Fisheries Research 188 (2017) 95–99 Contents lists available at ScienceDirect Fisheries Research journal homepage: www.elsevier.com/locate/fishres Gender-specific responses of mature Atlantic cod (Gadus morhua L.) to feed deprivation Tatiana N. Ageeva a,c,∗ , Malcolm Jobling b , Ragnar L. Olsen c , Margrethe Esaiassen c a Nofima AS, Muninbakken 9-13, Breivika, P.O. Box 6122, NO-9291 Tromsø, Norway b The Department of Arctic and Marine Biology, UiT The Arctic University of Norway, N-9037 Tromsø, Norway c Norwegian College of Fishery Science, UiT The Arctic University of Norway, N-9037 Tromsø, Norway a r t i c l e i n f o Article history: Received 6 September 2016 Received in revised form 5 December 2016 Accepted 12 December 2016 Handled by George A. Rose Keywords: Live-stored cod Starvation Weight loss Fillet protein Sex differences a b s t r a c t Atlantic cod (Gadus morhua L.) is one of the most important commercial fish species in Norway and the peak fishing season coincides with spawning from January to April. Live-storage of cod may extend the marketing season for fresh cod products. Cod can be held for up to 12 weeks after capture, and current regulations allow the fish to be held without feeding for four weeks. We investigated whether the response to long-term feed deprivation differed between mature males and females. The fish, caught off Andenes (Norway) in March 2015 using Danish seine, were held without feeding for 82 days, and samples were taken 2, 26, 54 and 82 days after capture. At each sampling, the weights of whole and gutted fish (head on), liver and gonads were measured. Additionally, fillet protein concentrations were analysed. Females lost total weight, gutted weight and liver mass more rapidly than males, but the reduction in gonad mass was significantly higher in males than in females. At termination, after 82 days, fillet protein concentration in males was higher (16.3% ± 0.4) than in females (14.9% ± 0.4). With regard to loss of gutted weight and reduction in muscle protein concentration, the tolerable fasting period of mature spawning Atlantic cod of good biological condition is 54 days, but this can vary depending on upon the initial condition of the fish © 2016 Elsevier B.V. All rights reserved. 1. Introduction Atlantic cod (Gadus morhua L.) is one of the most important commercial species in Norway with seasonal supplies being linked to the annual spawning cycle. Northeast Atlantic cod migrate from feeding areas in the Barents Sea to the Norwegian coast to spawn, and spawning occurs from the end of January to April/May (Nordeide and Båmstedt, 1998; Brander, 2005). Most cod are caught during the first five months of the year and the supply of fresh cod is limited for the remainder of the year. Extending the season through live-storage could create new possibilities for marketing fresh cod products. Atlantic cod display natural seasonal variations in weight and condition related to fish size, seasonal feeding patterns and spawn- ing (Fordham and Trippel, 1999; Schwalme and Chouinard, 1999; Mello and Rose, 2005), with somatic weight and condition usually decreasing during maturation and spawning. Cod is a lean fish and ∗ Corresponding author at: Muninbakken 9-13, Breivika, P.O. Box 6122, NO-9291 Tromsø, Norway. E-mail address: tatiana.ageeva@nofima.no (T.N. Ageeva). the liver is the main organ for energy storage in the form of lipids (Love, 1988). Variations in liver weight can be linked to food sup- ply (Black and Love, 1986; Jobling et al., 1991), and if the fish are deprived of food, liver lipids are mobilized and used as an energy source. Muscle tissue, primarily muscle protein, is also mobilised (Black and Love, 1986). Most Atlantic cod taken in the Norwegian coastal fisheries are caught in spring during the spawning season. Norwegian regula- tions (FOR-2004-12-22-1878, 2004) allow wild-caught fish to be held in sea cages for up to 12 weeks, with an initial four weeks without feeding. It is currently unknown what implications these regulations have for the welfare of the live fish and fillet quality after slaughter. Consequently, it is of interest to investigate changes that occur when mature cod are held without food for several weeks, and to examine whether there are gender-specific differ- ences. At present, little is known about how the nutritional status of females and males affects mobilization and utilization of energy reserves during feed deprivation. The objective of the present study was to investigate whether mature female and male Atlantic cod differ in their responses to feed deprivation during the spawning and post-spawning periods. http://dx.doi.org/10.1016/j.fishres.2016.12.010 0165-7836/© 2016 Elsevier B.V. All rights reserved.