Delisting the Endangered Humpback Chub?

The Humpback Chub, one of the original species included for protection under the Endangered Species Act in 1967, has been identified for potential delisting to a "Threatened" status by the US Fish and Wildlife Service. According to a press release from the agency last week, a Species Status Assessment (SSA) has been completed that indicates the fish is no longer in imminent danger of extinction.

Native to the Lower Colorado River, the Humpback Chub is a warmwater species adapted to the periodic high water volumes in the Grand Canyon. With a characteristic, raised shoulder profile that is thought to help the fish remain close to the stream bottom when strong spring flood flows are raging overhead, the Humpback evolved in the millennia before hydroelectric dams were built on the river. A contentious issue between southwest environmentalists and water stake holders, management of the species has been at the center of controversy since federal mandates required "High Flow Experiments" (HFE's), where large amounts of water were released downstream from Lake Powell to mimic the spring floodwaters of naturally flowing rivers. Critics -- and there are many spread across various sectors -- have said the management practice is wasteful of the most precious commodity in the desert southwest and does nothing to permanently benefit down river stream bottom conditions favorable to the Humpback.

What's the concern for anglers if the Humpback is not a sport fish? The immediate tailwater section of the Colorado below the Glen Canyon Dam at Lee's Ferry is a world renowned venue for fly fishermen, with rainbow trout thriving in the cold, clear water that the outflow of the lake above provides. Like many large reservoirs in the west, Lake Powell acts as a thermal sink for impounded river water, maintaining cold temperatures in its depths and allowing settling of suspended sediments. Water that is released down river is perfectly suited for Rainbow Trout, (a species native to the cool pacific northwest), at least for the first few miles before the southwestern sun heats up the main river again. Recognizing this, trout were initially introduced downstream by the USFW after construction of the dam to benefit to the sporting public. This stocking effort included other unique environments such as Bright Angel Creek, a side stream 80 miles down river that naturally expresses cool water conditions as a consequence of the stream running below ground for much of its length before entering the main stem of the Colorado. Humpback Chub and trout populations do not typically physically interact due to the fundamentally different environmental requirements of each species. Politically, however, the two are closely intertwined.

figure itemprop="image" itemscope itemtype="https://schema.org/ImageObject" class="story-image no-margin-top"> Lee's Ferry. Photo by Wikipedia

From a sport fishing perspective, the conflict arises when High Flow Experiments in spring are at odds with the desires of fishermen at Lee's Ferry. Huge amounts of water coming down river during HFE's make wading impossible -- if not downright dangerous -- and trout are displaced into shallow margins where their feeding habits are disrupted. This makes for a significant interruption in the fishing season. In a region with few recreational resources, the fishery at Lee's Ferry represents a significant driver of the local economy for decades.

I spoke with Terry Gunn, owner of Lee's Ferry Anglers at Marble Canyon, about the recent USFWS announcement, and it potential implications. For an outfitter invested in a precariously positioned scenario, his objectivity surprised me.

"Well, first off," said Gunn "I think this is a wonderful thing for both the Humpback and the trout. The sporting community has supported the efforts of the USFWS over the years to restore the Humpback Chub, and has accommodated it's management practices."

Gunn has been operating at Lee's Ferry for almost 30 years, and has seen some changes to the environment, both natural and man-made, that have influence on the issue.

"With the lowering of water levels in Lake Mead in the last few years, it seems like the sand bars far down river that are favorable for Humpback spawning have reestablished themselves. This may be a function of increased sedimentation in the dam outflow, and probably needs to be looked at. Whatever is going on currently, I think everyone is in agreement that policy needs to be science-based."

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When asked what specifically he would like to see if the new potential status for the Humpback drives regulatory change, Gunn replied, "No more physical removal of trout in areas where the two species are existing adjacent to each other. The electroshocking of Bright Angel Creek being a prime example."

While the unusually cool natural water conditions in Bright Angel are unsuitable for Humpback reproduction, the robust -- if nonnative -- population of trout in the creek provides a unique fishing experience for anglers either floating down river or who are willing to make the grueling hike to the bottom of the Grand Canyon just to take a shot at them.

Gunn specifically dismissed the idea that any new regulations would include reducing overall annual flows, as long-standing legal compacts with other states guarantee the delivery of minimum amounts of water for public and industrial use. But the new population status of the Humpback Chub could very well result in adjusted timing and flows that could be of benefit to sportsmen.

Whatever dynamics have driven the positive changes for the Humpback Chub, it's status as one of the initial species with designated protections under the Endangered Species Act make it a topic of intense interest for environmental management, with numerous potential outcomes -- both intended and not -- for federal policy makers.