Studying fjord populations of roundnose grenadier

Janne Stenseng Høie and Aurelien Delaval have embarked on their Master’s projects: studying the feeding ecology and population structure of roundnose grenadier (Coryphaenoides rupestris) in Norway’s fjords. The dynamic duo has fished deep in Norway’s fjords to collect the samples, and shared quality lab time dissecting these charismatic fish. But their projects are targeting two very different aspects on grenadier biology.

The roundnose grenadier is a gadiform fish inhabiting the deep waters (180–2200 m) of the North Atlantic, including southwestern Norway. They have a slow life history that is typical of deep-sea fishes, growing slowly, maturing late, and living long (up to 72 years). They are therefore highly susceptible to overfishing, and commercial landings since the 1960s have seen their stocks depleted and the species listed as ‘critically endangered’ on IUCN’s Red List. Relatively little is known about roundnose grenadier biology, and their fjord populations are yet to be studied in depth. Expanding our knowledge of the species is therefore important for its conservation and sustainable harvest.

In her thesis "Diel vertical migration and feeding ecology of the roundnose grenadier (Coryphaenoides rupestris) in Masfjorden, western Norway", Janne will be focusing her attention on the feeding ecology and behaviour of roundnose grenadier in Masfjorden. She will be analysing their stomach contents to identify what they eat, and where and when they feed. Janne will combine this with acoustic sampling techniques to determine whether these fish migrate vertically in the water column, and what might cause them to do so.

Aurelien, with his thesis "The population structure of roundnose grenadier in southwestern Norway", will be studying the spatial population structure of roundnose grenadier across southwestern Norway. This will involve genetic analyses of multiple fjord and oceanic populations. The aim is to answer questions of biological and evolutionary interest (What role do fjords play in the life of the species? How related are they to other populations? Have the populations diverged, and if so, why?) and management importance (At what spatial scale should roundnose grenadier be managed? Can they be sustainably harvested?).

Janne is supervised by Anne Gro Vea Salvanes from EvoFish and Jennifer Devine from the Institute of Marine Research. Aurelien is supervised by Anne Gro Vea Salvanes and Geir Dahle from the Institute of Marine Research.