Seal & fisheries interactions

For management purposes, it is of great importance to investigate interactions between human activities and seal conservation. Previous research show that harbor seal and grey seal diet often consist of commercially important fish species harvested by human. Hence, information about the effects of seals on marine fisheries is crucial, and it is of great importance to investigate seal foraging areas and how they overlap with areas important for commercial fisheries. Further, suggestions have been made that one of the main reasons for the decline in the Icelandic harbour- and grey seal populations is by-catch in lumpsucker and cod gillnets.

In order to better understand the factors contributing to declines in Icelandic seal populations, we urgently need to increase knowledge regarding spatial and trophic interactions between seals and fisheries and also to assess the impact of environmental variability on seal foraging habitat. By using state-of-the-art biologging tags, we are the first to track the movements of grey seals in Iceland. This data will be used to quantify spatial overlap with commercial fisheries, identify important at-sea areas and undertake species distribution modelling.

In brief, movement data will initially be processed using statistical packages that allow us to integrate location error and model the most likely positions of an animal at a specific time. We will then explore seal behaviour in several ways including (1) quantifying the proportion of time each individual spends in different areas, (2) defining different behavioural states along a foraging route (e.g., transit, or foraging) using Hidden Markov models, and (3) developing species distribution models based on habitat data (bathymetry, sea surface temperature, and proxies of marine productivity). In short, our project will provide the baseline data that is necessary to understand grey seal habitat requirements and ultimately the factors contributing to population trends. Areas that are identified as important at-sea areas for grey seals will be compared to areas used for commercial fisheries.