Fatty acid composition and energy allocation in muscle and gonad tissues indicate that the female mackerel icefish Champsocephalus gunnari is an income breeder.

The energy density and fatty acid composition profiles of the muscle and gonad tissues of female mackerel icefish Champsocephalus gunnari from the South Orkney Islands in Antarctica were investigated throughout ovarian development to better understand the reproductive allocation strategy and the role of specific fatty acids in the reproductive process. Energy density in gonads increased from resting to spawning stages as the ovaries developed (19.60-25.10 kJ g dry mass [DM]). In contrast, energy density in muscles remained constant throughout ovarian development (20.13-22.87 kJ g DM), suggesting that the spawning events of the C. gunnari rely on energy income from feeding rather than on the energy stored in body. In addition, the variation in fatty acid composition between muscle and gonad tissues may reflect the role of main FAs as energy source. These results suggest that C. gunnari may utilize an income breeding strategy.