All posts by Angus Mackay

Southern British Columbia & Puget Sound Chum Salmon Mixed-Stock Identification

Southern Chum stock strength must be monitored to facilitate their management, in accordance with Annex IV, Chapter 6 of the Pacific Salmon Treaty (Treaty). Catch composition in fisheries targeting Southern origin Chum populations informs managers of stock strength, mixed fishery components and exploitation rates. . We are proposing to sample Southern BC and US mixed stock Chum fisheries to determine stock composition to the levels of Canadian Conservation Unit (CU) and United States Management Unit (MU) level using genetic mixed stock analysis. Along with other stock assessment information, such as escapement, the data provided from this work is a critical component required by the ChumGEM model for run-reconstruction and eventually for forecasting run strength. This proposal follows from a previous Southern Fund project ‘Joint US and CA mixed-stock Chum fisheries sampling design’ which occurred 2012-2015. The goal is to assess the mixed stock Chum fisheries for four consecutive years in a multi-agency sampling effort.

 

Mark Recovery Program Coded Wire Tag Sampling, Dissection and Reporting

This project is one component of the Coast Wide CWT System which includes fully integrated CWT tagging, sampling, lab operations, analyses and data exchange along the entire west coast of North America with a high level of coordination and cooperation among the coastal states and Canada across many political jurisdictions. The funding supports fishery CWT sampling from Commercial, First Nations economic, and recreational fisheries in BC that encounter Chinook indicator stocks, as well as head lab operations and the management of resulting data.

CWT data is essential in annual analyses in deriving Canadian and US allotments of chinook total allowable catch, assessing compliance under the PST, calculating fisheries and stock specific statistics (i.e. exploitation rates, survival rates, maturation rates), monitoring trends in marine survival, assessing fishing impacts, forecasting pre-fishery ocean stock abundances, and evaluating the effectiveness of hatchery production and experimental programs. CWT data is also important for assessing stock status, forecasting stock abundance, and monitoring trends in regional survival patterns for climate change investigations and ecosystem-based assessments. Long-term time series of CWT data is key information to discern variations in salmon abundance resulting from variations in ocean survival and human-induced impacts.

 

Juan de Fuca Strait Chum Sampling Program

The establishment of a chum sampling program for the Strait of Juan de Fuca has been identified as a top research priority through the Southern Endowment Fund by the Chum Technical Committee and other interested parties.

Strait of Juan de Fuca Sampling Program:

With the goal of stock reconstruction for Southern BC and Washington Chum salmon, one significant data gap is the diversion of chum populations through the Southern Route via Juan de Fuca Strait. This project will work towards addressing that data gap by sampling this migration route in both US and Canadian waters to determine:

  • The spatial and temporal stock composition of chum salmon migrating through the Southern Diversion route,
  • Provide sampling platform for stock identification, migration rate studies etc.
  • Develop time series of Catch per Unit effort data to pair with the Johnstone Strait Test Fishery to determine diversion rate of various chum populations.

This multi-year program will be broken into 2 phases. Phase 1 will involve assessing the feasibility of a structured sampling program (2016) in Juan de Fuca Strait (Canadian Area 20 and US Area 5). This will involve chartering a Purse Seine vessel to fish 4 days/week starting the 1st week of October for 5 weeks. Catch per Unit Effort information will be collected as well as biological samples for stock identification purposes. All fish will be released except for the 400 samples/week (a total of 2,000 chum) that will be collected during the program. Phase 2, dependent upon the 1st year of the program, will expand the sampling program to include a tagging component to evaluate the migration rates of chum salmon via migration route which is a key parameter in the reconstruction model (2017-2019).

Nass Chinook Mark-Recapture Project

Since 2009, the Pacific Salmon Commission (PSC) Chinook Technical Committee (CTC) has established a 15% coefficient of variation (CV) as an acceptable level of uncertainty for estimating Chinook Salmon populations that are used in managing US and Canadian Chinook Salmon fisheries. Overall, the Nass Chinook Salmon program has achieved the CV data standard in 15 of 24 (63%) years since the start of the Nisga’a Fisheries Program in 1992. The main factor determining CV has been the number of marked Chinook Salmon recovered at terminal spawning areas in the Upper Nass River. Achieving an adequate number of marked recoveries has required two conditions to be met: (1) a sufficient number of Chinook Salmon are marked (>1250) at the fishwheels and (2) sufficient effort is made on the spawning grounds for recovering marks such that >50 marks are recovered. Results from the past funded studies have indicated that these requirements can be met, even in low return years, by marking adult Chinook Salmon at both fishwheel marking locations (Gitwinksihlkw and Grease Harbour), examining fish throughout the run at Meziadin Fishway and the Kwinageese videocounting weir, and conducting carcass surveys at Damdochax Creek. These three Upper Nass spawning systems represent on average 39% of the aggregate spawning stock based on stock composition estimates and are geographically separated to be representative of all stocks that spawn above the marking sites.
The primary purposes of the proposed project are to: (1) continue to augment marking and recovery efforts, (2) improve methods for generating accurate and precise MR escapement estimates for the Upper Nass River Chinook Salmon aggregate stock, and (3) achieve unbiased population estimates that meet the PSC CTC data standard (CV – 15%).

Sampling to Investigate Klukshu Early/Late Population Structure

The purpose of this project is to improve information regarding the population structure and status of early and late run Klukshu River sockeye salmon.

The early and late runs together serve as an indicator stock for international management of Alsek River sockeye salmon, which is linked to Klukshu weir counts. Differences in timing, spawning locations, and life history between the two runs are not well understood, and previous work is inconclusive. Fillatre (2002) and Petkovich (2000) document differences between early and late components, but Eggers and Bernard (2011) developed biological escapement goals for total Klukshu sockeye, because (a) they considered the evidence for biologically distinct sub-populations insufficient, and (b) catch could not be separated into early and late components. DFO currently uses a cut-off date of August 15 to track weir counts for early and late components, but Fillatre (2002) showed that the timing of migration pulses varies substantially between years. Some years show two clear peaks with variable timing and different degrees of overlap (1977, 1991, 1992, 2002, 2006), but years with 3 peaks or 1 peak have also occurred. Any summary based on a fixed break-point can be highly misleading. As an illustration, consider that moving the break-point about 10 days earlier or later gives opposite abundance trends.

The current working hypothesis by the WG is that there are two distinct populations: (1) Early migrating river-spawners with unknown juvenile rearing behaviour, and (2) Late migrating lake spawners, which are true lake-type sockeye. However, the annual migration timing is strongly influenced by hydrology making it difficult to accurately assign samples (genetic baseline, scales) purely based on the timing curve.

 

Stikine Chinook Aerial Surveys

Chinook salmon in the Stikine River comprise one of over 50 indicator stocks included in annual assessments by the Chinook Technical Committee of the Pacific Salmon Commission to determine stock status, effects of management regimes, and other requirements of the Pacific Salmon Treaty (Der Hovanisian and Etherton 2006). The Stikine River is one of the largest producers of Chinook salmon in Northern B.C. and Southeast Alaska (Der Hovanisian and Etherton 2006).

Stikine Chinook aerial surveys provide Chinook counts from index sites in both the upper (Little Tahltan, Tahltan, and Beatty) and lower reaches (Christina and Verrett) of the Stikine River which loosely corresponds to DFO’s Wild Salmon Policy prescribed conservation units (stocks), in concert with augmenting the current Little Tahltan weir, and providing some measure of validation of the system wide mark-recapture based escapement estimates.

 

Kuthai Lake Sockeye Review & Access Improvement Assessment

This project began with an investigation into why Kuthai Lake sockeye escapement has dramatically declined and remains low. The focus will be upon evaluating migration access for the Kuthai stock, along with estimating relative abundance and stock proportions for Kuthai and co-migrating early run main-stem sockeye.

In the later stages, this project will involve two field surveys which will inform the development of design and cost estimates for improving sockeye migration access to Kuthai Lake. The results of which strongly indicate that access to the lake is particularly restricted in the lower reach of the Silver Salmon River.

The primary objective of this project is to focus on increasing the abundance of fish stocks by opening freshwater habitat to salmon spawning and rearing. In specific instances, it will be possible and appropriate to rehabilitate previously productive habitat that has been degraded as a result of human or natural activity.

Tahltan River (Stikine River) Slide Remediation

This project developed a salmon passage remediation plan at the site of a large rock slide that occurred on the lower Tahltan River (Stikine River watershed) in May 2014. The rock slide partially in-filled the Tahltan River channel, constraining the River, and resulting in a seasonal barrier to adult sockeye and Chinook salmon attempting to migrate upstream to spawning grounds in the upper Tahltan River watershed.
The goal of the project was to re-establish adult salmon passage past the site of the slide for adult Chinook and sockeye salmon at flow levels and velocities typically experienced within the Tahltan River between May and August.
After qualified experts surveyed the slide area, assessed the slide materials, and evaluated conditions of the river canyon including hydrology and flow dynamics, an engineered plan was devised and executed. By March 2018 slide remediation operations were successfully completed that allowed adult Chinook and sockeye salmon to re-establish passage at a broader range of flows.

 

Increased CWT Application in Southern B.C. Coho Indicator Stocks

The 2005 PSC Report of the Expert Panel on the Future of the Coded Wire Tag Recovery Program for Pacific Salmon identified shortcomings of coho indicator stocks due to low tag recoveries. With the prolonged low marine survival rates of Southern B.C. (SBC) coho and subsequent reduction in fisheries, the coho stocks in SBC fail to obtain sufficient recoveries of coded-wire-tags (CWTs). In addition to the increased sampling already implemented as part of the CWT improvement program directed towards coho, increasing the number of CWT’s applied to coho will provide better information regarding marine survival, distribution and exploitation rates of SBC coho. This project proposes to increase CWT application at 4 hatchery stocks to provide this information to analysts and fishery managers.

 

Little Tahltan River Chinook Assessment

Historically, Little Tahltan River Chinook have been a major contributor to the overall Stikine production, but have declined in recent years, both in abundance and relative contribution to the total Stikine Chinook run. This project would be a preliminary investigation into why the Little Tahltan River Chinook escapement has declined and remains low. The scope of the project would be focused upon evaluating environmental conditions that may possibly be affecting spawning and incubation habitats. A field survey would be conducted in order assess or monitor habitat factors that may have influenced the decline or be limiting productivity.