Journal of Oceanography

, Volume 62, Issue 5, pp 693–703 | Cite as

Diel vertical migration of Euphausia pacifica (crustacea, euphausiacea) in relation to molt and reproductive processes, and feeding activity

  • Yoshinari EndoEmail author
  • Fuhito Yamano
Original Articles


We investigated the diel vertical migration of Euphausia pacifica in relation to molt and reproductive processes and feeding activity in April and September 2001 at fixed stations off northeastern Japan. The vertical distribution of this species was shallower in April than in September during both day and night, which was partly explained by a high surface temperature (19°C) and the existence of a subsurface chlorophyll maximum in September. It has been demonstrated for the first time that diel vertical migration of this species is influenced by molt processes because upward migration of molting individuals was restricted compared with non-molting ones. Feeding activity of molting individuals was reduced throughout the day, being lower than or similar to the daytime feeding activity of non-molting ones. The percentage of molting individuals was least (2–4%) among the gravid females, which suggests that gravid females molt less frequently than other stages of females and males. Molt and reproductive processes therefore seemed to be coupled in this species.


DVM molt cycle maturity feeding Euphausia pacifica 


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Copyright information

© The Oceanographic Society of Japan/TERRAPUB/Springer 2006

Authors and Affiliations

  1. 1.Laboratory of Aquatic Ecology, Graduate School of Agricultural ScienceTohoku UniversitySendaiJapan

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