Role Reversal on the Colorado

The fishery is world famous, the pride of the Arizona Game and Fish Department. I knew I could count on the department for a strong opinion about federal trout control, and fisheries biologist Bill Persons didn't disappoint me. Was he outraged? Well, no. In fact, just the opposite.

"From the lower end of Lees Ferry and the rest of the river we'd like to manage for our four remaining native fish--that's humpback chub, flannelmouth sucker, bluehead sucker and speckled dace," he said. "In the first 15 miles below the dam we're trying to maintain a quality tailwater trout fishery. The condition and average size of those trout is way down. Growth is very poor. There just aren't enough groceries to go around." The fish sampled by the department's electro-fishing crews average eight inches. Foster reports that fish caught by his anglers average better than that—about 13 inches—but that the trophy fishing days at Lees Ferry are definitely over. With flow fluctuations Persons and his colleagues expect the size and condition of Lees Ferry trout to dramatically improve. Moreover, because the flow fluctuations won't be as severe or as sustained as they were previously, the trout will probably be able to sustain themselves. But Persons says this: "I think if we lost three year classes in a row, we'd want to go in with a stocking of fingerlings so we didn't have a big hole in the fishery."

What I find astonishing is that precisely the same reservations articulated by Gunn and Foster are being articulated by biologists who advocate trout control. Sometimes the biologists even use the same words. "A shot in the dark," for example, is also how University of British Columbia fisheries professor Dr. Carl Walters describes trout removal in the vicinity of the Little Colorado. For the past six years Walters has worked as a consultant to the Grand Canyon Monitoring and Research Center; and, being from Canada, he doesn't carry any of the bureaucratic baggage that might cloud his objectivity. Sometimes, he explains, you have to take shots in the dark because once a native ecosystem has been nuked by a dam, there aren't lots of options. "We don't know why the chub population is declining," he says. "We think it has something to do with too many predators at the mouth of the Little Colorado. But we're not absolutely sure. And we're not sure that if those trout are taken out, the chubs can survive."

What's more, both Persons and Walters share Foster's opinion that "what's good for the trout is good for the chubs." Here's how Walters describes the mutually beneficial influence of fluctuating flows: "At Lees Ferry we went from a trophy fishery to your standard jillions of 12-inch rainbows. I've worked on rainbow trout for 50 years, and I've never seen densities this high. For 12 miles they're lined up like cordwood. The first time I walked down there I thought I was back in one of those California fish hatcheries I grew up in. That's exactly how it smelled. [He's not sure what he was smelling - maybe the fish themselves, maybe their excrement, maybe both.] Even if there weren't a native-fish issue, I think we'd recommend fluctuating flows to kill some of the eggs and try to get better sizes of fish. The river can grow lots of little trout or a few big ones. Gunn and Foster understand this. But some of the other guys keep thinking more fish, more eggs, more fish. . . . That's just wrong; it's a rat race that has been played out in tailwaters all over the United States, and it always backfires."

But what about the browns at Bright Angel Creek? It's clear that they're eating lots of chubs; and, once they get out into the Colorado, they have no problem growing.

Fisheries consultant and former Fish and Wildlife Service biologist Dr. Richard Valdez, who has conducted extensive studies on humpbacks and other native Colorado River fish, reports seeing 10- and 12-pound browns in and around Bright Angel. "They swim from there up to the Little Colorado; that's a big [27-mile] migration, but browns will do that," he told me. "I suspect that there are some guys who know that this is one of the best-kept secrets for big browns and that they're not pleased about this effort [to eliminate them]."

But managers don't have a choice - morally or legally. First, the Endangered Species Act mandates the action. Second, while the river from Lees Ferry to the dam is managed by the Park Service as part of the Glen Canyon National Recreational Area, the next 277 miles are managed as part of Grand Canyon National Park. Above Lees Ferry the agency's mission is recreation (although this mission is trumped by the Endangered Species Act whenever it conflicts with the welfare of a listed species). Below Lees Ferry the mission is to protect and restore all the natural parts and, within reason, allow "natural processes to proceed unimpeded."

One reason trout are so prolific in the Colorado is that the squawfish---the only large predator fish that evolved in the stretch managed by the Park Service—has - been eliminated. This minnow, which can attain weights of 80 pounds or more, is a salmonid-eating machine in other systems, frequently to the dismay of managers. There has been talk about re-introducing squawfish; but they wouldn't spawn in the cold tailwater, and the idea of put-grow-and-eat-trout management turns off biologists. "There's concern about fiddling too much," says Randall Peterson, BuRec's rep on the Adaptive Management Work Group (a diverse collection of stakeholders including government agencies, Indian tribes, power companies, sportsmen and environmentalists that advises the US Interior Dept. on how to operate the dam). "When we saw the unexpected outcome of the exploding trout population it taught us all to go slow and careful."

More serious thought has been given to reintroducing river otters, a project that by no means fits the definition of "fiddling." Otters may have been extirpated when the first dam releases drowned kits in their dens and when the Glen Canyon Dam and the Hoover Dam downstream blocked gene flow. "Without its top aquatic predator the Colorado River ecosystem is just as out-of-whack as Yellowstone used to be without wolves," comments park biologist Elaine Leslie. "We should be looking at native species restoration wherever possible, and the restoration of ecosystems. The problem at Grand Canyon is that there doesn't appear to be a viable population of Sonoran river otters [the subspecies that belongs in the park] anywhere in the Southwest. So, if we were to reintroduce otters, we'd want to get the closest possible relative to the Sonoran otter. The issue of most concern with otter reintroduction is the potential impact on the highly endangered humpback chub, which is slower moving than brown or rainbow trout." But otters target whatever fish is most abundant—i.e. they could be relocated because they'd be wearing radio collars), the impact would be insignificant.

Carl Walters says this: "I don't think otters would hurt the chubs; they'd be well adapted to this kind of predation. The biggest threat to the chubs, beside the trout and the warmwater fish, is each other. They're pretty fierce cannibals. I wouldn't worry about adding otters."