Summary: MARINE ECOLOGY PROGRESS SERIES
Mar Ecol Prog Ser
Vol. 325: 181186, 2006 Published November 7
The mesopelagic fishes Benthosema glaciale and
Maurolicus muelleri are dominant planktivores in
deep, western Norwegian fjords (Kristoffersen 1999,
Salvanes 2001, Aksnes et al. 2004). The fjord basins,
extending from sill depth down to the bottom, make up
the main part of their habitat (Salvanes 2001, 2005).
The 2 species have been intensively studied in Mas-
fjorden, western Norway (reviewed by Salvanes 2001),
where they position themselves vertically according to
the ambient light level (Baliņo & Aksnes 1993) and
conduct extensive diel migrations (Kaartvedt et al.
1996, 1998), suggesting that light is an important cue
for their life history decisions. This observed sensitivity
to water column optics initiated studies on the optical
properties of the basin water in Lurefjorden and Mas-
fjorden, 2 contrasting pelagic ecosystems (Eiane et al.