Catching crustaceans is easy. The animals live on rocky coasts below the intertidal zone and are hidden in hollows in the rocks during the day. After dark, they come out to hunt. Lobster fishermen lower so-called lobster pots or cages to the bottom, metal or pottery barrels or wire mesh cages, with some bait. All you have to do is pull those things up during the day and pluck the lobster out. Because the animals taste so good and there is a growing wealthy public for them (eating crawfish is expensive), this leads to overfishing in the long run.
Putting young lobsters back in the sea
The Stella Mare marine biological institute, beautifully situated on the beach wall of the large lagoon south of Bastia, has now discovered how to breed the crawfish in captivity. Success depends on several factors such as the size of the basins, the number of lobsters, the amount of sunlight and the acidity of the water, plus the finicky crustaceans have strict dietary requirements
Temperature also plays a role: in the cool Atlantic Ocean it takes a year for a larva to become a juvenile crustacean, in the Mediterranean it takes five months and in Corsican aquariums only three months; that helps. The ultimate intention is to breed millions of young crustaceans and then put them back into the sea. Some of it will eventually end up in the bouillabaisse again, but the rest will contribute to the recovery of the population. The spiny lobster resembles a lobster, but without the claws. The fish meat is mainly in the tail. Like many other popular consumption fish, the spiny lobster has been overfished. In the 1950s, around 300 tons of spiny lobster were caught per year around Corsica. In the past 2 years that was only 61 tons.
Despite measures such as quota limiting catches, periods of fishing bans and a ban on catching females with eggs, the spiny lobster is in danger of coming to an end due to overfishing. “The only step left to take would be a complete ban on fishing,” said Jean-José Filippi, researcher at the institute Stella Mare, in The Guardian. “But nobody wants that, it would mean the end of fishing in Corsica.”
The lab managed to raise 6 juvenile crustaceans from eggs, with an encouraging 50% survival rate
The crawfish catch yields a modest €4 million annually, but accounts for about 70% of Corsica’s fishing income. If management measures prove to be ineffective and catches continue to fall, a ‘list’ must be devised, say fishermen and researchers.
The Stella Mare researchers believe they can provide this. They want to breed crawfish in such large numbers that stocks will return to a healthy level – and local fishermen will be able to catch enough crawfish again. According to Filippi, cultivating crawfish in the lab is easier, faster and more sustainable than any agreement or regulation process.
However, there are still quite a few obstacles in the way of breeding crawfish. This spring Stella Mare announced a ‘breakthrough’ at. The lab had managed to raise 6 juvenile crustaceans from eggs, with an encouraging 50% survival rate. Breeding crawfish proves to be particularly difficult and since the 1980s, various breeding attempts have been unsuccessful. The shape and size of the breeding tank, the number of animals per tank, the amount of sunlight and the acidity of the water all play a role. The larvae are vulnerable and what they eat is very sensitive. “Everyone is currently using the same standard crustacean and plankton food,” says Filippi. “But that’s not suitable for lobsters. It lacks the vitamins and minerals that crawfish need.”
Another important factor is the water temperature. In the Atlantic Ocean, a larvae takes 12 months to develop into a juvenile crustacean, in the Mediterranean it takes 5 months. And only 3 in the Stella Mare basins. No wonder the institute wants to scale up the process and start breeding millions of crawfish.
Other researchers are startled at the mention of such numbers. Breeding species outside their natural environment could impact genetic diversity in the ocean if they are eventually reintroduced. “Using lab-grown lobsters and introducing them into the natural population may have genetic effects,” cautions Marcelo Vasconcellos, fisheries officer at the UN Food and Agriculture Organization (FAO). “You have to be very careful not to cause inbreeding effects.”
Stella Mare also recognizes that risk. “But we are specialists in this field,” says Filippi, “We have been involved in genetics, adequate genetic mixing and monitoring the stocked populations for years.” In other words, we know what we’re doing. Greenpeace thinks otherwise. The NGO sees cultured crayfish as part of the long-term sustainable fisheries picture, but points out that more is needed: from regulations for large-scale fisheries to marine reserves and regional conservation obligations.
In addition to crawfish, Stella Mare also wants to breed other endangered species such as flat oysters, sea urchins and spider crabs.
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Corsicans go for breeding crawfish – Six juvenile breeding animals start ‘millions’ of crawfish – Foodlog