Nushagak Test Fishery

About

The Nushagak test fishery is a project that has been operated by BBSRI since 2019 to assess the early portion of the sockeye run entering the Nushagak fishing district. At the project's inception, contracted gillnet boats begin to fish the mouth of the Nushagak Bay about 1 week before the scheduled commercial sockeye salmon season opener and relayed catch data to area managers.

Although the test fishery originally ran from mid-June to early July, it has been shortened to a week or less in recent years since sockeye escapement triggers have restricted the flexibility of season opening times.

Project Goals

The primary goal of the test fishery is to reduce the possibility of a very large passage of sockeye into the escapement early in the season. Prior to the 2023 management plan, the fishery could be opened early if the test fishery detected an unexpected surge of sockeye before the season opened.

The test fishery is also a useful tool for estimating selectivity trends for gillnet mesh sizes used in the commercial sockeye fishery. While the effects of mesh size on average salmon body size is still a point of debate, the test fishery creates a controlled environment to compare the effects of multiple common mesh sizes on the size of fish caught, number of fish caught and total catch by weight.

Test Fishing Methods

Standardized

Before the opener and during closures, the boats follow a Test Fishing protocol. The net is set straight in the water (not hooked), and the boat backs away from the net as it soaks to avoid scaring fish into it. This method is designed to standardize the catch as much as possible.

Commercial

When the commercial fishery is open, the test fishing boats use traditional methods to maximize catch, including hooking and running the net while it's soaking. However, nets with alternating mesh sizes are still used so that the size selectivity of various mesh sizes can be assessed.

Data Collection

As salmon are hauled aboard the test fishing vessels, the crew sorts them into marked totes based on which mesh size they were caught in.

Once sorted, all of the sockeye are measured for mid-eye fork length (mm).

The crew also record net length, soak time, set and retrieve times which are used calculate a test fishing index. This index is used to estimate how many fish are passing into the district based on how many fish are caught by the test fishing vessel.

2024 Results

In 2024, the Nushagak Test Fishery operated from June 22- June 25 and caught just over 33,000 sockeye, fishing between 19-24 sets per day. The figures below model catch per unit effort (CPUE) of sockeye and Chinook at each station fished that day. The polygon height increases with higher sockeye CPUE, and the polygon color becomes more red with higher Chinook CPUE.