Abstract
Despite a substantial commercial fishing pressure, Nephrops norvegicus production remains high, and the question is what supports this production ? A major source of subsidies to marine systems origin from fishing, as unwanted catch is routinely thrown back to the sea, so-called discard. Commercial fishing has been estimated to produce 27 million tonnes of discard worldwide and in traditional Swedish Nephrops trawl fisheries 70-80% of the catches are discarded. The primary goal of this project is to quantify the importance of discarded biomass as subsidy to Nephrops fishing grounds. The objective is to quantify both direct and indirect effects of discarded by-catch under as close to natural conditions as possible in the field and in laboratory mesocosms experiments. The direct effect of discard on Nephrops is its importance as food source. Utilisation rate may however be modified by: Nephrops population density, the presence of other scavengers (including fish) or the spatial distribution, quantity or quality (nutritional value) of the discard itself. In addition, discard may indirectly have an impact on Nephrops through effects on the macrofaunal benthic community and sediment chemistry. The relationship of these potential effects may in turn vary with the habitats exposure to physical disturbance (trawling). This project will give us a basic understanding of the consequences of discard in Nephrops habitats, and how this links in with Nephrops production.
Sweden