Marine Life & Conservation
Cendrawasih’s whale sharks…. not such homebodies after all
For the past five years, Cendrawasih Bay’s friendly whale shark population has been attracting a lot of attention, primarily because of the near-certainty of having outstanding (and lengthy!) whale shark encounters during a visit to the region. Unlike many of the other known whale shark aggregations in the world (such as Ningaloo, Isla Mujeres, Belize, Galapagos and Donsol), which are highly seasonal, we now know with certainty that Cendrawasih has whale sharks present in the bay year round. Indeed, based on our observations combined with photos submitted by visitors to our BHS whale shark database, some highly-recognizeable individuals seem to be present throughout the year. Of course, one of the surest ways to confirm this is to monitor individual animals’ movements through satellite tagging – which is exactly what we’ve been doing in collaboration with the Cendrawasih Bay National Park Authority and Pak Bram Maruanaya and his local Kalilemon homestay in Kwatisore.
Since June 2015, we’ve been able to tag 15 male whale sharks (ranging in size from 3 to 7 m in length) from Cendrawasih, using custom-made fin-mounted satellite tags by Wildlife Computers. These fin-mount tags have extended battery life which we hope will provide data for up to two years, and we’ve been delighted with their performance to date. All but one of the tags has been transmitting data very regularly (on average every 2-5 days) – basically each time one of the tagged sharks spends enough time on the surface for the tag to uplink to the ARGOS satellite network.
As previously reported back in November, the initial data received from June through October 2015 seemed to confirm what many suspected – that Cendrawasih whale sharks are largely “homebodies”, preferring to stay close to shore and feed upon the abundant ikan puri baitfish schools that abound in the coastal bays and estuarine areas of the southern and eastern coastlines of Cendrawasih. Which of course is a great thing for BHS marine tourism, as it means visitors can pretty much plan a trip any time of the year and have a very good chance of excellent whale shark interactions.
By December, however, we started to observe some very different behaviours that indicate Cendrawasih’s whale sharks might not be such homebodies after all! Just before Christmas, four of the sharks almost simultaneously moved towards the small exit to the bay between the eastern tip of Yapen Island and the Papuan mainland. Though two soon turned back, both “Jude” and “Wally” proceeded down the coastline towards Jayapura. Jude eventually turned back and returned to Kwatisore, but Wally continued down the coast – becoming the first of our tagged sharks to become an international visitor when he crossed into PNG waters in early January. While he appeared at one point to be returning to Cendrawasih (making it as far west as Jayapura), he’s since returned to the Wewak region of PNG (near the Sepik River outlet) and seems to be happily enjoying an extended vacation there!
Similarly, one of our most recently tagged whale sharks, Ke’Opulupulu, headed almost immediately north into the center of the Bay (near the Auri Islands and atolls), then navigated to the south coast of Biak and Supiori Islands, where he’s remained for the past few weeks.
But horizontal movements are only part of the excitement we’ve recently recorded. The past 3 months have also seen a dramatic increase in deep-diving behaviour of many of our tagged sharks. While we did previously report a 672m deep diving record in October, we’ve now seen four of our sharks venture below 1000m depth, with the aptly-named “Moby” smashing the depth record (but fortunately not his tag’s depth gauge!) at 1416m!!! Even the “wee” 3m “Fijubeca” has dived to 700m depth. It’s still not clear why the sharks have shown such deep diving behaviour over the past few months – perhaps the El-Nino warmed surface waters are not providing enough food and they are searching for deeper plankton…
Overall, we’re delighted to see these fin-mount tags proving so successful at divulging some of the secrets of Cendrawasih’s whale sharks. Its particularly noteworthy that the first 5 months’ of data seemed to simply confirm our scattered direct observations, but the past 4 months have revealed numerous exciting behaviours we didn’t expect. Who knows what the next few months’ data might reveal? Stay tuned and we’ll happily report back as the data keeps flowing in. And please remember – you too can contribute to our expanding knowledge and understanding of the charismatic megafauna of the Bird’s Head by contributing your photo IDs and observations of whale sharks and manta rays in the region to the databases maintained by our site.
Mark Erdmann is Conservation International’s Vice President of Asia Pacific Marine Programs. Though now based in New Zealand after 23 years in Indonesia, he is still intimately involved with the Bird’s Head Seascape and frequently disappears into its remote corners for weeks on end….
Shawn Heinrichs is an Emmy Award-winning cinematographer, photographer and marine conservationist. An independent filmmaker, he is the founder of Blue Sphere Media, a production company specializing in underwater, adventure and conservation media. His work was recently featured in the film Racing Extinction.
A special thanks to Audrey, Shannon and Dennis Wong, Sally Timpson, and the management and guests of the True North expedition vessel for generously sponsoring the fin-mount whale shark satellite tags reported here, to Patti Seery and her amazing staff and crew of the Si Datu Buah liveaboard for hosting our most recent deployment expedition, and to OceanMax for continuing to support the tagging program with PropSpeed silicone foul-release coating for our satellite tags.
Marine Life & Conservation
New report shows simple measures needed to cut beach plastic pollution
The Marine Conservation Society has launched its annual State of our Beaches 2023 report, highlighting the need for less single-use plastic items and more refillable options.
The charity’s beach cleaning programme, now in its 30th year, asks volunteers to record all litter that they find within a 100-metre stretch of beach. By gathering vital data from across the UK and Channel Islands, the charity creates change for cleaner seas and a healthier planet through policy and industry change. Last year, over 148 kilometres of beach were surveyed by volunteers, who removed 17,208kgs of litter from our coast.
Using data collected by over 14,000 volunteers, the State of our Beaches 2023 report shows that half of all litter collected came from public sources – either dumped, blown or washed onto our beaches.
Drinks-related litter, such as plastic bottles, caps and cans were one of the most found items, with an average of 16 found per 100 metres of beach surveyed. This figure is up 14% compared to the charity’s 2022 report.
Plastics caps and lids were recorded on 89% of surveys, with over 30,000 found in total. Plastic bottles were also commonly collected, with 73% of surveys finding this single-use item – a 4% increase compared to 2022. The charity’s inland litter pick survey, Source to Sea, also reported finding plastic bottles on 92% of cleans.
However, the charity’s State of Our Beaches 2023 report also indicates that some types of litter are on a downward trend. Although still in the top 10 litter items, disposable plastic cutlery, trays and straws were found on 5% fewer beaches across the UK, showing that bans on these plastic items between 2022 – 2023 could be working. The presence of plastic cotton bud sticks also dropped by 14%.
Lizzie Price, Beachwatch Manager at the Marine Conservation Society, said, “Half of the litter found on our beaches originates from public sources, underscoring the pressing issue of single-use plastic. Evidence shows that refillable alternatives and litter return schemes effectively reduce rubbish, as demonstrated by the decline our data has shown in items like plastic bags and disposable cutlery.
“Urgent and decisive action from UK governments is needed to accelerate our shift towards a circular economy, where we reuse, repair and recycle. The public needs greater access to refillable products and systems need to be implemented in which manufacturers are responsible for their waste.”
Governments across the UK have committed to delivering deposit return schemes from October 2025. However, the proposed scheme in England does not include glass items, despite glass being found on 52% of beaches in 2023. The charity is calling for governments across the UK to introduce compatible all inclusive deposit return schemes as soon as possible. This would see aluminium cans, and plastic and glass bottles have a 20p deposit which would be returned when recycled which would reduce drinks-related pollution.
Businesses are, however, starting to take refillable and reusable options into their own hands. Supermarket chain, Aldi, the largest corporate funder of the charity’s 2024 Beachwatch programme, is already leading the charge in refillable items by trialling refillable options for cereals and porridge oats in their stores over the past 5 months.
Plastics and Packaging Director, Luke Emery, from Aldi, who are running 4 beach cleans for staff and volunteers in 2024, said, “We are continually working to reduce single-use plastics and packaging, and making unpackaged product options more commonplace for our customers is a key part of this. We are really pleased with the uptake of our refillable range so far by customers. Not only are we making sustainable shopping more accessible, but we also offer refill products for a better price than the packaged alternative, helping our customers save money.”
Marine litter is one of the biggest threats to our seas, with plastic breaking down over time into microplastics and threatening marine life which can ingest or become entangled in them. The Marine Conservation Society is urging the UK Government to move faster on its policies to cut down plastic waste and prevent items from reaching our seas.
To find out more about the charity’s beach cleans and how to get involved, please visit mcsuk.org/beach-cleans
Blogs
Guarding Against Coral Invaders
Protecting (Dutch) Caribbean Reefs from Unomia stolonifera
Recent reports highlight the concerning spread of the invasive soft coral, Unomia stolonifera, currently devastating Venezuela’s marine ecosystems and detected in Cuba. With the potential threat of its expansion to the (Dutch) Caribbean islands, urgent action and awareness are essential to safeguard marine biodiversity and local economies from possible catastrophic consequences.
Invasive species are animals or plants from another region of the world that don’t belong in their new environment. These species can have major ecological effects by decimating native flora or fauna. They can also cause large economic losses and impact human health. Invasive species also pose a significant threat to marine ecosystems worldwide, including the Dutch Caribbean. Among these invaders is the octocoral species Unomia stolonifera or “Pulsing Xenia”, originally from the Indo-Pacific. With its rapid growth and lack of natural predators, this species can outcompete native species and disrupt fragile marine habitats such as seagrass beds and coral reefs.
Background
The invasive soft coral U. stolonifera was first identified in 2014, off the coast of Venezuela. It is believed to have been introduced via the illegal aquarium trade. Since this species can reproduce sexually and asexually (or fragment), even small pieces can regenerate to spread. Once introduced it quickly took over shallow reefs and hard substrate at depths of 0-50 meters, outcompeting local corals and seagrass for space. Follow on surveys found that this coral species exhibited average percentage cover as high as 80%, vastly outcompeting native corals. In highly colonized areas, fish are disappearing due to loss of habitats.
In 2022, during a survey conducted in Cuba by the University of Havana, an unknown octocoral was discovered which was later identified as the invasive Unomia stolonifera. It is suspected that the coral larvae arrived in ballast water from fossil fuel ships originating from Venezuela, as nearby sites adjacent to Venezuelan ports have been heavily affected by the invasion.
How to help
Prevention through continuous monitoring, particularly in high-risk areas such as marine harbors and oil facilities, is paramount. Early detection plays a pivotal role in mitigating the threat posed by Unomia stolonifera.
The public’s involvement and awareness are also vital. Local communities, recreational divers, tourists, and all stakeholders are urged to participate in early detection efforts by reporting sightings (photo, location and date) of this invasive coral to their respective Protected Area Management Organization (PMO’s)- the Fundacion Parke Nacional Aruba (FPNA), STINAPA Bonaire, CARMABI Curaçao , Saba Conservation Foundation (SCF), Nature Foundation St. Maarten (NFSXM) and St. Eustatius National Parks (STENAPA). If an invaded area is confirmed, follow the recommendations by the local PMO’s.
Keys to Success
Despite the challenges, early detection is key to mitigating the threat posed by Unomia stolonifera. With continued vigilance, research, and community engagement, there is hope for containing this potential issue before it becomes a major threat.
About the DCNA
The Dutch Caribbean Nature Alliance (DCNA) supports (science) communication and outreach in the Dutch Caribbean region by making nature related (scientific) information more widely available through amongst others the Dutch Caribbean Biodiversity Database, DCNA’s news platform BioNews and through the press. This article contains the results from several scientific studies but the studies themselves are not DCNA studies. No rights can be derived from the content. DCNA is not liable for the content and the in(direct) impacts resulting from publishing this article.
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