The theme music alone of the classic film Jaws is scary but the dramatic footage of the giant fish itself, albeit a mechanical model, would be enough to give anyone nightmares. It is hard to believe that this iconic movie is half a century old this year but it is probably the most significant piece of negative publicity that sharks have ever received. Ask anyone you know what they think about sharks and the reply is rarely positive. The movie was based loosely on Peter Benchley’s novel Jaws which describes a renegade great white shark on the east coast of the United States.
Previously unknown in Irish waters, there are now confirmed records of this species as far north as the Bay of Biscay but reports around Ireland and the UK are confined to anecdotal sightings. Ireland is a globally recognised hotspot for other shark species, such as the basking shark, porbeagle and tope shark, but great whites have yet to be formally recorded here. Found throughout the world’s oceans, great white sharks were historically common throughout the Mediterranean before overfishing caused major declines. In 2024, a team of scientists embarked on a major survey with the goal of documenting the presence of the great white shark in Irish waters. Dr Nick Payne of Trinity College Dublin, who led the expedition, said he was optimistic about the team’s chances of confirming its presence off the Irish coast.
I have never seen a great white shark but I have had an encounter with the largest fish in the Atlantic Ocean. I was sailing off the coast of Mayo when a pair of fins appeared in the water beside the boat, moving slowly on the surface. As the fins came closer, I realised that they were both part of the same animal, a basking shark. It moved sinuously across the sea with a large open mouth capturing the rich harvest of plankton. Basking sharks were once plentiful around the Irish coastline, migrating into our waters in summer and disappearing in the winter. The location of my sighting was not far from Keem Bay at the very western tip of Achill Island. This is a cliff-bound cove with a beautiful sandy beach at its head. Throughout the early 20th century this was the location for the capture and killing of basking sharks and large quantities of the valuable shark oil were exported to England.
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A shortage of fuel after second World War led to an increasing market for shark oil for use in certain industrial products. The slow-moving basking sharks swam into the bay to feed on dense swarms of plankton near the sea surface. Here they became entangled in nets set by the islanders who then launched their lightweight curraghs and killed the struggling fish, stabbing them with scythe blades attached to long poles. Over a 30-year period up to the 1970s more than 12,000 basking sharks were landed on Achill – an average of at least 400 fish per year. Not surprisingly, catches declined markedly towards the end of this period and, with the availability of alternative mineral oils, the market for shark oil disappeared, allowing the few remaining animals to survive. Today, basking sharks are back, their population slowly recovering from this classic example of overfishing.
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Other shark species are not immune from the pressures of overfishing either. These species fill ecological niches that are important in maintaining a balance within the ecosystem. Their removal can result in cascading effects that have a negative effect on marine biodiversity right down through the food chain. Irish waters are known to contain 71 cartilaginous fish species (sharks and rays), over half of the European list. Of these, 58 were assessed using the latest international categories in the Irish Red List. Six species were considered to be critically endangered – Portuguese dogfish, common (blue) skate, flapper skate, porbeagle shark, white skate and angel shark. For example, numbers of angel sharks recorded in tagging programmes show a decline of over 90 per cent since the 1980s. A further five species were assessed as endangered while six more species were rated as vulnerable. Sharks tend to grow slowly and produce small numbers of young each year, which can make them particularly vulnerable.
While there are no longer any vessels fishing commercially for threatened cartilaginous fish in Irish waters, some are taken as by-catch in other fisheries, involving both Irish and non-Irish boats. Ireland is not unique in this as, since 1970, the global abundance of sharks and rays has declined by 71 per cent owing to an 18-fold increase in relative fishing pressure. Sharks could use some good PR to encourage better protection and recovery of the threatened species.
Richard Nairn is an ecologist and writer. His latest book is Future Wild: Nature Restoration in Ireland
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