Endangered Species The Fish and Wildlife Service’s endangered species triage Buried in petitions to list new species, the Fish and Wildlife Service proposes a system for prioritizing who gets help first.

Right now, in the Black River south of Carlsbad, New Mexico, rare Texas hornshell mussels are trying to multiply. It’s a bizarre and complicated process: Male mussels spit sperm into the river, where the females catch it. After brooding fertilized eggs for about a month, they chuck the larvae into the water, too. There, the would-be mussels hope to be eaten by certain kinds of fish, attaching to their gills and forming parasitic cysts. Then they develop into juveniles before cutting loose from the fish and wriggling to the river bottom, where they can live for up to 20 years.

Texas hornshells are native to the Pecos and Rio Grande basins of southern New Mexico and Texas, where they help maintain water quality by filtering out sediment and other particulates. They’re the only surviving species of New Mexico’s eight native mussels, and the stretch of river near Carlsbad is one of their last strongholds.

Their troubles are nothing new, though. In 1989, the U.S. Fish and Wildlife Service classified the Texas hornshell as a candidate for the endangered species list, but it had too little information about them to support listing. In 2001, after studies showed that the mollusks were being harmed by low flows in rivers and water pollution, the agency decided protection was justified. But it still couldn’t list them because too many other, higher-priority species also needed protection. Now, the mussel’s time may have finally come: In August, the agency proposed listing it as endangered.

Joel Lusk/USFWS

Most species that have landed on the endangered species list in recent years got there when they did as a result of litigation by green groups, and the Texas hornshell mussel is no exception. Almost no one is happy with this pattern, though. “(If) the Service is simply responding to lawsuits, it’s not being very strategic,” or necessarily focusing on the plants and animals in greatest need, says Ya-Wei Li, an endangered species expert with Defenders of Wildlife. So Fish and Wildlife is now working to reform its process for listing species.

It has proposed prohibiting so-called “mega-petitions,” where environmental groups ask the agency to protect up to hundreds of species at a time, and it recently finalized a new five-tier system for prioritizing decisions on petitions. First in line are species that data clearly show are critically imperiled. Lower down are species for which states are already developing conservation plans, as well as species the agency lacks data on.

The agency simply can’t keep up with all the petitions it gets to list species, says Fish and Wildlife spokesman Brian Hires. Environmentalists filed petitions on behalf of 1,230 species between 2007 and 2010, enough to almost double the number protected by the Endangered Species Act over the previous 30 years. The overwhelmed agency rarely meets its own deadlines for responding, and so environmentalists often sue in response.

The mussel is one of 757 species included in a 2011 legal settlement with the Center for Biological Diversity, in which the agency agreed to deadlines for clearing its considerable backlog. “The states have been frustrated, because we feel like litigation shouldn’t drive conservation,” says Nick Wiley, vice president of the Association of Fish and Wildlife Agencies. Wiley says states — the feds’ main partners in endangered species work — are generally pleased with the planned reforms, which they hope will help them prioritize their own data collection and conservation work.

Some environmental groups are also supportive. “This is a very good move for the Service to take control of its own destiny,” says Li. But others argue that the reforms could consign at-risk wildlife to bureaucratic purgatory. “It creates excuses for ongoing delays in decisions on whether species should be protected,” says Tierra Curry, senior scientist with the Center for Biological Diversity. She fears that lower-priority species will slip closer to extinction while they wait for conservation plans or studies that could bump them up in line.

The system also “biases decisions towards popular and well-studied species,” she says, mainly birds and mammals. But some of the most imperiled groups are also the least studied — freshwater mollusks, for instance. The fact that we understand the outlines of the Texas hornshell’s lifecycle makes it fairly unusual among mollusks, Curry notes: For many of the creatures, basic population data doesn’t even exist.

Mussels, snails and insects may well get shortchanged under the new system, Li says. In a perfect world, Fish and Wildlife would be flush with funding, and wouldn’t need to prioritize. “Nobody likes to make those judgment calls,” he says. But relative to the number of species it’s charged with saving, the agency’s funding is decreasing, not increasing, he points out. One way or another, “there are going to be species that come out ahead, and some that fall behind.”

Contributing editor Cally Carswell writes from Santa Fe, New Mexico. Follow @callycarswell