In 2016, the ASP-AGC Northern Cod Acoustic Tracking (NCAT) Project was developed to identify and address gaps in our understanding of the Northern Cod complex, with the goal of improving long-term management of the stock. Six fundamental questions (determined via thorough review of available literature and in-depth input from DFO scientists) form the basis of the three-phase research plan:
1. Migration Patterns: Do offshore cod components follow predictable spatial patterns and timing of movement that can be integrated into stock assessment models to gain insight into relative exploitation patterns? Identify these patterns of movement.
2. Migration Timing: What is the timing of the migration cycle for each component?
3. Migration vs Residence: What proportion of each offshore stock component undergo annual migration to the inshore areas?
4. Stock Components: What are the number and location of major spawning/pre-spawning aggregations?
5. Productivity: What is the productivity of each major component and how static are these characteristics over time? Identify differential growth, survival and recruitment patterns among the components.
6. Managing Exploitation Rates: Given the results of the investigations of 1 to 5, how could fishing efforts be managed (spatial and temporally) such that specific stock components can be sustainably harvested?
Northern Cod Acoustic Tracking (NCAT) Project
In 2017, the Northern Cod Acoustic Tracking (NCAT) project commenced Phase 2 to design an acoustic array, acquire acoustic tags and receivers and plan for the deployment of this gear to monitor movement of cod on a multi-year basis. With key funding provided through the Development of Autonomous Marine Observation Systems (DAMOS) project by the Canadian Foundation for Innovation, the NCAT project represents world class innovation through collaboration of academic, government and industry organizations including Dalhousie and Memorial Universities, Ocean Frontier Institute (OFI), Ocean Tracking Network (OTN), Fisheries and Oceans Canada (DFO) and the ASP-AGC FIP.
The Northern Cod Acoustic Tracking (NCAT) Project hosted an acoustic tracking array design workshop in September 2017. Since then, the project has progressed with the formation of Steering and Technical committees to oversee project development, purchase of acoustic tags, acoustic receivers and releases, development of a deployment plan and tagging procedures and sourcing of vessel platforms suitable for on-water activities scheduled to commence in 2019.The Steering and Technical committees include experts from project partners including Dalhousie University, Memorial University, Fisheries and Oceans Canada, Ocean Tracking Network (OTN), Association of Seafood Producers and Atlantic Groundfish Council.
1) Tagging – Acoustic and conventional tagging and genetic sampling of 260 cod occurred in the summer of 2019 in the inshore areas of 2J, 3K and 3L during a collaborative training process between DFO and OTN technicians. Genetic information generated during the tagging program will allow additional delineation of the cod population structure; this along with the acoustic results will provide key data on both population structure and migration patterns.
2) Acoustic Array – The acoustic array consists of 75 receiver moorings that will be deployed in 16 “gates” (a line of receivers) spaced approximately 5km apart in key habitat depths of 250-500m. The gates will cover hundreds of kilometers from the northern part of area 2J, south through 3K and 3L. Of those, 13 will be stationed along the continental shelf edge, and 3 others will be strategically located in mid-shore channels along a frequent travel path for cod. Each receiver mooring consists of a buoy holding up an acoustic receiver and an acoustic release attached to an anchor. Acoustically tagged cod migrating through or milling around the receivers will be recorded, including the unique acoustic tag number, date and time.
3) Wave Glider data collection – Data will be collected by a solar powered wave glider, controlled out of Halifax by experts at the OTN. The wave glider will travel between the 75 receiver stations, connecting remotely to each receiver via a radio frequency modem in the receiver, uploading data into its memory. Once connected, it is uploaded to Ocean Tracking Network. Data upload will occur at least once a year. Being able to collect data remotely is significantly more cost effective with a much lower carbon footprint compared to uploading data individually using a vessel platform.
Data collected will have broad benefits
In addition to improving the scientific assessment and sustainable management of Northern Cod, this acoustic array will benefit scientists working on other species. Any fish or mammal tagged with the same acoustic transmitter technology that travels through the 16 gates (e.g., Atlantic Halibut, Greenland Halibut, sharks, etc.), will be detected and the data will be shared by Ocean Tracking Network with other research projects.
- The NCAT acoustic array design of 75 VEMCO VR4 acoustic receivers was deployed in NAFO divisions 2J, 3K and 3L in 2020. The array consists of 13 receiver gates along the eastern continental shelf edge and 3 mid-shore gates in the Bonavista Corridor, Notre Dame Channel and southern branch of the Hawke Channel. This will allow detection of the newly tagged cod as they arrive in the offshore over the course of the winter in preparation for spring spawning.
- 1,260 VEMCO V16 acoustic tags and 2,400 conventional floy tags were purchased, 775 acoustic and over 1,500 floy tags have been deployed.
- Genetic samples have been collected from all acoustically tagged fish. Other biological data and photos have been collected from each fish.
- Initial data upload trials from the acoustic receivers using the Waveglider have been conducted and data quality review is underway.