Marine Research to Better Understand the Decline of Atlantic Salmon Populations

2019-04-21

Pedro Nilo and Martin Castonguay

The King of the River, Salmo salar, is currently the subject of increased attention. This emblematic species is the foundation of a regional economy that employs First Nations and forms part of their traditional lifestyle. The decline in wild salmon populations or their stability at low levels, as observed for over 40 years, is troubling to resource users and managers. As a result, Canada implemented a Wild Salmon Policy in 2005 and one of the results of the Cohen Commission (2012) was the launch of the Atlantic Salmon Research Joint Venture in 2016.

Several factors may account for the decline in Atlantic Salmon, such as resource overexploitation, barriers to migration, negative impacts of fish farms and aquaculture, habitat losses south of the distribution range, pollution, climate change, increased mortality at sea, etc. The current survival rates of smolts, or juveniles that go to sea after growing up in rivers, are very low. Although we do not know why returns are so low, it is suspected that the marine portion of the life cycle is crucial to population abundance. This currently guides research aimed at clarifying the causes of mortality at sea, as well as determining the predators and characteristics of the migration routes.

In order to monitor salmon during their marine voyage, they are caught in rivers using rotating traps or passage structures equipped with multiple dams. Internal acoustic transmitters are then implanted in the smolts, making it possible to monitor their journey as they pass through various recording stations. The Government of Quebec, in collaboration with Fisheries and Oceans Canada, Quebec Region, launched projects in 2017 on the Jacques-Cartier River (in Donnacona) and the Vieux-Fort River (on the Lower North Shore). Smolts leaving the Gulf of St. Lawrence are recorded at the Strait of Belle Isle and the information is sent to the network of acoustic receivers operated by the Atlantic Salmon Federation. The smolts then migrate to the waters along Labrador and the feeding areas west of Greenland.

Preliminary data for smolts (tracked using transmitters) from the Jacques-Cartier and Vieux-Fort rivers indicate low detection rates, in the order of 1% to 5% for the Gulf of St.Lawrence only. Research now aims to identify the locations where death occurs at sea and what the causes may be, which is a major challenge.

Canada's Policy for Conservation of Wild Pacific Salmon

Establishing an Atlantic Salmon Research Joint Venture

Fish like salmon and eel fall under provincial jurisdiction in Quebec (Ministère des Forêts, de la Faune et des Parcs) and Ontario (Ontario Ministry of Natural Resources and Forestry). In 2017, the Atlantic Salmon Research Joint Venture gave Fisheries and Oceans Canada, Quebec Region and the Ministère des Forêts, de la Faune et des Parcs du Québec the opportunity to launch a joint research program on the marine biology of salmon in Quebec rivers, a program that involves two components: telemetry and opportunistic sampling.