Marine Life & Conservation
Tags on leatherback turtles reveal by-catch hotspots
A study using satellite data from tagged leatherback turtles has identified possible “by-catch hotspots” in the Pacific Ocean.
By tracking 135 turtles, researchers highlighted areas where the critically endangered animals were likely to come into contact with fishing vessels.
The authors hoped the findings could be used to help cut the number of turtles accidentally killed as by-catch.
The paper appears in the Proceedings of the Royal Society B journal.
The species, scientifically known as Dermochelys coriacea, is globally listed as vulnerable by the International Union for Conservation of Nature’s Red List of Threatened Species.
However, conservationists have identified a number of distinct populations in the world’s various oceans. Within the Pacific, the two populations – eastern and western – are considered to be critically endangered.
For this study, data was collated from numerous projects between 1992 and 2008, explained lead author John Roe from the University of North California’s Pembroke campus.
“To really get an idea about where the leatherbacks go, you have got to have turtles tagged from multiple locations,” he said.
“So it took getting just about everyone who has put a satellite tag on a leatherback for other research purposes to collaborate to get a sample size large enough to allow us to answer that question.”
Dr Roe and his colleagues from a range of US and Costa Rican institutes then integrated the turtle location data with similar data of where the longline fishing activity in the Pacific Ocean was highest.
“We used that data to overlay with the data of the areas the turtles were using in order to figure out where the turtle hotspots matched with the fisheries hotspots to identify the areas where by-catch was most likely to occur.”
Writing in their paper, the team observed: “For East Pacific nesters, an area of potential risk occurs along the primary leatherback migration corridor between Costa Rica and the Galapagos Islands.
“For the West Pacific population, …the greatest by-catch was predicted to occur adjacent to nesting beaches in north-west New Guinea.”
They added that the analysis represented the largest compilation of data of its kind.
However, Dr Roe said that more tagging data was required in order to establish a more detailed picture.
“We need to target these areas to see if the turtle persistently use these areas over and over again,” he said.
“That would provide really useful information in the management of by-catch because the fisheries authorities would have that knowledge and adjust their fishing efforts accordingly.”
He added: “We are just trying to highlight some areas to make it easier to look for these needles in a haystack.
“The idea now is to try and get some more refined information in those targeted areas but we now know where and when to look, and where to concentrate our efforts.”
Source: www.bbc.co.uk/news
The great white shark, known scientifically as Carcharodon carcharias, embodies the apex predator of the ocean. This majestic creature’s life is a testament to survival, adaptability, and the intricate balance of the marine ecosystem.
Born in the waters off coastal regions, a great white shark begins its life as a pup within the safety of nurseries, typically found in warm, shallow waters. The pups, measuring around 5 feet in length at birth, are immediately equipped with an innate instinct for survival.
As they grow, great whites embark on a journey, venturing into deeper and cooler waters, often covering vast distances across the ocean. These apex predators are perfectly adapted hunters, relying on their impressive senses to detect prey. Their acute sense of smell, aided by specialized sensory organs known as ampullae of Lorenzini, helps detect the faintest traces of blood in the water from several miles away.
Feeding primarily on seals, sea lions, and other marine mammals, great whites are known for their powerful jaws lined with rows of razor-sharp teeth. Their hunting techniques often involve stealth, utilizing their streamlined bodies to approach prey from below and striking with incredible speed and force.
Despite their fearsome reputation, great whites play a crucial role in maintaining the health of marine ecosystems. As top predators, they help regulate the population of prey species, preventing overpopulation that could disrupt the balance of the food chain.
Reproduction among great white sharks is a slow and careful process. Females reach sexual maturity between 12 and 18 years of age, while males mature earlier, around 9 to 10 years old. Mating occurs through complex courtship rituals, with females giving birth to a small number of live pups after a gestation period of about 12 to 18 months.
However, the life of a great white shark is not without challenges. Human activities, including overfishing, pollution, and habitat destruction, pose significant threats to their population. Additionally, despite their formidable presence, great whites are vulnerable and face dangers from entanglement in fishing gear and accidental bycatch.
Despite these challenges, great white sharks continue to inspire awe and fascination among scientists and nature enthusiasts. Their presence in the ocean serves as a reminder of the delicate balance and interconnectedness of marine life, emphasizing the need for conservation efforts to protect these magnificent creatures for future generations to admire and study.
Want to learn more about sharks? Visit The Shark Trust website: www.sharktrust.org
Photos: avalon.red
Sea Mammals: The Past and Present Lives of Our Oceans’ Cornerstone Species by Annalisa Berta
This is a book packed with information about some of the most iconic and charismatic marine species. I have a particular soft spot for the pinnipeds, seals and sea lions, due to some incredible diving encounters over the years. So these were the pages I first turned to.
Once picked up this book is hard to put down. Polar Bears, Narwhal, Sea Otters, manatees, whales and dolphins adorn the pages with beautiful photographs and illustrations. Each turn of the page lures you in to discover more about a species you love, one you want to learn more about, some you have never heard of and even includes the details of fascinating animals that are sadly now extinct.
I think what I love most about this book is how it is organised. Rather than simply lump the animals into taxonomic groupings, they are put into chapters that tell you a story about them. Whether it is the story of their evolution, how they were discovered, their biology, behaviour or need for conservation. Once you have decided on an animal to delve deeper into, each species has its own story, as well as key information about size, diet, distribution, habitat and conservation status.
There is plenty to enjoy in this delightful book. Plenty to learn too. As the cold dark nights draw in, I can see myself delving into this book time and time again. This is a perfect gift for anyone that loves the ocean and its inhabitants. Or just treat yourself.
What the publisher says:
From the gregarious sea otter and playful dolphins to the sociable narwhal and iconic polar bear, sea mammals are a large, diverse, and increasingly precious group. In this book, Annalisa Berta, a leading expert on sea mammals and their evolution, presents an engaging and richly illustrated introduction to past and present species of these remarkable creatures, from the blue whale and the northern fur seal to the extinct giant sperm whale, aquatic sloth, and walking sea cow.
The book features more than 50 individual species profiles, themed chapters, stunning photographs, and specially commissioned paleo-illustrations of extinct species. It presents detailed accounts of these mammals’ evolutionary path, anatomy, behavior, habitats, and conservation. And because these are key species that complete many food chains and have the widest influence of all sea life, the book also offers insights into a broad variety of marine worlds today and in the future.
About the Author:
Annalisa Berta is professor emerita of biology at San Diego State University. A specialist in the anatomy and evolutionary biology of marine mammals, especially baleen whales, she formally described a skeleton of the early pinniped Enaliarctos. She is the author of Return to the Sea: The Life and Evolutionary Times of Marine Mammals and the editor of the award-winning Whales, Dolphins, and Porpoises: A Natural History and Species Guide.
Book Details
Publisher: Princeton University Press
Hardcover
Price: £25
ISBN: 9780691236643
Published: 26th September, 2023
Pages: 224
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