Marine Life & Conservation
Tourists key to future of rare manta nursery
Scientists from the Marine Megafauna Foundation and Murdoch University are reporting a large number of juvenile manta rays in the waters of Nusa Penida, a small island 18km southeast of Bali, suggesting the area may be a nursery for this threatened species.
Reef mantas (Mobula alfredi), which grow up to 5m, tend to reside and feed in shallow, coastal habitats. They also visit ‘cleaning stations’ on coral reefs to have parasites or dead skin picked off by small fish. In Nusa Penida, they are present year-round making the Marine Protected Area (MPA) a snorkeling and diving hotspot.
One of the popular dive sites (Manta Bay) described in this new study is predominantly frequented by juvenile males looking for food. Some are as small as 1.5m in disc width on first sighting, providing strong evidence that the site forms part of a nursery habitat and foraging ground for the local reef manta population. Most individuals have been seen repeatedly across multiple years.
Image: Simon Pierce (www.simonpierce.com)
“Where manta rays are born and grow up still baffles us. Our research in Indonesia suggests there might be a reef manta nursery in the Nusa Penida area and possibly also in the famous Raja Ampat archipelago”, said lead author Elitza Germanov. “It’s really important for us to know where these nurseries are. They provide a safe space for young, vulnerable manta rays to grow and develop away from the reach of predators.”
Interestingly, mature males and females seem to prefer Manta Point, a second dive site a mere 12 km away. Here, the manta rays are mostly observed visiting cleaning stations and engaging in social activity as well as courtship display during the mating season (peaking in May).
Nusa Penida attracts more than 200,000 tourists each year. Of the 11 main dive spots in these waters, Manta Bay and Manta Point are frequented most by tourism operators, putting the local manta ray population under increasing pressure. While manta rays are protected in Indonesia2, there are currently few regulations in place to manage the growing tourism industry. The number of boats allowed to enter manta ray habitats is not limited and codes of conduct for manta ray interactions are voluntary. The average annual number of boats present at the two manta ray sites has increased by 60% since 2012 and tourism is highest during the mating season.
Germanov commented: “Large diving groups and boat engine noise can cause chronic stress to these vulnerable animals. Tourists may disrupt the foraging, cleaning and mating behavior of manta rays if they get too close, which can have serious implications for their growth and fitness.”
Limiting the number of tourism vessels allowed at one time and making codes of conduct for diving and snorkeling with manta rays mandatory are proposed as a way to minimize the impact from tourism. Seasonal closure of Manta Point could also be considered to protect the manta rays from disturbance during the mating period.
Artisanal fishing poses a further threat to the local population. During the study, 14% of manta rays were either trailing hooks and lines or had injuries and even amputations from fishing gear cutting through their skin and cartilage skeleton. While all fishing activities are officially prohibited in both Manta Bay and Manta Point, the whole west coast of Nusa Penida could be closed off as a precautionary measure.
Dr Andrea Marshall, principal scientist and co-founder of the Marine Megafauna Foundation said: “This is clearly an important habitat for reef mantas. In fact, the resighting rates in the Nusa Penida MPA are higher than anywhere else in the world.
“The two aggregation sites are very close to each other but used for different purposes. We still don’t know much about when and how the mantas move between the feeding, cleaning and mating grounds. Putting the pieces of this puzzle together will help us figure out how to protect these slow-growing animals.”
For more information about the work of the Marine Megafauna Foundation visit their website by clicking here.
Marine Life & Conservation
Leading UK-based shark conservation charity, the Shark Trust, is delighted to announce tour operator Diverse Travel as a Corporate Patron
Corporate Patrons provide a valuable boost to the work of The Shark Trust. The Trust team works globally to safeguard the future of sharks, and their close cousins, the skates and rays, engaging with a global network of scientists, policymakers, conservation professionals, businesses and supporters to further shark conservation.
Specialist tour operator Diverse Travel has operated since 2014 and is committed to offering its guests high quality, sustainable scuba diving holidays worldwide. Working together with the Shark Trust will enable both organisations to widen engagement and encourage divers and snorkellers to actively get involved in shark conservation.
“Sharks are truly at the heart of every diver and at Diverse Travel, we absolutely share that passion. There is nothing like seeing a shark in the wild – it’s a moment that stays with you forever!” says Holly Bredin, Sales & Marketing Manager, Diverse Travel.
“We’re delighted to celebrate our 10th year of business by becoming a Corporate Patron of the Shark Trust. This is an exciting partnership for Diverse and our guests. We will be donating on behalf of every person who books a holiday with us to contribute towards their vital shark conservation initiatives around the world. We will also be working together with the Trust to inspire divers, snorkellers and other travellers to take an active role – at home and abroad – in citizen science projects and other activities.”
Paul Cox, CEO of The Shark Trust, said:
“It’s an exciting partnership and we’re thrilled to be working with Diverse Travel to enable more divers and travellers to get involved with sharks and shark conservation. Sharks face considerable conservation challenges but, through collaboration and collective action, we can secure a brighter future for sharks and their ocean home. This new partnership takes us one more valuable step towards that goal.”
For more information about the Shark Trust visit their website here.
For more about Diverse Travel click here.
Marine Life & Conservation
Shark Trust Asks Divers to help with Shark Sightings this Global Citizen Science Month
Whether you are stuck for ideas of what to do with the kids or are off on the dive trip of your dreams. You can get involved in Citizen Science Month and help the Shark Trust by providing vital data about sharks are rays both close to home and further afield.
In addition to reporting the sharks and rays you see on your dives, the eggcases you find on the beach, the Shark Trust is looking for some specific data from divers who are asked to report any Oceanic Whitetip and Basking Sharks.
Oceanic Whitetip Sharks
The Shark Trust are looking specifically for Oceanic Whitetip Shark sightings over the coming weeks and months. So, if you are diving anywhere in the world, please report your sightings via the website or app.
Website: https://recording.sharktrust.org/
App: Search The Shark Trust in your app store
The Oceanic Whitetip. Known for their incredibly long dorsal and pectoral fins, this species was once the most abundant oceanic-pelagic species of shark on the planet.
Large and stocky, they are grey or brown above, and white below and famous for their huge rounded first dorsal fin and paddle-like pectoral fins. The fins also highly prized within the shark fin trade. Whilst they are mostly solitary, Oceanic Whitetips do occasionally hunt in groups.
An inquisitive species, they were easy prey for fisheries. Combined with their low reproductive rate, they were inevitably at high risk of population depletion. And declines of up to 99% have been reported in certain sea areas. They are listed as Critically Endangered on the IUCN Redlist (2019).
Conservation efforts to discourage further declines include listing on CITES Appendix II and CMS Appendix I. They’re also the only species prohibited from take by all the Tuna RFMOs (Regional Fisheries Management Organisations). However, these measures do not mean that Oceanic Whitetips are not still caught – whether targeted or as bycatch – in some parts of the world. With populations declining at such a high rate, effective implementation of management measures is essential to ensure that the species can recover.
If you are lucky enough to get an image of an Oceanic Whitetip and you record your sighting on the Shark Trust app or website YOU CAN WIN! All images submitted with sightings, that also give consent to use in conservation messaging, will be in with a chance to win an Oceanic Whitetip T-shirt and mug. The competition will run until the end of “Shark Month” in July – so keep those sightings (and images) coming in.
Basking Sharks
Basking Shark (Cetorhinus maximus) season is upon us, and the Shark Trust is asking everyone to keep an eye out for these majestic giants over the summer months. If you see any, you can record your sighting to the Basking Shark Sightings database.
Each year, these mighty fish return to British waters to feed on plankton. You may see one, (or a few if you’re really lucky) from around April-October. They can be seen feeding at the surface of the water, where they look like they’re basking in the sun. Thus, their name!
Sighting hotspots around the British Isles include southwest England, Isle of Man, north coast of Ireland, and western Scotland. The Sea of the Hebrides is the most prolific sightings area in Scotland, but they have been spotted all around the coast and have even ventured into some of the sea lochs. The Shark Trust has received thousands of sightings since the Basking Shark project began, but more data is needed to truly understand what is going on with population numbers and distribution. You can help by recording your sightings this summer.
Great Eggcase Hunt
The Shark Trust has an Easter Egg Hunt with a difference for you to try. Take part in the Great Eggcase Hunt and get involved with a big citizen science project that helps shark, ray and skate conservation. And it’s an enjoyable activity for all the family.
The Shark Trust also want snorkellers and divers to record their underwater eggcase findings. Underwater records help pinpoint exactly where sharks and skates are laying their eggs and can help link to beach records. Learning the depth and substrate that they lay on also helps better understand the species.
Find out more: https://www.sharktrust.org/great-eggcase-hunt
Whether you are diving, snorkelling or exploring on the beach you can take part in Citizen Science Month and get actively involved in shark and ray conservation. Find out more: www.sharktrust.org
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