Highest Number of Leatherback Sea Turtle Hatchlings in 20 Years Recorded on Thai Beaches

Conservationists in Thailand have found the largest number of leatherback sea turtles (Dermochelys coriacea) nesting on their beaches in two decades, Reuters has reported.

Leatherback sea turtles are the largest of the seven sea turtle species, reaching up to 2.4 m in length and 900 kg in weight. They are currently endangered in Thailand and are listed as Vulnerable worldwide on the IUCN Redlist. Like other turtle species, they must come ashore to lay their eggs and will usually do so in dark, quiet areas where they are less likely to be disturbed by humans. As a result, tourism can have a negative impact on the turtles' ability to reproduce.

But beaches in Thailand are now free of tourists due to the current COVID-19 pandemic. As of writing, Thailand has had 2,989 confirmed positive cases and 55 deaths, resulting in a ban on international flights and citizens being encouraged to stay at home. While incredibly unfortunate, this has allowed leatherback sea turtles to nest in areas they would normally avoid, particularly due to the absence of tourists.

Leatherback sea turtle nesting in the sand

Authorities have found 11 nests on Thai beaches since November. This may not sound like much but it is the highest number recorded since the early 2000s. And it gets better. In late March, staff at a national park in Phang-Nga, a province in southern Thailand which borders the Andaman Sea, recorded 84 leatherback sea turtle hatchlings after monitoring eggs for two months.

Kongkiat Kittiwatanawong, the director of the Phuket Marine Biological Centre, explained why this new development is so important:

"This is a very good sign for us because many areas for spawning have been destroyed by humans. If we compare to the year before, we didn't have this many spawn, because turtles have a high risk of getting killed by fishing gear and humans disturbing the beach."

For the last five years, there had been no nests found at all on Thai beaches, so this year's numbers are a significant improvement. While the circumstances that brought about this change are truly awful, it has certainly highlighted the impact that human activity can have on the wildlife around us.

LED Lights on Fishing Nets Help Reduce Bycatch

A simple technique to illuminate the exits in trawling nets could cut accidental bycatch by half a recent study has shown. The study, published in the Journal of the Marine Biological Association of the United Kingdom, found that attaching LED lights to the larger holes in a net allows non-target species to escape, reducing the number that are killed. The research was conducted by a team from Bangor University, led by marine ecologist, Dr Lucy Southworth.

Bycatch, the capture of non-target species, can significantly damage the populations of these species, many of which are vulnerable or endangered, and drastically reduce their numbers. Similarly, seabirds and marine mammals can become victims of accidental bycatch through entanglement in fishing nets, which often kills them in the process.

But it's not just the environment that is negatively affected by bycatch. There is also a significant cost to the fishermen. Under EU law, fishermen are required to bring almost everything they catch to shore, including that which is not a part of their quota. If too many non-target fish are caught, the entire fishery may be closed to allow stocks to recover. As a result, even fishermen doing their best to comply with the rules can cause unintended damage and end up risking their livelihoods.

Trawler at sea

The new study, conducted between June and August 2017, is a clever inversion of an old fishing technique: shining a light on the water to attract fish into the net. The team set out to test the effect of lights in reducing the number of haddock and flatfish that were accidentally caught in a queen scallop fishery off the Isle of Man.

They found that, while the devices that are currently used to reduce bycatch were effective in shallower waters of around 29 to 40 m, they had little to no effect in deeper waters of around 45 to 95 m. This is likely due to the lack of light and, therefore, visibility. Once LED lights were attached to the net exits in these deeper waters, haddock bycatch was reduced by 47% and flatfish bycatch by 25%.

The team even found of evidence of sharks escaping the lit nets, which could be a topic for future research. LED lights could also potentially reduce the number of whales, dolphins, and porpoises entangled in nets each year as they alert the animals to the presence of these nets and give them the chance to avoid the hazard.

Dr Southworth and her colleagues believe that this could be a popular solution to the current issues with bycatch. Not only are LED lights fairly cheap, they are easy to apply to the nets and can be easily adjusted for different environments. Though there is still a long way to go before the issue of bycatch is solved, it's certainly refreshing when simple answers can be found for complicated problems.

Aquatic News: October 2019

October has been another eventful month in our watery world. If you're an aquarium keeper, it turns out you could be the key to saving several species of freshwater fish. Florida has been hit with its second red tide of this year. We have the good news that dolphins are living in the Potomac River, and the bad news that whales are living in the Great Pacific Garbage Patch.

A new initiative to save fish from extinction

Freshwater fish are a highly diverse group, but they are also the most threatened of the vertebrates. Many species go extinct before conservation efforts can even begin.

A recently published study by Dr Jose Valdez, of Aarhus University, and Kapil Mandrekar, of SUNY College of Environmental Science and Forestry, has shown that aquarium hobbyists can play an important role in freshwater fish conservation.

In some cases, dedicated hobbyists are actually more knowledgeable on certain species than the scientific community due to their hands on experience with the fish. In fact, some species that have not yet been scientifically described are already well-known to hobbyists. When these hobbyists are able to share their knowledge, they can make a real difference and have already helped discover new species and save others from extinction. Some have even provided individuals from their own aquariums to conservation efforts.

The largest organisation coordinating such conservation programmes is the CARES (Conservation, Awareness, Recognition, Encouragement, and Support) preservation programme. It encourages hobbyists to keep the most endangered (or even extinct in the wild) freshwater fish species to ensure their survival. In many cases, these species would have been otherwise overlooked by conservation efforts.

Valdez and Mandrekar found that CARES listed almost 600 freshwater fish species, over 80 of which are unknown by the scientific community. There are also more than 30 species included that are already extinct in the wild.

As it turns out, many of these species are only still here because of hobbyists breeding them in their aquariums. With that in mind, collaboration between scientists and aquarium hobbyists could prove to be a real turning point for the effective conservation of freshwater fish.

Further reading

Deadly red tide returns to Florida

Example of a red tide, this one in La Jolla, California

A new red tide began in Florida in early October. Samples of water taken off the shore of Collier County showed high concentrations of Karenia brevis, the toxic algae responsible for this nasty phenomenon. It also kills marine life and can cause respiratory problems in humans, both of which have been recorded in the affected area.

The locations currently affected include Barefoot Beach, Naples Bay, and around the Gordon River. The species most affected by the toxicity so far has been mullet (of the family Mugilidae).

The last red tide in this area cleared up just eight months ago and, at 15 months in duration, it was the longest lasting red tide in decades. It began in November 2017 and ended in February of this year. Thousands of fish, turtles, and marine mammals were killed and all three of Florida's coasts were affected.

This current red tide is, so far, only affecting the southwestern coast. It is not known how long it will last or how far it will spread as these things are difficult to accurately predict. Hopefully, it won't be as long, or as destructive, as the previous red tide.

Further reading

Dolphins have returned to the Potomac

Dolphins were once common in the Potomac River in the 1800s but, by the 1960s, it was so badly polluted that they could no longer survive there. So they moved on.

This kickstarted 50 years of cleanup efforts that have finally paid off as there are now around 1,000 bottlenose dolphins (of the genus Tursiops) living in the river. Even better, one dolphin was seen giving birth there back in August. The fact that dolphins are now choosing to reproduce and raise their young in the Potomac is a really good sign for the improving health of the river. Long may it continue.

Further reading

Whales are living in the Great Pacific Garbage Patch

The Great Pacific Garbage Patch is the largest accumulation of ocean plastic in the world. It is located between Hawaii and California, where ocean currents to form the North Pacific subtropical gyre. There is a shocking 80,000 tonnes (or 88,000 US tons) of plastic in this patch.

A survey of the area has found that there are, in fact, whales and dolphins living there, some with calves. This could prove to be very dangerous for them.

As you are probably aware, ocean plastic is a significant issue for marine life. There are more and more reports in the news of whales washing up dead after accidentally swallowing plastic waste. For example, in Indonesia, a sperm whale (Physeter macrocephalus) recently washed ashore with a whopping 115 drinking cups, 25 plastic bags, plastic bottles, two flip-flops, and thousands of pieces of string in its stomach. It's an issue of great concern.

The most common debris found in the Great Pacific Garbage Patch is ghost nets, which is fishing gear that has been discarded or lost. They can drift for years, trapping marine life. Whales and dolphins can easily become ensnared in these nets and their calves are especially vulnerable.

The findings of this survey should be a real wake-up call to clean up the area. It needs to be made safer for the whales and dolphins living there and efforts must be made to protect marine life as a whole. If we don't act soon, we will simply continue to see reports of dead whales on the news for the foreseeable future.

Further reading