Relation between temperature and survival of eggs and first-feeding larvae of northeast Arctic cod (Gadus morhua L.)

The spawning of northeast Arctic cod in the Lofoten area, the abundance and distribution of eggs and first feeding larvae, and their food organisms, copepod nauplii, have been monitored for a series of years. The observation that the year-class strength of northeast Arctic cod, represented by the abundance of three-year old cod, is related to the environmental temperature during the early life stages, is explained. A seasonal constancy of cod spawning, independent of temperature, is demonstrated. The spawning of Calanus finmarchicus varies up to 6 weeks between a cold and warm year. This leads to a mismatch between first-feeding cod larvae and their prey organisms in extreme warm (1960) and cold (1981) years, and a match in years with normal environmental temperatures during the early life stages.