Net Pen Rearing and Release of Hatchery Stocks on the Oregon Coast
Tod Jones, August 29, 2013
Subject: Net Pen Rearing and Release of Hatchery Stocks on the Oregon Coast
As I have indicated to you on several previous occasions, Jim, the science of net pen rearing for the purpose of acclimation and imprinting anadramous species is a settled science. It has been practiced for many decades from as far south as the Sacramento River in California to Kodiak, Alaska. I personally have used this strategy not only in South East Alaska but here at the mouth of the Columbia River when I managed the Clatsop County Fisheries Project. (Formerly known as CEDC)
In Alaska and British Columbia all five species of salmon have been acclimated very successfully. We developed remote release sites to isolate the harvest of hatchery stocks to avoid harvest of wild stocks. This enabled the sport and commercial fishers the opportunity to maximize harvest to satisfy the market and provide a quality recreational experience unimpeded or constrained by protected wild salmon and steelhead. Here in Oregon and Washington, the net pen strategy has been appreciated but underutilized and with the legislature and governor shutting down the gillnet harvest on the main stem of the Columbia River this strategy will likely be greatly expanded.
Your selection of Spring Chinook on the central Oregon coast has two attractive advantages in that it provides a significant expansion of the recreational opportunity that did not exist in the past and known wild stocks are isolated from your proposed release sites. Known wild stocks are very limited and far enough away from you selected release sites to rarely if ever see a stray from your project. Uncaught fish will seek a spawning opportunity, but unlikely to leave the terminal area and swim a hundred miles to find another fresh water source. The only significant staying of Youngs Bay salmon has been in fall Chinook released as pre-smolts, which remain for a few weeks in the estuary of the Columbia River and as such have been seen in the Grays River on the Washington side of the river. The numbers, however, have rarely been more than four or five fish on any given year, this with a release of over 1.5 million a year.
There is no known established ratio of hatchery vs. wild fish that can be applied to your project or any project of this kind. Each is based on a variety of factors that come into play and, frankly, even given the best of baseline data, must be evaluated and adjusted as the project develops. Your approach to start with a relatively small number of molts, is an adaptive management approach that tells me you are following sound biology. Having looked at the proposed sites and the probable stocks of origin, I doubt very much that any issues with Spring Chinook straying will be an issue. It will be more likely that you will have a lot of pressure to increase the size of the project as the public appetite for the opportunity to catch the returning fish will escalate and being five year old fish, it will take a full decade to see those benefits.
That said, here at the mouth of the Columbia over five million smolts and pre-smolts are released each year with a mix of fall Chinook, Spring Chinook and Coho. I anticipate an expansion of that effort to include late-run Coho and late run fall Chinook and very likely increases in the existing Spring Chinook releases both in Oregon and Washington. The project is heavily monitored both at the net pen sites to prevent environmental degradation during feeding time and in the harvest of adults to ensure non-target species are free to transit the harvest sites without experiencing unacceptable harvest impacts. Over 50% of fish harvested are checked at Oregon and Washington processing facilities, which is a very high percentage and provides excellent in-season management data for adjustment of harvest times in the terminal areas. I see no reason your project cannot be managed in a similar manner using creel census strategies to gather the same information.
Please let me know if I can provide any additional information.
Tod Jones, Former Manager
Clatsop Count Fisheries Project