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Marine Life & Conservation

Madagascar emerges as hotspot for endangered whale sharks

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A new study published in the journal Endangered Species Research has revealed that juvenile whale sharks swim to Madagascar, a newly-identified hotspot for these huge fish, to feed. Eighty-five individual sharks were identified in a single season using photographs of their distinctive spot patterns. An isolated ‘island continent’, famed for animals and plants that exist nowhere else in the world, Madagascar’s nutrient-rich waters are also home to an incredible array of marine life attracting increasing numbers of tourists.

Whale shark and fishes – Copyright Simon J Pierce, www.simonjpierce.com

Whale sharks are primarily seen around the small island of Nosy Be, in northwest Madagascar. This area is a globally important hotspot for large marine species, including manta rays, sea turtles, humpback whales and even rare Omura’s whales. The study is part of the Madagascar Whale Shark Project, a collaboration initiated in 2016 by researchers from the Marine Megafauna Foundation, Florida International University, and Mada Megafauna.

Lead author and project leader Stella Diamant said: “We’ve found that whale sharks regularly visit Nosy Be between September and December. That has led to a growing ecotourism industry, as people travel to see and swim with these gigantic, harmless sharks. We’re still learning about their population structure and movement patterns, but it’s clear the area is an important hotspot for the species.”

Whale sharks are the largest fish in the world, growing up to 20 meters long. However, all of the sharks seen in Madagascar have been juveniles of less than nine meters.

We identified 85 individual whale sharks over our first season in 2016. Some of the sharks were present across several months. They spend a lot of time in the area and seem to come here to feed,” Diamant said.

Stella Diamant on boat – Copyright The Madagascar Whale Shark Project

The marine biologists uploaded photographs of the sharks’ unique spot patterns to Wildbook for Whale Sharks (a global database of sightings) and compared them with data collected from known feeding areas in the Indian Ocean, including Djibouti, the Maldives, Mozambique, Seychelles and Tanzania, but found no overlap.

Whale sharks are a globally endangered species due to overfishing, accidental catches and boat strikes. Major declines in sightings have been seen in Mozambique, where we’ve documented a 79% decline in sightings since 2005, and the Seychelles. I was hoping that some of those sharks might have shifted over to Madagascar”, said co-author Dr Simon Pierce, co-founder and principal scientist at the Marine Megafauna Foundation.

Unfortunately, that doesn’t seem to be the case. It’s great news for Madagascar though. These sharks can be a major asset for the country. There’s already a good marine ecotourism industry developing”, he added.

As part of this study, the team attached eight satellite tags to immature whale sharks to track their movements in near real-time. They found that the sharks spent most of their time in shallow waters between 27.5-30°C around the tagging area in Nosy Be.

Stella Diamant with tagged shark – Copyright Simon J Pierce, www.simonjpierce.com

Half of the tagged sharks also visited a second hotspot near Pointe d’Analalava, 180 km south of Nosy Be. Five of the sharks swam over to Mayotte and the Comoros islands, and two swam right down to the southern end of Madagascar. One of those sharks then swam back to Nosy Be, a total track of 4,275 km. The sharks are slow-swimmers, travelling an average 21 km per day. Three sharks were resighted in the Nosy Be area the following season after having lost their tags.

It was exciting to see that there is a second hotspot for the sharks in the area. We will be exploring the area later this year. Madagascar clearly provides an important seasonal habitat for these young whale sharks, so we need to ensure they are effectively protected in the country”, concluded Diamant.

Madagascar is a known location for shark fishing and finning. Whale sharks are currently afforded no formal protection except in two Marine Protected Areas located to the southwest and northeast of Nosy Be.

Over the last decade, shark populations have declined dramatically in Madagascar due to overfishing. However, the most significant threat to this species is the incidental catch in coastal gillnets and industrial purse seiners operating offshore”, said Dr Jeremy J Kiszka, a marine biologist at Florida International University and co-scientific lead of the Madagascar Whale Shark Project.

Whale sharks are listed as ‘endangered’ on the IUCN Red List of Threatened Species since 2016 and received an Appendix I listing the UN Convention on Migratory Species in 2017. As a signatory to the Convention, Madagascar is obligated to protect the sharks and their migratory habitat in national waters.

The study was supported by Les Baleines Rand’eau, Aqua-Firma, PADI Foundation, IDEA WILD, Waterlust, the Shark Foundation, and two private trusts.

Stella Diamant, Christoph A Rohner, Jeremy J Kiszka, et al. ‘Movements and habitat use of satellite-tagged whale sharks off western Madagascar’ was published on 17 May 2018 and is available here.


For more information about Marine Megafauna Foundation please visit:

Website: www.marinemegafauna.org
Facebook: www.facebook.com/MarineMegafauna

Images by www.simonjpierce.com

Marine Life & Conservation

New report shows simple measures needed to cut beach plastic pollution

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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

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Guarding Against Coral Invaders

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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 BonaireCARMABI 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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