Friends of the Eel River submitted both federal ESA and CESA petitions to list Northern California Summer Steelhead as an Endangered Distinct Population Segment. Read our press release here.
Both petitions are largely based on a combination of the extensive 2017 report by Moyle et al on the status of California salmonids, State of the Salmonids: Status of California’s Emblematic Fishes 2017, and two papers that have come out of Mike Miller’s UC Davis lab over the last couple of years.
Northern California summer steelhead are truly extraordinary fish. They include the largest adult steelhead in coastal rivers, the southernmost surviving summer steelhead, and fish (in the interior rivers like the Eel) capable of withstanding higher stream velocities and jumping higher than any other salmonid. As Moyle et al make clear, once you accept that summer steelhead are biologically and reproductively distinct from winter steelhead, the status of summer steelhead on the far North Coast is quite dire. There are probably fewer than 1000 adults spawning in all of the rivers they still inhabit, from Redwood Creek in the north to the Mattole in the south.
However, our primary strategic goal at FOER in seeking recognition and protection for summer steelhead was to advance the cause of cause of removing Scott Dam. The dam blocks 98% of potential habitat for the Upper mainstem Eel River population of summer steelhead that was apparently wiped out by dam construction. If a population of summer steelhead could be restored to the upper main Eel, it would be the longest summer steelhead run in the state. It would also hugely improve the conservation status of the overall summer steelhead population on the North Coast. Because we call O. mykiss steelhead when they run to the ocean, but rainbow trout when they stay in freshwater, there remains some possibility that surviving native rainbow trout above the Lake Pillsbury reservoir could still retain the key premature migration gene.
The evolutionary basis of premature migration in Pacific salmon highlights the utility of genomics for informing conservation (Prince 2017)
This paper lays out the evidence that premature migration in both spring Chinook and summer steelhead is the result of a specific genetic mutation that occurred roughly 25,000 years ago in both species. As a consequence, Miller and company argue, the present conservation strategy of lumping winter and summer run steelhead together for listing purposes is failing to protect the truly significant genetic and life history diversity that summer steelhead represent.
Anthropogenic habitat alteration leads to rapid loss of adaptive variation and restoration potential in wild salmon populations (Thompson 2018)
This paper shows how the premature migration gene is rapidly lost from a salmonid population (in this case, Rouge River spring Chinook) when we alter their habitat to favor genetically dominant late-running fish.