Bristol Bay Fisheries Report: July 27, 2020

Jul 27, 2020

A retrospective (and future) look at biology and ecology in Bristol Bay and beyond. 

Boats anchored in the Naknek River, July 2019.
Credit Sage Smiley / KDLG

 


As of the last numbers we have, the total run is 55.9 million fish -- about half a million away from last year’s baywide total run. 

This is the fifth-largest harvest on record for the Nushagak District. 

Total harvest is at 37.7 million. Total escapement is at 18.1 million. 

The Naknek-Kvichak run is far and away the largest in the bay at 24.2 million fish -- we’ll hear from the Naknek-Kvichak biologist later in the week. 

Nushagak - Fish and Game's Management biologist puts the year in context

The Nushagak District had its fifth largest harvest on record this year at 8.9 million fish, and its sixth largest run at 12.6 million fish. But ADF&G biologist Tim Sands says that this season was a little bit strange. KDLG’s Tyler Thompson spoke with Sands earlier about this year’s run.

 


Egegik & Ugashik - Aaron Tiernan

In the Egegik and Ugashik districts, the season was relatively smooth, considering the constraints of a pandemic and a fairly compressed, late run.

Egegik and Ugashik management biologist Aaron Tiernan last week gave his thoughts on his first full season managing the southern districts in Bristol Bay.

 


Fish Size

The salmon returning to Bristol Bay have been smaller than average. Here’s Stacy Vega, the assistant area research biologist for the region.

 

The historic average for a 2 ocean fish is about 4 and three quarter pounds and a 3-ocean fish grows up to six and a half  pounds. Vega went on to compare this year’s average to last year, with this year’s average fish weight being the smaller. 

The main factor in how big fish are is how many years they spend in the ocean. That’s according to Dan Schindler, a professor of aquatic and fisheries sciences at the University of Washington.

Schindler says that over the past couple decades, there’s been a trend toward smaller size and age for both two and three ocean fish. 

There are two main factors that affect sockeye size within an age class. One is ocean temperature -- Schindlers says warmer oceans generally mean more food, which means faster growth. 

The other important factor is competition, and for Bristol Bay sockeye, that comes from two main sources. That competition comes from other sockeye -- a bigger run generally means the fish are smaller, because there are more of them competing for the same amount of food. 

It also comes from increasing numbers of hatchery pink salmon.

Schindler says that in pink years, Bristol Bay sockeye tend to grow more slowly and survive at lower rates. The additional pinks released from hatcheries is adding to the odd-even year cycle. 

 

Koktuli salmon at the proposed Pebble Mine site

The U.S. Army Corps of Engineers released the final environmental review of the proposed Pebble Mine at the end of a big year for Bristol Bay sockeye. Some scientists say the health of the sockeye run depends on genetic diversity and that one piece of that diversity would be especially vulnerable if the mine is built. 

Chignik's salmon runs are low - Management biologist Ross Renick discusses

This is the third year in a row that the sockeye run in the Chignik area is severely depressed. But it’s not just sockeye. King and pink runs at the Chignik weir are low, and the Chignik management biologist says chums are struggling this year as well. 

As of yesterday, 5,240 sockeye passed the Chignik weir, and 4,857 late run sockeye. That brings the total Chignik sockeye run to 222,546, with 85,046 in the late run. 18 kings passed the weir yesterday, bringing the total king run to 929. 60 pinks also passed the weir, for a total Chignik pink run of 818. 

Here’s part of a conversation with Chignik management biologist Ross Renick about what’s going on in the Chigniks.

 

We’ll have more of this interview, and look at more possibilities for why the run is declining, as well as a broader look at the effect of a withering salmon run on the Chignik community during Friday’s Bristol Bay Fisheries Report.

Weather Wednesday

It’s not Wednesday, but Rick Thoman with UAF Climate Research Center has some insights into how Bristol Bay’s summer is measuring up.

Messages to the fleet:

We have a birthday message that we weren’t able to play on Saturday, it’s for Kelly Stier on the Honey Badger from his son Beckett.


Update: This episode of the Fish Report has been updated with a new version of the story on Koktuli salmon near the site of the proposed Pebble Mine that clarifies the Army Corps' analysis of the mine's potential impacts to fish.