In this series, the Shark Trust will be sharing amazing facts about different species of sharks and what you can do to help protect them.
This month we’re taking a look at some truly swell sharks, the Swell Sharks!
Swell Sharks are a group of catsharks belonging to the family Scyliorhinidae. Their most unique feature is probably their threat response: they are able to expand their bodies to twice their normal size by swallowing water! This wedges them into their hiding spot, making it more difficult for predators to bite them from inside.
There are 18 different species of swell shark. In this article, we will focus on two of them, the Swell Shark (Cephaloscyllium ventriosum) and the Australian Swell Shark (Cephaloscyllium laticeps).
The Swell Shark (Cephaloscyllium ventriosum)
In 2019, scientists discovered the molecules responsible for a special ability of the swell shark – their biofluorescence. In the dark, special amino acids in their skin reflect the moonlight, appearing bright green in the darkness. This has been found to be species specific, and sex specific, and therefore this unique adaptation may function to help sharks species recognise each other or even potential mates. It may also play a role in camouflage.
Australian Swellshark, Cephaloscyllium laticeps
The Australian Swellshark is also sometimes known as the Draughtboard Shark due to its colouration: It has 11 brown ‘saddles’ that alternate with blotches on its flanks, forming a pattern resembling that of a checkerboard.
Like many other species of Swell Shark, the Australian Swellshark is oviparous. This means that the adult swell shark lays an eggcase with the embryo inside. Depending on the species, the shark may lay two at a time. These eggcases contain a developing embryo and a yolk. Before hatching, the embryo can feed on this yolk for sustenance as it grows. Once fully developed, the embryo hatches out as a fully formed miniature version of the adult shark.
Australian Swell Sharks have a particularly interesting eggcase: cream-coloured and flask shaped, this eggcase has 19-27 transverse ridges (lined horizontally across the eggcase). As with most catsharks, there are long curly tendrils on either end too.
Although the Swell Shark is listed as Least Concern globally on the IUCN Red List of Threatened Species, some species of are listed as Critically Endangered. Take, for instance, the Whitefin Swellshark, endemic to southeastern Australia. Much of its habitat overlaps with areas of intensive fishing effort – as such, although not a target species, they were and still are frequently caught as bycatch. According to the IUCN, populations have reduced by >80% over the past three generations,
Scientific Name: Cephaloscyllium ventriosum
Maximum Size: 110cm
Diet: Small crustaceans, cephalopods and fish
Distribution: Eastern Pacific, most commonly found at 5m to 40m depth.
Habitat: Usually found in rocky areas of kelp beds.
Conservation Status: They’re not typically targeted for food as their meat is generally considered to be of poor quality. They are however, often caught as bycatch in gillnets and trawls.
IUCN Red List Status: Least Concern
For more great shark information and conservation visit the Shark Trust Website
biofluorescence (Sparks, J. S.; Schelly, R. C.; Smith, W. L.; Davis, M. P.; Tchernov, D.; Pieribone, V. A.; Gruber, D. F., CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons)
laticeps (Mark Norman / Museum Victoria, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons)
Eggcase 1 ‘Cephaolscyllium ventriosum’ (vagabondvince310, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons)
Eggcase 2 ‘Cephaloscyllium laticeps eggcase’ (Museum Victoria, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons)
The Thrilling Encounter with Tiger Sharks at Beqa Lagoon’s ‘The Colosseum’ with Coral Coast Divers
Nestled in the heart of Fiji, Beqa Lagoon is not just another dive destination; it’s a world-renowned haven for shark enthusiasts. Often hailed as the shark diving capital of the world, this magnificent lagoon offers an unparalleled underwater adventure. Let’s delve into the depths of Beqa Lagoon to understand what makes it a pinnacle of shark diving.
The History Of Shark Diving In The Beqa Lagoon
This journey began decades ago, evolving from the initial fascination and respect the local Fijian communities had for these magnificent creatures. In the early stages, shark diving in the lagoon was a rare and awe-inspiring experience, primarily pursued by adventurous divers seeking close encounters with these misunderstood predators. Dive centers began working with local communities and fishermen by protecting the area from fishing, and also shark baiting to encourage sharks to attend the dive sites. This had a profound effect not only on the shark population but on the local reefs and other fish populations as well. The local reefs are now much healthier than they were in the early 2000’s, there is a much greater population of other marine life, and the shark diving is world class! Over the years, as knowledge and appreciation of this area for sharks grew, Beqa Lagoon emerged as a premier destination for shark enthusiasts worldwide. This transformation was fueled by the collaborative efforts of local dive operators, conservationists, and the local Fijian people, who worked together to develop sustainable shark diving practices and by protecting large areas from fishing. These efforts not only positioned Beqa Lagoon as a global hotspot for shark diving but also played a pivotal role in shark conservation and research. Today, the legacy of shark diving in Fiji continues, offering a window into the fascinating world of these apex predators and a testament to the power of sustainable tourism in marine conservation.
What Makes The Beqa Lagoon So Great For Shark Diving
Beqa Lagoon’s geographical features make it an exceptional location for shark diving. Encircled by one of Fiji’s most extensive barrier reefs, this natural fortress creates a serene and protected sanctuary, ideal for the flourishing marine life within. The barrier reef not only acts as a buffer against strong ocean currents but also nurtures a vibrant underwater ecosystem, providing a haven for a wide array of marine species, including sharks. Just outside the lagoon, the ocean floor descends into deep drop-offs, creating an environment where pelagic species can live and explore. This unique topography allows divers to experience both the colorful, shallow coral gardens and the thrilling depths where larger sharks roam. The healthy state of the reefs and surrounding oceans in the area is a crucial factor in sustaining a diverse marine population. This blend of a protected lagoon with the proximity to the deep ocean makes Beqa Lagoon not just a safe and accessible diving location but also a dynamic and exhilarating shark diving hotspot. This deep water surrounding the Beqa Lagoon is where the beautiful tiger sharks reside.
Why “The Colosseum” Has The Highest Rate Of Tiger Shark Encounters
The dive site called “The Colosseum”, which is a marine sanctuary operated in an agreement between the dive center Coral Coast Divers and the local Fijian community of Yanuca Island, is the dive site where Tiger Sharks are most commonly seen. This dive site is located on a reef which is very close to the outer edge of the Lagoon. So, while it may take an extra 20 minutes or so travel time via boat to reach this dive site, the increased likelihood of witnessing Tiger Sharks makes it all worthwhile. The Tiger Sharks in the area generally roam the deeper waters just outside of the lagoon. Once the bait is lowered into the water on the first dive, the scent begins traveling. The Tiger sharks pick it up and generally meet the divers on the second dive of the trip for an incredible shark feeding experience!
The Shark Diving Experience at Beqa Lagoon:
Diving in Beqa Lagoon is an immersive experience. The clear, warm waters offer excellent visibility, allowing divers to witness the majestic beauty of sharks in their natural habitat. From the awe-inspiring Tiger Sharks at ‘The Colosseum’ to the formidable Bull Sharks, the lagoon is a stage for some of the most thrilling underwater performances.
The Diversity of Shark Species: Up to 8 Species Of Sharks On 1 Dive
What truly sets Beqa Lagoon apart is the diversity of shark species. In addition to Tiger and Bull Sharks, divers can encounter up to eight different species in a single dive, including Lemon Sharks, Nurse Sharks, and potentially even the rare Silver Tip Sharks. This diversity is a testament to the health and richness of the marine ecosystem in Beqa Lagoon.
A Shark Diving Capital Of The World
Beqa Lagoon stands unrivaled as the shark diving capital of the world, not just for the thrill of the dive but for the holistic experience it offers. It’s a place where nature, conservation, and culture converge to create an unforgettable diving adventure.
About the Author: Jonathan Rowe
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CCMI RESEMBID project reveals the crucial role of diversity in coral restoration and climate change resilience
The Central Caribbean Marine Institute (CCMI) and project partner, Dr John Bruno, University of North Carolina, have completed a two-year coral restoration research project investigating how Acropora corals with different genetic makeup (genotypes) respond to climate change-related stress.
The project, which is supported by RESEMBID, funded by the European Union and implemented by Expertise France, examined key desirable traits of different coral genotypes that could translate to increased resilience at a restoration site or coral nursery. These traits included resistance to coral disease, faster growth rates and tolerance of warmer waters.
CCMI’s project initially aimed to examine and test thermal tolerance within a laboratory setting, through controlled experiments. However, the extended period of warmer waters in the Cayman Islands over summer 2023 provided a unique opportunity to monitor responses in the lab and on the reefs of Little Cayman.
Although devastating to watch corals bleach and die, the bleaching event gave CCMI’s researchers invaluable insight into how different genotypes respond to conditions that will become more common in the future due to climate change, in both natural and lab-based environments.
Both the lab-based and field studies found that no one coral genotype clearly displayed all desirable characteristics that would be linked to resilience. Instead, some genotypes showed higher resistance to coral disease, but lower thermal tolerance, whereas others displayed higher thermal tolerance and less bleaching, but slower growth rates or lower disease resistance.
In the field, all corals in the nursery bleached or died during the coral bleaching event, except one specific genotype with remaining healthy colonies which was also shown through lab results to have a higher thermal tolerance. However, this specific genotype also showed much slower growth rates than other corals.
CCMI’s Director of Research, Dr Gretchen Goodbody-Gringley explains what these results mean for coral restoration under a changing climate:
“These results emphasize the importance of maintaining genetic diversity in our standing stock of corals used for restoration to bet hedge for increased resilience against the myriad of threats that could impact survival now and in the future.”
CCMI’s results show that preserving the diversity of genetics within coral restoration projects is crucial to boost coral resilience to stress. Coral reefs are complex ecosystems that are exposed to a wide range of threats from climate change and human activity, and restoration should reflect this complexity. Boosting genetic diversity and building this into coral restoration practices is likely to be the best and only way to increase the resilience of coral reef restoration efforts in the Anthropocene.
Coral reefs are an essential ecosystem that underpin societal well-being through services such as food provision, storm protection, and economic activities. As the impacts of climate change become more severe and events like this year’s coral bleaching become more common, coral restoration is an essential tool to buy time, improve coral populations and provide hope for vulnerable coral reefs, while the world battles to reduce emissions and slow climate change.
Coral restoration may be part of the solution, but it is also highly vulnerable to the impacts of climate change. As such, future restoration efforts must be climate-smart, and designed around resilience-based concepts to ensure that these benefits are realised.
Through this project, CCMI has continued our commitment to science-based, innovative coral restoration, producing recommendations and a coral restoration handbook to support managers and practitioners locally and internationally with incorporating resilience principles into their restoration efforts.
CCMI has also released a video, available here: http://tinyurl.com/RESEMBID-project-outcomes, a coral restoration handbook (https://reefresearch.org/wp-content/uploads/2024/01/RESEMBID-HANDBOOK-2024-ENGLISH.pdf) and will be holding a press conference on 18th January at 10am EST to discuss these results and how they can be applied to climate-smart coral restoration for the future of coral reefs in a changing climate.
Register for CCMI’s coral restoration press conference here: https://fb.me/e/6er9UvEYv
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