The Food Intake of Iceland Cod (Gadus morhua) over the Summer Seson

• Main Author: Viðar Engilbertsson 1988-
• Other Authors: Háskóli Íslands
• Format: Thesis
• Language: English
• Published: 2012
• Subjects: Líffræði; Þorskur; Fæðuöflun dýra; Kring; Gadus morhua; Iceland
• Online Access: http://hdl.handle.net/1946/11875

From the beginning of fish research in Iceland, great interest has been drawn to the food intake of Iceland Cod (Gadus morhua). The importance of dietary studies is to reveal the predator-prey relationship which can provide deeper understanding of the marine ecosystem. Stomach samples were collected on fishery trawlers from three areas around Iceland over the 2010 and 2011 summer seasons. A total of 1249 cod stomachs collected. The samples were categorized to species, counted, weighted and measured for size when possible. The hypothe-sis to be tested included: a) no relationship between cod size and diet and b) no difference in food composition between areas. The results showed that fish composition did vary with cod length where the proportion of fish in the diet increased as the cod increased in size. This was especially pronounced among cod greater then 60-70 cm. Also the composition of the cod’s diet differed substantially between the three geographical areas. This was likely due to differ-ence in availability of preys among the different areas. For example, capelin was present in high numbers in area 1 but not in areas 2 and 3. The most common fish species in cod´s diet were capelin, herring, blue whiting and sandeel. Fish count for 70%-90% of cod´s dietary composition and the remaining diet consisted primarily of crustaceans. Áhugi hefur verið fyrir þekkingu á fæðunámi þorsks (Gadus morhua) allt frá upphafi fiskirannsókna á Íslandi. Mikilvægi fæðurannsókna felst í að efla vitneskju um samband milli afræningja og bráðar sem getur gefið dýpra innsæi við rannsóknir á vistkerfi sjávar. Magasýnum var safnað um borð í ísfrystitogurum á þrem svæðum í kring um Ísland að sumarlagi árin 2010 og 2011. Alls var safnað 1249 sýnum. Sýnin voru greind til tegunda, talin, þyngdarmæld og lengdarmæld þegar við átti. Tvær tilgátur voru prófaðar sem voru a) enginn munur á milli lengdar þorsks og fæðusamsetningar og b) enginn munur á fæðusamsetningu þorsks milli svæða. Niðurstöður úr fæðugreiningu voru í samræmi við fyrri ...