The distribution of Helicocranchia pfefferi from Hawaiian waters is shown on the right. There is a clear pattern of ontogenetic descent with squid occurring in progressively deeper water as they get larger. Diel vertical migration does not seem to occur in this species. The dominance of nighttime captures for young stages is a result of the low sampling effort in shallow depths during the daytime and doesn't indicate the daytime absence of small squid at these depths.
Figure. Vertical distribution chart of H. pfefferi, Hawaiian waters. Captures were made with both open and opening/closing trawls. Bars- fishing depth-range of opening/closing trawl. Circle- Modal fishing depth for either trawl. Blue-filled circles- Night captures. Yellow-filled circles- Day capture. Chart modified from Young (1978).
In the Atlantic Lu and Clarke (1975) show a similar vertical distribution pattern for Helicocranchia pfefferi. Most captures at less than 30 mm ML were made between 100 and 200 m. Around 30 mm ML an ontogenetic descent began although their largest specimen (49 mm ML) was taken between 300 and 400 m. Presumably the size/depth trend would continue for larger individuals.
Species occur throughout the world's tropical and subtropical oceans and, in the Atlantic Ocean, in north temperate waters (Voss, 1992).
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