The U.S. Fish and Wildlife Service on Wednesday added two tiny fish found in the Verde River and Fossil Creek to the endangered species list and designated as critical habitat 796 miles of streams in Arizona and New Mexico.
The spikedace and loach minnow once gobbled up mayflies in stream riffles all over Arizona, but have dwindled to 5 percent or 10 percent of their former range.
Environmental groups have been pushing for years to force the federal government to declare the two native minnows endangered and designate extensive critical habitat, which would restrict future federal actions that might harm the fish.
The announcement on Wednesday represented a victory in that effort, with the Fish and Wildlife Service proposing a nearly 50 percent increase in critical habitat from its last, disputed proposal.
The listing will provide a new tool to protect riparian areas in Arizona, one of the most endangered but vital habitats in North America. Studies suggest that perhaps 90 percent of Arizona wildlife depend on these riparian areas for some critical phase of their life cycle, but that 95 percent of the state’s riparian areas have been destroyed or degraded.
“Continuing to conserve stream habitat, including reducing competitive and predatory non-native fish in certain waters, is essential to reversing the decline of these Arizona natives,” said USFWS Arizona Field Supervisor Steve Spangle.
“Critical habitat designation doesn’t establish preserves or change land ownership, but it does muster greater federal assistance and identifies locations essential to conservation.”
The ruling will have the greatest impact on federally owned land, which encompassed the 61 percent of critical habitat.
It won’t affect private land, unless the landowner needs a federal permit — like a grazing allotment.
The White Mountain, San Carlos and Yavapai Apache tribes already have plans in place to protect the minnows and help them recover.
Both native minnows live in fast, shallow streams without too much silt, since they hunt their insect prey among the rocks, gravel and pebbles in the riffles of a year-round stream.
The two, three-inch-long minnows live in the same stretches of stream and mostly eat the same stuff. However, the loach minnow has eyes permanently pointed upward and tends to hunker down behind rocks that create a little swirl of still water in the midst of a riffle.
Ordinarily a drab olive color, the males take on a brilliant flush of red and orange during the mating season.
The spikedace has spikes on its back, which perhaps make it hard to swallow, but which might also help it wedge into crevices during floods.
Both fish once lived in streams all over Arizona, but now hang on mostly in the upper reaches of the Gila River and its tributaries.
Existing populations remain on the Verde, Salt, San Pedro, San Francisco and Blue rivers, plus Bonita and Eagle creeks. Biologists also returned them to Fossil Creek five years ago, when the removal of non-native fish and the return of the creek to its historic bed made that Rim Country creek one of the best native fish refuges in the state.
Both fish live mostly on mayflies and their larvae, although they eat a host of other aquatic insects as well. Both spend most of their time in relatively swift, clear water in rocks and pebbles, but both also need streams with backwaters and slow moving stretches for their baby fish.
They’ve been hard hit by the widespread introduction of non-native fish, from Red Shiners who compete for space to predatory fish that gobble them up, including bass and catfish.
Biologists say the warm, flood-prone, relatively isolated streams and rivers of Arizona harbored a relatively short list of native fish, which probably didn’t therefore adapt to intense predation. The catfish, bass and trout that have been widely introduced generally come from more diverse streams and rivers with much more ruthless and efficient predators.
Almost all of Arizona’s native fish are now endangered as a result of competition with non-native fish and the dramatic change in almost every riparian environment in the state.
For instance, the two native minnows have evolved still mysterious adaptations to the great floods that once occurred regularly on most Arizona streams and rivers. Biologists still don’t know how the tiny fish manage to find shelter and avoid being swept away by these floods.
However, repeated studies have shown that the floods benefit the spikedace and loach minnow in several ways.
For starters, the floods typically sweep away silt and mud on the key riffles on which the minnows depend.
Moreover, the floods do typically sweep away the non-native fish. Fish biologists have frequently noted that streams with lots of non-native fish and holdout populations of native fish will end up with mostly native fish after a flood.
The latest action by the Fish and Wildlife Service represents an increase in miles of stream designated as critical habitat from 522 miles to 796 miles.
The designation will require any federal agency undertaking some project that might affect the minnows to consult with the Fish and Wildlife Service about how to minimize those impacts.
The designation should also provide a source of federal money to protect the fish and perhaps expand its range.
Private landowners don’t have to consult with the federal government when their actions affect the fish on their own land, but the federal government will likely consider such impacts when issuing any necessary permits to private landowners.
The USFWS has developed an array of tools to forge agreements with private landowners to protect endangered species. For instance, the law allows private landowners to sign on for management agreements, which protect endangered species but don’t prevent things like cattle ranching.
Such agreements in Rim Country, for instance, have led to the reintroduction of Chiricahua Leopard Frogs in the stock ponds and streams on some local ranches.