I actually took the time to read the report and while it is hard to fault some of the findings it does present only part of the issue.

Some background: Chinook salmon evolved to advantage of freshwater habitat features over that used by other salmonids. Chinook are mostly large river fish that evolved to successfully use that habitat including spawning in very large substrate. That success required a large body size which historically they did in spades! Most of our rivers have fish that were normally 30 and 40#s with nice mix of even larger fish with some rivers (Elwha, Columbia, etc.) producing fish over 100#.

Orcas are large animals that over time learned to take advantage of those large Chinook as a food source. Remember that an adult orca might require 450# of fish day. They are designed to eat larger animals; the transient orcas regularly feed on adult harbor seals and the oceanic orcas have learned to kill great white sharks. Those resident orcas who are fish eaters have shown a strong preference for large body Chinook (fewer fish to catch with less energy spent). One study that I read showed that orcas where 6 times more likely to take a 5 year old Chinook over a 4 year old more than 45 times more likely than a 3 years.

What the report found was that even with decreased fishing the over size of the Chinook declined as the northern resident orcas increased. That result is hardly surprising as the it is clear that compared to the historical size distribution today's are significantly smaller with lot fewer larger Chinook with those that might be considered larger much smaller than in the past. Clearly to feed a given population under that situation the overall exploitation rate on the so-called larger Chinook on the over Chinook populations has to increase. It takes ever increasing portion of the Chinook population to supply the needed biomass to feed them which only gets worst as the number of orcas. I find in unfair to blame the size decline on the Chinook as the whole mess has been largely driven by man's actions.

The average Chinook is declining because of ocean fisheries (largely hook and line) are selectively harvesting the faster growing and longer lived individuals in the population. Those impacts continue. Gill net fisheries (both tribal and non-treaty also exert selective pressure on the Puget Sound size and those continue today. Even though over all fishing exploitation rates have declined it remains the case that smaller fish are more likely to survive to contribute to the next generation.

Fishing is only one aspect of driving us to smaller Chinook. Habitat alterations have also dramatic the habitats that once were favorable to Chinook. Examples of those habitat changes include truncation of river lengths, decrease size of the stream bed substrate (no long need to be large females to construct their redds), stream bed instability, etc. Again these new conditions not only continue they continue to get worst leading to continued shrinking Chinook.

Hatcheries themselves also are playing an important role in the shrinking of our Chinook. Adult size and age at spawning experience different selection pressures in the wild than a hatchery (less benefit from being a large fish in the hatchery). The combination of the fishery selection on each hatchery generation assure that the fish escape fisheries are younger/smaller than their parents. To date little effort has been made at the hatcheries to establish spawning protocols that might reverse some the size selective being exert while the fish are at sea. Currently the spawning protocol is take the returning the adults randomly. The combination the spawning protocols and fishing has result in increased numbers of jacks (2 year old males) in the hatchery spawning population. Younger fish in the breeding population results in younger and smaller Chinook.

The smaller hatchery fish and river habitat problems are intersecting in many of PS rivers. In some of the rivers; especially those relying on the Green river fall stock hatchery fish contribute a significant portion of the natural spawning population. For example over a 5 year periods (2014 to 2018) on the Cedar river 30% of the natural spawners where hatchery fish, on the Nisqually 32% were hatchery fish, on the Puyallup 66% were hatchery fish, on the Green 74% were hatchery fish and on the Skokomish 96%were hatchery fish. Those high contribution rates of shrinking hatchery Chinook are passing on that tendency to the wild populations.

The big question given what is presented in the citied and all the above can the shrinking Chinook size and the corresponding impacts on the resident orcas be reverse? Or perhaps of even more importance do we as society even want to address the issue?

Curt