[MARMAM] New Publication: Abundance estimation of gray whale calves from shore-based surveys.

Hector Perez hector.perez at prescott.edu
Mon May 29 11:34:01 PDT 2017

Dear colleagues from MARMAM community,

My co-authors and I are pleased to announce the following publication through Marine Mammal Science:

Pérez-Puig, H., Heckel, G. and Breiwick, J. M. (2017), Abundance estimation of gray whale (Eschrichtius robustus) calves from shore-based surveys undertaken near Ensenada, Baja California, Mexico, 2004–2006. Mar Mam Sci, 33: 593–610. doi:10.1111/mms.12401


Gray whale calf abundance was estimated from shore-based surveys near Ensenada, Baja California, during their northbound migration. Over the course of 129 effort-days (756.5 observation hours), 162 calves were counted, comprising 42, 41, and 79 calves in 2004, 2005, and 2006, respectively. To estimate the number of undetected calves during the observation periods in 2006, detection probabilities were estimated by simultaneous and independent counts using a Huggins model. The detection probabilities ranged from 0.655 to 0.997. The number of calves estimated during effort periods were divided by their estimated detection probabilities, while the total number of calves were estimated by fitting a generalized additive model (GAM) to the passage rate (whales/h) and effort (time) data. The final gray whale calf abundance estimates were 451 (95% CI = 430, 513), 253 (95% CI= 245, 308), and 442 (95% CI = 396, 510) calves for 2004, 2005, and 2006, respectively. The estimates were lower than those reported for Piedras Blancas, California, during the same years, with one possible reason being that an important number of cow/calf pairs migrate too far from shore (>10 km) to be detected from the observation site used in this research.

The article can be downloaded here: http://onlinelibrary.wiley.com/doi/10.1111/mms.12401/full. If you would like a pdf copy or have any further inquiries please email to gheckel at cicese.mx<mailto:gheckel at cicese.mx> or myself hector.perez at prescott.edu<mailto:hector.perez at prescott.edu>

Best regards,

MC. Héctor Pérez Puig.


Programa de Investigación y Conservación - Programa de Mamíferos Marinos
Centro de Estudios Culturales y Ecológicos
Prescott College A.C.
Bahía de Kino, Sonora, México.
e-mail: hector.perez at prescott.edu<mailto:hector.perez at prescott.edu>
teléfono: (01662) 242-0024.
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