From pg. 9 of the below report:

"As discussed previously, much of the delayed-release program production was accomplished in saltwater net pens due to lack of available cool-water summer rearing space at hatcheries. During on-going evaluations of hatchery programs, the WDFW determined that survival of delayed-release yearling Chinook salmon had significantly declined (order of magnitude) along with the contribution to the recreational fisheries (Figure 4). Additionally, there were concerns about straying of adult Chinook salmon from the net pen programs and the domestication effect of a non-native life history (yearling vs. zero age at smolt migration) to ESA-listed natural populations. Ultimately, in the early 2000’s, WDFW made a shift to support the release of Chinook salmon subyearlings directly from hatcheries using PSRFE funding, and the use of saltwater net pens for yearling releases was discontinued."

Because of relatively low rates of contribution to catch (a combination of lower survival rates and reduced fisheries because of ESA limitations) the cost of producing one Chinook in the catch was/is significantly higher than producing one coho in the catch (roughly 7 - 20 times more expensive to contribute one Chinook to catch). Pg. 10 of the linked report shows the smolt to adult survival of net pen Chinook over time. Pg. 17 of that report shows some cost analysis for various Chinook and coho programs. But, there were others that were not evaluated in this report that ended because just a couple of handfuls of fish were caught from programs releasing 20 tons of fish. Chinook are also more difficult to rear in salt water than coho and disease problems at some facilities caused those programs to be terminated.

...In addition to the other issues pointed out above.


HSRG Final Report to PS Sport Fish Enhancement Oversight Comm, 2018