Tag Archives: Exploitation Rate

Skeena River CWT Equipment Procurement

The Skeena Fisheries Commission (SFC) is made up of five First Nations who do fisheries work within their respective traditional territories in both the Skeena and Nass Watersheds. They include the Gitxsan, Gitanyow, Wet’suwet’en, Lake Babine Nation and Lax Kw’alaams. Currently, both the Gitxsan and Gitanyow conduct annual coho coded-wire tag (CWT) projects in the Skeena Watershed to monitor coho abundance, estimate smolt production, fisheries exploitation and to determine Skeena coho ocean survival. These programs are important because the information collected improves fisheries managers’ abilities to manage coho salmon stocks in the Skeena River by better understanding exploitation rates in U.S. and Canadian fisheries. It also allows managers to determine ocean survival rates for upper and middle Skeena coho stocks because both the Gitxsan and Gitanyow programs accurately enumerate all marked and unmarked returning adult coho annually (fence operations), something that is often not available in many other CWT programs in BC.
SFC is requesting funds from the PSC Northern Fund to purchase CWT equipment. SFC will retain ownership of the equipment in the event that it is decided by SFC commissioners/technical experts that the equipment could be put to better use within one of the other areas where our signatory First Nations conduct works. Any decision to move the equipment for use in another part of the watershed would be done in consultation with the GFA.


Boundary Area Coho Escapement

The Hugh Smith Lake coho salmon population is substantially exploited by mixed-stock fisheries in both the U.S. and Canada and is, therefore, a key indicator stock used to monitor total adult abundance and escapements, and the pattern and intensity of exploitation by these fisheries on populations in the northern boundary area. It is the only system in the southern portion of Southeast Alaska where a total count (with back-up mark-recapture estimate) of coho salmon escapement has been routinely collected since 1982. Its location 70 km southeast of Ketchikan makes it a particularly strategic indicator stock for boundary area fisheries. It has also been one of three key indicator stocks used to measure the overall abundance of wild coho salmon available to the Alaska troll fishery and to measure the exploitation rate by the fishery.
Escapement projections are made from both the cumulative weir count and estimation models based on recovery of coded-wire tags to provide real-time information for management of fisheries for escapement. Peak helicopter survey counts at other Boundary Area streams provide an index with greater coverage that complements higher resolution assessment at Hugh Smith Lake.


Exploitation rate estimation for coho salmon in south coast marine fisheries using genetic stock identification

In 2014, an exploitation rate cap on Interior Fraser River (IFR) coho in Canadian fisheries was increased from 3% to 16% in response to improved status and rebuilding of these stocks as well as fishery needs. Pre-season predicted fishery impact on IFR coho was generally determined using historic (1986-97) exploitation and coded wire tag (CWT) recovery rates scaled by current effort, which have changed over time, so current CWT recoveries do not provide a measure of fishery impact. Instead, DNA will be used to estimate the number of ‘wild’ unmarked IFR coho caught in fisheries which would provide an independent estimate of exploitation rate.

Atnarko River Chinook Escapement Estimation

The Atnarko River was identified as a potential escapement and exploitation rate indicator for Central BC early summer Chinook, and in 2009 the Atnarko River Chinook stock was proposed as an exploitation rate indicator. It was funded under the Coded Wire Tag (CWT) Improvement program, and the purpose of the five-year mark-recapture program was to improve escapement estimates for early summer Chinook.
Since then, the program has met the data standard of a coefficient of variation (CV) of 15% or less. Continued mark-recapture estimates on the Atnarko River will build on the information thus far. The project will estimate the escapement of Chinook salmon and generate estimates such that the fraction of CWT fish is known relative to the wild and/or unmarked escapement, and this data is essential for Chinook run reconstruction calculations. This program is part of a comprehensive group of programs on Atnarko River Chinook salmon that includes the production of Chinook fry and CWT application (under separate submission to the Northern Fund) and terminal fishery monitoring.