Shark conservation – preserving Ireland’s unique species
Irish scientists are lobbying the EU to protect a unique species of shark in Irish waters following eye-opening research on the relatively unknown predator. Juno McEnroe (BA 2000) learns from Dr Stefano Mariani how researchers spent several years tracking the reproductive habits of the starry smooth-hound shark, a grey-brown medium-sized fish found around Irish shores.
The shark — which can grow to almost one and a half metres in length — is one of 28 species of shark inhabiting Irish waters. Researchers at UCD School of Biology & Environmental Science now want a protection scheme established for the slender shark amid concerns the survival of the species could be under threat.
With starry smooth-hounds in the Mediterranean being fished almost to extinction, there is concern about a lack of regulations on its catch in Northern waters, and the prospect of foreign trawlers fishing out the species.
UCD researchers also discovered traits about the shark’s maturing age and its infrequent reproductive cycle which have raised questions about the strength of its population.
Dr Stefano Mariani, head of the research project at the UCD School of Biology and Environmental Science, explained: “We set out to compare distribution and the population structure and the main life history of this animal around the coastal waters of Ireland. This included studying the age of the fish, when they mature, how they reproduce, what is their reproductive potential and what is their growth rate. If we don’t know anything about how these animals live, we cannot estimate how to manage them.
Dr Stefano Mariani
“This was a particular problem because these animals were not being managed. It’s not one of those fish that receives attention year after year in terms of how their stocks are doing. They’re not primary targets for big commercial fishers. They end up being caught as a by-catch. But some of them are being targeted by southern European countries.”
On the continent, starry smooth-hounds are highly sought after and the landings from French boats, currently about 2,500 tonnes annually, are rising.
“We don’t eat these sharks but the French, the Spanish, the Italians, the Portuguese, do,” added Dr Mariani.
Others on the shark research team included Dr Edward Farrell, a PhD graduate at UCD, Dr Maurice Clarke from Galway’s Marine Institute, and Dr William Roche from Inland Fisheries Ireland.
Supported by the Irish Research Council for Science, Engineering and Technology (IRCSET), under the EMBARK initiative, the team began its work in late 2006 examining 200 dead as well as 600 live specimens of the shark over three years.
This involved catching fish by rod in shallow waters around Ireland and abroad and also trawling through commercial catches.
Using a genetic test and clipping fragments of the shark’s fin, the research team were able to confirm the shark was the starry smooth-hound and not a related species that it is often confused with, called the common or grey smooth-hound.
Dr Edward Farrell with smooth-hound off Irish coast
They caught shark pups along the Wexford coast, a popular birthing ground for the species. The shark likes to feed on the seabed on shellfish and monitoring its movements in shallow Irish waters was relatively easy.
While not a fast swimmer, it gobbles up crabs and other shellfish like prawns and its teeth are more similar to human molars than typical jagged shark teeth. It is thought that tens of thousands of sharks of all different sizes come in and out Irish waters, in areas considered either feeding grounds or good nursing areas for newborns.
Until recent years, smooth-hound species were mixed up with others. But research carried out by the UCD-led team has thrown new light on the starry smooth-hound species.
Females do not mature until six or seven years of age and only reproduce every two years, taking a break between cycles. This means that if the average female lives until 15 years of age, it only has essentially four years within which to reproduce.
Pups develop inside the female for around 12 months before being born, after which the female has a rest period of another year before she is capable of becoming pregnant again.
“We now have clear data about the forecasts of the shark’s population which we didn’t before. It grows much more slowly than previously thought and the late maturity in both male and females has consequences for reproduction,” added Dr Mariani.
The species spends spring in Irish waters mating or giving birth. Researchers not only looked at the shark in the Irish Sea but also in the English Channel, the North Sea and the Bay of Biscay, along with other locations.
According to scientists, the consequences of over-fishing the shark could see changes in the marine ecology in Irish waters. With less starry smooth-hounds, there could be more of an abundance of shellfish like crabs and prawns and the sea could literally become “soupy” with more jellyfish and smaller organisms in the waters instead of being cleaned up by the small predator.
The fish also attracts angling tourists to Ireland who after catching the shark put it safely back in the waters. This is a revenue earner for the country that should not be lost, say the UCD team.
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Researchers want to also stress that Irish people should be proud that their coastline provides beach-goers with a chance of swimming alongside these unique and harmless sharks.
Dr Edward Farrell, the UCD PhD student who initiated the four-year research, explained: “I have always been fascinated with sharks. Most people don’t even consider that sharks could be in Irish waters.”
“It’s more vulnerable to exploitation than we previously thought. People had thought it was an early maturing [shark] and had a high reproductive output. At the moment, there’s no management for it. We need to start looking at plans otherwise it will be fished out.”
The 27-year-old researcher added that the Spurdog or Spiny Dogfish was nearly fished to extinction in the 1980s in the Northeast Atlantic.
“From a moral point of view, it’s good to conserve species, especially as we have very few native species in Ireland. The few we do have are in the marine world and we should do our best to manage them,” stressed Dr Farrell.
The shark investigation team have published research papers in Oxford University Press’s ICES Journal of Marine Science as well as the UK’s Journal of Fish Biology.
Researchers now plan to lobby EU officials as well as the Irish government through the Marine Institute to roll out a marine protection plan for the starry smooth-hound.