Because many fish needed to be revived, a successful commercial selective fishery in this setting is expected to require a high ratio of marked hatchery to wild fish.
For the record, the mark rate for Chehalis fall chinook is exceedingly LOW
We did observe that many coho and Chinook captured in tangle nets and gill nets in this environment were lethargic and needed to be revived. This differs from similar studies in the Columbia River, where most spring Chinook and steelhead were in vigorous condition at capture.
Fish are going to be much more stressed by this gear type in warmer estuary water
Based on the condition at capture and method of capture results, a net that is appropriate for a tangle net coho fishery will also act as a tangle net for fall Chinook bycatch. Similarly, a net that acts as a gill net for a coho fishery will also act as a gill net for fall Chinook bycatch.
As mentioned earlier, we did not detect a difference between the tangle net and gill net for Chinook post release survival.
These results contrast sharply with a similar evaluation of the post-release survival of spring Chinook salmon on the Columbia River (Vander Haegen et al. 2004). In that study, spring Chinook captured and released from tangle nets did not differ in immediate survival from gill net captured fish but did survive at significantly higher rates following their release than Chinook released from gill nets.
Different species are known to have different responses to the same stressors (Schreck et al. 2001), and so may not respond to the nets in the same ways. A given species may also display a different response in a more stressful environment than a less stressful environment. Another possibility is that environmental stressors may override and mask survival benefits provided by the tangle net. In our study, the estuarine environment was likely unfavorable to capture and release because the water was relatively warm during the coho migration. Fishing in better conditions (e.g. cooler water, fewer predators) would most likely increase survival, although we do not know the magnitude of the difference. On the Columbia River, spring Chinook salmon were captured after they had migrated about 140 miles upstream, and were presumably habituated to the river environment.
To date, WDFW personnel have conducted several studies to evaluate the usefulness of different gear types in reducing the release mortality of non-targeted stocks in commercial selective fisheries. A three-year study in the Columbia River found statistically significant differences in long-term survival among fish released from a tangle net versus those caught and released from gill nets. This study found no statistically significant differences in long term survival among fish caught and released from tangle versus gill nets.
I think that last paragraph says it all
"Let every angler who loves to fish think what it would mean to him to find the fish were gone." (Zane Grey)
"If you don't kill them, they will spawn." (Carcassman)