Combing the beaches for mermaid’s purses

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While scooping up undesirable litter from the Island’s beauty spots, you can also help with a study on shark, skate and ray populations.

The marine biology section of the Société Jersiaise has been asking the public to collect mermaid’s purses – the egg cases of sharks, rays and skates.

The distinctive cases, well known to most beachcombers and parents of dedicated rockpoolers, can be taken to its marine biology section offices at 7 Pier Road. Collectors are asked to note the location and date the egg cases are found.

‘Collecting mermaid’s purses gives us an alternative and non-invasive method of indirectly monitoring the distribution of certain ray and small-shark species and their population trends over time,’ said Société Jersiaise marine biology chairman Gareth Jeffreys.

‘Mermaid’s purses generally belong to demersal (or bottom-dwelling) species, which are rarely seen in their natural environment and so, before people began collecting and handing in their egg cases to the marine biology section, the only other significant source of data was through commercial and recreational catch records.’

The Société Jersiaise has been working with the Shark Trust UK on the project since 2012, when they were presented with a bag of mermaid’s purses.

They soon started receiving hundreds a month and to date have recorded over 12,000 – two-thirds of which were collected by one person.

‘More than 8,000 were collected by Geoff Walker, who unfortunately for us will be leaving the Island shortly,’ Mr Jeffreys said. ‘The data give us an indication of the reproductive life cycles for each species from when we see peaks in the number of mermaid’s purses being washed up throughout the year.

‘Although we don’t yet have a reliable estimate for how long it takes from when eggs hatch to when the first egg cases start washing up on our beaches or how to gauge the age of an egg case by its condition.’

While there is more to learn, the new information from the egg cases has already proved enlightening.

Mr Jeffreys said one species – the cuckoo ray – was discovered to be present in local waters only when its egg case was identified. It had never before been reported in Jersey.

Over the course of the study, two species of locally present shark have been identified – the small-spotted catshark and nursehound – and six different rays – undulate, blonde, small-eyed, spotted, thornback and cuckoo.

While people can log finds on the Shark Trust UK website themselves, Mr Jeffreys said egg cases should still be handed in, so they can be verified and properly recorded.

The JEP Coastal Clean-up takes place at Grève de Lecq, Green Island, Havre de Pas, Bel Royal and Bouley Bay on Sunday 10 June.

All are welcome between 9 am and noon to join with volunteers from the JEP, the Probation Service, Close Finance, Jersey Gas, and Jersey Electricity.

Santander volunteers will also be working at Ouaisné next Friday.

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