Some of you may have seen the headline “Endangered Nevada Fish Makes Comeback” from the Las Vegas Review-Journal.
Could it be? Could the endangered Moapa Dace (Moapa coriacea) really make a come back and get off the endangered species list? If you aren’t familiar with this species, it is a thermophilic minnow endemic – meaning they don’t occur anywhere else in the world – to the Muddy River and the warm, thermal springs associated with this system in Clark County, Nevada.
Being endemic to specific reaches of a single river drainage, this species may be prone to extinction naturally. But what really is hurting this species? Historically, there were probably a few things. The river this species is endemic to, the Muddy (or Moapa) River, was dammed in 1935 by the Hoover Dam to build Lake Mead. Because this species has such narrow habitat requirements, converting a river channel to a large, flooded area with little to no water flow isn’t ideal for this species. Further, this completely goes against the thermophilic requirements of this fish. This species also has had to deal with introduced species including the shortfin molly (Poecilia mexicana), channel catfish (Ictalurus puncatus), common carp (Cyprinus carpio), fathead minnow (Pimephales promelas), black bullhead catfish (Ameirus melas) (US Fish and Wildlife Service 2014). It also faces parasites that were introduced with these species so it may still be an uphill battle for this species to get off the endangered list. And I didn’t touch much on it, but water withdrawals by humans will certainly have negative impacts on this species (Hatten et al. 2013).
So, what is the big news about? Recent surveys informed managers that the population is made up of at least 2,248 individuals, a count up by almost 33% from the count a year ago (Brean 2014). Obviously, this is positive news and the population is trending up. For them to be downgraded from “endangered” to “threatened,” there must be at least 4,500 Moapa dace counted (Brean 2014). To be “delisted”, the population must be a minimum of 6,000 individuals and at least 75% of the fish’s native habitat must be restored (Brean 2014). It’s tough to imagine this species not receiving some level of protection given it’s small native range, but if it was downgraded to “threatened”, that would certainly represent additional progress in the right direction.
Brean H. 2014. Endangered Nevada fish makes comeback. Las Vegas Review-Journal. Available at http://www.reviewjournal.com/news/nevada/endangered-nevada-fish-makes-comeback
Hatten JR, Batt TR, Scoppettone GG, Dixon CJ. 2013. An ecohydraulic model to identify and monitor Moapa Dace habitat. PLoS One, DOI: 10.1371/journal.pone.00055551.
Moapa Dace. 2014. US Fish and Wildlife Service. Available at http://www.fws.gov/nevada/protected_species/fish/species/moapa_dace.html