Behavior of individual mesopelagic fish in acoustic scattering layers of Norwegian fjords

Stein Kaartvedt*, Thomas Torgersen, Thor A. Klevjer, Anders Rostad, Jennifer A. Devine

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Mesopelagic acoustic scattering layers (SLs) in 2 fjords were studied from a stationary research vessel. Diel vertical movements of SLs were assessed by hull-mounted transducers, while in situ behavior of individuals constituting the SLs was resolved by a submerged echo sounder. The study focused on SLs made up of the lightfish Maurolicus muelleri and the lanternfish Benthosema glaciale. Individual fish migrated in a pronounced stepwise manner, alternating between vertical movements and stationary phases both during ascent and descent. Mean lengths of steps varied between 2.01 and 0.40 m, and mean duration of stationary phases between 69 and 36 s for fish in different SLs. Such travel-pause behavior concords with saltatory search, where fish scan the water for prey during the stationary phases, relocate and scan a new water parcel. Little activity was recorded among individuals in deep water, apart from infrequent, short shifts in vertical distribution. This study shows that stationary submerged echo sounders can provide detailed information on in situ behavior of mesopelagic fish.

Original languageEnglish (US)
Pages (from-to)201-209
Number of pages9
JournalMarine Ecology Progress Series
Volume360
DOIs
StatePublished - May 22 2008

Keywords

  • Acoustics
  • Benthosema glaciale
  • Diel vertical migration
  • Fjords
  • Maurolicus muelleri
  • Saltatory search

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology

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