‘Banba’ a female basking shark tagged in July with a satellite transmitter off Malin head, Co. Donegal has just released its transmitter west of the Cape Verde Islands, over 5000km away from where it was originally tagged.
The five meter long female shark was one of five basking sharks tagged as part of the Monster Munch Basking Shark Community Awareness Project run by the Irish Basking Shark Study Group in association with the Inishowen Development Partnership and Queens University Belfast.
The movement by the shark ‘Banba’ into warm tropical waters off West Africa, coupled with similar findings by leading American shark biologist Greg Skomal in the western Atlantic, questions the validity of the established theory that basking sharks inhabit temperate waters only. Previous basking shark tracking studies undertaken in the north east Atlantic have only recorded shark movements within temperate waters.
The majority of tracked sharks have displayed a seasonal onshore - offshore migratory pattern, with movements of one or two hundred miles offshore onto the continental shelf edge during winter and return shifts to coastal waters during summer months. This seasonal pattern allows the sharks to feed year round on copepods, a type of zooplankton, their stable food source. However, the recording of this magnificent journey by a basking shark from Malin head to warmer tropical waters questions many of the fundamental theories marine biologists have regarding the species and its lifecycle.
Basking sharks were once hunted off the coasts of Ireland, but they are now classed as endangered in the North Atlantic. The Irish Basking Shark Study Group have been pioneering research on the iconic marine leviathan which can weigh more than an African elephant and grow to over 11m in length. In recent years the group have had internationally significant findings in DNA sampling, population surveys, tagging and tracking.
The groups’ motivation is to see the shark protected in Irish waters, one of the last western European territorial water bodies where they remain unprotected. Emmett Johnston, a co-founder of the group, spoke briefly about Banba’s journey. “The group are delighted with the finding, but it is a bit premature to be rushing out to change the shark biology books. We are awaiting the pop-off of the remaining three satellite transmitters attached this summer, recovering five complete basking shark tracks will allow us to compare the data and make informed conclusions. Until then there is not much we can say other than this is a highly unusual place to find a species that is presumed to inhabit temperate waters.” The satellite transmitter tags used to track the basking sharks incorporate pioneering Fastloc GPS technology coupled with depth and water temperature sensors which will allow researchers to recreate the track of the shark in three dimensions.
Emmett added, “Understanding where the sharks are and what they do when they are there, is essential to making informed management decisions regarding this endangered species.”
A number of years ago, Dr. Simon Berrow, a co-founder of the group, noticed a parasite on the sharks called pannella when undertaking shark tagging off Malin head. This parasite is often recorded on cetaceans which have travelled through tropical waters so the group have had an inkling that basking sharks visiting Irish shores might have travelled through warmer waters prior to arriving on our coast. However, in marine biology circles it is one thing to propose theories and another to actually prove them.
The Monster Munch project was set up to bridge the gap between marine scientists undertaking research and the local communities in which the work is undertaken. The Inishowen Development Partnership, Queens University Belfast, and the Irish basking shark study group funded the initiative which delivered a primary school based awareness programme encouraging local fishing dependent communities on the Inishowen peninsula in Co. Donegal to take ownership of the basking shark species and assist in its conservation.
Malin head on the Inishowen peninsula, where the shark ‘Banba’ was originally tagged and named by pupils at Scoil Naomh Mhuire, has recently been recognised as one of the world’s top summer hotspots for the basking shark. Banba’s magnificent journey to the Cape Verdes from the waters off Malin head is a valuable piece in the elusive jigsaw of the lifecycle of the sharks. This new finding by may prove to be a significant insight into the underwater world of one of the most endangered and iconic sharks in the Atlantic Ocean.
For more information and to see a magnificent video of the shark, log on to www.baskingshark.ie.
** Emmett Johnston works with the Irish Basking Shark Study Group