Zeller-BIOL-3305-Lec-14-Fassbender-sharks PDF 2024

Nico Fassbender Pristine habitat, pristine populations? PhD Candidate The status of Seychelles' sharks Sea Around Us – Indian Ocean / Marine Futures Lab The oceans oldest apex predators (Illustration: Marc Dando) Pelagic sharks Sp...

Nico Fassbender Pristine habitat, pristine populations? PhD Candidate The status of Seychelles' sharks Sea Around Us – Indian Ocean / Marine Futures Lab The oceans oldest apex predators (Illustration: Marc Dando) Pelagic sharks Spend majority of life in the pelagic realm Often large home ranges and large migrations Many classified in concerning categories on IUCN Redlist Targeted by commercial fishing and often caught as bycatch Salinas‐de‐León, P. et al., (2024). Longest recorded migration of a silky shark (Carcharhinus falciformis) reveals extensive use of international waters of the Tropical Eastern Pacific. Journal of Fish Biology. (Illustration: Marc Dando) Coastal sharks Spend majority of life in inshore environments (reefs, sandflats,…) Often smaller home ranges compared to pelagic sharks but some migrate Many classified in concerning categories on IUCN Redlist Targeted by artisanal fishery and often caught illegally Speed, C. W. et al., (2010). Complexities of coastal shark movements and their implications for management. Marine ecology progress series, 408, 275-293. (Illustration: Marc Dando) Sharks’ ecological functions What are ecological functions? For sharks: Eat sick and old animals Exert top-down forcing Can help environments in times of disturbance New discoveries in shark ecology Whitehead, D. A., & Gayford, J. (2023). First record of bottom‐feeding behaviour in the whale shark (Rhincodon typus). Journal of Fish Biology, 103(2), 448-452. Shark fishing ©|Save our Seas Foundation   Catch reconstruction Global catch data of 14 oceanic sharks and fishing effort of longline and seine gears. Increasing effort across gear types High unreported catch Pacoureau N. et al. (2021) Half a century of global decline in oceanic sharks and rays. Nature 589, 567–571 Shark finning Shark finning, often conducted illegally, is a major conservation problem globally Pelagic sharks are often specifically targeted Blue shark only classified as near-threatened – for how long? Scalloped hammerhead critically endangered – how long until it’s extinct? Some restrictions in place (UK trade ban / Seychelles carcass to fin ratio) but often not enough is done Cardeñosa D. et al. (2022) Two thirds of species in a global shark fin trade hub are threatened with extinction: Conservation potential of international trade regulations for coastal sharks. Conservation Letters, 15.5 ©Paul Hilton|Greenpeace Climate change as an additional pressure sonoma.edu Duncan M.I. et al. (2019) Localised intermittent upwelling intensity has increased along South Africa’s south coast due to El Niño–Southern Oscillation phase state. African Journal of Marine Science, 41.3: 325-330. © nsri.org.za  Established in 1964 Features more than 150,000 species Including 37% of sharks and rays Contains information on range, population size, habitat and ecology, use and/or trade, threats, and conservation actions that will help inform necessary conservation decisions Can directly catalyse action for policy change © Nico Fassbender | Save Our Seas Foundation © Nico Fassbender | Save Our Seas Foundation The status of sharks in the Indian Ocean In the Indian Ocean, shark abundances have declined steeply since 1970 - overall decline of 84.7% Indian Ocean areas were highlighted as in crucial need of protection and were identified as a priority region to implement shark-based management approaches. With many species in urgent need of protection, more data are needed to correctly assess and subsequently protect shark stocks. LPI = a measure of the state of the world's biological diversity based on population trends Pacoureau N. et al. (2021) Half a century of global decline in oceanic sharks and rays. Nature, 589(7843), 567-571. Lack of data yet strong conservation potential MacNeil M.A. et al. (2020) Global status and conservation potential of reef sharks. Nature 583, 801–806. Seychelles shark populations – a case study © James Lea|Save Our Seas Foundation Seychelles fishing history The total reconstructed domestic catch was ~ 1.5 times larger than the baseline reported by the (FAO) Domestic catches (i.e., excluding the large-scale industrial pelagic catches) increased by over 500% throughout the time period Christ H. et al. (2020) A baseline for the blue economy: catch and effort history in the Republic of Seychelles’ domestic fisheries. Frontiers in Marine Science, 7, 269. Current status of sharks Bullock R.W. et al. (2022) Using Global Red List data to inform localised research and conservation priorities—A case study in the Republic of Seychelles. Diversity, 14(8), 681 Shark fishing in Seychelles © SFA Artisanal Commercial Illegal, unreported & unregulated (IUU) (Incidental) (Bycatch) (Targeted) Shark fishing in numbers As of 2023 – only 2 small vessels currently target sharks (Berke and Nevill, pers. comm.) Nevill J. et al. (2007) Republic of Seychelles National Plan of Action for the Conservation and Management of Sharks.  Hammer sp. Guitarshark O. whitetip Whitetip r. Blacktip r. Grey reef Shark spp Grey reef Sandbar Silvertip Lemon Others Tiger Bull Nevill J. et al. (2007) Republic of Seychelles National Plan of Action for the Conservation and Management of Sharks. Conservation challenges © SFA © Tripadvisor © seychelles-fishing.com © SFA Conservation challenges “What, we doing catch and release now? You’ve never been hungry, have you?” Conservation and research initiatives What can be done? Benchmarking Remote + Protected = Near pristine Baited remote underwater video © Blue Safari systems (BRUVS) Marine monitoring Targeted diver surveys Incidental sightings © Nico Fassbender | Save Our Seas Foundation IUCN Important Shark and Ray Areas - ISRAs Jabado R et al., 2023. Western Indian Ocean: A regional compendium of Important Shark and Ray Areas. Dubai: IUCN SSC Shark Specialist Group. Tracking of sharks Allows us to gather important data for conservation and management © Ornella Weideli | Save Our Seas Foundation Residency Habitat use Home range Migration patterns Within and between species movements Overlap with threats – for example overlap with fishing effort Survival © Nico Fassbender | Save Our Seas Foundation Shark tagging can include: PIT (Passive Integrated Transponder) tags - Internal Acoustic tags - Internal or external Satellite tags - External Accelerometers - External Intrauterine tags - Internal © Nico Fassbender | Save Our Seas Foundation  PIT tagging Think of it like micro-chipping your dog Small size (mm scale) yet extreme longevity (+10 years) © NOAA Used in a variety of fields both marine and terrestrial For sharks – mark-recapture is the most common form, but often also used as a add-on for other forms of tagging or monitoring Data collected includes residency and survival, along with © Henriette Grimmel | Save Our Seas Foundation additional data such as growth rates, body condition and population demographics © Nico Fassbender | Save Our Seas Foundation  © Gerard Larose Weideli O.C. et al. (2023) Elucidating the role of competition in driving spatial and trophic niche patterns in sympatric juvenile sharks. Oecologia 201.3 Acoustic telemetry Passive or active tracking Medium size (cm scale) yet extreme longevity (up to 10 years) Used in a variety of environments and for a large range of species For sharks – internal acoustic tagging is the most common form Data collected includes residency and habitat use from small to medium-scale movements. Additional data collected as part of tagging: size, body condition, DNA sample, faecal or oral DNA sample, maturity Often done in conjunction with PIT tagging © Henriette Grimmel | Save Our Seas Foundation Tags and receivers © INNOVASEA © Nico Fassbender|Save Our Seas Foundation © Nico Fassbender|Save Our Seas Foundation The Amirantes Acoustic Receiver Array © Save Our Seas Foundation Daly R. et al. (2021) Ontogenetic shifts in home range size of a top predatory reef- associated fish (Caranx ignobilis): implications for conservation. Marine Ecology Progress Series, 664, 165-182  © Marc Dando Tag Cotton bud Acoustic tagging faecalDNA swabbing Receiver Shark habitat use at a remote atoll © Marc Dando Lea J.S.E. et al. (2016) Acoustic telemetry and network analysis reveal the space use of multiple reef predators and enhance marine protected area design. Proceedings of the Royal Society B: Biological Sciences, 283.1834 Satellite tagging Two types: Satellite tracking and pop-off data logging Medium size (cm scale) yet extreme longevity (up to 10 years) Used in a variety of environments and for a large range of species © Guy Harvey Ocean Foundation For sharks – dorsal tagging is the most common form Data collected includes migration patterns and home range size from medium to very large-scale movements. Additional data collected as part of tagging: size, body condition, DNA sample, faecal or oral DNA sample, maturity Can be done in conjunction with other tagging efforts like accelerometers or animal borne cameras © Tobey Curtis Pop-up satellite archival transmitting (PSAT) tags © Russel William Bradford Musyl M.K. et al. (2011) Performance of pop-up satellite archival tags. Marine Ecology Progress Series, 433, 1-28 Accelerometers “Fitbits” for sharks – accelerometer, gyroscope, compass Large size and usually used short term (hours) to collect fine-scale data Relatively novel For sharks – usually attached to first dorsal fin Data collected includes 3D movement behaviour and locomotion through the water column Can be used in conjunction with other tagging methods and often used with animal-borne cameras Andrzejaczek S. et al. (2019) Biologging tags reveal links between fine-scale horizontal and vertical movement behaviors in tiger sharks (Galeocerdo cuvier). Frontiers in Marine Science, 6, 229 Accelerometers Hounslow J.L. et al. (2023) Behaviour-specific spatiotemporal patterns of habitat Gleiss A.C. et al. (2013) Contrasting diel patterns in vertical movement and locomotor activity of use by sea turtles revealed using biologging and supervised machine whale sharks at Ningaloo Reef. Marine Biology, 160, 2981-2992 learning. Journal of Applied Ecology Intrauterine tagging Sulikowski J. A. and Hammerschlag N. (2023) A novel intrauterine satellite transmitter to identify parturition in large sharks. Science advances 9.9 Takeaways Fishing is the main driver of shark population decrease globally The Indian Ocean has many countries with critical conservation challenges but also great conservation potential Conservation approaches such as fishing restrictions and MPA design always depend on the context and location Tagging can be a major help in identifying habitats of conservation importance and overlap with threats such as fishing areas What actions can you take? Be aware of how the seafood you consume was caught Join conservation initiatives and get into the field! © Madison Stewart  Opportunities Only one part of a much larger, Seychelles-wide project Get in touch with the Sea Around Us and Marine Futures Lab for research project opportunities Email: Dirk Zeller – [email protected] Email: Nico Fassbender – [email protected] © Nico Fassbender|Save Our Seas Foundation