Fish stock assessment and harvest quota

We develop methods for assessing stocks and setting harvest quotas for fish and marine mammals, promoting sustainable use of marine resources.

The image shows a fish farm in Northern Norway and a boat passing by. In the background a mountainous coastline is visible. — *Fish farming is an important industry in Norway. Here seen in Astafjorden in Troms and Finnmark.* Image: Ximonic / Wikimedia Commons.

Ensuring sustainable fisheries

Knowledge of the current status of a fish stock is crucial for a sustainable fishery. Overestimation of the abundance of a fish stock can give too high quotas and thus overfishing and possibly extinction of the stock. On the other hand, unnecessarily low quotas result in poor utilisation of an important resource.

Population models to estimate fish abundance

Data is collected for the most important fish stocks and marine mammals, such as seals and whales. The data includes surveys with echosounders, and trawling and sampling from commercial catches. These are then used in a population model to estimate the fish and mammal abundance within each age.

We are developing new models for stock assessments and harvest quota, and enhancing previous methods. This includes modelling errors in age readings and interpretation of echosounder signals, combining age and length data and spatial modelling over an area. We are also refining the population models, specifically looking at how they are used to set fishing quotas.

We also participate in international working groups organised by the International Council for the Exploration of the Sea (ICES).