SCUBA Nov 2026 issue 170 | Page 53

A still from the video showing a diver spearing a turtle

Diver arrested over turtle killing

A Chinese diver has been prevented from leaving Indonesia while authorities investigate allegations that a turtle was killed and eaten during a dive trip in Raja Ampat. Wei Shang was detained by immigration officers at Sultan Hesamuddin International Airport in Makassar on 14 September as he prepared to board a flight to Kuala Lumpur. Makassar Immigration said the action followed a request from the Raja Ampat Regency Government. Authorities have said the suspect is a diving instructor.

observations, keeping the vessel stationary did not reliably decrease interaction intensity, while accelerating caused apparent loss of interest,” the research paper says.“ However, improved mitigation measures are needed to prevent harm to humans and killer whales, securing longterm coexistence.”

Sharks in a changing climate

Shark Trust MD Paul Cox weighs up the implications of the developing El Niño climate event for shark migrations and conservation

Following on from last month’ s article about the excitement generated when heatwaves, sharks and climate change end up in the same news item, we now have predictions of a powerful El Niño gathering pace in the tropical Pacific. I’ m on high alert for questions about sharks and climate shifts once again. So, I thought it would make sense to dig into the science a bit and see what we actually know.

El Niño, by disrupting ocean temperatures, currents, rainfall and marine productivity, will affect ecosystems far beyond the region in which it begins. For sharks, an extreme El Niño may be less an ocean-wide heatwave than an ecological reshuffle – moving the cool water, the food and ultimately the sharks themselves.

There’ s no doubt that climate change is altering the oceans, but its effects on sharks are way more complicated than the notion that‘ warmer seas mean more sharks’ – or the familiar suggestion that rising temperatures will bring an influx of exotic species into British waters.

Sharks are certainly sensitive to temperature. It influences their metabolism, movements, migrations and reproduction. Studies have recorded tiger sharks extending their range northwards in the western Atlantic and young bull sharks remaining longer in warming estuaries. Some previously unsuitable areas have even become shark nursery grounds.

But sharks don’ t follow temperature alone. They follow prey, currents, oxygen and productive habitats. When any of these moves, the sharks may move with it.

During the extreme El Niño of 2015-16, warming and increased stratification reduced the nutrients reaching surface waters across parts of the eastern Pacific. This affected plankton, fish and squid, sending consequences up the food chain. Research around the Galápagos found changes in the feeding ecology and local occurrence of scalloped hammerheads.

Elsewhere, the same event helped concentrate whale sharks in a productive

“ Sharks are moving through a world of fixed boundaries”

refuge in Mexico’ s Gulf of California. The unusually large gathering might easily have been interpreted as good news for conservation. In reality, the sharks may simply have been converging on one of the few places where sufficient food remained, bringing increased interactions with boats and tourism.

Even the direction of temperature change is not always obvious. Recent research off South Africa showed how changes in winds and currents can intensify sudden upwellings of cold water. One such event killed hundreds of marine animals, including sharks and rays. Climate change could therefore lure warm-water species towards higher latitudes while exposing them to abrupt and sometimes lethal cold shocks.

Young sharks may be especially vulnerable. In one recent experiment, 82 % of small-spotted catshark embryos hatched under present-day and moderate-emissions conditions. But, under an extreme warming scenario, that figure fell to just 11 %, with high summer temperatures proving particularly damaging.

So, will climate change bring new sharks to Britain? Perhaps some species will become more frequent, while others may retreat or change their seasonal movements. But an unusual sighting does not necessarily represent a new resident population; and more sharks in one place may simply mean fewer somewhere else.

The greater concern is that sharks are moving through a world of fixed boundaries. Marine protected areas, fishing regulations and national jurisdictions do not shift when shark habitat does. Climate change may move depleted populations beyond protected waters, into fishing grounds or across busy shipping routes.

Fishing remains the greatest direct threat to sharks. Climate change does not replace that threat; it complicates and magnifies it. The future will not simply contain warmer seas and different sharks. It will contain a less predictable ocean – and conservation must stay flexible enough to follow. www. sharktrust. org

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