Dear MARMAM community, My co-authors and I are pleased to announce the publication of our new manuscript in Marine Ecology Progress Series.
Hildebrand, L., Sullivan, F.A., Orben, R.A., Derville, S., & Torres, L.G. (2022). Trade-offs in prey quantity and quality in gray whale foraging. Marine Ecology Progress Series 695:189-201. doi.org/10.3354/meps14115 Abstract To forage optimally, predators face complex decisions regarding target prey distribution, quantity, and quality. We paired theodolite tracking of gray whales *Eschrichtius robustus* in Port Orford, Oregon, USA, with concurrent sampling of their zooplankton prey to examine foraging decisions relative to prey quantity (abundance) and quality (caloric content). We tested the hypotheses that whales (1) feed more than search or transit in areas with high quantity and quality prey and (2) select foraging habitat dominated by the calorically rich mysid *Neomysis rayii*. Relative prey abundance was assessed through standardized image analysis of camera drops, and zooplankton prey community was determined from net tows. These data were spatially interpolated and modeled to generate daily layers of species-specific prey abundance and calories (20 m grid) for comparison to whale behavior derived from tracking data. Whales fed significantly more in areas with higher prey abundance and calories than where they searched and transited. Whales increased foraging effort as overall prey availability increased, yet foraging probability was significantly correlated with the quantity and quality of the mysid *Holmesimysis sculpta*, which has significantly lower calories than *N. rayii*. However, during the study period, the maximum abundance of *N. rayii* was 4 times lower than that of *H. sculpta* and never reached the quantity threshold determined by a logistic regression needed to support whale foraging behavior. Hence, gray whale prey selection involves trade-offs between prey quantity and quality to maximize energetic gain, and prey quality should be considered alongside abundance in ecological studies investigating predator decision-making. Please contact lisa.hildebr...@oregonstate.edu if you would like a copy of the manuscript or if you have any questions. Best regards, Lisa -- Lisa Hildebrand, M.S. (she/her/hers) PhD Student Geospatial Ecology of Marine Megafauna Lab <https://mmi.oregonstate.edu/gemm-lab> Marine Mammal Institute and Dept. of Fisheries, Wildlife, & Conservation Sciences Oregon State University MMI Profile <https://mmi.oregonstate.edu/people/lisa-hildebrand> | GEMM Lab Blog <http://blogs.oregonstate.edu/gemmlab/> *Land Acknowledgement:* Oregon State University in Corvallis, OR is located within the traditional homelands of the Mary's River or Ampinefu Band of Kalapuya. Following the Willamette Valley Treaty of 1855 (Kalapuya etc. Treaty), Kalapuya people were forcibly removed to reservations in Western Oregon. Today, living descendants of these people are a part of the Confederated Tribes of Grand Ronde Community of Oregon ( https://www.grandronde.org) and the Confederated Tribes of the Siletz Indians (https://ctsi.nsn.us).
_______________________________________________ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
