Yarkon River Yarkon River The Yarkon River in central Israel. (Photo: Ron Almog / Flickr)

Once near extinction, rare fish swims again in Israeli river

Just a few years ago the Yarkon bream was extinct in the wild. Now it is thriving.

A conservation success story is swimming through the waters of the Yarkon River in central Israel. Just a few years ago, the tiny fish called the Yarkon bream was extinct in the wild. The only remaining members of the species lived in captivity. Today, however, thousands have been restored to their native habitat. The species has recovered to the point that the International Union for Conservation of Nature (IUCN), which assesses extinction risk, moved it from the "extinct in the wild" category to "vulnerable," indicating that its numbers are rapidly approaching healthy levels.

The decline of the Yarkon bream began more than half a century ago after agriculture started making use of the water in the fish's river habitats, which once covered most of Israel's coastal waterways. Populations declined between 1950 and 1970, but after that they remained stable for a few decades.

A drought during the 1990s changed that. Populations again took a nosedive and only three small populations survived. That's when Menachem Goren from Tel Aviv University suggested bringing the remaining fish into captivity to keep them safe and allow them to breed.

That happened just in time. Goren and his colleagues managed to find 150 fish. Thirty of them died. But those that survived proved able to reproduce in captivity. Within five years Goren's team had 14,000 fish living at the university. Meanwhile, the Israeli government put new rules into place that restored the flow of water to the Yarkon River.

Yarkon bream fishThe Yarkon bream. (Photo: Menachem Goren/IUCN)

Beginning in 2006, scientists working under the auspices of the Israel Nature and Parks Authority started reintroducing the fish to the river that bears its name. They released 9,000 to start, and the fish started breeding in the wild immediately. Today the IUCN estimates that there are five generations of fish swimming through the river and nearby artificial ponds, which were built exclusively to hold the bream.

But the Yarkon bream is not completely out of the woods. The IUCN's most recent assessment of the species concludes that it "still requires some continued conservation management, such as maintaining sufficient hard substrate for spawning and shelter for the juveniles." Meanwhile, the threat of future drought remains. The fish still has a total range of between 9 and 13 square kilometers, which is just a fraction of the number of waterways it once swam. And there's always the chance that the reintroduction will fail, as did an earlier attempt in 2002.

Still, it's almost unheard-of for a species that was once extinct in the wild to return to nature and thrive. Although the Yarkon bream has not and probably never will return to its historic numbers, its status has definitely improved in its natural habitat.

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