Category: 2020

Proposal to assess the feasibility of a new approach to estimating wild coho status

Many Canadian Coho Management Units (MUs) have been “data limited” since the reduction in assessment priority for coho which started about the same time as the Southern Coho Plan was finalized in 2002. The implementation plan for the 2020 Pacific Salmon Treaty (PST)  brings an opportunity to improve coho assessment and management. The PST Chapter 5 Southern Coho management framework is based on assessment of Canadian and US management units into one of 3 status zones (Low, Moderate, and Abundant), which have commensurate total exploitation rate (ER) caps and sharing of this ER between the US and Canada. This proposed approach could address the current inability to assess status in several Canadian MUs.
Tools such as DNA can accurately identify wild coho to the Conservation Unit (CU), MU, or even river of origin and can accurately identify hatchery of origin through a combination of parental based tagging (PBT) and regular genetic stock identification (GSI) (see Beacham et al. 2019). We propose that these assessment tools can be the basis for estimating wild coho escapement.
The proposed approach uses September fishery information, combined with representative DNA information from the fishery and escapement results from key hatchery indicators, to form the basis for estimating aggregate escapement of wild coho, especially in the GST management unit, but also Lower Fraser, Southwest Vancouver Island (SWVI), and other stock aggregates. The objective is to track catch of wild coho catch and escapement by management unit. These tools will also be used to estimate exploitation rate.

Salmonscape Workshop: scoping a life history approach to assessing and modelling freshwater and marine bottlenecks to inform salmon management

We propose a workshop to review the current approaches to assessing and modelling salmon survival across freshwater/coastal and marine life history stages and to recommend options that will inform the host of management tools/processes that require consideration of the full life history. We will bring together experts possessing experience with these techniques to share their knowledge in a structured manner. Case studies drawn from Pacific Salmon Treaty stocks that have requisite information will be developed that can be used to test the modelling approach. A Workshop Technical Planning Team will be convened from North Pacific Anadromous Fish Commission -International Year of the Salmon partner government agencies, NGO’s and academia to ensure relevance of the work to management and to assist in identifying a complete complement of experts. Experts will include representatives from Pacific Salmon Commission Secretariat staff and Technical Committees (Chinook, Coho, Chum and Sockeye). We will support travel for experts from Asia, Canada, Europe and the U.S. to attend. It will be essential for us to incorporate approaches to understanding freshwater and marine ecosystem status with Indigenous Peoples. Additionally, we will assess the potential for the development of new and emerging technologies and citizen science to augment this work.

UAV based enumerations of chum salmon in Clayoquot Sound Rivers

We are developing unmanned aerial vehicle (UAV) or “Drone” based enumerations of chum salmon within Clayoquot Sound and applying Artificial intelligence (AI) based software that aids in the detection and enumeration of salmon within the output video footage. By the end of the Project streamlined drone enumeration methodology will be produced that can then be applied to other species and stocks. AI-based software used to for ecological research applications will be optimized to be used for processing the drone video footage that is collected during the enumeration process. For this application fish can be detected and counted by the automated software making the process highly efficient. Streams will be enumerated traditionally by snorkel or bank walks at the same time as the drone-based surveys so the methods can be compared, and a survey efficiency can be determined. We are working with researchers from Uuathluk Fisheries, Quest University, University of Toronto, Pacific Salmon Foundation, CDFO, and other local organizations and to ensure the UAV based enumerations and analysis is designed to meet management requirements of expanded chum enumerations.

Establishment of a chinook snorkel index survey in East Creek on Northern Vancouver Island

Presently, only two index streams are surveyed for chinook salmon in Area 27 on Northern Vancouver Island. Both streams have been influenced by present or past hatchery operations and escapement estimates reflect marine mortality rates, as well as hatchery production rates. East Creek is a moderately sized system flows just north of Brooks Peninsula, and has only recently become accessible by logging road. Historical surveys associated with expanding hatchery production in the period 1960-1980 revealed a natural chinook population in East Creek but there has been no history of hatchery augmentation.
Establishing an index snorkel survey in East Creek would provide an opportunity to examine population abundance trends in a system unaffected by hatchery production. We propose to establish an index snorkel survey in East Creek, and to determine possible hatchery stray contributions through a complete sampling program including DNA, scales and otoliths on adult chinook post-spawn mortalities.

Corroboration of age estimates derived from otolith thermal marks, scale analysis and whole otolith analysis for Chum and Sockeye salmon

Age data derived from scale, whole otolith, and otolith thermal mark analyses are critical to sustainable fisheries management and the assessment of salmon fisheries and to evaluate recovery efforts for imperilled salmon populations. However, to our knowledge, a formal comparison of age estimates derived from these methods has not been completed for Chum and Sockeye salmon. The objective of this proposal is to provide corroboration of age estimates that are paramount to the run-reconstruction, in-season fishery management, and forecasts of these stocks. We propose to compare paired age estimates derived from scale (Chum) and whole otolith (Sockeye) analysis and otolith thermal mark analysis (Chum and Sockeye) for greater than 12,500 adult Chum and Sockeye salmon over the last two decades in Washington State. This analysis will identify the level of precision between estimates and any bias between methods and directly addresses Southern panel priority of improving salmon escapement assessments.

Improving Chum salmon escapement assessments for Grays Harbor, WA

Since 2015, the Washington Department of Fish and Wildlife (WDFW) has been working to improve Chum escapement estimates resulting in two technical reports (Edwards and Zimmerman 2018; Ronne et al. 2019). Previous work assessed distribution inside versus outside index reaches, area-under-the-curve estimates within index reaches, carcass tagging estimates of abundance in select index reaches, estimates of spawner stream life duration, and total spawner abundance of Chum salmon within tributaries of Grays Harbor. This proposal seeks to further implement an accurate and precise method for estimating escapement of Chum in sub-basins yet to be evaluated. Utilizing new methods, we also seek to revise run size estimates of historical abundance. This methodology can be used in other systems throughout the area covered by the Pacific Salmon Treaty. Current escapement estimates in Puget Sound and coastal Washington are derived from methods developed in the 1970s with the understanding that those methods were based on unsubstantiated assumptions that would later be revisited and refined. Over 40 years later, those methods are still being used for escapement estimates. Chum have become a constraining stock on the Grays Harbor salmon fisheries. Therefore, refined Chum assessments may alter management strategies moving forward.

Enumeration of Coho in the Lower Chilcotin River

This project’s goal is to estimate the Coho escapement to the Lower Chilcotin River using resistivity methods which are highly reliable, efficient, and cost effective. The Lower Chilcotin system supports Interior Fraser Coho but is not currently enumerated and no other systems in the Chilcotin watershed are monitored using accurate and precise methods. Obtaining Coho spawner counts from the Lower Chilcotin will improve our ability to assess the stock status of Interior Fraser Coho against PST management reference points which include returns to sub-populations. This project will also provide information that will improve stock recruit modeling and could form an important component of a system wide estimate for IFC using high accuracy counts and PIT tags. As well, DFO is now monitoring Chinook escapement using a resistivity counter at the Lower Chilcotin system, which provides an opportunity to extend the field program to produce a high quality estimate of Coho escapement.

Retrospective growth analyses of Chum salmon (Oncorhynchus keta) in relation to adult returns and environmental factors

Due to the complicated life history of Pacific salmon, which environmental factor (s) has major influences on their growth and productivity remains unknown, particularly accounting for their entire life history. Most previous studies focus on the short time period when they first enter the ocean. We will fill the gap by investigating salmon growth in all their marine years. We plan to use Chum salmon in southern British Columbia as an example to address this question because Chum salmon migrate to the ocean right after hatching, providing the great candidate to compare marine growth in the multiple years and seasons.
We propose to process the historic scales, measuring the seasonal (summer and winter separately) growth and identifying stocks, to reconstruct stock-specific long-term time series of growth rates of Chum salmon in multiple ocean years. Fish scales provide a record of individual growth during their entire life history and have long been used to study age structure and growth. The scales of Chum salmon have been consistently collected with fish length measured during a test fishery in Johnstone Strait since 1980. In recent years, along with the scales, tissues for genetic stock identification have been collected and processed on a fairly consistent basis from that test fishery. The number of stock-specific adult returns (2008-2019) can be estimated using the Chum Genetic and Environmental Management Model (ChumGEM) based on recent catch, escapement, and the genetic data.

By linking growth rates of Chum salmon stocks with density dependence and ocean conditions (1980-2019), this project will attempt to define which environmental factor(s) would be the best indicator of returns for each stock; by linking growth rates of Chum salmon stocks with the stock-specific adult returns, this project will determine which season and year of growth rate would be the best indicator of adult returns for each stock.

Investigating thermal windows of juvenile sockeye salmon populations in freshwater

There is a general consensus that increasing temperatures have negative impacts on many species of fish. Laboratory studies demonstrate fish growth exhibits a‘thermal window’, increasing with temperature to species-specific thermal optima, beyond which additional increases in temperature lead to decreases in fish growth (Portner et al.2017). Slower growth can result in lower survival, leading to reduced stock productivity.
In British Columbia, annual maximum air temperatures has increased by 0.031°C/year since the 1950s, resulting in increases in the average number of days per year that the Fraser River at Hope is above 19°C from just two days/year in the 1950’s to over 20 days/year in 2010’s (David Patterson. Personal Communication). This increase in water temperature is posing physiological challenges to salmon migration, in some cases inducing pre-spawning mortality (Eliason et al., 2011; Martins et al. 2011).
The influence of climate warming on the growth of juvenile Fraser River Sockeye Salmon rearing in nursery lakes, remains poorly understood, particularly in the context of the multiple factors that regulate growth in these environments. This represents a key area where climate change and other forcings may be influencing stock outcomes (i.e. productivity), unbeknownst to fisheries managers.
We aim to address this knowledge gap by reconstructing stock-specific, long-term time series of annual freshwater growth rates of juvenile Sockeye Salmon in relation to their thermal environments and other key biological and environmental factors.
Scales have long been used to study fish age and growth. The scales of at least eight major Fraser River Sockeye Salmon stocks have been consistently collected by the Pacific Salmon Commission (PSC) since the 1950s, which can be paired with otolith samples since the 1970s.
We propose to non-destructively extract a time series of returning Fraser River Sockeye Salmon (1970 – 2019) freshwater growth from the existing PSC scale archive, and conduct a suite of statistical analyses on these data to define growth variability and change within Fraser River Sockeye Salmon.

The use of spatial stream network models to evaluate the effects of rearing environment on wild coho life history to better inform pre-season forecasts

The proposed work will address Southern Panel Priority #3: Coho Biological Studies, with the specific objective of understanding the effect of climate change on salmon life history with benefit to pre-season forecasts. One of the simplest coho forecast methods involves a sibling regression model, which uses the abundance of returning males (i.e., jacks – fish that return to freshwater after spending only ~6 months at sea) as an indicator of adult returns. These models are based on an association between jack marine survival in the first few months at sea and adult marine survival the following year. The models rely on a stable age structure, an assumption that does not always hold. Marine survival of wild coho salmon in coastal Washington is measured at Bingham Creek, the site of a long-term life-cycle monitoring program operated by the Washington Department of Fish and Wildlife. Marine survival estimates inform pre-season forecasts, and are important in the determination of allowable exploitation rates in bilateral fisheries. Estimates of survival come from release and recovery of coded-wire tagged (CWT) wild coho marked as smolts during the outmigration period and recovered as adults from fisheries and a weir trap. Preliminary analysis established an inverse relationship between rearing streamflow rates and jack survival.

The proposed work will expand on these observations and evaluate the effects of rearing temperature on jack rates. The goal is to make predictions about age-at-maturity by utilizing spatial stream network models of stream temperature (“Thermalscapes”) for the Grays Harbor coho population. The models can be used to hindcast and forecast rearing temperature based on variations in air temperature and streamflow, which allows for analyzing historical data in addition to predicting jack rates under future climate scenarios.