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Genetic diversity of Boeseman´s Rainbowfish (Melanotaenia boesemani) reared in I

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HayoAqua

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Media Fitri Isma Nugraha, Laurent Pouyaud, Odang Carman, Utut Widyastuti, Muhammad Zairin Junior, Kadarusman and Jean-Christophe Avarre: Genetic diversity of Boeseman´s Rainbowfish (Melanotaenia boesemani) reared in Indonesian farms compared to endangered natural populations, Tropical Conservation Science 8 (3), pp. 796-812.

Abstract
Endemic to two lakes (Ayamaru and Uter) of West Papua (Indonesia), the Boeseman´s Rainbowfish  Melanotaenia boesemani Allen & Cross, 1980 is a very popular ornamental freshwater fish. As a result, this   rainbowfish species faces great threats and is on the red list of endangered species. Therefore, rearing of this species in aquaculture systems appears to be a promising solution to limit capture of wild speci mens and prevent its extinction. Although its reproduction cycle has been controlled for more than 30 years, very few farms still raise M. boesmani , probably due to the problems reported by the farmers, such as decline of production, higher proportion of females per spawning, loss of coloration, lower growth rate and fecundity. Using 12 microsatellites previously developed for this species, comparison of genotypes within six farms around Jakarta indicated that all reared strains originated from Ayamaru Lake. No deficit in heterozygotes was evidenced, suggesting that there was no major inbreeding in these reared populations. Genotype analysis also suggested that M. boesemani species is a metapopulation composed of genetically differentiated populations. Altogether, these results indicate that the problems experienced by the farmers are due not to inbreeding depression but to other factors such as inadequate management and/or poor water quality. Yet, increasing aquaculture production is probably the most effective way to alleviate the pressure that M. boesemani faces in its natural environment.

http://tropicalconservationscience.mongabay.com/content/v8/tcs_v8i3_796-812_Nugraha.pdf
 

Re: Genetic diversity of Boeseman´s Rainbowfish (Melanotaenia boesemani) reared
« Reactie #1 Gepost op: september 30, 2015, 03:40:22 pm »
 

HayoAqua

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Poor management ails endangered Boeseman’s Rainbowfish aquaculture

Poor water quality and poor management of aquaculture farms may be responsible for the loss of coloration and productivity in the Boeseman’s Rainbowfish, a recent study suggests.

• Some Indonesian Boeseman's Rainbowfish aquaculture farms appear to have hit a slump, study says.
• Unsuitable rearing conditions may be responsible for this, researchers suggest.
• Improving rearing conditions could increase production of these fish in aquaculture farms, which could in turn alleviate pressure on the wild endangered rainbowfish populations, researchers write.


Boeseman’s Rainbowfish is endangered in the wild and is a popular ornamental fish. Photo from Wikimedia Commons.

The endangered Boeseman’s Rainbowfish (Melanotaenia boesemani), found only in the Ayamaru region of West Papua in Indonesia, is a popular ornamental fish. Over-harvesting of this brilliantly colored rainbowfish has pushed the species towards extinction. So increasing production of these fish in aquaculture farms could alleviate pressure on the wild populations. But some Indonesian rainbowfish aquaculture appear to have hit a slump.

Unsuitable rearing conditions may be to blame, suggests a recent study published in Mongabay’s open-access journal, Tropical Conservation Science.

“At present, farmers claim a decrease of both quantity and quality: males are not as colored as in the wild, growth rate and fecundity are slower; and morphological abnormalities frequently occur,” the authors write in the paper. “They attribute these observations to loss of genetic variability and possible inbreeding.”

To test whether the farmers’ claims were indeed true, researchers from Indonesia and France assessed the genetic diversity of captive strains of rainbowfish reared in six aquaculture farms located around Jakarta, and compared them with that of wild rainbowfish populations.


Boeseman’s Rainbowfish is found only in Ayamaru and Uter Lakes, and their tributaries, in West Papua in Indonesia. Map from Nugraha et al, 2015.

The team found that aquaculture-reared rainbowfish had similar genetic diversity as those found in the wild. This suggests that there was no major inbreeding in the reared populations, the authors write.

So problems observed in reared rainbowfish could be due to poor water quality and poor management of the aquaculture farms, they speculate.

“All investigated farms are located in industrial and densely populated peri-urban areas,” the authors write. “As Jakarta and its suburbs have no waste water treatment system, the water used for rearing these fish is probably of very poor quality, and may contain many chemical and hormonal pollutants, both of which have been proven to alter major fish traits such as reproduction and growth.”

The researchers add that the loss of coloration in the male rainbowfish could be because of altered turbidity conditions of the water. But this needs further investigation, they note.

So by adapting better management of the quality of waters used for rearing the rainbowfish, farmers may be able to harvest better-looking and more productive fish, the authors write.

“The results presented here… indicate that, in spite of the threats that Ayamaru is facing, it is still possible to prevent the extinction of Boeseman’s Rainbowfish,” they add.

Citation:

• Nugraha, M. F. I, Pouyaud, L., Carman, O., Widyastuti, U., Zairin Junior, M., Kadarusman and Avarre, J. C. 2015. Genetic diversity of Boeseman ́s Rainbowfish (Melanotaenia boesemani) reared in Indonesian farms compared to endangered natural populations. Tropical Conservation Science  8 (3): 796-812.

Bron: http://news.mongabay.com/2015/09/poor-management-ails-endangered-boesemans-rainbowfish-aquaculture/