Dear MARMAM colleagues, My coauthors and I are pleased to share our recent open access publication on killer whale call detection rates in the North Pacific. Myers, H.J., Olsen, D.W., Konar, B.H., Whitney, A., Birch, K., Dugan, P., Mueter, F., Guazzo, R., Horstmann, L.H., Matkin, C.O. 2025. Killer whale call detection rates vary among ecotypes and populations in the North Pacific. *Scientific Reports*, *15*, 21072. https://doi.org/10.1038/s41598-025-06041-6 ABSTRACT: Killer whales (*Orcinus orca*) in the North Pacific have diverged into subspecies with distinct diets, social structures, and vocal behaviors. Understanding the rate at which killer whales of different subspecies vocalize provides insight into their communication with conspecifics as well as the environmental factors shaping vocalization patterns. Estimating a population’s calling rate can also enable the number of animals present to be estimated acoustically. We used killer whale dialects, long-term photo-identification records, and year-round autonomous acoustic data across multiple locations to estimate call detection rates during vocal bouts for three killer whale populations, one resident (fish-eating) and two transient (mammal-eating). We focused on call detection rates, or the number of calls detected rather than the true number produced, in order to capitalize on this large autonomous dataset to investigate the influence of spatiotemporal and social factors across many observations. Generalized additive mixed models showed that the call detection rate for southern Alaska resident killer whales was consistent across locations, seasons, which pod was calling, and the presence of other pods. Gulf of Alaska transient killer whale call detection rates differed across locations. We detected fewer, more tightly spaced discrete calls from AT1 transients than from Gulf of Alaska transients, and the mean AT1 call detection rate was stable across spatiotemporal factors. Although transients call less often than residents, we found that once vocalizing, they did so at a higher rate. These call detection rates provide novel insight into killer whale vocal behavior and can support passive acoustic group size estimation for these populations. Please do not hesitate to reach out with any questions regarding this study. Thank you, Hannah -- *Hannah Myers, PhD* Assistant Professor, Department of Fisheries College of Fisheries and Ocean Sciences University of Alaska Fairbanks 2150 Koyukuk Drive Fairbanks, Alaska 99775 hmyers8@alaska.edu