Spatial variability in size and lipid content of the marine copepod Calanus finmarchicus across the Northwest Atlantic continental shelves: implications for North Atlantic right whale prey quality

Laura K Helenius; Erica J H Head; Phoebe Jekielek; Christopher D Orphanides; Pierre Pepin; Geneviève Perrin; Stéphane Plourde; Marc Ringuette; Jeffrey A Runge; Harvey J Walsh; Catherine L Johnson

doi:10.1093/plankt/fbad047

Spatial variability in size and lipid content of the marine copepod Calanus finmarchicus across the Northwest Atlantic continental shelves: implications for North Atlantic right whale prey quality

J Plankton Res. 2023 Dec 9;46(1):25-40. doi: 10.1093/plankt/fbad047. eCollection 2024 Jan-Feb.

Affiliations

¹ Fisheries and Oceans Canada, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, NS B2Y 4A2, Canada.
² School of Marine Sciences, University of Maine, 5706 Aubert Hall, Orono, ME 04469-5706, USA.
³ NOAA, NMFS, Northeast Fisheries Science Center, 28 Tarzwell Drive, Narragansett, RI 02882, USA.
⁴ Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, P.O. Box 5667, St. John's, NL A1C 5X1, Canada.
⁵ Fisheries and Oceans Canada, Institut Maurice-Lamontagne, P.O. Box 1000, Mont-Joli, QC G5H 3Z4, Canada.

Abstract

Copepod size and energy content are influenced by regional and seasonal variation in temperature and food conditions, with implications for planktivorous consumers such as the endangered North Atlantic right whale (Eubalaena glacialis). Historical data (1990-2020) on Calanus finmarchicus stage CV copepodite prosome length and oil sac metrics were analyzed to determine the extent of variation in individual body size and estimated lipid and energy content in five regions of the Northwest Atlantic continental shelves [Gulf of Maine (GoM), Scotian Shelf (SS), Gulf of St. Lawrence (GSL), St. Lawrence Estuary (SLE) and Newfoundland Shelf]. Large-scale spatial patterns in size and lipid content were related to latitude, indicating that C. finmarchicus CV in the GSL and SLE were historically larger in body size, and had significantly higher lipid content compared with those in the GoM and the SS. The observed patterns of C. finmarchicus CV size and lipid storage capacity suggest that regional variation in whale prey energy content can play a role in the suitability of current and future whale foraging habitats in the Northwest Atlantic, with the larger lipid-rich individuals in the GSL providing a high-quality diet compared with those in southern areas.

Keywords: calanoid; energy content; oil sac.