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Fisheries Ecology and Aquaculture

Florian Eggers

Florian is studying the dynamics in population structure of Atlantic herring in a local brackish inland lake and adjacent water

Of particular interest in the Skagerrak area is a brackish water environment inside Landvikvannet, an inland lake in southern Norway connected to the open sea through an artificial canal. The very different environment inside and outside Landvikvannet, as well as the tidal effects on currents in the human made canal, makes the area interesting for studying potential environmental drivers in herring behavior. It is also an interesting area with regard to potential population differences in behavior and internal drivers, such as maturation status of individual fish. Here, three putative herring populations are observed to co-occur at maturing, spawning and spent stages from March to June, where one population, ‘Landvik herring’, shows high fidelity to the brackish inland lake. Besides ‘Landvik herring’, coastal Skagerrak spring spawning herring exist in neighboring fjords, without conducting large annual migrations like those of Norwegian spring spawning herring, which are also found here. Norwegian spring spawners occur in this area mostly in March before starting their annual migration. ‘Landvik herring’ differs totally from other occurring populations, both phenotypically and genetically.

 

The project aims mainly to increase the understanding of population structure in Atlantic herring in particular with main focus on Landvikvannet and adjacent waters. As a continuation of his Master thesis project and on the basis of two published papers the overall goal of this project is both to quantify the previous found results and increase the knowledge of the life-time history of ‘Landvik herring’, beginning at egg and larval stages up to mature and spawning adult herring. The results may have implications in management and conservation, as local fish populations may play an important role in fisheries and they are also highly vulnerable.