Most of the red salmon were carrying worms

Surface Waters / Wetlands

Fish

Invertebrates

Unusual Size / Abundance

Parasite

Kenai, Alaska, United States

Nearby

From the images shared, these appear to be Philemona, a freshwater parasite. Philomena is a food quality concern but is Not considered a human health concern. With proper preparation, the salmon is safe to eat.

Observation by Cindy Lawrence:

I have attached the pictures of my fish I got that were infested with worms! These fish are from Kenai, caught on 7/14/24. From the Kenai I had 8 fish, and 7 out of 8 were infested. Then from Kasilof a few weeks ago, there was 15 out of 16 infested!

LEO Network Comment:

Thanks Cindy for sharing your observation. Worms in Alaska fish has been a hot topic in recent days. Last week the Anchorage Daily News published an article (attached) about worms in saltwater fish. This at a time when the peak run of red salmon is occurring in Southcentral rivers and many people are busy harvesting with dip nets or rod and reel. Social media has been buzzing with discussions about worms in Kenai Peninsula reds. I posted an observation to LEO Network in 2021 after finding worms in 10 percent of the Kenai red salmon I harvested. Erica Lujan the same year found worms in over 85 percent of her fish from Kasilof. You can see these observations attached along with consults provided by Jayde Ferguson from ADF&G. Now in 2024, the percentage reported in this observation by Cindy Lawrence is more like 90 percent, both Kenai and Kasilof!

These two stories, 1) the ADN article, and 2) the post in LEO Network focus on two different types of worms, one that is a human health concern (marine worms) and one that is yucky but not a human health concern (the freshwater worms). The increase in the number of marine worms has now been associated with the increase in marine mammal populations. The reason for the perceived increase in the fresh water worms is unknown but suspected to be linked to climate change. We have shared this post with Jayde Ferguson at the ADF&G Fish Pathology Lab for his insights. The take home message is that salmon, like chicken and other other foods requires proper preparation if risks are to be minimized. If you have questions about how to do this, see guidance at the links provided. M. Brubaker

Comment by Jayde Ferguson:

The worms in the photos are Philonema sp. and are a freshwater parasite, so not related to marine mammals at all. These mature in fish and they infect fish via zooplankton that could be related to climate change. Here is more info on the freshwater Philonema worm (attached) that can occasionally be a fish health issue at high burdens where visceral adhesions can occur, but I didn’t see any in the photos: https://www.adfg.alaska.gov/static/species/disease/pdfs/fishdiseases/philonema.pdf

Another type of worm is Anisakids (coiled worms), a marine parasite. Anisakids are NOT a fish health concern, but they are a HUMAN health concern. I attached the FDA guidelines for properly preparing fish, specifically regarding anisakids that are very hardy worms.They do appear to be increasing recently based on a UW study (which includes Alaska salmon). It can be an issue for people if they don’t prepare their catch properly. These have not been associated with disease and mortality in fish though. Parasitism is an important part of nature that provides biodiversity and ecosystem services, where anisakids appear to be returning to similar levels prior to the establishment of the marine mammal protection act. See article here. Other factors have been associated or thought to be likely. For example, climate change may also be involved.