| dc.description.abstract | It is well established that biodiversity varies throughout the year, over many years and between areas, and that biodiversity plays an important role in the overall health and resilience of an ecosystem. As fisheries management moves towards a more “holistic” view, ecosystem-based fisheries management, the accurate and up-to-date status of biodiversity will be necessary for managers and scientists. Fisheries dependent data should be used carefully for biodiversity studies because of the narrow selectivity of commercial fishing gears. However, it is worth exploring the possible uses for determining trends in biodiversity of species accessible by commercial gears. This thesis explores the temporal changes in commercially harvested or catch biodiversity between two areas using similar fishing gears over several years. The fisheries dependent data were collected from the Norwegian reference fleet. To get a comprehensive overview of a complex topic like biodiversity, many measures were used including basic species richness, evenness and diversity indices and more complex species composition analyses. Overall, no difference was found between seasons of the same fishing area and no distinct trend in biodiversity through years of the same season and fishing area was detected. All measures of biodiversity found a significant difference between the two studied areas. However, the two areas used in this study are fished by different vessels, Britt Evelyn and Tramsegg, so further research is required to determine whether the differences observed are true variations in the catch biodiversity of the ecosystems or the difference between fishermen. | en_US |
