Revealing New Discoveries of Canada’s Redfish

As part of its role in managing our country’s aquatic resources, Fisheries and Oceans Canada is responsible for providing scientific advice and research on over 650 fish, invertebrates and marine mammals. By studying the DNA profiles of some of these species, the Department is better able to distinguish between species, understand their population structures and provide sound advice on how to manage them sustainably. Today's redfish fishery is a perfect example of how genomics research is assisting the Department, particularly in the areas of management and conservation.

A Tricky Fish

Redfish (Sebastes sp.) is a major commercial species in Canada. With landings worth $27 million in 2012, it is the country’s fourth most valuable groundfish fishery. As the name implies, redfish can be easily identified by their orange-red colour. However, the various species of redfish are difficult to tell apart by eye, which has posed many challenges for the conservation and management of the species. Because of the species’ similarities and the difficulty in determining their distribution across the Northwest Atlantic (the ocean area between Canada and Greenland), redfish have historically been managed as a single resource. For conservation and fisheries management purposes, it is important for Fisheries and Oceans Canada to clearly understand the biology of each redfish species, where they are located, and how the species are structured into populations.

Redfish

Photo taken by Richard Larocque.

Research

With funding through the Genomics Research and Development Initiative, scientists at Fisheries and Oceans Canada, led by Dr. Jean-Marie Sévigny, have been collaborating with university researchers to examine the genetic make-up of redfish. By studying fragments of DNA called microsatellites, they were able to distinguish between two very similar-looking species of redfish: the Acadian redfish (Sebastes fasciatus) and the deepwater redfish (Sebastes mentella).

New Discoveries - Location

Because our scientists developed a reliable tool for identifying the different species of redfish, Fisheries and Oceans Canada now has a greater understanding of redfish stock structure than was previously possible. This research has, among other things, confirmed the presence of separate Acadian redfish populations in an area of Canadian water where it has never been done before, off the Grand Banks of Newfoundland and Labrador.

Map of the North Atlantic Ocean showing the positions and labels of the samples used to describe Redfish population structure.

Description: Map of the North Atlantic Ocean showing the positions and labels of the samples used to describe Redfish population structure.

New Discoveries - History

This genomics research also provided some key historical information about the species. A single piece of tissue, even several decades old, is enough to determine the genetic make-up of a fish and identify a species. Based on this property, the scientists extracted ancient DNA from the Department’s archived otoliths (an otolith is a structure from the inner ear that is sampled to determine a fish’s age). This method makes it possible to "go back in time" and analyze redfish history. While it was previously believed that the Acadian redfish populations were variable from year to year, we now know that they have actually remained stable through time.

Impact on Fisheries Management

Knowledge generated from this genomics research has also provided new scientific advice for fisheries managers. It is now recommended that the Acadian redfish and deepwater redfish be managed as separate resources. The research also helped play a role in the Committee on the Status of Endangered Wildlife in Canada’s evaluation of the status of the deepwater redfish. In 2010, the Committee assessed the deepwater redfish as threatened in the Northwest Atlantic.

The research has also facilitated a partnership with redfish harvesters. A collaborative effort is underway to identify the redfish species being caught in the Laurentian Channel in the Gulf of St. Lawrence. This is important because a moratorium has been in effect on the Gulf of St. Lawrence redfish fishery since 1995.

Going Forward

European research shows that genetically distinct populations of deepwater redfish are found at different water depths in the North Atlantic. Fisheries and Oceans Canada plans to examine this theory within Canadian waters and beyond.

"The distribution of the deepwater redfish is essentially continuous across the North Atlantic. In order to ensure sustainable management of the redfish fishery in Canada, it is important to understand the population structure not only within our waters, but in international waters as well."
— Dr. Jean-Marie Sévigny, Fisheries and Oceans Canada Scientist

Continued genetics research will answer even more questions about the mysterious redfish species. Most importantly, it will provide insight on how to best manage and conserve this valuable resource for generations.

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