PSF’s State of Salmon Report: Methods & Results

DRAFT

1 Overview

Currently, there is no place where the public can readily find answers to general questions regarding the state of salmon in BC and the Yukon. It is difficult to find credible answers to questions such as:

• How are salmon populations doing?
• What are the major factors influencing the state of salmon?
• What is being done - and what could be done - to mitigate threats and recover salmon populations and the habitats they depend on?

This lack of publicly accessible information about the state of Pacific salmon and opens the door to misinformation that can hinder and harm our ability to conserve salmon.

The Pacific Salmon Foundation (PSF) is developing an inaugural State of Salmon report, which will address these questions and be tailored to the questions of a salmon-informed public audience. The outputs will be updated regularly (e.g. annually or biennially) to reflect new data and changes to the state of Pacific salmon populations.

As part of the State of Salmon report, PSF’s Salmon Watersheds Program is developing simple metrics to report on the status and trends in regional abundance for each species. This document outlines the data sources and analytical approach used to estimate time series of spawner abundance and total returns (including catch) for each species and region, as well as draft results. This information is intended to be shared with external partners in order to garner feedback on preliminary results that will inform our approach moving forward. Our analyses are ongoing, and the information here is subject to change on a regular basis, but we will endeavor to keep it up-to-date.

2 Methods

2.1 General Approach

We report spawner abundance for each of nine regions that represent all major Pacific salmon-bearing watersheds in Canada: Yukon, Transboundary, Haida Gwaii, Nass, Skeena, Central Coast, Vancouver Island & Mainland Inlets, Fraser, and Columbia. These regions are also used to organize data in the Pacific Salmon Explorer. There are a relatively small number of Pacific salmon that spawn in the MacKenzie River basin in Arctic Canada that are currently not considered here.

We separate five species of Pacific salmon: Chinook, chum, coho, pink, and sockeye. We also report status of steelhead trout for regions where spawner data are are available and can reasonably be expanded to yield an estimate of regional abundance (Nass, Skeena, interior Fraser, and Columbia). When assessing biological status, pink salmon are often separated into even- and odd-year lineages due to their consistent 2-year life cycle. However, for the general overviews provided in State of Salmon we consider generational averages, which take the running average of even- and odd-year lineages for pink salmon. This approach of using generation running averages also smooths over dominant years for sockeye salmon, for which many populations display cyclic dominance. Shifts in dominance between even- and odd-year pink populations or declines in sub-dominant years of sockeye salmon are considered in a more nuanced way in our reporting when discussing how changes in abundance have been reflected in the diversity and distribution of each species within the region.

For each of these species, where data are available, we construct an index of spawner abundance at the regional scale. We focus on spawner abundance because these data are more readily accessible and easily summarised at different spatial scales. Spawners represent the abundance of salmon available to reproduce and contribute to future generations, as well as to meet cultural and ecological needs within watersheds, and thus provides a measure of status relevant to communities and ecosystems. We recognize that commercial catch has historically been a substantial portion of salmon that return to the coast, and that ignoring declines in catch will underestimate the declines in overall salmon abundance. Therefore, we include information on total abundance (i.e. spawners plus catch) for species and regions with reliable data. This assessment of the data landscape is ongoing, and one of the reasons why the results here should be considered preliminary.

We have based our assessments on the best available data for each region and species. For example, stocks that are governed by international treaties may be monitored by the Pacific Salmon Commission (PSC), and tend to have reliable time series of abundance available at regional scales. These data sources are outlined in the Region-Specific Data section. For species and regions where aggregate abundance is not reported by the PSC or DFO at the scale needed, we adapted our approach to make the best use of available data. In most cases, this meant expanding spawner abundance from stream-level estimates to get a regional scale index of spawner abundance using two types of expansion factors (English et al. 2016). This expansion process is described in the Expansion Factors section.

R code and data for the analyses described here are available on GitHub at https://github.com/salmonwatersheds/state-of-salmon.

2.2 Region-Specific Data Sources

Here we describe specific data sources for the abundance of salmon and steelhead at the regional scale.

2.2.1 Yukon

Yukon has been updated with data to 2024.

The Canadian portion of the Yukon River is home to Chinook, chum, and coho salmon. Border escapement and total abundance (i.e., run size) of Canadian-origin Chinook and fall chum salmon in the mainstem Yukon River are counted at the Eagle Sonar station on the Yukon/Alaska border, and are available from the Yukon River Panel in their Joint Technical Committee (JTC) Reports. Specifically, we used Chinook RR Spawning escapement estimate and RR Canadian origin total run size estimate from Appendix B11 of (YukonRiverJointTechnicalCommittee2025YukonRiverSalmon?). Canadian-origin fall chum spawner abundance was taken as the Spawning escapement estimate in Appendix B16 and total abundance as the Total estimated Canadian-origin run size from Appendix B20 of (YukonRiverJointTechnicalCommittee2025YukonRiverSalmon?).

There are also Chinook, chum, and coho salmon in the Canadian portion of the Porcupine River, which joins the mainstem Yukon River in Alaska. Data on escapement to the Porcupine River are more patchy and not currently included here.

2.2.2 Transboundary

Updated to 2024 except for Chinook.

Chinook numbers from the PSC’s Chinook Technical Committee will need to be updated with final exploitation rates when the “Annual Report of Catch and Escapement for 2024” is released (antipicated in July 2025).

The regional spawner abundance and total return of Chinook was calculated as the sum of escapement and total return, respectively, to the Stikine, Alsek, and Taku indicator stocks. For each of these stocks, we used escapement and exploitation rates provided by the PSC’s Chinook Technical Committee as part of their Synoptic Evaluations of Stock Status. These data were downloaded from their Data Application. Total abundance was calculated from the escapement, \(E\), and exploitation rate, \(r\), as \(E/(1-r)\).

For coho, sockeye, pink, and chum, we assessed regional abundance in the Transboundary using estimates of border escapement provided in the PSC’s Joint Transboundary Technical Committee Reports. The most recent TTC report (Transboundary Technical Committee 2022) includes data through 2021. Updated report appendices were provided by Aaron Foos (DFO) on April 15, 2025 in advance of report publication, and numbers for 2023 and 2024 should be considered preliminary.

Sockeye spawner abundance and total return were taken from the updated TTC report appendices. Specifically, Stikine sockeye spawner and total abundance were the Escapement/broodstock and Terminal Run, respectively, summed across the Stikine River (Appendix B26) and the Taku River (Appendix D17).

Coho spawner abundance and total abundance are available for the Taku River only, taken from Appendix D22 (Escapement and Terminal Run respectively) of the TTC updated report appendices.

Pink and chum salmon are less extensively monitored in the Transboundary, with ongoing escapement available only from the Canyon Island fish wheel on the Taku River. We used the index of escapement from the Canyon Island fish wheel as an index of regional spawner abundance for pink and chum (Transboundary Technical Committee 2022). There are some historical data for pink salmon spawner abundance in the Nakina River of the Taku watershed, but this location has not reported data since 1998 and thus we did not include this stream survey in our index of regional abundance.

Steelhead trout have also been enumerated at the Canyon Island fish wheel since 1987, though recent estimates have been patchy and the timing of the fish wheel likely misses a substantial portion of the Taku summer run steelhead. Thus, we do not use the Canyon Island counts as an index of steelhead abundance.

We recognize that our approach in the Transboundary lacks information from many un-monitored watersheds, in particular the smaller watersheds of the Chilkat, Unuk, and Whiting Rivers. In the absence of better monitoring, we choose to report available data as a proxy for regional abundance, and note that the contribution of these smaller watersheds to total regional abundance for each species is likely small.

Internal note: Processing of raw excel file from Aaron Foos to extract relevant tables and fields is in population-data/transboundary-data/code/sos-data-extract.R

2.2.3 Haida Gwaii

Expansion factors have been updated to include the most recent spawner survey data, which goes to 2023.

For Haida Gwaii, we followed the Expansion Factors approach described below, with the exception of Chinook salmon for which the only data are from a single enumeration project on the Yakoun River. We show Yakoun River spawner abundance up to 2006, but no estimates were available for the most recent generation making the current status for Haida Gwaii Chinook “Unknown”.

For other species, we compared our expansion approach to estimates of escapement to Area 1 reported in the TCNB (2023) (Appendix 30) but found the Area 1 estimates were much lower (except for Chinook, for which Appendix 30 matched the Yakoun River estimates exactly).

2.2.3.1 Expansion Factors by Species

Chum

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (teal) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. Alternative time series from the PSC’s Northern Boundary Technical Committee Report (Appendix 30) is shown in red. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade. See section on Expansion Factors below for further details.

Coho

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (teal) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. Alternative time series from the PSC’s Northern Boundary Technical Committee Report (Appendix 30) is shown in red. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade. See section on Expansion Factors below for further details.

Pink

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (teal) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. Alternative time series from the PSC’s Northern Boundary Technical Committee Report (Appendix 30) is shown in red. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade. See section on Expansion Factors below for further details.

Sockeye

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (teal) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. Alternative time series from the PSC’s Northern Boundary Technical Committee Report (Appendix 30) is shown in red. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade. See section on Expansion Factors below for further details.

2.2.4 Nass

Nass pink and chum updated using spawner surveys; other specues in progress. Output from LGL is not available for 2024 and so alternative approaches are being explored. Text below is from last year.

Chinook spawners and total return were taken from the PSC’s Chinook Technical Committee (CTC) data sets and are reported on in CTC (2024). Specifically, Nass River (Area 3) escapement and terminal run are provided in Table B3 (fields Esc and t.run respectively). Preliminary 2024 data on run size was available from the Nisga’a Fisheries Nass Stock Assessment Updates, and are shown below for comparison.

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Above: Comparison of Nass Chinook spawner and total abudnance from CTC and Nisga’a Fisheries Nass Stock Assessment in-season estiamtes of total return to Canada (TRTC).

Nass coho escapement and total return were reconstructed by English et al. (2023) for each of the three coho Conservation Units in the Nass region for 1992-2022. We summed the total escapement (TE) and total return (Total Run) across these three Conservation Units to yield the regional aggregate abundance. Alternative data options include * Nisga’a Fisheries Nass Stock Assessment Updates from September 2024 that includes in-season estimate of TRTC (but no escapement estimate), and * NuSEDS expansions for spawner abundance, which tends to be lower than the English2023 approach. See below for visual comparison.

Above: Comparison of Nass coho data: for the 2024SOS we used the sum of three CU estimates from English et al. (2023) (black and grey open points). This is not being updated for 2024, but there is an in-season estimate of run size from the Nisga’a Fisheries and/or estimates of spawner abundance expanded from NuSEDS.

Nass sockeye escapement and total return were derived from the Northern Boundary Sockeye Run Reconstruction (NBSRR) Model that estimates total escapement and total return for the Skeena and Nass Rivers (English et al. 2004; English et al. 2017). Specifically, we used fields TE (Total Escapement) and Total run for Area 3 sockeye from the 2022 update to the North and Central Coast (NCC) Salmon Database Version 2, maintained by LGL Ltd. with support from PSF (English et al. 2016; Challenger et al. 2018; English et al. 2018).

The index of Nass steelhead spawner abundance and total return are for the Nass Summer CU, developed in collaboration with the Nisga’a Fish and Wildlife Department and LGL Ltd. (English et al. 2023). There is another steelhead CU in the Nass region - Nass Winter - which is not well monitored and therefore not included in our index of spawner abundance.

Chum and pink salmon were expanded from available spawner surveys, as described below in Expansion Factors. Note that the designation of indicator streams for the Nass region was based on English et al. (2018) rather than the indicator designation in NuSEDS.

2.2.4.1 Expansion Factors by Species

Chum

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Pink

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

2.2.5 Skeena

Skeena coho and pink updated using spawner surveys, steelhead updated from Tyee data; other species in progress.

Chinook spawners were taken from the PSC’s Chinook Technical Committee (CTC) data sets and are reported on in CTC (2024). Specifically, Skeena River (Area 4) escapement is provided in Table B3 (field GSI esc). There is no total return for the Skeena River provided in the CTC data sets.

For Skeena chum salmon, we used escapement to Area 4 reported in Table 32 of TCNB (2023) rather than expanding escapement from spawner surveys because surveys of indicator stream have been increasingly patchy over the last 30 years, making expansions uncertain.

Skeena sockeye escapement and total return were derived from the Northern Boundary Sockeye Run Reconstruction (NBSRR) Model that estimates total escapement and total return for the Skeena and Nass Rivers (English et al. 2004; English et al. 2017). Specifically, we used fields TE (Total Escapement) and Total run for Area 4 sockeye from the 2022 update to the North and Central Coast (NCC) Salmon Database Version 2, maintained by LGL Ltd. with support from PSF (English et al. 2016; Challenger et al. 2018; English et al. 2018).

The index of Skeena steelhead spawner abundance is derived from estimated escapement of Skeena Summer steelhead at the Tyee Test Fishery (1956 - present), provided by the Province via email. As for other regions, these estimates may not capture winter-run steelhead, for which data are not available.

Skeena coho and pink salmon were expanded from available spawner surveys, as described below in Expansion Factors. We are exploring potential spawner abundance reconstructions for pink salmon available from North Coast DFO staff (Shaun Davies, pers. comm.).

2.2.5.1 Expansion Factors by Species

Chum

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (teal) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. Alternative time series from the PSC’s Northern Boundary Technical Committee Report (Appendix 32) is shown in red. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade. See section on Expansion Factors below for further details.

Coho

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (teal) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. Alternative time series from the PSC’s Northern Boundary Technical Committee Report (Appendix 32) is shown in red. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade. See section on Expansion Factors below for further details.

Pink

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (teal) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. Alternative time series from the PSC’s Northern Boundary Technical Committee Report (Appendix 32) is shown in red. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade. See section on Expansion Factors below for further details.

2.2.6 Central Coast

Expansion factors have been updated to include the most recent spawner survey data, which goes to 2023.

Estimates of spawner abundance for all salmon species on the Central Coast were expanded from available spawner surveys, as described below in Expansion Factors. Monitoring and reporting of observed spawners on the Central Coast has declined in recent decades, thus requiring larger expansion factors to arrive at an area-wide estimate that can be compared through time. As such, estimates of spawner abundance for the Central Coast over the past decade are more uncertain and should be interpreted with caution.

There are two spawner surveys for Steelhead trout on the Central Coast that we report in the Pacific Salmon Explorer. However, these surveys have been patchy through time with the most recent estimates from 2016. Therefore, spawner abundance and total return for Central Coast steelhead was considered unknown.

2.2.6.1 Expansion Factors by Species

Chinook

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Chum

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Coho

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Pink

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Sockeye

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

2.2.7 East Vancouver Island & Mainland Inlets

Expansion factors have been updated to include the most recent spawner survey data, which goes to 2023.

In the 2025 State of Salmon report, we have split the former “Vancouver Island & Mainland Inlets” region into two: East Vancouver Island & Mainland Inlets and West Vancouver Island. This split was made to better reflect the different ecology and habitats of salmon between the regions that may lead to different status and trends.

Initial time series of spawner abundances for all salmon in East Vancouver Island & Mainland Inlets were expanded from available spawner surveys, as described below in Expansion Factors. For the assessments, we trunctaed the time series of spawner abundance to years 1953+ because earlier years had high expansion factor values indicating lack of monitoring on key indicator streams (see figures below). We are exploring the potential use of well-monitored Chinook indicator stocks to inform an index of spawner abundance and total return for Chinook (CTC 2024).

2.2.7.1 Expansion Factors by Species

Chinook

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Chum

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Coho

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Pink

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Sockeye

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

2.2.8 West Vancouver Island & Mainland Inlets

Expansion factors have been updated to include the most recent spawner survey data, which goes to 2023.

In the 2025 State of Salmon report, we have split the former “Vancouver Island & Mainland Inlets” region into two: East Vancouver Island & Mainland Inlets and West Vancouver Island. This split was made to better reflect the different ecology and habitats of salmon between the regions that may lead to different status and trends.

For Chinook, we used the West Coast Vancouver Island (WCVI) 14-stream index escapements of Pacific Salmon Commission Chinook Technical Committee wild Chinook salmon escapement indicator stocks, available in Appendix B5 of CTC (2024). We truncated this time series to only include years from 1995 onwards, because earlier escapement estimates used different methodology and have not been calibrated (CTC 2024). Although catch of WVI Chinook is also reported by the CTC, there is no allocation of catch to the index streams used for escapement or other calculation of total abundance that we could draw on for the State of Salmon report, so WVI Chinook are assessed by spawner abundance only.

Reconstructions of sockeye spawners and recruitment are compelted by DFO (Nicholas Brown, pers. comm.) for three Conservation Units on West Vancouver Island: Sproat, Great Central, and Hucuktlis (formerly Henderson). We used the sum of spawners and total return for these three Conservation Units as the index of sockeye spawner and total abundance for WVI. We acknowledge that this index does not account for lake-type sockeye in other watersheds (e.g., Muchalat, Kennedy, Clayoquot) or river-type sockeye in West Vancouver Island and Northwest Vancouver Island CUs, which tend to be in much lower abundance.

For chum, coho, pink, and steelhead, spawner abundance was expanded from available spawner surveys, as described below in Expansion Factors. For the assessments, we trunctaed the time series of spawner abundance to years 1953+ because earlier years had high expansion factor values indicating lack of monitoring on key indicator streams (see figures below).

2.2.8.1 Expansion Factors by Species

Chinook

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Chum

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Coho

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Pink

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

Sockeye

Above: (a) Time series of spawner abundances showing raw sum of counts for indicator streams (red) and expanded estimates of spawner abudnance to indicator and non-indicator streams (black). This expanded time series is what is used to assess the current state and trends in spawner abundance for the region and species. (b) The values of Expansion Factor 1 that accounts for unmonitored indicator streams in a given year, and is calculated based on the proportional contribution of the unmonitored indicator stream(s) to the sum of all indicator streams in a (reference) decade.

2.2.9 Fraser

Fraser pink and sockeye (spawners) updated to 2024 from PSC’s Fraser River Panel data application, . Chum in progress (data requested), coho to do (data not being updated by DFO), Chinook awaiting PSC CTC data (July 2025).

Escapement of Fraser Chinook is provided in the PSC’s Chinook Technical Committee (CTC) data sets and are reported on in CTC (2024). We took the sum of escapement to indicator stocks in Table B6 (all Spring/Summer, Harrison, Lower Shuswap, Nicola, Lower Chilcotin, and Chilko) as an index of spawner abundance. Catch of Fraser Chinook is provided in Table A14 but cannot be directly added to indicator escapement to yield total return. PSF is pursuing Chinook run reconstruction output for the Fraser to inform total return.

Fraser chum catch and escapement are reported by PSC’s Chum Technical Committee (TTCHUM 2023), however the most recently published report only contains estimates for 2010-2019 and the data were not otherwise made available to us. As such, we estimated spawner abundance from available spawner surveys in NuSEDS as described below in Expansion Factors. We note that, although most NuSEDS data was updated to include surveys in 2022, for Fraser chum the most recent data was from 2020.

For interior Fraser coho CUs, spawner abundance and total return were provided by DFO on data request (pers. comm. Marissa Glavas, Data Manager, Fraser River Stock Assessment). We report total return as the sum of “Total Pre-Fishery Abundance” to all CUs and spawner abundance as the sum of “Total Return” (i.e., final spawner estimate plus fish removed from the system by DFO Salmon Enhancement Program or First Nations) to all CUs (we note the term “total return” is used differently in this data set to represent spawners!). We recognize that using these estimates ignores coastal coho populations, for which monitoring has been patchy through time.

Data on total return and spawner abundance of pink salmon and sockeye salmon in the Fraser region are provided by the PSC and accessed through the Fraser Panel Annual Report: Data Application (Pacific Salmon Commission 2024). Total escapement for Fraser sockeye was not yet available for 2023, and 2023 total return is considered preliminary. We note that Fraser River pink salmon are only counted in the dominant, odd-year run.

Steelhead trout in the Fraser are monitored by the Province in at least 10 different streams, but these data are not readily available. Relatively reliable estimates of steelhead spawner abundance are available at the CU-level for interior Fraser steelhead from the Thompson Summer CU (monitored at the Thompson River) and Mid Fraser Summer CU (primarily monitored at the Chilcotin River; data in the Pacific Salmon Explorer). We used the sum of CU-level spawner abundance for these two CUs as an index of Fraser steelhead abundance. We note that this approach does not include more coastal populations, such as the Lower Fraser Summer steelhead monitored in the Coquihalla River or Boundary Bay Winter steelhead, which may not have declined to the same extent over the past decade. However, a lack of publicly accessible data on coastal Fraser steelhead has limited our ability to include these CUs in our index of abundance.

2.2.10 Columbia

We used CU-level estimates of spawner abundance (run reconstructions) sourced from DFO (Ogden, pers. comm.) for Chinook and Stockwell and Hyatt (2003) and subsequent updates for sockeye.

There is no monitoring of steelhead trout in the Canadian portion of the Columbia region, but the Okanagan Nation Alliance does enumerate steelhead in akskwəkwant (Inkaneep Creek) and estimate a Canadian portion of steelhead spawning abundance. These data can be found in associated report (e.g. OBMEP (2022)) and are available in the Pacific Salmon Explorer as the CU-level spawner abundance for the Mid Columbia Summer CU.

2.3 Expansion Factors

For species and regions that lacked reliable data on spawner abundance and total return at the appropriate scale, we estimated regional-scale abundance from stream-level surveys. We started with spawner survey data shown in the Pacific Salmon Explorer. Spawner surveys were each assigned to one of the nine regions we considered based on their geographic location. We note that this is slightly different from how spawner survey data are organized in the Pacific Salmon Explorer, where data are organized by Conservation Units (CUs) that may span regional boundaries (e.g. for pink salmon that have relatively geographically large CUs). In cases of trans-regional CUs, the spawner surveys appear in both regions in the Pacific Salmon Explorer, whereas here we assign spawner surveys to the region in which they fall geographically, regardless of the CU boundary.

Spawner survey data are largely derived from river-level estimates in DFO’s New Salmon Escapement Database System (NuSEDS), but are cleaned up to address issues of, for example, inconsistent naming of streams through time or duplicate data. The spawner survey abundance is equal to the MAX_ESTIMATE in NUSEDS for each year and river population, calculated as the maximum of all fields containing spawner abundance data (e.g. natural adult spawners, natural jack spawners, total broodstock removals). Each of these river populations has been designated as an indicator stream or non-indicator. Indicator streams are observed more consistently in recent decades, tend to have higher spawner abundance, and tend to be monitored using more intensive methods that provide greater accuracy [EnglishEtAl2016NorthCentralCoast]. For further information on the compilation of spawner survey data, see the Pacific Salmon Explorer Technical Report.

Expansion Factor 1, \(F_{1,y/d}\), expands the observed spawner abundances in indicator streams to account for indicator streams that are not monitored in a given year. It is calculated for each year \(y\) of the spawner time series, and relies on a decadal contribution of each indicator stream to the total escapement to all indicator streams, \(P_{d,i}\) in decade \(d\) [EnglishEtAl2016NorthCentralCoast]. The calculation of this decadal contribution requires at least one estimate from each indicator stream for the decade. If a decade does not contain sufficient information (i.e. one or more indicator streams are not monitored at all in a decade), then a reference decade is used to calculate \(P_{d,i}\). This reference decade is chosen to be: (1) the closest decade (historical or future) with sufficient information, or failing (1), (2) the 20-year period from 1980-1999 (Challenger et al. 2018).

For each decade (or reference decade if insufficient information) \(d\), the average number of spawners returning to indicator stream \(i\) is calculated as:

\[\bar{S}_{d,i} = \sum_{y = 1}^{Y_{d,i}} \frac{\hat{S}_{y/d, i}}{Y_{d,i}} \] where \(Y_{d,i}\) is the number of years for which spawner estimates are available within decade \(d\) for stream \(i\). From the average number of spawners for all indicator streams, the decadal proportional contribution of each indicator stream is calculated as:

\[P_{d,i} = \frac{\bar{S}_{d,i}}{\sum_{i=1}^{I} \bar{S}_{d,i}}\] where \(I\) is the total number of indicator streams.

Expansion Factor 1 is then calculated for each year within the decade \(y/d\) based on the decadal contributions and which streams were monitored or not in a given year:

\[F_{1,y/d}=\left( \sum_{i=1}^I P_{d,i} w_{y/d,i} \right)\] where \(w_{y/d,i}\) is 1 if stream \(i\) was monitored in year \(y\) and 0 if stream \(i\) was not monitored in year \(y\). Expansion Factor 1 is then multiplied by the sum of the observed spawners in all indicator stream to yield the expanded estimate of spawner abundances in all indicator streams in the region:

\[S'_{y} = F_{1,y/d} \sum_{i=1}^I \hat{S}_{y,i}\]

Expansion Factor 2 \(F_{2,d}\) expands the spawner abundance to all indicator streams, \(S'_{y}\), to account for non-indcator streams. Unlike Expansion Factor 1, this is calculated for each decade (rather than each year) and then applied to all years within a decade. Like Expansion Factor 1, there needs to be sufficient information within the given decade in order to calculate \(F_{2,d}\), or else a reference decade is chosen. See English et al. (2016) for detailed on how reference decades are chosen in that case.

Expansion Factor 2 is calculated as:

\[F_{2,d} = \frac{\sum_{i = 1}^I \bar{S}_{d,i} + \sum_{j = 1}^{J} \bar{S}_{d,j}}{\sum_{i = 1}^I \bar{S}_{d,i}}\] where \(\bar{S}_{d,i}\) and \(\bar{S}_{d,j}\) are the deacdal average number of spawners in indicator and non-indicator streams, respectively, calculated above. \(J\) is the total number of non-indicator streams. The adjusted total number of spawners in both indicator and non-indicator streams is then calculated as: \[ S''_{y} = F_{2,d} S'_{y} \]

Note that when expanding spawner abundance for spawner-recruit analysis, a third expansion factor is applied to account for streams that are never monitored and for observer (in)efficiency (Peacock et al. 2020). We did not apply this third expansion factor because it is highly undertain and we are interested in relative changes in abundance through time, so we do not require to expand to absolute abundance.

2.4 Smoothing

We smoothed time series of spawner abundance and total return using a right-aligned running geometric mean over the length of a generation. This reduces the influence of dominant years and produces an index that is less sensitive to stochastic interannual variability that is common in salmon population dynamics. The generation length was based on the dominant life-history type for each species in a particular region. The smoothed spawner abundance in year \(y\) given a generation length \(g\) was calculated as: \[ \bar{S_{y}} = \left( \prod_{t = y-g+1}^y {S''_t} \right)^{1/g} \]

We smoothed abundance from the first year to the most recent year of raw abundance data. If there were intermediate years with missing data, the smoothed abundance was still calculated using the available years (i.e. ignoring the missing data, with the exponent \(1/g\) adjusted so that \(g\) reflected the number of years with data in the generation). If all years in a generation were missing data, than the smoothed abundance was NA.

When plotting, we show the smoothed abundance relative to the long-term historical average, so that species that have vastly different abundances within a region can be plotted on the same y-axis for comparison.

2.5 Quantifying change

We summarize the time series of smoothed spawner abundance or total return at the regional scale using three different metrics:

1. Current status relative to historical average;
2. Long-term trend over the entire time series; and
3. Short-term trend over the most recent three generations.

The currents status provides information on how the most recent spawner abundance compares to past values, while the two trend metrics provide information on the average direction of change and are less sensitive to the magnitude of current abundance.

The current status relative to historical average is calculated as: \[ (\bar{S_{y}} - \bf{S}) / \bf{S} \] where \(y\) is the most recent year for which the index of spawner abundance could be calculated and \(\bf{S}\) is the average smoothed spawner abundance over the entire time series.

The long-term trend is calculated following the recommendations of D’Eon-Eggertson et al. (2015), who found that the correct identification of declines in salmon population abundance may be most reliable when considering the entire time series, and applying regression-based estimates of change calculated from log-transformed and smoothed spawner abundances. As such, we fit a simple linear model to the time series of \(\log ( \bar{S}_{y} )\) over \(y\). The resulting slope, \(m\), gives an average estimate of annual change:

\[ m = \log \left( \frac{\bar{S}_{y}}{\bar{S}_{y-1}} \right)\].

With some rearranging, we can calculate the average annual percent change as: \[ \frac{\bar{S}_{y} - \bar{S}_{y-1}}{\bar{S}_{y-1}} = \frac{ e^m \bar{S}_{y-1} - \bar{S}_{y-1}}{\bar{S}_{y-1}} = e^m - 1\]. If the slope \(m\) is not significantly different from zero (\(p \geq 0.05\)), then the trend is classified as “stable” regardless of the magnitude of the estimated slope. If the slope is significantly different from zero (\(p < 0.05\)), then the trend is classified as increasing if \(m > 0\) or decreasing if \(m < 0\).

The short-term trend is calculated as described above, but only using the time series over the most recent three generations.

Above: Simulated time series of spawner abundance (grey line), smoothed with a running geometric mean over the generation length (4 years; black line). The three metrics are illustrated: Current status relative to historical average (black); Long-term trend over the entire time series (green); and Short-term trend over the most recent three generations (clay). The shaded regions of the regression lines indicate the 95% prediction intervals. In this example, the short-term trend is not statistically significant (p > 0.05), and so the trend is characterized as ‘stable’ despite the negative slope.

2.5.1 Additional Considerations

The standardized approach to quantifying change described above was applied across regions and species. We then considered two additional attributes prior to reporting on the State of Salmon:

1. If the species and region had no data in the most recent generation, the current status was “Unknown” even if historical abundance information was available. This was the case for Haida Gwaii Chinook, for which there were no reliable estimates of spawners since 2006.

2. If the time series of abundance (spawners or total return) contained fewer than 20 years of data, we could not reliably establish a historical baseline and the current status was therefore “Unknown”. This applied to Columbia Chinook and Columbia steelhead, both of which have been monitored since 2006.

3 Results

NOTICE!

These are PRELIMINARY results and the following figures should not be taken as a statement on the status of salmon in these regions. At this time, we are working to verify datasets and refine our methods.

• These trends in aggregated spawner abundance provide a broad overview of how salmon are doing, but must be interpreted with caution due to the diversity of populations with potentially different outlooks within each region and species.
• The status of spawner abundance is, in most cases, more positive than the status in total return, highlighting that declines in fisheries have been pervasive.

Highlights > Not yet updated for 2025

3.1 All regions

Spawners

Below: Summary of current status for spawner abundance across regions and species, comparing between previous years’ outcomes and revised outcomes. Regions and species below historical average are in red and above historical average are in green. Black cells indicate species that are not thought to be present in the given region, and grey cells indicate status was Unknown. For some regions and species, numbers have changed even though the year is the same because (1) the long-term average is calculated from raw instead of smoothed abundances or (2) an updated or different data source was used (e.g., final “synoptic evaluations” have been published for Transboundary Chinook post-release of SOS2024, and final numbers changed slightly; see Region-specific Data Sources).

Runsize

Below: Summary of current status for total abundance across regions and species, comparing between previous years’ outcomes and revised outcomes. Regions and species below historical average are in red and above historical average are in green. Black cells indicate species that are not thought to be present in the given region, and grey cells indicate status was Unknown. For some regions and species, numbers have changed even though the year is the same because (1) the long-term average is calculated from raw instead of smoothed abundances or (2) an updated or different data source was used (e.g., final “synoptic evaluations” have been published for Transboundary Chinook post-release of SOS2024, and final numbers changed slightly; see Region-specific Data Sources).

3.2 Yukon

Highlights

Above: Spawner abundance through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Above: Total return through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Below: Summary of the three metrics for spawners and total return. For long-term trends and short-term trends, the percentage is the average annual change calculated over the respective time period. Grey values indicate the % change was not significantly different from zero (i.e., stable), red values indicate declining trends, and green values indicate increasing trends.

3.3 Transboundary

Highlights

Above: Spawner abundance through time as a percentage of the long-term average. Spawner abundance is smoothed using a one-generation geometric running average (right-aligned), and plotted relative to the historical average for each species. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Above: Total return through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Below: Summary of the three metrics for spawners and total return. For long-term trends and short-term trends, the percentage is the average annual change calculated over the respective time period. Grey values indicate the % change was not significantly different from zero (i.e., stable), red values indicate declining trends, and green values indicate increasing trends.

3.4 Haida Gwaii

Highlights

Above: Spawner abundance through time as a percentage of the long-term average. Spawner abundance is smoothed using a one-generation geometric running average (right-aligned), and plotted relative to the historical average for each species. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Above: Total return through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Below: Summary of the three metrics for spawners and total return. For long-term trends and short-term trends, the percentage is the average annual change calculated over the respective time period. Grey values indicate the % change was not significantly different from zero (i.e., stable), red values indicate declining trends, and green values indicate increasing trends.

3.5 Nass

Highlights

Above: Spawner abundance through time as a percentage of the long-term average. Spawner abundance is smoothed using a one-generation geometric running average (right-aligned), and plotted relative to the historical average for each species. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Above: Total return through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Below: Summary of the three metrics for spawners and total return. For long-term trends and short-term trends, the percentage is the average annual change calculated over the respective time period. Grey values indicate the % change was not significantly different from zero (i.e., stable), red values indicate declining trends, and green values indicate increasing trends.

3.6 Skeena

Highlights

Above: Spawner abundance through time as a percentage of the long-term average. Spawner abundance is smoothed using a one-generation geometric running average (right-aligned), and plotted relative to the historical average for each species. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Above: Total return through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Below: Summary of the three metrics for spawners and total return. For long-term trends and short-term trends, the percentage is the average annual change calculated over the respective time period. Grey values indicate the % change was not significantly different from zero (i.e., stable), red values indicate declining trends, and green values indicate increasing trends.

3.7 Central Coast

Highlights

Above: Spawner abundance through time as a percentage of the long-term average. Spawner abundance is smoothed using a one-generation geometric running average (right-aligned), and plotted relative to the historical average for each species. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Above: Total return through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Below: Summary of the three metrics for spawners and total return. For long-term trends and short-term trends, the percentage is the average annual change calculated over the respective time period. Grey values indicate the % change was not significantly different from zero (i.e., stable), red values indicate declining trends, and green values indicate increasing trends.

3.8 East Vancouver Island & Mainland Inlets

Highlights

Above: Spawner abundance through time as a percentage of the long-term average. Spawner abundance is smoothed using a one-generation geometric running average (right-aligned), and plotted relative to the historical average for each species. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Above: Total return through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Below: Summary of the three metrics for spawners and total return. For long-term trends and short-term trends, the percentage is the average annual change calculated over the respective time period. Grey values indicate the % change was not significantly different from zero (i.e., stable), red values indicate declining trends, and green values indicate increasing trends.

3.9 West Vancouver Island

Highlights

Above: Spawner abundance through time as a percentage of the long-term average. Spawner abundance is smoothed using a one-generation geometric running average (right-aligned), and plotted relative to the historical average for each species. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Above: Total return through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Below: Summary of the three metrics for spawners and total return. For long-term trends and short-term trends, the percentage is the average annual change calculated over the respective time period. Grey values indicate the % change was not significantly different from zero (i.e., stable), red values indicate declining trends, and green values indicate increasing trends.

3.10 Fraser

Highlights

Above: Spawner abundance through time as a percentage of the long-term average. Spawner abundance is smoothed using a one-generation geometric running average (right-aligned), and plotted relative to the historical average for each species. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Above: Total return through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Below: Summary of the three metrics for spawners and total return. For long-term trends and short-term trends, the percentage is the average annual change calculated over the respective time period. Grey values indicate the % change was not significantly different from zero (i.e., stable), red values indicate declining trends, and green values indicate increasing trends.

3.11 Columbia

Highlights

Above: Spawner abundance through time as a percentage of the long-term average. Spawner abundance is smoothed using a one-generation geometric running average (right-aligned), and plotted relative to the historical average for each species. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Above: Total return through time as a percentage of the long-term average. Closed points highlight the most recent index of spawner abundance. The percent shown is the percent change from the historical average to the most recent year.

Below: Summary of the three metrics for spawners and total return. For long-term trends and short-term trends, the percentage is the average annual change calculated over the respective time period. Grey values indicate the % change was not significantly different from zero (i.e., stable), red values indicate declining trends, and green values indicate increasing trends.

4 References

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D’Eon-Eggertson, F., Dulvy, N.K., and Peterman, R.M. 2015. Reliable Identification of Declining Populations in an Uncertain World. Conservation Letters 8(2): 86–96. doi:10.1111/conl.12123.

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Peacock, S.J., Hertz, E., Holt, C.A., Connors, B., Freshwater, C., and Connors, K. 2020. Evaluating the consequences of common assumptions in run reconstructions on Pacific salmon biological status assessments. Canadian Journal of Fisheries and Aquatic Sciences 77(12): 1904–1920. Canadian Science Publishing. doi:10.1139/CJFAS-2019-0432/ASSET/IMAGES/CJFAS-2019-0432IEQ43.GIF.

Stockwell, M.M., and Hyatt, K.D. 2003. A summary of Okanagan sockeye salmon (Oncorhynchus nerka) escapement surveys by date and river segment from 1947 to 2001. Can. Data. Rep. Fish. Aquat. Sci. 1106: 34 p. Available from https://salmonwatersheds.ca/library/lib_508/.

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