Observation by Virginia Commack:
Have you heard about dead salmon on the beaches on the Kobuk River? Our environmental coordinator is making a trip upriver to record the locations of the heaviest dead fish areas and to do water sampling at the same time. So far, the report is that it's the oxygen level. We are, however, also doing our own water sampling starting today. We had water sampling done down the Kobuk River very recently with our students from Kobuk, Shungnak, and Ambler, and this dead fish appeared after that trip. Thankfully, she is out testing the water. The biologists assume it is lack of oxygen with too much fish, but I know as a person who fishes that we still have a lot of water on the river, higher than other seasons. It may be the abundance of fish. We have been concerned about some brown, foamy stuff in the bottom of the river, which is not usually there. Some people saw something in the water and were afraid to even walk in. The water is also really turbid and you cannot see the bottom in some areas. This may be coming in from erosion.
Susan Georgette, Manager at the Selawik National Wildlife Refuge, who has been involved in site surveys over the past few days, writes: (8-25-2014)
Last Friday, the Alaska Department of Fish and Game's Fish Pathology Lab called to say they had examined the salmon carcass we had shipped them earlier in the week. Fortunately, the sample arrived in decent shape and they were able to run standard tests for bacteria and viruses. Results of these tests, however, take from 1 week to 1+ months. The Pathology Lab also did a necropsy (dissection) of the fish. They said it appeared to be a healthy salmon, close to spawning.
The one interesting thing they found was algae (diatoms) on the gills and skin. They said there would have to be a lot of algae in the water to stick to fish. The Pathology Lab said that algae on the fish's gills and skin supports the idea that "low dissolved oxygen" in the water caused the salmon die-off. Algal blooms consume lots of oxygen in the water, and combining that with a huge return of salmon could have led to enough oxygen depletion to kill salmon. The Pathology Lab said they found several different types of algae on the fish sample, so it was probably not one type of algae bloom in the river.
Sunny, warm weather increases the growth of algae and other plant life in the water, and it's likely that the stretch of hot, clear weather we had in mid-August contributed to this. Last Thursday, one of my co-workers, Brittany Sweeney, and I took a boat ride from Kiana to Coal Mine (about 25 miles upriver from Kiana) to collect water samples and check on the salmon kill. We are now looking into labs that might be able to test these samples for algae. Ambler and perhaps other upper Kobuk villages also did water sampling in their area. During the boat ride above Kiana, we stopped at one sandbar where we counted 284 salmon carcasses in a little less than 1/2 mile.
We'd like to thank the Kiana Tribal Council and Dan Douglas for the boat ride and the assistance with collecting water samples. We'd also like to thank Jayde Ferguson at the ADF&G Pathology Lab for his responsiveness and for sharing his extensive knowledge. The number of salmon returning to the Kobuk River this year is indeed impressive.
