Dear colleagues, My co-authors and I are excited to share our new paper that is available for early view in Marine Mammal Science that describes how body mass, food intake, and energy intake in northern fur seals varies with age, season, sex, and reproductive status. McHuron EA, Rosen DAS, Carpenter J, Leonard P, Sirpenski G, Sterling JT. 2022. Variation in body mass and food intake of northern fur seals (*Callorhinus ursinus*). Marine Mammal Science. https://doi.org/10.1111/mms.12919 *Abstract * Estimates of prey and energy consumption are important for effective management and conservation of marine mammals and the ecosystems they inhabit. We used routinely collected husbandry data on body mass, food intake (kilograms), and energy intake (megajoules) from northern fur seals (*Callorhinus ursinus*) in zoological institutions to examine how these variables changed throughout the year, and with age, sex, and reproduction. Fur seals exhibited seasonal changes in all three variables, but the magnitude and timing of trends varied among age and sex groups. Notably, adult males exhibited rapid increases in body mass leading up to the breeding season. Fur seals were most efficient at converting energy intake to mass gain in the spring and least efficient in the fall. Intake increased into adulthood as animals grew in body mass. Sex-specific differences in intake were detectable early in development, likely related to size dimorphism. Pregnancy was energetically inexpensive compared with lactation, with food and energy intake rapidly increasing post parturition to values that were double those during early pregnancy. This study highlights the importance of accounting for different age, sex, and life history stages when estimating prey consumption of northern fur seals. Please feel free to email me (emchuron@uw.edu) if you would like a copy and do not have access. Best, Liz McHuron Elizabeth McHuron, PhD Research Scientist, UW CICOES