An investigation of key processes affecting trophic interactions in the North Sea fish assemblage and their significance for multi species fisheries assessment
In this Ph.D. thesis, diet selection and predator-prey overlap were studied as the key processes affecting trophic interactions in the North Sea fish assemblage. As the investigation of the significance of these processes for multi species fisheries assessment in the North Sea was an important appli...
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky
2005
|
| Subjects: | |
| Online Access: | http://nbn-resolving.de/urn:nbn:de:gbv:18-25584 https://ediss.sub.uni-hamburg.de/handle/ediss/1034 |
| Summary: | In this Ph.D. thesis, diet selection and predator-prey overlap were studied as the key processes affecting trophic interactions in the North Sea fish assemblage. As the investigation of the significance of these processes for multi species fisheries assessment in the North Sea was an important applied aspect of the study, the analyses focused on commercially important fish species. This thesis is structured in six chapters, that correspond to manuscripts for publications, preceded by an introduction and secluded by a chapter on conclusions and perspectives. In the first manuscript “Explaining diet composition of North Sea cod (Gadus morhua L.): prey size preference vs. prey availability”, the nature and significance of size preference for fish prey in the diet selection of North Sea cod was analysed. The second manuscript “Analysis of prey size preference of North Sea whiting, saithe and grey gurnard” extended the first by investigating the size preference for fish prey of North Sea whiting, saithe and grey gurnard predators and relating the results to optimal foraging theory. In the third manuscript “Grey gurnard (Eutrigla gurnadus (L.)) in the North Sea: an emerging key predator ?“ the influence of grey gurnard on cod and whiting stock dynamics was investigated. In the fourth manuscript “Distribution of North Sea fish in relation to hydrographic fronts - Investigating predator-prey overlap” a spatially resolved estimate of the total North Sea fish biomass in the 3rd quarter of the years 1991 - 1997 was derived. In the fifth manuscript “Recruitment of North Sea whiting (Merlangius merlangus (L.)): the interplay of bottom - up and top - down processes”, the significance of spatial predator - prey overlap and diet selection for multi species fisheries assessment was assessed by developing a whiting recruitment model that takes these processes explicitly into account. In the sixth manuscript “Feeding hot spots” - Investigating local predation impacts of whiting on the survival of juvenile North Sea cod” the ... |
|---|