Boxer Pupfish Hatch with Hope for their Species.
29 tiny Boxer Pupfish (Cyprinodon simus) are swimming around their tank at Bristol Zoological Society, representing some of the great work that zoos, and private collections can do.
Where are Boxer Pupfish from?
These tiny fish are important as their habitat is so limited, only from Lake Chichancanab on the Yucatan Peninsula. In this area so many fish live in the hard water Cenotes, deep sink holes in the limestone bedrock. But this lake has a thick clay layer, and no rivers entering or leaving. There is at least one spring in the lake bed, but the lake is saline, and in periods of extreme drought the water can get so hard the gypsum will precipitate out of the water.
You might wonder how they can survive this frankly harsh conditions, well they are related to the Devils Hole Pupfish, this family can thrive in some pretty horrible conditions.
Lake Chichancanab was designated as an internationally important wetland 21 years ago. One of the few locations with inland mangroves, crocodiles stalk these waters. But there are surprisingly few species of native fish. There are 7, at least, species of Cyprinodon, and one other species Gambusia sexradiata.
In this location the 7 species of Cyprinodon have each adopted ecological niches. Their common ancestor was from a more saline environment, so the brackish water hasn’t caused any issues.
But several of these species are now extinct in the wild, including the litter Boxer Pupfish. Last seen in the wild in 2009, there is little chance that there is a thriving population in the lake.
Why is the Boxer Pupfish extinct in the wild?
Invasive species, specifically a species of cichlid variously refered to as the Mayan cichlid, Oreochromis, and Nile Tilapia (two of those are from different contintents) and Astyanax fasciatus. The cichlids will see the smaller species as food. As well as this these larger fish have encourage birds in to feed on them. This has increased the parasite load in the lake. Many fish parasites are passed on via bird droppings and then snails. The pupfish are being hit much harder by the parasites than the other species in the lake. The others coming from a freshwater ancestor may have more innate immunity.
Is this the only colony of Boxer pupfish.
No, Whipsnade Zoo have the original colony, 50 eggs were transported to Bristol to start a second colony there. On the 11th of February 29 had hatched.
What about inbreeding
So fish don’t suffer from inbreeding to the same extent as other groups purely down to the sheer numbers that are hatched each generation. The variation in those individuals, even from a single clutch of eggs means that inbreeding is much less of an issue. That’s not to say it might not be an issue further down the line, but hopefully by then DNA technology will mean we can screen the eggs for issues.
Could they be reintroduced.
Yes, but only once the lake has been cleaned up in terms of invasive species and the parasites. Chester Zoo has had some success with the Tequilla Splitfin reintroduction, also in Mexico. Here’s hoping that we see future generation back in the ancestoral home.
