Seasonal patterns of growth, lipid deposition and lipid depletion in anadromous Arctic charr

• Published in: Journal of Fish Biology
• Main Authors: Jøsrgensen, E. H., Johansen, S. J. S., Jobling, M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1997
• Subjects: Arctic; Arctic charr
• Online Access: http://dx.doi.org/10.1111/j.1095-8649.1997.tb01668.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.1997.tb01668.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1997.tb01668.x

Seasonal patterns of growth, lipid deposition and lipid depletion were studied in anadromous Arctic charr from a north Norwegian population. Samples were collected in late May when fish were migrating between fresh water and the sea, and in mid‐July when the fish re‐entered fresh water. A sample of maturing fish captured in mid‐July was held in captivity until late September to assess lipid mobilization linked to the final stages of maturation. The fish increased substantially in weight during their 40–50‐day summer residence in sea water (immatures from c . 300 to 600 g; maturing fish from c . 500 to 800 g), and body lipid stores were increased approximately fivefold. The carcass (head, skeleton and skin) was the major lipid depot, accounting for c . 50% of the total lipid content when the fish re‐entered fresh water from the sea. The muscle of the ascending charr contained 35–40% of the body lipids, whereas the gut and liver each held 4–5%. Body lipid decreased 30–40% during the period between the re‐entry of the fish to fresh water and spawning; although lipids were depleted from all depots the carcass and muscle were quantitatively the most important. By the time of spawning, the gonads of the females held almost 25% of the body lipid, whereas in the males the gonads accounted for <3% of the total lipids. Females lost c . 80% of their body lipid during spawning and overwintering, and, consequently, the lipid depots were severely depleted by the early spring. By contrast, lipid depletion in the males amounted to 50–55% of total lipid in the same period. These data suggest that the combination of spawning and overwintering in fresh water imposes a greater load on the females than on the males. It may be that the severity of the depletion prevents females from spawning in successive years.