A smartphone app developed at Edinburgh’s Napier University will allow the general public to help Brazilian fishers catch a tasty national delicacy. The ‘Citizen-Science’ app has been created to reinforce research into a sustainable fisheries policy for mangrove crabs along the South American country’s coastline.
The crabs, which support the livelihoods of thousands of professional fishers, are vulnerable to capture in huge numbers during andada, the mass-mating events which see them march from their burrows in their tens of thousands to seek companions.
However, marine scientists want the public to help them develop a fuller understanding of the crabs’ reproduction patterns, which appear to be influenced by the moon.
Dr Karen Diele, marine scientist at Edinburgh Napier University and St Abbs Marine Station, said: “The crabs search for mates around new or full moons. In some years they mate exclusively around new moon, while only around full moon in others. To confuse us further, on rare occasions they mate around both new and full moon.”
Dr Anders Schmidt, of Brazilian partner institution, the Federal University of Southern Bahia, said: “Due to this lack of knowledge and as a precaution, the capture of mangrove crabs is currently prohibited around both full moon and new moon in most areas in Brazil.
“However, when closures occur but the crabs do not mate, then fishers are unfairly prevented from gaining an income, which has resulted in conflict and a waste of public resources on policing.”
Karen, Anders and the research network REMAR with partners from 10 institutions are now seeking to pinpoint when and why the walks occur along Brazil’s 7500km of coast.
They are studying connections between the crabs’ reproduction and geophysical cycles from north to south Brazil to develop a tool that will allow regulators to robustly predict mating events and to define adequate closed seasons.
Those most interested in knowing in advance when andada happens, fishers and crab fisheries managers, along with the wider public, are now invited to contribute to the scientists’ crab monitoring by using the new smartphone app REMAR CITIZEN.
This app, co-developed with computing colleagues and students at Edinburgh Napier, will allow anyone, anywhere along the Brazilian coast to record occurrences of mass mating events.
Karen said: “Our android app is freely downloadable from Google Play Store and will be invaluable to gather information on when the crabs mate during forthcoming reproductive seasons, in different parts of the country.”
Anders added: “We have already tested a prototype of the app here in Brazil and it is very easy to use. The data provided by the citizen scientists will be sent to a server from where we can access it. We hope that a lot of people in Brazil will use the app and contribute to our research in this way.”
Ulisses Scofield, from Brazil’s Center for Research and Conservation of Marine Biodiversity in the Northeast, said: “Unravelling the secret behind the timing of the crabs’ mate-searching will allow a more adequate fisheries management in places where the capture of reproducing crabs is prohibited.
“Fishers and traders would no longer lose income due to wrongly placed capture bans, and it would also reduce the costs for policing.”
The REMAR CITIZEN app launched in Brazil on Thursday.
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