Why are salmon shrinking? UAF professor tackles the topic at Rainforest Festival

When you hear the word rainforest, people often associate it with something tropical. Residents of Southeast Alaska might think differently though, since they’re surrounded by the 17-million-acre Tongass National Forest, a temperate rainforest. In Petersburg, the gifts of Alaska’s coastal rainforest were celebrated this month in a festival organized in part by Sunny Rice, Alaska Sea Grant’s Marine Advisory Program leader.

The 11th annual Rainforest Festival was held this year from September 6th-9th in Petersburg, a fishing community on an island in Frederick Sound. The festival’s goal is to: “Bring people closer to the natural world through education, exploration, and the arts.”


Local artist Grace Wolf designed this year’s artwork for the festival.

Every year several hundred people attend the Rainforest Festival. The mostly local Alaska attendees spend the weekend directly after Labor Day learning about both the marine and terrestrial environments of Southeast Alaska.

“Before the Rainforest Festival there were not a lot of options for the average Petersburg resident to attend a scientific talk about the world around them” said Rice, who is a professor at the University of Alaska Fairbanks, College of Fisheries and Ocean Sciences.

Rice and others decided to create the festival to provide an opportunity “to raise the level of scientific discussion within the community.”


Photo of Mycologist Ron Hamill, explaining the various types of Alaska fungi. (Photo courtesy of the Rainforest Festival Facebook page.)

A town with about 3,330 residents, Petersburg is located approximately halfway between Juneau and Ketchikan. It’s in the heart of Alaska’s famed Inside Passage, an archipelago of some 1,100 islands and home to some of America’s last healthy runs of wild salmon. The economy is mostly driven by commercial fishing, which made the theme of this year’s festival that much more appealing.

“We chose to focus the festival this year on salmon because it’s such an important part of this region’s culture, economy and identity,” said Rice.

The keynote talk was given by Megan McPhee, associate professor at UAF’s College of Fisheries and Ocean Sciences. It was titled “Why are salmon shrinking and what does it mean?”

McPhee has been conducting research on why salmon seem to be getting smaller. Is it because they are returning to spawn earlier and thus have not had as long to grow? Could it be that they are returning using their usual timeline and are smaller due to some other factor?

Salmon are anadromous, meaning they are born in fresh water, spend a majority of their lives in the ocean, and return to fresh water to spawn.

McPhee’s research indicates that salmon are growing faster, maturing earlier, and returning from the ocean to their natal streams smaller than before. The research suggests that the biological cue Alaskan salmon get to return home to spawn is occurring earlier, resulting in overall smaller salmon. Why the fish are receiving this biological cue earlier is unknown, but could be caused by warming Alaskan waters in the Bering Sea, McPhee told the audience.

Commercial fishermen are concerned about the smaller size of salmon for biological and financial reasons. Smaller salmon mean a decline in usable pounds of meat per fish. Therefore, commercial fishermen may be catching the same number of fish but getting less usable product and thus less money, according to the research.

But the festival was about a lot more than science and economics. It was jam-packed with art shows, field trips, workshops, and children-focused events.

Over 60 children attended the popular fairy and troll house-building event this year where kids use forest materials, such as moss and birch, to build tiny homes for their fairy and troll friends.

The Rainforest Festival is unique in the way that it hosts educational events. Generally, every person who gives a brown bag or keynote talk also accompanies attendees on a field trip to help illustrate what they spoke about. For example, U.S. Forest Service fisheries biologist Heath Whitacre gave a talk on “Restoring Watersheds for Healthy Salmon Habitats.” He then led a fieldtrip down to the Ohmer Creek Watershed Restoration project in order to give the attendees a visual example of watershed restoration in action.


Photo of Ohmer Creek courtesy of U.S. Forest Service.

This educational approach allows both audio and visual learners a chance to absorb the information and ensures the message of every talk resonates with the attendees.

The festival also offers a 5-course, “Taste of the Rainforest,” wild foods dinner for $75 per person.

Read more about the festival here.