Nass Data Summary
November 22, 2024
Background
This resource document shows information on salmon escapement and harvest (Canadian and total exploitation) in the Nass watershed. We display escapement for Area 3 (Nass) overall, escapement by Conservation Unit and stream, and exploitation rates for each salmon species. TRTC for steelhead trout in the Nass watershed is also presented. We are also working to forecast sockeye returns for the Meziadin system specifically, and show preliminary results from forecast models here.
Data Sources
Data on each salmon species’ escapement by Conservation Unit comes from the NUSEDS database.
Meziadin sockeye return and age class data comes from the Meziadin fishway counts and from [ ]
Data on TRTC, Canadian harvest, and SEAK harvest comes from [ ]
Summary
Escapement Goals
Map showing the Nass watershed extent (figure taken from Peter Hall’s CSAS paper on Skeena / Nass )
Sockeye Salmon
Area 3
Annual Sockeye Escapement by Conservation Unit
Annual Sockeye Escapement by CU and Stream
Exploitation Rates
Meziadin Sockeye
The Meziadin River is a major tributary to the Nass River in northwestern British Columbia, an important area home to five species of Pacific salmon. Sockeye salmon returning to the Meziadin system comprise a significant proportion of the total Nass sockeye run. Since the creation of the Meziadin Fishway in 1966, it has been found that 70-80% of Nass sockeye return to the Meziadin system via the Meziadin River. Meziadin sockeye are a highly valued and culturally significant food source for Gitanyow and Nisga’a First Nations, and also harvested in Alaskan commercial fisheries during their ocean migration.
Predicting the sockeye returning to the Meziadin is important for understanding the conservation status of this population. We are working to create a Meziadin-specific return forecast for sockeye salmon using the ForecastR tool.
Total return of Meziadin sockeye, 1982-2024
Total return of Meziadin sockeye by age class, 1995-2024
Data on age-3 (jack) sockeye returns were only available starting in 1995.
Using ForecastR to predict Sockeye Returns
We are using ForecastR, an R package and Shiny app, to predict total returns of sockeye salmon from the Meziadin system based on previous years’ data on Meziadin total return and escapement. The Meziadin total return data is a subset of the Nass total return, including escapement plus the salmon harvested in fisheries which do not make it back to spawning grounds. The sockeye total run numbers for each year are categorized by age, with sockeye separated into age classes 3, 4, 5, and 6.
ForecastR uses forecasting models to predict salmon terminal run and escapement, based on data entered by the user. This data can be age-specific and include environmental or biological covariates. Multiple forecasting models can be explored, compared, and ranked using the app. Here we have started forecasting Meziadin sockeye total return using ages with no covariates, and intend to add relevant environmental and/or biological covariates to make these predictive models more informative in the future. Plots shown are using the naive model, which was found to be the best fit for ages classes …. assigns exponentially decreasing weights to past observations (i.e. more recent data points are more important for forecasting), and captures seasonal variation.
Total Return vs Predicted Total Return by year using Sibling Regression Model
Observed vs fitted return numbers using Naive model for Age Class 3
Age 3 sockeye must be predicted using the naive model (forecast based on avg of the 5 previous years) because there is no younger age class to relate it to in a sibling regression.
Plot of observed vs fitted return numbers using simple sibling regression prediction model for Age Class 4
Observed vs fitted return numbers using simple sibling regression prediction model for Age Class 5
Observed vs fitted return numbers using simple sibling regression prediction model for Age Class 6
Forecast plot showing the distribution of forecasted return estimates by age
Chinook Salmon
Area 3
Annual Chinook Escapement by Conservation Unit
Annual Chinook Escapement by CU and Stream
Exploitation Rates
Coho Salmon
Area 3
Annual Coho Escapement by Conservation Unit
Annual Coho Escapement by CU and Stream
Exploitation Rates
Pink Salmon (even years)
Area 3
Even-Year Pink Escapement by Conservation Unit
Even-Year Pink Escapement by CU and Stream
Exploitation Rates
Pink Salmon (odd years)
Area 3
Odd-Year Pink Escapement by Conservation Unit
Odd-Year Pink Escapement by CU and Stream
Exploitation Rates
Chum Salmon
Area 3
Annual Chum Escapement by Conservation Unit
Annual Chum Escapement by CU and Stream
Exploitation Rates
Steelhead Trout
Area 3
Conservation Units
Streams
Exploitation Rates
References
Nisga’a Lisims Government. 2023. 2023 Nass River Salmon Stock Assessment Update - Friday, 14 July. Public update from the Nisga’a Lisims Government Fisheries and Wildlife Department.
Pacific Salmon Foundation. 2016. The Nass Area: Cumulative Pressures on Salmon Habitat (summary report cards), Vancouver, BC.
Vélez-Espino, L.A., Parken, C.K., Clemons, E.R., Peterson, R., Ryding, K., Folkes, M., and Pestal, G. 2019. ForecastR: tools to automate procedures for forecasting of salmonid terminal run and escapement. Final Report submitted to the Southern Boundary Restoration and Enhancement Fund, Pacific Salmon Commission, Vancouver BC. 117 p.