Seeing some Worms in Kenai Salmon

Observation by Mike Brubaker

We were on the Kenai River dip netting on the 27th of July. This is the drift boat fishery. It has been several years since either of us have participated in this fishery so we were interested in the size and condition of the salmon, along with wanting to get some reds. We fished one tide and harvested 22. Mostly looking bright, and a nice size. Upon cleaning the fish we found at least two that had internal parasites - worms in the gut. Not sure if this is typical but these days, but I don't recall seeing any in years past. I vacuum-packed and froze the salmon, and plan to grill rather then eat as sushi. Had not worried about this in the past, but don't want to take chances or upset anyone who is eating a salmon and may find a worm on their plate. We did not keep any this year for caviar as we usually use pink or chum eggs.

Jayde Ferguson, Pathologist with the Alaska Department of Fish and Game, writes:

These look like a philometra nematode, like the last one. Hard to tell if they’re in the gut or just associated with the belly fat based on the photo. Usually gut doesn’t attach to the fillet if done properly. Here’s the link to more info on this parasite:

Regarding possible causes that may be associated with some salmon, but certainly not all, could include the climate change aspect. That is probably a pretty important factor. Also, some fish are actually getting bigger. Two, back-to-back records of pink salmon in the Kenai a few years back was just one example. Some reds in the Kenai this year are very large (reports of 10-12lbs+) , so there are still some of the bigger fish being caught out there.

As with most biological systems, there is likely no single factor. I do think that climate change is one of the more important factors. Heavy parasite burden can also contribute, which is also tied to climate change. West coast Chinook are doing poorly, but sockeye are at an all time high in abundance (e.g., Bristol Bay, Cook Inlet, etc.) and large fish are being harvested. Each species is affected differently by these multifactorial processes. These are almost impossible questions to answer, but the world’s best minds are working on it.

Comments by LEO editors

LEO has received a similar observation by member Erica Lujan on July 23th in Kasilof.

An article by UC Santa Cruise's Newscenter "Alaska’s salmon are getting smaller, affecting people and ecosystems explains:

"A comprehensive study of four salmon species across all regions of Alaska finds salmon are returning to rivers smaller and younger than in the past... A comprehensive study of four salmon species across all regions of Alaska finds salmon are returning to rivers smaller and younger than in the past." One such factor the study mentioned is climate change. The study continues: “We know that climate drives changes in ocean productivity, and we see a consistent signal of climate factors associated with decreasing salmon size,” Palkovacs said.

There have been recent publications explaining that the general size of returning salmon and their parasite load is increasing, possibly affecting many factors of the salmon's growth and health. This study published by Science Daily states:

"The higher levels of mortality only show up with significant increases in the parasite burden. And that increase in parasite numbers, Kent said, is a slow, gradual response to warmer waters and heavier nutrient loads that can be a result of logging, agriculture, inadequate streamside protection and other land use or management changes over many years. The study will be published soon in the journals Aquaculture, Journal of Parasitology, and International Journal of Parasitology. It was done by researchers from Oregon State University and other agencies, and concluded that heavy loads of parasites can affect salmon growth, weight, size, immune function, saltwater adaptation, swimming stamina, activity level, ability to migrate and other issues. Parasites drain energy from the fish as they grow and develop."

In the "Related Posts" tab, check out more information on Erica's story. Chyna Perez-Williams