2nd coelacanth population found off Tanzania coast
A team of Japanese researchers has discovered a hitherto unknown population of coelacanths, a fish species known as a “living fossil,” off southeast Africa.
The researchers from Tokyo Institute of Technology and other entities said the newly found breeding group of coelacanths linked to the site has existed for more than 200,000 years without genetic contact with other groups.
Researchers had believed there was only one breeding group of the species off Africa.
The team published the results in an online edition of the Proceedings of the National Academy of Sciences of the United States.
Coelacanths have been found only in the sea off Africa and Indonesia. In Africa, an area in the sea around the Comoros Islands near Madagascar is home to the only previously known population of the fish.
Tokyo Institute of Technology Prof. Norihiro Okada and his colleagues analyzed genes of more than 20 coelacanths caught off Tanga, northern Tanzania, and nearby sites. The areas are nearly 1,000 kilometers north-northwest of the Comoros Islands.
The results showed the fish belong to a population genetically distinct from that off Comoros Islands.
The two groups seem to have separated 200,000 to 2 million years ago, the researchers said.
Considering the number of fish caught, the researchers assume the newly discovered population may comprise hundreds of coelacanths near the site.
Second and Third Photo Credit: by Sandra J. Raredon, Preserved specimen of a coelacanth from the Fish Division specimen collection at the Smithsonian National Museum of Natural History
Until 1938, coelacanths were known only as an order of peculiar lobe-finned fishes which appeared in the fossil record almost 400 million years ago and then seemed to go extinct about 80 million years ago. So the discovery of a live coelacanth off the coast of South Africa in 1938 was understandably met with great excitement. A subsequent fourteen-year search for a second specimen of this extraordinary fish resulted in the discovery of the “true” home of the living coelacanth, Latimeria chalumnae, in the Comoran archipelago in the western Indian Ocean. Since that time about 200 specimens of have been caught in the Comoros. A few other specimens have also been caught near Madagascar and Mozambique, but genetic analyses suggest that these are simply “strays” from the main Comoros population. The scientific community was shocked again in 1998 when UC Berkeley researchers announced the discovery of a coelacanth in North Sulawesi, Indonesia, almost 10,000 kilometers from the Comoros. Dr. Mark Erdmann first saw a coelacanth in Indonesia in September 1997, while on his honeymoon with his wife, Arnaz. Arriving at a fish market, Arnaz noticed a large, strange-looking fish being wheeled by in a cart. Dr. Erdmann immediately recognized the fish as a coelacanth and excitedly photographed it and briefly interviewed the fisherman. Doubting that they could really have stumbled upon such a major discovery, they concluded that coelacanths must have been found in Indonesia previously. Unfortunately, they did not purchase and preserve the coelacanth. Upon further investigation following their arrival in Berkeley a week later, they found that this was indeed an important and unexpected discovery.
Dr. Erdmann returned to Sulawesi in November, 1997 in search of another coelacanth. During a 5 month period, he interviewed over 200 fisherman in the coastal villages around North Sulawesi, but found very few fisherman who seemed familiar with the fish. Finally, he interviewed two fisherman who said they occasionally caught the coelacanth, which they called raja laut, translated as, “king of the sea.” After careful monitoring of their catch for several months, Dr. Erdman was rewarded with a second Sulawesi coelacanth on July 30, 1998. The second Sulawesi coelacanth was caught by Om Lameh Sonatham in a deep-set shark gill net off of Manado Tua island in the Bunaken Marine Park (see “where do they live” for map of location). The coelacanth was barely alive when it was delivered to Dr. Erdmann. After they temporarily revived the animal by towing it behind their boat, they photographed it in shallow water (see photo on “home” page). When the injured fish eventually died, it was frozen and later donated to the Indonesian Institute of Sciences. A French and Indonesian research team named the Sulawesi coelacanth as a new species (Pouyand, L., et al. 1999 “A new species of coelacanth.” Comptes Rendus v322(4):261-267).
In October, 1999, a paper appeared in the Proceedings of the National Academy of Sciences reporting more detailed molecular and morphological analyses of the Sulawesi coelacanth (Holder, M.T., M.V. Erdmann, T.P. Wilcox, R.L. Caldwell and D.M. Hillis. 1999. Two Living Species of Coelacanths? Proc. Nat. Acad. Science 96:12616-12620). Conducted by scientists from the University of Texas, Austin and the University of California at Berkeley, Holder et al. concluded that the Comoran and Sulawesi populations most likely diverged 5.5 million years ago and perhaps as long as 16 million years ago. This is significantly earlier than the 1.2 to 1.4 million years ago suggested by Pouyand et al. The differences are due to sequencing errors made by Pouyand et al. as well as in the way that they calculated the age of divergence. The Texas and Berkeley teams conclude that the molecular evidence suggests that the two populations probably do represent different species. However, when Holder et al. looked at morphological traits reported by Pouyand et al. to differ between the Sulawesi fish and the Comoran population, they did not find them. This is due to the fact that Holder et al. used a larger sample size of Comoran fish which provided a better estimate of the amount of variation that occurs. The definitive answer regarding the relationship of these two populations of Latimeria probably won’t be determined until additional Indonesian fish are captured and a more detailed morphological study is completed.
The annoucement by Erdmann et al. of the capture and preservation of a living coelacanth almost 10,000 kilometers from the Comoros appeared as a cover story in the journal Nature (Erdmann, M.V., Caldwell, R.L., and Moosa, M.K. 1998. “Indonesian ‘King of the Sea’ Discovered” Nature v.395:335). The discovery was also featured in television, radio, and newspaper articles around the world; including CNN, ABC News, and National Geographic. Discover magazine even listed the discovery as one of the top science stories of 1998 (January 1999, p.49).
The first formal descriptions of the two known Sulawesi coelacanths and how they were discovered were published in 1999 by Dr. Erdmann in Environmental Biology of Fishes. (Erdmann, M.V. 1999. An account of the first living coelacanth known to scientists in Indonesian waters. Env. Biol. Fishes, 54: 440-444; Erdmann, M.V., R.L Caldwell, S.L. Jewett and A. Tjakrawidjaja. 1999. The second recorded living coelacanth from north Sulawesi. Env. Biology of Fishes, 54: 445-451). In the first paper, Dr. Erdmann describes the events that lead up to the discovery and photographing of the first Indonesian coelacanth in the fish market in Manado. The second paper describes the fish captured off Manado Tua on July 30, 1998, its preservation and donation to the Indonesian government. Acknowledgements: Dr. Erdmann’s research was funded by the National Science Foundation (#INT-9704616) and the National Geographic Society (#6349-98). Ongoing research has also been supported by generous equipment donations of TidBit ® temperature loggers from the Onset Computer Corporation and a Splash-Cam ® Deep Blue underwater video camera from Ocean Systems . Research in Indonesia was conducted under the sponsorship and support of Dr. MK Moosa and the Indonesian Institute of Sciences.