| Summary: | Age and length (i.e. composition) data are, along with abundance indices, some of the most basic yet informative data collected in fisheries science. Measurements on age and length have been collected since the study of fish and fish stocks began in the 19th century. Composition data are crucial for estimating growth, mortality, selectivity, and, in some cases, recruitment in fisheries stocks. The importance of these data to many types of fisheries models cannot be understated, and yet some of the issues associated with composition data still continue to vex models employed in fisheries. This thesis focuses on some of the issues associated with composition data in fisheries models as well as the importance of including these data in integrated assessment models. There are five chapters in this thesis; the first two focus on issues in using age and length data to estimate growth in fisheries, the third chapter describes in a novel manner the drivers for spatiotemporal growth for an important fish stock in Icelandic waters, Atlantic cod (Gadus morhua L.). The last two chapters focus on the importance of age and length data in integrated assessment models for how they impact both point estimates as well as uncertainty estimates. Overall, this thesis has advanced the understanding of composition data in fisheries models by: a) revealing new aspects to selectivity bias through aspects of growth that can enhance or increase bias, b) comparing methods to correct for selectivity bias, c) describing in a novel manner the drivers for spatiotemporal growth for an important fish stock in Icelandic waters, d) and systematically testing for the importance of age and length data in both point estimates for parameters of integrated assessment models as well as associated uncertainty estimates. Gögn um aldur og lengd fiska, ásamt vísitölum úr stofnmælingum, eru undirstöðuupplýsingar í fiskifræði. Mælingum á aldri og lengd hefur verið safnað síðan rannsóknir hófust á fiskum og fiskistofnum á nítjándu öld. Þessi gögn um aldurs- ...
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