Dietary comparison of two Hawaiian monk seal populations: the role of diet as a driver of divergent population trends

Abstract

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 20:137-146 (2013) - DOI: https://doi.org/10.3354/esr00491 Dietary comparison of two Hawaiian monk seal populations: the role of diet as a driver of divergent population trends M. K. Cahoon1,*, C. L. Littnan2, K. Longenecker3, J. R. Carpenter4 1Joint Institute for Marine and Atmospheric Research, 1000 Pope Road, Honolulu, Hawaii 96822, USA 2Pacific Islands Fisheries Science Center, National Marine Fisheries Service, NOAA, 1601 Kapiolani Boulevard, Honolulu, Hawaii 96814, USA 3Bishop Museum, 1525 Bernice Street, Honolulu, Hawaii 96817, USA 4Department of Human Nutrition, Food and Animal Sciences, University of Hawaii at Manoa, 1955 East West Road, Honolulu, Hawaii 96822, USA *Email: maire.cahoon@noaa.gov ABSTRACT: Divergent trends in population abundance of Endangered Hawaiian monk seals Monachus schauinslandi are apparent between the northwestern Hawaiian Islands (NWHI) and the main Hawaiian Islands (MHI). The smaller, recently established MHI seal population is increasing, exhibits higher juvenile survival, and seals appear to be in better condition overall relative to seals in the NWHI. Using traditional dietary analysis we characterize the diet of MHI monk seals for the first time and examine the hypothesis that diet and prey availability may be driving these regional trends. Prey remains from feces and regurgitates (n = 120) were identified to the lowest possible taxonomic level and compared with results from NWHI historical data. The most common prey taxa, by percent frequency of occurrence, were Balistidae (48.3%), Crustacea (37.5%), Acanthuridae (32.5%), Muraenidae (30.8%), Serranidae (20.8%), Cephalopoda (18.3%), Holocentridae (17.5%), Labridae (16.7%), and Scaridae (10.8%). Results indicate that MHI and NWHI seals eat similar diets; however, an incongruity in body conditions of seals between regions indicates a possible difference in intra- or inter-specific competition, prey availability, and quality. Further research assessing foraging behavior and habitat use would aid in identifying the regional differences observed. KEY WORDS: Monachus schauinslandi · Fecal prey remains · Diet assessment · Hawaiian Islands Full text in pdf format PreviousNextCite this article as: Cahoon MK, Littnan CL, Longenecker K, Carpenter JR (2013) Dietary comparison of two Hawaiian monk seal populations: the role of diet as a driver of divergent population trends. Endang Species Res 20:137-146. https://doi.org/10.3354/esr00491 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 20, No. 2. Online publication date: April 23, 2013 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2013 Inter-Research.