See part 1 here.
As we work to protect the last remaining Spring Chinook, molecular biologists have now confirmed what area tribes have known all along – Spring Chinook are genetically distinct from their fall-run cousins. UC Davis researchers have discovered a small difference in the DNA of Spring and Fall Chinook that correlates with run-timing.
Incredibly, researchers were also able to extract ancient DNA from salmon bones found in historic fishing sites in the Upper Basin known to be important to Klamath Tribes. These samples ranged in age from 5,000 years-old to post European contact and were found to feature the spring-run genetic markers, further proving that Spring Chinook made it beyond Upper Klamath Lake to spawn.
This important discovery emphasizes an inconvenient truth: time is short and very few wild Spring Chinook remain.
Dams block Spring Chinook migration into the upper watershed, but dams are not the only problem; in the Middle Klamath, early settler efforts to help Fall Chinook undermined Spring Chinook survival.
Settlers wanted to help salmon make it further upstream to spawn in places like the Salmon River. They witnessed Fall Chinook stacking up behind waterfalls and rapids, unable to go further upstream. A short-sighted plan followed as settlers dynamited these natural barriers, allowing Fall Chinook to reach the once exclusively Springer habitat. What this means for today is that large numbers of Fall Chinook are now spawning with and on top of small numbers of Spring Chinook, effectively diluting the spring-run genetic material. The consequences are severe—if a copy of a fall-run gene is combined with a copy of the spring-run gene, fish are genetically programmed to meet in the middle and return mid-summer when the Klamath is least hospitable to salmon. Thus, these ‘heterozygotes’ never make it to spawn.
With Klamath dam removal set to occur as soon as 2023, tribal and Oregon State biologists are already working on a plan to reintroduce these fish to their historical range. We hope one day to have large numbers of returning Spring Chinook so that, once again, everyone can enjoy a taste of the Klamath’s determined delicacy!