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Monterey Bay Salmon and Trout Project Deserves a Pat on the Back
By Dougald Scott
Monterey Bay Salmon and Trout Project Deserves a Pat on the Back
By Dougald Scott
Last month, two biologists from the National Marine Fisheries Service (NMFS) Southwest Fisheries Science Center (Santa Cruz Laboratory) presented results from their studies on steelhead and coho salmon in the central coast to a special Board meeting of the Monterey Bay Salmon and Trout Project (MBS&TP). The data showed that under careful scrutiny, hatchery reared fish can be included as one of the strategies for recovery of local steelhead and coho salmon populations. These results validated years of determination and hard work by MBS&TP volunteers, and Dave Streig, its hatchery manager (and life-time member of the Santa Cruz Fly Fishermen).
The Monterey Bay Salmon and Trout Project is a nonprofit environmental organization founded in 1977. Their mission is "dedicated to the restoration, conservation, and enhancement of native wild silver (coho) salmon and steelhead populations and their coastal and marine habitats from San Mateo to the south Monterey Bay area." Their strategy is to supplement local populations with hatchery reared fish stocked into local streams. Over 1.9 million juvenile silver salmon and steelhead have been released in area streams by MBS&TP.
As wild salmon and steelhead stocks declined throughout their ranges in the 1980s and 90s, alarm bells began going off in state and federal agencies responsible for their management. In 1996 coho salmon in the central coast were listed as "Threatened" under the Endangered Species Act. A year later steelhead were also listed as "Threatened." A number of causes for the decline were proposed: logging; agriculture; urbanization; dams; pollution; and hatcheries. It was argued that hatchery propagation was diluting the gene pools of wild populations of salmon and steelhead, and thus contributing to their demise. In addition, some studies indicated that competition and predation from hatchery fish was causing a decline in wild fish populations. Most of the criticism was based on practices at large hatchery operations turning out tens of millions of juvenile salmon and steelhead each year.
The MBS&TP hatchery operation on Big Creek (tributary to Scott Creek) subscribed to very different procedures than the large hatcheries. At Big Creek, all fish produced in the hatchery were fin clipped before release. As a result, returning fish of hatchery origin could be identified, and not used for hatchery spawning; only wild fish were spawned in the hatchery. In addition, wild fish used for spawning fish were not selected on the basis of size, or other characteristics desirable to fishermen. Every effort was made to mimic "wild" spawning in the hatchery process. The numbers of juvenile salmon and steelhead released were also much smaller than at the large river hatcheries. In spite of the differences in hatchery operations, the two main questions still dogged the Big Creek operation: 1) are hatchery fish affecting the gene pools of wild fish; and 2) are hatchery fish harming wild fish populations through competition predation.
To answer these questions, MBS&TP has been working with NMFS biologists on two studies. The first is a large-scale evaluation of genetic population structure for steelhead and coho salmon populations in the Northern California/Central California Coast, and is led by Dr. Carlos Garza. The second is a reproductive study and takes advantage of the fact that Scott Creek "provides an excellent natural laboratory to study life history characteristics and interactions between naturally-spawned and hatchery-produced salmonids." This study is lead by Dr. Sean Hayes. Both scientists spoke at the Board meeting.
Dr. Garza made the first presentation. Using molecular genetics techniques akin to DNA fingerprinting, his group can identify genetic population profiles that do not correspond to a naturally reproducing population; in other words, populations thrown out of balance by some factor, such as a hatchery. Dr. Garza reported that his data showed no large scale genetic displacement due to introductions of hatchery fish. The data revealed "a clear grouping according to basins and geography." So it appears that there are no adverse genetic effects caused by the MBS&TP hatchery operation; that the wild population is safely being supplemented with hatchery reared fish.
In his presentation, Dr. Hayes observed that compared to wild fish, juvenile hatchery fish move down stream very rapidly (within a week), and spend little time in the lagoon. This seems to minimize the time for interaction between wild and hatchery fish. In fact, Dr. Hayes could find no apparent competition or predation on wild fish by hatchery salmon and steelhead as they migrated from the hatchery to the ocean. An interesting outcome from this study was the finding that many of the wild steelhead juveniles stay in the lagoon for extended periods, sometimes doubling in size over the summer. Food is more abundant in the lagoon and the increase in size makes the wild fish much more fit when they enter the ocean. Dr. Hayes noted that this makes the estuary "incredibly important to survivorship," and has management implications where some coastal lagoons (such as Aptos Creek) are purposely breached during the summer months.
Dr. Hayes also studied interactions between hatchery and wild adult fish. He found that the timing of the runs were no different, and that there was no significant difference in age and size in returning adults. Wild and hatchery fish spawn together. The only difference observed between hatchery and wild spawning behavior was that hatchery males would not compete with other males to the same extent as wild males would. In summary, Dr. Hayes' studies have shown that fish from the MBS&TP hatchery are not harming wild populations through competition or predation. He is quick to point out that these findings only relate to Scott Creek, and may not apply to larger river systems or hatcheries.
The MBS&TP deserves a huge pat on the back for persevering through years of criticism and endless permit applications, and for skillfully navigating through federal and state bureaucracies. Look at how the MBS&TP operation is described on a NMFS website: "A hatchery, the Kingfisher Flat Fish Facility operated by the Monterey Bay Salmon and Trout Project in cooperation with California Department of Fish and Game , on a Scott Creek tributary produces both steelhead and coho for supplementation to natural spawning that has significantly enhanced the persistence of both species in the watershed" (emphasis added by author).