Another interesting thread to read through I am not sure what it is about. I thought it might be related to wild steelhead survival but I think it may be more about who gets the last one. Three of the 4 H’s, habitat, harvest, and hatcheries, are a big part of the discussion. Science, management, and law are a part of the discussion. I think its is important to realize that management operates in a framework of laws, laws enacted by politicians, hopefully representing the public and not some special interest. Science is the attempt to understand the physical and natural world. The public, lawmakers, and management can embrace science that supports their beliefs, can ignore science that conflicts with what they want, even suppress what might be deemed dangerous, and on occasion change to accept a scientific reality.
Salmo g. posted a good example of the above from the current issue of the Osprey. The thesis is “The basic step to recovery is GET RID OF HATCHERY STEELHEAD. PERIOD.” The arguments to support the thesis are a hodgepodge of bits of science, of opinion, and wistful conjecture. I am not convinced that the argument supports the thesis. A better article that appeared in the same issue of the Osprey is by Elizabeth Daly, “Wild Steelhead Survive Better than Hatchery Fish in Marine Environment”. I am not going to post the article but a summary of what it contains can be found in the link below. Look at the first abstract in Session Five - Climate Change And Ocean Ecology of Steelhead. For those who believe there is little science related to steelhead explore this link and learn.
Steelhead Science If it were possible to eliminate hatcheries, eliminate harvest (would follow if hatcheries were gone), restore freshwater habitat to what is was 100 years ago, and even get rid of dams I doubt that there woulds be a dramatic increase in wild steelhead populations. Habitat is the problem, for anadromous species habitat includes the marine environment. For salmon, steelhead and chinook in particular, the marine component of their life history is a critical stage. Salmon deposit a lot of eggs in the gravel, 1000’s per female, to insure that enough adults return to maintain the population. Only a small number of those eggs make it to the marine environment as smolts. The majority of their growth and maturation take place in the marine environment. Steelhead are unique among Pacific salmon in that they don’t stay in the coastal zone for an extended period of time. That is a significant point in the Daly article mentioned above. In the many years of sampling steelhead smolts leaving the Columbia River were at the western boundary of the sample zone in 10 days or less. Steelhead are resident in the marine environment, from one up to four years, in the Gulf of Alaska and the Eastern Pacific and during that time there is always some ongoing mortality. Ocean sampling has demonstrated that steelhead are only found in a narrow range of sea surface temperatures (SST). There is a southern high temperature limit and a northern low temperature limit. This narrow band of SST’s suitable for steelhead extends across the North Pacific. With climate change this band will shift North. SST measurements show this is happening and models predict how it will change. A quick look at a globe or a map shows that as the southern thermal boundary moves North the suitable ocean habitat for steelhead shrinks. One model predicts that by the end of the century ocean steelhead habitat will shrink by 36%. Look at the second presentation in Session Five in the link above.
Habitat loss due to thermal consideration is only part of the problem. Climate change, ocean acidification, and pollution all play a role. Not just steelhead are impacted, the entire marine ecosystem is changing. Temperature and ocean acidification is changing the food chain, pollutants are getting into the food chain at every level, and warm water predator species are moving North. With reduced habitat area, alterations in the food web, increased predators, and competition with other highly abundant salmon species the outlook for Northwest steelhead is bleak. It is the science we don’t want to know but it is in front of us.