Lipoprotein lipase in lactating and neonatal northern fur seals: exploring physiological management of energetic conflicts

Otariid lactation and neonatal growth are cyclical processes tied to maternal foraging and nursing patterns (i.e. at sea and on land). Both mother and pup undergo repeated shifts from a positive to a negative energy balance, the physiological mechanisms of which are unclear. We measured plasma and tissue lipoprotein lipase (LPL) in free-ranging northern fur seal mother-pup pairs throughout the first month of lactation. Plasma LPL levels were similar in lactating females (11.3–15.9 U) and growing neonates (8.2–15.2 U). Mammary LPL activity was variable, but highest during the attendance period (3.1 U), while maternal blubber LPL was consistently low (