Skipped Spawning in Northeast Arctic Gadoids

Skipped spawning is the phenomenon whereby iteroparous spawners forego or ʻskipʼ spawning opportunities post initial sexual maturation. Unequivocally showing skipping spawning in teleosts is difficult due to the seasonal variation in gonad size and appearance and the fact that fish may mature at different ages and sizes. The presence of post ovulatory follicles (POFs) in female gonads offers conclusive evidence of past spawning activity. These follicles typically disappear shortly after spawning, but for the Northeast Artic (NEA) cod Gadus morhua and haddock Melanogrammus aeglefinus they last >> 1 year past spawning, thus offering a unique marker to establish past spawning activity. In this presentation I will demonstrate, through the detection of POFs in gonads of females not spawning the current year, frequent skipped spawning in female NEA cod and haddock. Females skipping spawning appeared to never start the annual oocyte maturation cycle, remaining on the Barents Sea feeding grounds and not undertaken the migration to the spawning areas in the Northern Norwegian sea. Skipping appeared associated with limited energy reserves, but was also more prevalent in certain age classes.