DOI: 10.25921/fwjc-fz89
title: Chum salmon catch per unit effort, CPUE, collected from small vessel Nita Maria in Strait of Juan de Fuca from 2019-10-01 to 2019-11-06 (NCEI Accession 0284473)

description: This dataset contains only cruise report on chum salmon survey in Strait of Juan de Fuca in autumn 2019. The project plan for 2019 was very similar to previous years. Once approvals were obtained for clearance to fish in both US and Canadian waters, the vessel Nita Maria was chartered to fish based on a 4day per week schedule (2 days in Canadian waters and 2 days in US waters) for a 6 week period starting the 1-st of October 2019 is the fourth year of this project. Through the initial work on the ChumGEM reconstruction model, it was very apparent that the diversion of Chum salmon stocks through the southern route (Strait of Juan de Fuca) was a significant gap in our information needed to populate the model. Currently the model structure is available to incorporate this information but the assumptions on the migration pathways being used require investigation and validation. The purpose of this project was to 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.

The program began as planned on October 1st and ran until November 8th. A total of 139 sets were completed (72 in Canadian waters and 67 in US waters). A total of 762 Chum were encountered and 640 were sampled for stock id and other biologicals. There was a moderately higher average Catch per Unit Effort (CPUE) in the US side of the Strait compared to what was encountered in Canadian waters. This was the complete opposite to the significantly higher CPUE seen in Canadian waters in 2017 and 2018, but very similar to what was observed in 2016. The catch information demonstrated a slightly later timing on the Canadian side of the Strait with a peak CPUE during week 43 and an earlier peak CPUE in the US waters during week 42. Over the period of the program, Chum CPUE alternated being higher in Canadian waters than in US waters. Stock composition information demonstrated that Canadian Chum stocks dominated the samples throughout the Canadian waters similar to previous years. US Chum stocks in Canadian waters varied in composition but increased later in the program. In US waters, US Chum stocks dominated the mixtures throughout the program. Stock timing and distribution differences were observed and this new information has improved our understanding of Chum stock composition and timing through the migratory pathways of Juan de Fuca Strait. Low Chum CPUE resulting in well below target sample size were the biggest issues during the 2019 program. While problematic in looking at weekly stock compositions, it did show that the sampling program was sensitive to the generally depressed Chum abundance that was observed in 2019 for most of these populations. The relationship between CPUE and abundance is there for the Northern Approach (through Johnstone Strait) and it is hoped that the information collected via this Southern Approach (through Juan de Fuca) would contribute to that relationship.

This cruise is U.S. State Department MSR U2019-023 as part of the World Data Service for Oceanography. Report is in PDF.