SHARK TAGGING IN UK WATERS
To improve the knowledge base on shark angling best practice, this project will be conducting scientific tagging of sharks caught in UK waters by recreational anglers. Results will help us better understand the post-release behaviour of individual sharks and which factors could potentially influence the survival on a species-specific basis.
The Project
In England, an estimated 823,000 recreational fishers engaged in recreational sea angling for a cumulative time of ~7,000,000 days between 2015-2017. A portion of this effort was directed towards catch-and-release shark fishing. However, little published research exists that measures the effects of catch and release angling for sharks or other large pelagic fish in UK waters. To ensure the long term occurrence of sharks around the UK, and hence also a thriving catch and release angling industry, a better understanding of shark response to capture is needed, including potential refinements and further promotion of good practice techniques for handling and releasing such species.
The project has the following aims:
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Investigate the potential effects that recreational shark fishing has on shark species through the deployment of electronic tags to establish the behaviour and fate of released animals;
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Work with shark anglers, angler organisations, and regional NGOs to minimise any potential negative effects to species of conservation concern, whilst maximising the potential for growth and socio-economic gain in the recreational catch and release fishery;
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Improve evidence-based guidelines on shark angling best practice, to be shared widely by the partners to promote shark post-release survivorship.
This project would not be possible without the engagement and knowledge of recreational sea anglers. We are incredibly grateful to those skippers that are already involved in the project. If you are a recreational angler who targets or regularly encounters sharks then we would be delighted to hear from you.
Electronic Tags
The project will deploy three types of tags to study recreationally caught sharks in South west waters. Each tag type provides a unique insight but with the common goal of improving information on post-capture release survivorship:
Wildlife Computers tags
(sPAT and MinPAT)
Cefas DST
(i) Survivorship tags (sPAT tags; Wildlife Computers); these tags detach at 30, 45 or 60 days post deployment, or prior if the animal dies. Data received via satellite indicate the fate of the animal and the location at which it detached from the animal. Physical recovery of these tags also provides raw data on depth and temperature encountered by tagged animals that enables more fine scale analysis of behaviour immediately post-release.
(ii) Cefas DST (PDST; Cefas Technology Limited); these tags record data on temperature, depth and acceleration. These tags detach from the study animal following corrosion of a galvanic link and then float to the surface and drift. These tags do not have a relocation system; they rely on being found by members of the public after they have drifted ashore. Plymouth Marine Laboratory will support this component of the project by providing access to their coastal seas oceanographic model to aid prediction of where tags might make landfall. The high frequency sampling rate of these tags will provide additional insight on fine-scale behaviour at the interval of seconds immediately post-release and then through the post-release recovery period. If you discover one of these tags please get in contact with us here.
(iii) Archival data and geolocation tags (MiniPAT; Wildlife Computers); these are simialr to sPATs, but provide richer information on the daily location of instrumented animals using a process termed ‘light-geolocation’, in addition to high-resolution accelerometry data. These tags detach from the study animal either at a programmed interval (e.g. 30 days following attachment) or if the shark has died. Data are then remotely transmitted via satellite, allowing information on shark behaviour to be gathered with the need to physically retrieve the tags. however more data can be obtained from the physical tag.
Species focus
A large number of shark species are caught in recreational fisheries in the South west and UK more generally. These include blue shark (Prionace glauca), tope (Galeorhinus galeus), porbeagle (Lamna nasus), starry smooth-hound (Mustelus asterias), nursehound (Scyliorhinus stellaris) and occasionally shortfin mako (Isurus oxyrinchus) and common thresher sharks (Alopias vulpinus). Given the critically endangered status of porbeagle sharks in European waters, the project will prioritise this species for tag deployment, with tope and blue sharks also likely to heavily feature. For more information, the Shark Trust has specific angling guides for conservation concern shark species and general information for the handling of sharks, skates and rays.
Porbeagle
Scientific name: Lamna nasus
Maximum size: 355 cm
Conservation status: Critically Endangered in the Northeast Atlantic (IUCN, 2015)
Ecology: Porbeagles are found in inshore waters and over continental shelf edges, offshore banks, and in the open ocean to depths of 1,809 m. They prefer temperate waters below 18°C. They produce litters of 1–5 (usually 4) pups, with a 8–9 month gestation period, an annual, but possibly biennial, reproductive cycle (IUCN, 2015). ID guide here.
Recreational advice: Avoid targeting Porbeagle Sharks between April-August, as pregnant females are moving through British waters. If hooked, release the shark as quickly and safely as possible. Avoid in-boarding the shark unless absolutely necessary (Shark Trust, 2019).
Tope
Scientific name: Galeorhinus galeus
Maximum size: 195 cm
Conservation status: Vulnerable in European waters, Critically Endangered globally (IUCN, 2015)
Ecology: Coastal-pelagic species found in the shallows to offshore, down to 470 m. Vulnerable to
fishing pressure due to slow life history characteristics and length of reproductive cycle. Historically one of the most widely fished shark species; important in commercial and recreational fisheries. ID guide here.
Recreational advice: It is prohibited to fish for Tope other than with rod and line. Rod and line anglers fishing from boats must not land their catches ashore alive or dead (Shark Trust, 2019).
Common Thresher
Scientific name: Alopias vulpinus
Maximum size: 465 cm
Conservation status: Endangered in European waters, globally Vulnerable (IUCN, 2015)
Ecology: Found nearshore to offshore, from the surface down to 650 m, often along the continental shelf. Uses its tail, which can be as long as rest of body, to stun and immobilise prey. Slow growing with a low fecundity make the species vulnerable to overexploitation. ID guide here.
Recreational advice: Avoid targeting adult females between March-June as they could be carrying pups. Where possible, also avoid tail-hooking thresher sharks as they exhaust quickly and often die when fight times exceed 1.5 hours due to limited water flow across the gills (Shark Trust, 2019).
Shortfin mako
Scientific name: Isurus oxyrinchus
Maximum size: 400 cm
Conservation status: Data deficient in European waters, globally Endangered (IUCN, 2015)
Ecology: Pelagic, oceanic shark, found from surface to 888 m. Migrates seasonally to follow warmer waters and is known to make long distance journeys of > 3000 km. An important bycatch species in high-seas fisheries, this species has undergone drastic declines. ID guide here.
Recreational advice: Extremely popular game fish due to its hard fight and habit of breaching when hooked. Due to potentially long fight times, release from the side of the boat, avoid boarding and resuscitate exhausted individuals prior to release.
Blue shark
Scientific name: Prionace glauca
Maximum size: 383 cm
Conservation status: Global and European populations are considered Near Threatened, however the Mediterranean population is Critically Endangered (IUCN, 2018)
Ecology: Widespread with a relatively high reproductive rate, blue sharks have a global distribution and are highly mobile, undertaking annual transatlantic migrations. Believed to be the most heavily fished shark species globally, substantial catches are reported pelagic longline fisheries targeting tuna and billfish, where they are mostly caught and discarded as "bycatch". ID guide here.
Recreational advice: Blue sharks are commonly encountered by recreational anglers in summer months when they migrate to coastal waters. Little is known about their post-release behaviour or survival.
Bluntnose Sixgill shark
Scientific name: Hexanchus griseus
Maximum size: 550 cm
Conservation status: Global populations are considered Near Threatened (IUCN, 2019)
Ecology: A large deep-water shark known to have a global yet patchy distribution. It is found off continental slopes and shelves, and occasionally inshore, but mostly at depths of 200–1,100 m. It has large litters but an estimated late age-at-maturity that reduces its capacity to recover from fishing pressure. The species has high distribution overlap with intensive fishing pressure and a lack of species-specific management across its entire range. ID guide here.
Recreational advice: Sixgill sharks are not a common encounter for recreational anglers in the UK, but some hotspot areas have been found in the Atlantic. As this is a deep-water species, it is recommended that time at the surface/on the boat is kept as short as possible, to minimize the potentially negative effects that high temperature and light levels might have on the animals. Little is known about their post-release behaviour or survival.