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

• Published in: Marine ecology. Progress series (Halstenbek) 2007-01, Vol.341, p.141-152
• Main Authors: Feinberg, LR, Shaw, CT, Peterson, WT
• Format: Article
• Language: English
• Subjects: Euphausia pacifica; Marine
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps341141

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 degree C and comparing the egg production of females collected from 2 populations, 1 from Heceta Bank off central Oregon (44 degree N, n = 27 individuals), and the other from waters near Santa Barbara, California (34 degree 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 super(-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 super(-1) (average of 1.7% d super(-1)).