Coho Salmon (Oncorhynchus kisutch) with Dead or Dying Eggs

Observation by Mike Smith:

This coho salmon was caught today in Quinhagak. I believe those small orange bulbs in the sac are underdeveloped eggs or a growth of some sort. It only affected the egg sacs, no other deformities in the fish.

Observation shared via LEO Facebook Page

Ted Meyers and Jayde Ferguson, pathologists at the Alaska Department of Fish and Game, write:

They look like dead or soon to be dead eggs – hence the white spots. Probably due to a sub-optimal environmental issue. Probably any sub-optimal water quality parameter would have the potential [to damage the eggs]. Temp and pollution are two important ones. Maybe flow, supersaturated water (e.g., at base of waterfall/plunge pool), and low dissolved oxygen could be a few others, along with stress and overexertion from escaping predators or fishing gear.

Mike Smith comments:

We’ve had extremely low water all summer, very little to no rainfall. Water seemed to stay cool following the weather patterns (didn’t warm like last year). The only other big difference I’ve seen with that fish I caught was that salmon had WAY more than normal sea lice. Both sides of anal fin were covered, under pelvic fins were covered, and few were attached under the pectoral fins, and there was a patch around the lateral line above the anal fin that was consistent with sea lice scars. I’ve fished all my life and know the quality of fresh fish and know sea lice is a sign of fresh ocean fish. But the amount she had on her was a crazy amount. It is possible that caused stress, I’ve never seen so much on a single fish before, easily close to 50 sea lice.

Rick Thoman, Climate Scientist with the Alaska Center for Climate Assessment and Policy, writes:

Low rain for sure: it was the driest July-August at Bethel since 2002. Early snowmelt started the rivers off low, and then the lack of rain kept them that way.

Comments from LEO Editors:

This summer, two other LEO members have commented on how low water has affected fishing. In Nome, low water has prevented people from traveling to usual fishing areas. In Elim, commercial fishing has been very poor with very few fish. In July-August, the Tubutulik River measured 2 feet deep at the deepest transect.