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Marine Ecology Progress Series

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MEPS 341:141-152 (2007)  -  doi:10.3354/meps341141

Long-term laboratory observations of Euphausia pacifica fecundity: comparison of two geographic regions

Leah R. Feinberg1,*, C. Tracy Shaw1, William T. Peterson2

1Cooperative Institute for Marine Resources Studies, and 2NOAA/NMFS, Hatfield Marine Science Center, 2030 S. Marine Science Drive, Newport, Oregon 97365, USA

ABSTRACT: We tested the assumption that female Euphausia pacifica produce multiple broods of eggs during their spawning season by maintaining individual females under laboratory conditions at 10.5°C and comparing the egg production of females collected from 2 populations, 1 from Heceta Bank off central Oregon (44°N, n = 27 individuals), and the other from waters near Santa Barbara, California (34°N, n = 12 individuals). We documented the production of multiple, distinct broods by daily observation of females over periods from 1 to 9 mo. Median brood sizes were not significantly different between regions: 102 eggs for females from Heceta Bank and 116 eggs for females from Santa Barbara. Median interbrood period (IBP) was significantly different: 4 d for Santa Barbara females and 5 d for Heceta Bank females. Brood size and IBP were highly variable within and among individuals. The total number of eggs produced female–1 in the experiment ranged from 378 to 8600, and IBPs ranged from 1 to 79 d. A brood of eggs represented an average of 9% of the female’s weight in carbon, equivalent to 0.5 to 6% of body weight d–1 (average of 1.7% d–1).

KEY WORDS: Euphausia pacifica · Fecundity · Interbrood period · Brood size

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