Hydro-acoustics to locate cod spawning aggregations and trawls to collect biological samples to characterize the aggregation

Introduction

This project is aimed at enhancing knowledge of Atlantic cod populations in the southern Gulf of St. Lawrence, and to identify current spawning area and develop spawning ground specific indices of biomass to inform rebuilding plans, COSEWIC assessment, Species at Risk listing decisions, and stock assessments. Cod has been in the Critical Zone of the Precautionary Approach Framework since 2005 and the cod-directed fishery has been closed since 2009. Furthermore, southern Gulf cod have also been assessed as Endangered by COSEWIC. Atlantic cod spawn in tight aggregations with high density, sometimes forming vertical formations in the water column known as “spawning columns”. Cod also exhibit strong spawning site fidelity. The discovery and protection of spawning aggregations has been identified by some as of critical importance to rebuilding these stocks. This project will identify the spatial and temporal extent of cod spawning aggregations using hydroacoustic surveys conducted weekly following an adaptive sampling design. Additionally, we will use acoustics and sampling to estimate the biomass of the spawning population.

The contractors must choose fishers for conducting acoustic and trawl sampling. DFO will provide guidance and manage the project.

Task 1: A minimum of one fishing vessel will use an adaptive survey design to locate and delineate the spatial extent of the cod spawning area near Miscou Bank. Once located the survey will use a parallel transect pattern with transects placed at 1nm intervals to avoid double counting.

Task 2: One trawling vessel will be used to collect biological samples to allow for the calculation of target strength to enable echo interpretation.