MEPS 323:185-194 (2006)  -  doi:10.3354/meps323185

Variability in brood size and female length of Euphausia pacifica among three populations in the North Pacific

Jaime Gómez-Gutiérrez1,4,*, Leah R. Feinberg2, Tracy Shaw2, William T. Peterson3

1College of Oceanic and Atmospheric Sciences, Oregon State University, 104 Ocean Administration Building, Corvallis, Oregon 97331-5503, USA
2CIMRS, and 3NOAA/NMFS, Hatfield Marine Science Center, 2030 S Marine Science Drive, Newport, Oregon 97365, USA
4Present address: Centro Interdisciplinario de Ciencias Marinas, Instituto Politécnico Nacional, Departamento de Plancton y Ecología Marina, AP 592, CP 23096, La Paz, Baja California Sur, Mexico

ABSTRACT: We compared brood sizes among adult female Euphausia pacifica Hansen, 1911 from 3 populations in the North Pacific: Puget Sound, Washington, USA; Toyama Bay, Japan; and the Oregon coast, USA. Additionally, we used multiple linear regression models to compare the interspecific brood size as a function of female length and location. The females from Oregon attained larger brood sizes (maximum 600 eggs brood–1, mean 152 eggs brood–1) and were longer (mean length 20.1 mm) than females from the other 2 regions (means: 96 eggs brood–1 and 15.9 mm; 113 eggs brood–1 and 18.5 mm for Puget Sound and Toyama Bay, respectively). The brood size for females from the 3 populations increased with size, reaching a maximum when females attained lengths ranging from 19 to 22 mm. The brood size decreased substantially for larger individuals. When the relationship between brood size and length was corrected for differences in female length, the median brood sizes were statistically indistinguishable among the 3 regions, indicating an inherent reproductive potential probably associated with the carapace volume available for the gonads for a given female length.

KEY WORDS: Euphausia pacifica · Intraspecific scaling · Brood size · Reproductive effort · North Pacific

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