A lifeline for the Lake Acıgöl killifish. Fighting to stop an extinction before it’s too late

Last month, the Freshwater Life Project steering committee, voted unanimously in favour of supporting a project to help prevent the inevitable extinction of a critically endangered killifish from Turkey. The funding provided, enabled a team of researchers at Hacettepe University in Ankara, Turkey, to establish the very first captive-breeding population of the critically endangered Lake Acigöl killifish (Anatolichthys [formerly Aphanius] transgrediens), a species found only in the freshwater springs of Lake Acigöl and nowhere else in the world.

One of the last remaining habitats where the Lake Acigöl killifish can still be found

The Lake Acigöl killifish is listed in the top 100 most endangered species on Earth. The major threat that has caused its progressive decline has been the introduction of the non-native poecilid Gambusia holbrooki, a highly prolific fish that aggressively out-competes the killifish for habitat and resources. Gambusia holbrooki are also live-bearers, meaning they give birth to live young, and at a rate much faster than the killifish, an egg-layer, can keep up with; not only that, they also eat killifish eggs! Combined with other human-caused impacts such as habitat modifications, and over-extraction of water resources leading to occurrences of drought, the Lake Acigöl killifish has now come to a point of almost certain no return.

Research conducted by the local university team, including a funded survey in August 2022 supported by ZSL (below), produced results that indicate the species is heading speedily toward extinction, and without appropriate action, is likely to disappear in the coming years.

The funding, provided through the Mick Agnew Killifish Conservation Fund, enabled the local university team led by Professor Baran Yoğurtçuoğlu, to purchase and install mesocosms designed to protect the fish from predation by terrapins and birds and enable better acclimatization of the fish to their new environment, in a semi-artificial breeding pond. The breeding project is the first of its kind dedicated to the Lake Acigöl killifish in Turkey, and will not only ensure they can breed under safe and controlled conditions, but maintain a healthy and stable local stock that can act as the primary backup population utilized in reintroduction efforts.

Collection of some specimens of the Lake Acigöl killifish for the breeding program

As part of this project, Freshwater Life Project also funded the university team to purchase 6 aquariums with heaters and aerators to conduct scientific tests designed to determine the functional ecological response of the killifish to its competitor, Gambusia holbrooki. The functional ecological response is a powerful predictive tool utilized to forecast the ecological impacts of existing, emerging, and future invasive alien species on native ones. This research will assess and hope to quantify the impact of the invasive species on the Lake Acigöl killifish, for the first time, with the results forming part of a post-graduate thesis of one of the university students.

Over-extraction of water contributes to the threat of extinction

After many years without appropriate action to conserve this critically endangered fish species, it seems as though in the very near future, the Lake Acigöl killifish is very likely to become extinct in the wild. The establishment of this funded, local effort to preserve the Lake Acigöl killifish, will enable Professor Yoğurtçuoğlu and his team to now also pursue the first steps towards biobanking, a process involving the cryopreservation of the species’ DNA as a last-hope effort to preserve the species in some capacity after its extinction. With our full support, they will approach the related ministry in Turkey to pursue biobanking of the species for the first time.

The Lake Acıgöl killifish (Anatolichthys transgrediens)

For a species like the Lake Acigöl killifish, these conservation measures are the last lifeline, a final attempt that will help us to buy a little more time while we explore if there is any remote chance to conserve its habitat in a way that will enable its successful return. You can help us to raise funds to continue this work by donating directly here, or by buying one of our killifish t-shirts (click the image below!)

Photography: Baran Yoğurtçuoğlu, Alex Cliffe (ZSL)