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

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, whilein situbehavior of individuals constituting the SLs was resolved by a submerged echo sounder. The study focused on S...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 2008-05, Vol.360, p.201-209
Main Authors: Kaartvedt, Stein, Torgersen, Thomas, Klevjer, Thor A., Røstad, Anders, Devine, Jennifer A.
Format: Article
Language:English
Subjects:
Acoustic echoes
Animal migration behavior
Benthosema glaciale
Brackish
Fauna
Fjords
Marine ecosystems
Marine fishes
Maurolicus muelleri
Predators
Sounding
Swimming
Transducers
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Summary: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, whilein situbehavior of individuals constituting the SLs was resolved by a submerged echo sounder. The study focused on SLs made up of the lightfishMaurolicus muelleriand the lanternfishBenthosema 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 onin situbehavior of mesopelagic fish.
ISSN:0171-8630
1616-1599
DOI:10.3354/meps07364