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Title: Settlement ecology of juvenile cod Gadus morhua, haddock Melanogrammus aeglefinus and whiting Merlangius merlangus
Author: Demain, Dorota K.
ISNI:       0000 0004 2700 508X
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2010
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Cod, haddock and whiting are among the most economically important species in the Scottish demersal fishery. Juvenile settlement, the transition from pelagic to demersal habitat, has been identified as an important milestone for these species, but there is insufficient knowledge and data about this life stage. It is believed that the period of settlement has an impact on recruitment success, as important density-dependent processes may take place, such as competition for suitable substrate, refuge or prey. Also, knowledge of settlement timing and duration is relevant to understanding population connectivity and thus to the development of successful conservation measures. Sampling was conducted between April and August 2004, June and September 2005 and June and July 2006 at an inshore site off the east coast of Scotland. Over 4000 0- group cod, haddock and whiting were collected. Comprehensive morphometric and dietary analyses of the samples were carried out, followed by statistical analysis of the data. The results suggested clear differences in the patterns of settlement between the different species. Initially juvenile haddock favoured deeper, further offshore locations, while cod occupied shallower, inshore waters. Whiting settled much later in the season and over protracted period of time. Furthermore, cod showed an affinity for structured habitat, while haddock and whiting were found only over sand. The results also showed that the transition from the pelagic to the demersal habitat was associated with clear and progressive changes in the prey composition of the juvenile fish. The results also showed temporal, spatial and dietary niche segregation of settling juveniles, which is expected to reduce competition for resources and increase the potential for settlement success.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Cod fisheries ; Haddock fisheries ; Whiting (Fish) ; Aquaculture ; Ecology