Sharks play an essential rol in the health of our oceans

Information, News, Research

Summary EEA 2016

The Dutch Shark Society attended the European Elasmobranch Association conference in Bristol on October 28th – 30th. We thoroughly enjoyed the high quality of research presented and will be sharing a short summary of some of the talks here.

As the first day of the conference was a Friday, there was a session dedicated to skates and rays, in honour of Flatshark Friday.

Helen Cadwallader from University of Waikato presented the first results of her PhD study on the foraging habits of the New Zealand eagle ray. The eagle ray creates sand pits on the sand flats, and these sand pits can be used to see which habitats the eagle rays prefer for feeding.

Victoria Bendall from Cefas tagged common skates and retrieved tags of 10 of them. These tags showed that females are much more active than males (as is the case in many species including humans, she jokingly added). Males stick to the sea floor, while females move up and down in the water column.

Samantha Simpson from the Marine Biological Association tagged 4 species of skate: blonde ray, thornback ray, smalleyed ray and spotted ray. All species showed daily movements up and down the water column, which were of similar frequency and speed across all species. The movements happen between dusk and dawn, and seasonal differences were seen between species and sex.

Michelle Heupel of the Australian Institute of Marine Science showed some beautiful animations of the movements of grey reef, silvertip and bull sharks. The highest residency was found in grey reef sharks, the highest connectivity in bull sharks. She emphasized that the effectiveness of spatial management is determined by the movement patterns of the species involved.

David Sims of the Marine Biological Association presented the Global Shark Tracking Project Consortium, in which datasets of pelagic shark tracks and fishing vessels are combined. He also emphasized the importance of different organisations working together and understanding movements of patterns of species for understanding changes. They already found an 80% overlap of mako and blue shark tracks with longliners.

James Lea of Guy Harvey found similar results for tiger sharks with 86% overlap of tracks with longliners outside Marine Protected Areas, showing sharks are running the gauntlet between sanctuaries.

Christopher Bird from the University of Southampton looked at the movements of the deep-water shark Portuguese dogfish, finding males have higher residency than females. He used stable isotopes to determine habitat use, as different prey can be found in different areas (Image). There is sexual segregation in Portuguese dogfish, with females using shallower waters, which makes them more vulnerable to fisheries.

Staying with the deep-sea species, Nicolas Pinte from the Catholic University of Louvain studied the swimming capabilities of the velvet belly lanternshark. He found that luminescent sharks have a higher swimming speed than non-luminescent sharks. When looking at this on an enzyme level, more aerobic enzyme activity was found in the red and white muscles of luminescent sharks. This indicates that they have a higher cruising speed, needed for vertical migrations in the water column to stay at a constant ambient light level.

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The Saturday started with keynote Dean Grubbs from Florida State University showing us to look at papers critically. Many papers show doom and gloom using incorrect data, and rebuttals to these papers have very little effect. Incorrect papers like these direct limited recourses inappropriately and can also provide fodder for the opposition of conservation. The day continued with talks on elasmobranch species that are under threat.

Both Colin Simpfendorfer from James Cook University and Armelle Jung from Des Requinet Des Hommes are using eDNA to provide evidence for the presence of sawfish in Australian and West African waters respectively. This new technique can be especially useful in areas where laboratories are far away.

Alec Moore from the IUCN Shark Specialist Group urged us to learn from the sawfish disaster in order to protect guitarfish, which are already 70% threatened and data deficient according to the IUCN Red List.

Continuing with general papers, James Thorburn from Marine Scotland, has done an in depth study on tope sharks. Tagging revealed the longest migraton of a female, at 3600 kilometers and genetic studies showed a single stock of tope sharks in the North East Atlantic.

Tom Letessier from the Zoological Society of London deployed 1100 BRUVs to identify locations for refuges for sharks, showing the distance of the refuges to the nearest human markets needs to be 1200 kilometers in order to have no effect on shark body size.

Oliver Jewell, who is currently looking for a PhD position, used next generation biologgers, as well as tracking data, to show white sharks interacting with kelp forests and cold water reefs to hunt seals that use these ecosystem engineers to reduce opportunity for sharks ambushing them.

Felicie Dhellemmes from Bimini Biological Field Station tracked juvenile lemon sharks, showing their personality reflects space use. More explorative sharks have a bigger home range, can be found in deeper waters and further from shore. They are bigger risk takers, which can lead to higher mortality but also higher productivity. The last session of the day was about dentition and this topic turned out to have some of the most amazing imagery, as well as new technologies.

Christina Flammensbeck from Bavarian State Collection of Zoology used fossil tip-dating (combining morphological and molecular data) to show that the dogfish sharks have an origin around 152 million years ago, and the luminescence they are capable of has its origin around 133 million years ago.

Charlie Underwood from University of London used CT scanning of developing teeth of dogfish sharks to show the unique dentition of dogfish allows them to feed on large food items, giving them an advantage in low nutrient and cold environments.

Gareth Fraser from University of Sheffield looked at gene expression in teeth and denticle genes in sharks (Image). The gene Sox2 was expressed in teeth and taste buds, but not in denticles. This shows they both develop from dual function stem cells.

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Sunday, the last day, was a session aimed on conservation. Sonja Fordham from Shark Advocates talked about CMS and emphasizes that concrete fishing limits are needed.

Sarah Fowler from the Save Our Seas Foundation talked about CITES listings and thinks regional fisheries should be included as Scientific Authorities, and countries should have shared NDF’s when stocks migrate through multiple countries.

Ali Hood from the Shark Trust showed high landings of sharks in the Mediterranean Sea despite regulations, it is currently the most dangerous place in the world for sharks.

Adi Barash from Haifa University is Facebook stalking local divers and fishermen, asking for more information in comments to collect data on elasmobranch populations (Image). She has already collected 600 records on 17 species.

David Jacoby from the Zoological Society of London gave the last presentation of the conference, emphasizing the importance of behavioural research for managing shark reserves by determining hotspots.

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This was an extremely successful conference, with 67 talks in total, as well as many posters. In the closing session the importance of different organisations working together towards the same goals was emphasized.

A Big Thank You to the organizing Shark Trust! Great Job!

 

 

 

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