Ecological Archives C006-045-A1
S. Villegas-Amtmann, L. K. Schwarz, J. L. Sumich, and D. P. Costa. 2015. A bioenergetics model to evaluate demographic consequences of disturbance in marine mammals applied to gray whales. Ecosphere 6:183. http://dx.doi.org/10.1890/es15-00146.1
Appendix A. Duration of calf stages (Ts).
To determine the duration a calf spent in each stage, we assumed a mean birth date of January 27 (Rice et al. 1981, Withrow 1983, Jones and Swartz 1986) and a mean lagoon stay duration of three months for females with calves. Therefore calf ages utilized to estimate their FMR at breeding lagoons were 0–2 months old (Withrow 1983, Jones and Swartz 1986, Sumich 1986). We assumed an estimated lagoon departure date of May 1st (Pike 1962, Rodriguez de la Gala-Hernandez et al. 2008), and an arrival at foraging grounds of female/calf pairs on July 19th (Pike 1962, Rodriguez de la Gala-Hernandez et al. 2008) when calves are 5.7 months old. Hence calves’ FMR during northbound migration were estimated at 3–5 months old. Lastly, we assumed a mean lactation duration of 7 months, and estimated calves’ FMR at the foraging grounds when they are 5.7 and 6.5 months old (Tomilin 1957, Rice and Wolman 1971, Weller et al. 1999, Vladimirov et al. 2006).
Literature Cited
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Pike, G. C. 1962. Migration and feeding of the gray whale (Eschrichtius gibbosus) Journal of the Fisheries Research Board of Canada 19:815–838.
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Rice, D. W., A. A. Wolman, A. A. Withrow, and L. Fleischer. 1981. Gray whales on the winter grounds in Baja California. International Whaling Commission 31:477–493.
Rodriguez de la Gala-Hernandez, S., G. Heckel, and J. L. Sumich. 2008. Comparative swimming effort of migrating gray whales (Eschrichtius robustus) and calf cost of transport along Costa Azul, Baja California, Mexico. Canadian Journal of Zoology 86:307–313.
Sumich, J. L. 1986. Latitudinal distribution, calf growth and metabolism, and reproductive energetics of gray whales, Eschrichtius robustus. Dissertation. Oregon State University, Corvallis, Oregon, USA.
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Vladimirov, V. A., S. A. Blokhin, A. V. Vladimirov, M. K. Maminov, S. P. Starodymov, and E. P. Shvetsov. 2006. The distribution and abundance of gray whales of the Okhotsk-Korean population in the waters of northeastern Sakhalin Island during June-November 2005 (based in data from onshore, aerial and vessel-based surveys). Yuzhno-Sakhalinsk, Russia. http://www.sakhalinenergy.com/media/86553e62-aba7-4bc6-8df2-13d7f4a64659.pdf
Weller, D. W., B. Wursig, A. L. Bradford, A. M. Burdin, S. A. Blokhin, H. Minakuchi, and R. L. Brownell. 1999. Gray whales (Eschrichtius robustus) off Sakhalin Island, Russia: seasonal and annual patterns of occurrence. Marine Mammal Science 15:1208–1227.
Withrow, D. E. 1983. Gray whale research in Scammon's Lagoon (Laguna Ojo de Liebre). Cetus 5:8–13.