Study hopes to reveal more about Porbeagle sharks


A tagging scheme is underway in Ireland to find out more about sharks in our native waters.

Dr Ryan Saunders of the Marine Institute (MI) in County Galway is working together with anglers to study the migration and diving behaviour of Porbeagle sharks (Lamna nasus) in the northeast Atlantic, in a project which will end in 2011. These sharks are one of the top marine predators around Ireland, but very little is known about their movement patterns .

The study uses pop-up satellite tags which are fitted harmlessly to the back of the shark. The tags collect information on the animal's location and depth distribution, together with data on the environment in which the sharks live.

Then after nine months the tags pop-up to the surface and transmit the data to polar-orbiting satellites.

The Marine Institute is especially hoping to tag large adult females using pop-up satellite tags to establish their birthing grounds.

Like most pelagic sharks, the Porbeagle is vulnerable to commercial fishing pressure, slow growth rate and complicated reproductive cycle. And, due to a lack of information on its biology and ecology, there is no protective legislation in place for the species.

Marine Institute fisheries scientist Dr. Maurice Clarke said: "Understanding the biology and spatial ecology of the Porbeagle shark is key to the conservation of the species and for establishing successful ecosystem-based management strategies in the northeast Atlantic".

A pilot tag scheme deployed off Donegal in 2008 caught three Porbeagles and proved highly successful.

The tags tracked one juvenile male more than 2,400km to the Portuguese island of Madeira, whilst a second migrated to the Bay of Biscay, which has an abundance of species such as the Albacore tuna (Thunnus alalunga). The results also showed their diving behaviour is linked to the day-night cycle and monthly lunar cycle.

The Marine Institute is currently working with the Irish Elasmobranch Group, French Research Institute for Exploration of the Seas (IFREMER), and the Association for the Conservation of Sharks (APECS) to find further funding for the project.

They aim to establish links between the fishing industry, recreational anglers and the public to increase research and awareness for the conservation of these sharks.    

Dr Edward Farrell of IEG, said: "Pelagic sharks have received much global attention recently. Given the increasing pressures that threaten their survival, there is a pressing need for new research to underpin effective management measures."