How do halibut migrate? Clues are in their ear bones

By Charlotte Gauthier, Université du Québec à Chicoutimi (UQAC)

Rising temperatures, changes in major currents, oxygen depletion at great depths: the Gulf of St. Lawrence has undergone major changes in its environmental conditions in recent decades. That has put many species in danger and, as a consequence, made them more sensitive to the effects of fishing.

However, these changes are benefiting other species such as Atlantic halibut, which is beating records for its abundance and is presently seeing the highest stock in the Gulf of St. Lawrence in the last 60 years.

As a biology researcher, I’d like to shed some light on some of the mysteries that still surround this unusual species.

Atlantic halibut: champion of the Gulf of St. Lawrence

Atlantic halibut is a flatfish that lives at the bottom of the estuary and gulf of the St. Lawrence. It is prized for its fine, firm white flesh, which is highly appreciated by consumers.

Halibut can grow to impressive sizes of more than two metres. Because of the quality of its flesh and its popularity on dinner plates, it is currently the most commercially valuable fish in the Gulf of St. Lawrence.

But this has not always been the case. In the 1950s, the adult, harvestable portion of halibut populations, known as the stock, suffered a major decline due to overfishing.

If we want to continue to exploit this resource over the long term, we must not repeat the same mistakes we made in the past. To avoid these mistakes, it is vital to have a good understanding of the life cycle of halibut and the effects that fishing can have on the stock. So far, this has not been done to the fullest.

The challenges for sustainable fishing

The basic biology of Atlantic halibut is fairly well known. However, both the habitats they use throughout their lives and their movement between these places are more difficult to characterize.

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