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Title: Ecology and life history of a deepwater notothenid, Dissostichus eleginoides Smitt 1989, around the Falkland Islands, SW Atlantic Ocean
Author: Brown, Judith
ISNI:       0000 0004 2704 7466
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2011
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The aim of this research was to gain a better understanding of the ecology and life history of the deepwater notothenid, Dissostichus eleginoides, on the Patagonian Shelf. Archival tagging revealed strong site fidelity of adult toothfish with the majority of fish remaining within 50km of release. Furthermore depth data revealed three behavioural patterns showing feeding, seasonal and spawning activities. The trophic ecology of five notothenioids was studied, examining resource utilisation and niche separation on the Falkland’s shelf. Spatial, ontogenic and seasonal variations in the parasite fauna for juvenile D. eleginoides are described and potential species for use as biological tags to study toothfish population structure are suggested. Validated age readings gave maximum estimated ages of 35 (L = 214.3cm) and 26 years (L = 126.3cm) for females and males respectively and reasons for this sexual dimorphism are discussed. Comparisons of otolith transition zones and growth rates from different regions shows toothfish have adapted their life history traits dependant on their environmental and hydrological surroundings, with populations in warmer areas growing quicker than those in cooler waters. Reproduction in toothfish is discontinuous and group synchronous and final spawning was found to occur in batches. Toothfish predominantly spawn only in one region around the Falklands, on the Burdwood Bank, mainly during July/August. Evidence of skipped spawning was identified indicating that not all fish spawn annually and this aspect is discussed in terms of body condition, periodic strong recruitment and the lack of large scale migrations of adult toothfish. Toothfish around the Falklands have a higher fecundity compared to other regions, a potential adaption to living north of the polar front. This new information on age, growth, reproduction and movements of toothfish, combined with its role in the Patagonian shelf and slope ecosystems, is vital for accurate stock assessment and hence sustainable fisheries management.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Patagonian toothfish