Critical factors determining harp seal reproduction

Since 2009, the harp seal (HS) trade in Russia has ceased; however, pup production in the White Sea population remains low. Published data on HS nutrition, the energy expenditure on reproduction, and the state of the food supply are reviewed to identify the causes of low pup production. It has been shown that GT females, like all representatives of the pinniped order, have high costs for offspring. To successfully reproduce, females must gain over 85% of their body weight. The high costs of HS reproduction place high demands on the provision of food resources for breeding females. A critical factor for HS females, ensuring successful pup production, is the abundant generations of spawning capelin. Intense food competition for capelin with abundant generations of Atlantic cod reduces the ability of HS females to successfully prepare for reproduction. It was also shown that the cessation of the GT fishery caused a change in the intrapopulation structure, population aging, and an increase in the proportion of K-strategists, which also reduces the population’s reproductive potential.