Tag: basking sharks

Scottish fishers successfully trial innovative fishing gear to prevent whale entanglement in ropes

A breakthrough collaborative project with creel fishers has successfully trialled a simple and relatively low-cost solution to the problem of whale entanglement that could be rolled out internationally saving many whales and sharks.

The project led by marine charity Whale and Dolphin Conservation (WDC),and funded by the Scottish Government Nature Restoration Fund managed by NatureScot, trialled the use of specially designed rope in Scottish pot fisheries that sinks rather than floats.

The rope currently used in the fishery is buoyant and forms floating loops in the water rather than lying on the seabed.

These loops can be several metres high and have been found to entangle whales and other marine animals such as basking sharks. Previous studies had found the majority of whales and basking sharks entangled in static fishing gear (pots, or creels as they are known in Scottish fisheries) are caught in this floating groundline rope linking a line of creels together.

It is estimated that an average of 6 humpback whales, 30 minke whales, and 29 basking sharks become entangled annually.

Where entanglement type was known, 83% of minke and 50% of humpback whales, and 76% of basking sharks were caught in groundlines between creels. If there are no large floating rope loops, then whales and sharks cannot become entangled in them.

Over a period of 18 months 15 fishing vessels targeting langoustine and crabs from the Inner Sound and Sound of Sleat area east of the Isle of Skye replaced floating rope in their creel groundlines with sinking rope to assess whether there were any problems with using it. Fishers reported back each time they hauled their gear, and details of over 1500 hauls were logged in the trial.

Trials were needed to determine whether it was practical for fishers to use this sinking rope. Problems which were anticipated such as snagging, or being difficult to handle were very rare.

The fishers involved in the trial reported positive experiences with using the rope, and there were no impacts on the seabed. 

Susannah Calderan, who managed the project for WDC, said; ‘The Scottish inshore creel fishery plays an important economic and community role in rural coastal areas in Scotland. Resolving the issue of entangling whales would be a major step forward in fisheries management as well as animal conservation and welfare.

‘It’s been great working with the Inner Sound fishers on this project, and we have an almost-unique opportunity to make a real impact on whale bycatch. We now have to move to the next step, which is consulting with other fishers around Scotland and with the Government to understand the possible options for implementing sinking rope more widely.’

Sinking groundline represents a simple, relatively low-cost option to greatly reduce entanglement risk.

The very successful, bottom-up, partnership approach with Scottish creel fishers and the Scottish Creel Fishermen’s Federation (SCFF) demonstrated the importance of collaborative approaches to address complex conservation and management issues. Its implications are key to supporting the Scottish Government’s commitment to reduce incidental bycatch in fisheries.

Bally Philp from SCFF, who participated in this trial, said ‘This trial has shown there can be win-win outcomes for both fishermen and marine life, and we’re all working together to achieve this’.

Cool runnings: unravelling the winter movements of basking sharks

New research has revealed that basking sharks overwintering in tropical waters off Africa experience cooler temperatures than those remaining in the Uk and Ireland.

The research, published in Environmental Biology of Fishes, provides evidence to challenge previous assumptions that their disappearance from Irish coastal waters was linked to their search for warmer waters. 

The research team equipped four basking sharks with pop-off archival satellite tags off Malin Head, County Donegal to record water temperature, depth and location over a six-month period.  

Basking sharks are a regular visitor to Ireland’s shores in summer months. It has been widely believed that basking sharks prefer the warmer waters and that their seasonal disappearance is linked to falling water temperatures.  

Through the tracking devices, the research team discovered that two of the sharks travelled vast distances to the subtropical and tropical waters off Africa whilst the others remained in Irish coastal waters throughout the winter.

The sharks off the coast of Africa experienced colder temperatures on a daily basis than the sharks that resided in Ireland, suggesting that they didn’t move south simply in search of warmer conditions.

The cooler temperatures experienced off Africa resulted from the sharks diving each day to depths of up to 600m, most likely in search of prey. 

Dr Emmett Johnston, Lead Author from the School of Biological Sciences at Queen’s University Belfast, said: “Our findings challenge the idea of temperature as the main reason for winter dispersal from Ireland.

“Likewise, further evidence of individual basking sharks occupying Irish coastal waters year-round has significant implications for national and European conservation efforts. Now we know that basking sharks are foraging at these depths, it shows that these habitats should be considered alongside coastal hotspots in future conservation efforts.” 

Dr Jonathan Houghton, Co-author from Queen’s, added: “This study tempts us to think about basking sharks as an oceanic species that aggregates in coastal hotspots for several months of the year (most likely for reproduction), rather than a coastal species that reluctantly heads out into the ocean when decreasing water temperatures force them to.” 

Co-author, Dr Paul Mensink from Western University, added: “Our findings highlight the need to understand the role of deep, offshore foraging habitats for a species so commonly sighted just a few metres from our shores.” 

The international team will continue to monitor basking sharks as part of the EUSeaMonitor project to help inform and develop a collective conservation strategy for wide ranging species that have inhabited our waters for millennia. 

Photographs: E. Johnston