the region is explained by changes in their migration patterns.

Scientists are studying sharks to learn more about their behavior. Stewart said that blue sharks are likely pregnant when they are seen off the south-west coast of the UK, and almost all the sharks spotted there are female. The theory is that pregnant females move to these waters to avoid males, who can be aggressive during mating and may eat the pups when they hatch. This area could be a safe zone for female sharks, like a maternity ward. Scientists are still researching this idea. The warmer waters are also bringing other sea creatures, such as octopuses and bluefin tuna, to the region. People are paying attention to these changes and learning more about sharks and other marine life as the ocean environment continues to shift.