Coelacanths, a prehistoric fish species dating back hundreds of millions years ago, have surfaced once more due to shark fishermen’s gillnet hunting that reaches the deep seas. Already an endangered species, will this hurt their future?
A fish believed to be near extinct was rediscovered by shark fishermen off the coast of Madagascar. The coelacanth, with a history going back 420 million years ago, is referred to as the “four legged fossil fish” and is alive and well in the Indian Ocean, Newsweek reports.
Non-profit environmental conservation platform Mongabay News warns that “Demand for shark fins and oil has led fishers in southwestern Madagascar to set gill-nets in deeper waters. They are finding — and possibly harming — previously-unknown populations of these West Indian Ocean coelacanths.”
Scientists believed coelacanths went extinct about 66 million years ago, until a living specimen was found in 1938 off the coast of South Africa. Since then, there have been more incidents of the coelacanth (Latimeria chalumnae) getting caught off the coastlines of South Africa, Tanzania, and the Comoros Islands. According to Mongabay News, there is also “a different coelacanth species [that] turned up in Indonesian waters [Latimeria menadoensis].”
Researchers writing for the South African Journal of Science note that “The advent of deep-set gillnets, or jarifa, for catching sharks, driven by the demand for shark fins and oil from China in the mid- to late 1980s, resulted in an explosion of coelacanth captures in Madagascar and other countries in the Western Indian Ocean.”
Newsweek notes that the shark fishermen’s deep-set gillnets (jarifa) “are able to reach where coelacanths gather, about 328 to 492 feet (100 m to 150 m) below the water's surface.” According to Mongabay News, coelacanths are found in “undersea canyons at depths between 100 and 500 metres.”
Coelacanths “belong to an ancient group of fishes whose origins can be traced back 420 million years. They have eight fins, large eyes and a small mouth, and a unique pattern of white spots allowing each fish to be individually identified. They weigh up to 90 kilogrammes and give birth to live young after a gestation period of 36 months,” Mongabay News notes.
Of the two species, the West Indian one (Latimeria chalumnae) is “classified as Critically Endangered by the IUCN [International Union for Conservation of Nature], while a similar species found in the seas around Indonesia (L. menadoensis) is classified as Vulnerable.”
The critically endangered West Indian coelacanths caught off the shores of Madagascar are especially under threat, the authors of the South African Journal of Science article say. Andrew Cooke, Michael N. Bruton, and Minosoa Ravololoharinjara write that “The jarifa gillnets used to catch sharks are a relatively new and more deadly innovation as they are large and can be set in deep water.”
They warn that “There is little doubt that large mesh jarifa gillnets [one of two sizes of gillnets] are now the biggest threat to the survival of coelacanths in Madagascar. The nets are set in deep water, generally between 100 m and 300 m, within the preferred habitat range of coelacanths, and, unlike trawl nets, can be deployed in the rugged, rocky environments which coelacanths prefer.” They go on to say that the nets would be undetectable to the fish which have poor eyesight and in fact may even be attractive to them as they tend to be baited with smaller fish.
Lead author Andrew Cooke tells Mongabay News that they were astounded by the increase of accidental coelacanth catches. "When we looked into this further, we were astounded [by the numbers caught]...even though there has been no proactive process in Madagascar to monitor or conserve coelacanths," he says.
Mongabay News reports that other scientists are sceptical that large mesh jarifa gillnets are affecting coelacanths in a major way. Paubert Tsimanaoraty Mahatante, a marine researcher with the Madagascan government’s Institute of Fisheries and Marine Science (IHSM) tells Mongabay News that he does not believe that fishermen are deliberately targeting coelacanths for sale.
“Some fishermen from St Augustin used to bring them directly to the institute and ask for high prices. At the beginning we bought them at a high price but now we have about five or seven specimens and we don’t want to buy any more as that would incentivise fishermen.”
Mahatante expresses concern that some hotels in southern Madagascar were buying and displaying preserved coelacanth specimens to attract tourists.
Talking to Mongabay News, Mahatante continues as saying he doubted that the gill nets deployed in southern Madagascar go beyond 100m in depth, but if they were to go deeper then “it could be a big problem”.
“Catching a coelacanth is totally uncommon and people are in some ways even afraid to catch something that is so uncommon. So I don’t think that coelacanths are being targeted deliberately.”
The authors of the South African Journal of Science study suggest that due to the higher number of pregnant female coelacanths caught, and the not insignificant numbers of coelacanths caught in general, that conservation efforts may be needed to protect this ancient species.
They contend that an outright ban of jarifa gillnets may be unrealistic but suggest that “the use of jarifa gillnets in fisheries management areas and marine protected areas should be strictly controlled and their use should be restricted to areas where they do not pose a significant threat to threatened species,” among other recommendations.