All posts by Angus Mackay

SEAK Commercial Chinook Port Sampling

Chinook salmon are harvested in commercial fisheries in Southeast Alaska (SEAK) waters east of Cape Suckling and north of Dixon Entrance. These fisheries harvest mixed stocks of Chinook salmon, including those originating from Alaska, British Columbia, and the Pacific Northwest. Significant numbers of both hatchery and wild stock Chinook salmon have coded-wire-tags (CWTs) inserted into their heads before they are released from hatcheries or as they migrate to sea. These fish are marked externally by removal of the adipose fin. CWTs are recovered by sampling programs intended to sample a minimum proportion of fishery catches and escapements. Analyses of CWT data provide estimates of fishery exploitation rates and other statistics employed for stock/fishery assessments and planning.

The Pacific Salmon Commission (PSC) technical committees rely upon selected groups of CWT hatchery and wild Chinook and coho as surrogates to estimate impacts on natural stocks. Recent trends in Pacific Northwest towards mass-marking of Chinook salmon smolts released from hatcheries in conjunction with increased hatchery production up to 150 million smolts annually have resulted in a large volume of adipose fin clipped Chinook salmon in SEAK fisheries that do not contain a CWT (No Tags).

The presence of No Tags exceeded 70% of the adipose-clipped fish sampled during the SEAK summer troll fishery in 2015. Alaska Department of Fish and Game (ADF&G) commercial fisheries port samplers have utilized visual sampling of these adipose clipped fish to recover CWTs for over three decades. The escalating presence of No Tags in SEAK fisheries has impacted CWT sample rates by statistical week and area. Although most SEAK Commercial Fisheries port samplers are using electronic tag detection wands to determine if a tag is actually present in the head of adipose fin clipped fish; the No Tag rate is so high that it requires two samplers per sampling event to be efficient at examining adipose clipped Chinook salmon harvested in the SEAK troll fisheries to determine if valid CWTs are present before CWT processing protocols are invoked.

In an effort to increase or maintain CWT sample rates and decrease shipping costs we propose to continue funding port sampling staff in the ports of Craig, Juneau, Pelican, Wrangell, Petersburg, Ketchikan, and Sitka. Southeast Alaska port samplers will use electronic tag detection wands to examine adipose clipped Chinook salmon harvested in the summer Southeast Alaska troll fisheries to determine if valid CWTs are present before CWT processing protocols are invoked. The heads of any positively identified tagged fish will be collected and the tags decoded by ADF&G staff. This will increase sampling rates by decreasing the amount of fish heads to be organised and shipped.

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.

 

Gitanyow (Kitwanga) Lake Assessment

The Kitwanga River is a tributary of the Skeena River, located 250 km from the coast and supports significant runs of Pacific salmon. Kitwanga sockeye are genetically unique and a distinct conservation unit as described under Canada’s Wild Salmon Policy. Historically, sockeye returns to the Kitwanga were in the tens of thousands and they supported a number of sustenance and economic fisheries. In more recent times the stock has been depressed and in many years returns are not enough to meet the minimum biological requirements for the stock. In response to this conservation concern the Gitanyow, with help from organizations like the Pacific Salmon Commission and Fisheries and Oceans Canada, have initiated a rebuilding plan to preserve the genetic uniqueness of the stock and to try and rebuild it to more historical levels. Rebuilding efforts have included the creation of spawning platforms in 2006 and 2007 in Gitanyow Lake, the enhancement of the stock through hatchery production in 2006 & 2007 and a reduction in the overall exploitation rate on the stock through the implementation of strict fisheries management guidelines. The results of the rebuilding efforts have been mixed as the stock has responded positively in some year classes but not in others. To date, millions of dollars have been spent to rebuild the stock and many more millions of dollars have been foregone in lost revenues in the Canadian commercial catch, in efforts to get more spawners back to the Kitwanga River and Gitanyow Lake.

Since 1999, the GFA in partnership with DFO and other organizations have been studying Kitwanga sockeye and Gitanyow Lake in an attempt to better understand the stock and the environment where they reside. Annual smolt and adult enumeration operations have been ongoing for over 10 years, while Gitanyow Lake studies were performed between 1999 and 2003. Lake studies were abandoned due to funding constraints and because it was found that freshwater smolt production from the system at that time was very high and the lake limnology was not likely impacting smolt production. However, since that time we have noticed a significant decrease in freshwater smolt production which has renewed the need to look at the lake biology in more detail.

 

Northern BC Net Fisheries Coho CWT Sampling

The purpose of this project is to maintain the coho CWT sampling in Northern BC net fisheries. CWT sampling and lab operations methods and standard operating protocols are well established. The project includes:
-Coded wire tag sampling at a 20% rate in any coho retention fisheries in northern BC.
– Sampling at two major landing locations in June, July and August in Prince Rupert and in Port Hardy as required.
– Centralized head lab dissections and data management in Vancouver by a DFO-contracted service provider, as part of the overall DFO Mark Recovery Program
– DFO in kind data management, calculations of CWT estimates and uploads of data to RMIS (Jan 2017).
– Data will be maintained in the DFO cwt database and shared with the US CWT data repository (RMIS) ensuring domestic and international access.

The impacts of net fisheries where coho by-catch retention has recently been restored is an important management concern. Maintaining a core of coho exploitation rate indicators provides essential background for northern panel discussions of coho. Canada has coho exploitation rate indicators in Area 2E, Area 3 and the Skeena (3). CWT’s from Alaskan exploitation indicator stocks are also recovered in Canadian net fisheries. The project also supports evaluation of northern BC impacts on southern origin coho.

 

Evaluation of population-specific behavioural impairment and mortality in salmon incidentally captured in marine commercial purse seine fisheries

While targeting abundant species, Canadian commercial seine net fisheries for Pacific Salmon inadvertently capture species of concern that are required to be released. The survival of these released salmon is a key component of assessing the impacts of seine fisheries and developing harvest limits. However, there is poor understanding of post-release mortality in general, especially in chum salmon. Additionally, the handling and release practices employed by the commercial purse seine fleet are inconsistent among individual vessels, likely influencing the probability of survival for released fish.

If handling and release practices can be identified that beget good survival, their implementation would reduce mortality of salmon released from the entire fleet. Adoption of consistent and appropriate release practices will additionally appease public concerns, increase efficiency of harvest, potentially allow additional harvest opportunities and reduce impacts on stocks of concern. Moreover, sociological human dimensions research conducted this past year has identified that commercial fishers would be more willing to modify handling practices if the rationale for doing so was supported by scientific results.

In concert with this finding, the results of this study as well as those from previous research with the commercial fleet has been, and will continue to be, presented to staff from the Canadian Fishing Company (Canfisco), relevant environmental groups, and commercial fishers through seiners associations and advisory boards. Using the 2016 Pacific salmon purse seine fishery in Canadian Statistical Area 3 as a model system, we propose to evaluate how variable handling and sorting practices influence survival and condition following release, and how these relationships change throughout the season.

 

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).

Feasibility of Radio Frequency Identification Tags for Marking Juvenile Salmon for PSC Management Applications

This project will provide an assessment of the current state of RFID technology, its suitability for application to juvenile Chinook and Coho salmon, and its potential to provide more useful and reliable information than the current Coded Wire Tag (CWT) program. The Pacific Salmon Commission identified the following five objectives:

1. Review the current application of RFID tags for animal identification and management, including their advantages and limitations over current technologies.

2. Compare sizes, tag costs, and tag application costs of RFID tags (including PIT tags) with those of CWTs.

3. Review detection capabilities of RFID tags, including detection distances when embedded in animal tissue and when animals are moving through freshwater or seawater.

4. Evaluate the feasibility for mass screening for detection and reading of RFID tags in landings of Pacific salmon.

5. Evaluate the feasibility and cost of incorporating RFID microchips to replace CWT in marking juvenile salmon for coastwide Coho and Chinook salmon management.

These objectives were addressed by combining the information obtained through our review of the pertinent literature, CWT and RFID tagging programs; and structured inquiries of manufacturers of RFID tags used for tagging fish and detecting recoveries in marine fisheries, freshwater fisheries and spawning areas.

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.

 

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.