Premium
Vertical distribution and sexual maturation in cage‐farming of A tlantic cod ( Gadus morhua L .) exposed to natural or continuous light
Author(s) -
Skulstad Ole Fredrik,
Karlsen Ørjan,
Fosseidengen Jan Erik,
Kristiansen Tore S,
Taranger Geir Lasse,
Oppedal Frode
Publication year - 2013
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/j.1365-2109.2012.03095.x
Subject(s) - gadus , atlantic cod , biology , cage , sexual maturity , zoology , gadidae , diel vertical migration , fishery , ecology , fish <actinopterygii> , mathematics , combinatorics
The vertical distribution and seasonal timing of sexual maturation were investigated in Atlantic cod in four large commercial sea cages in Northern Norway during their second year of on‐growth. Replicate cages were exposed to either natural light ( NL ) or continuous light ( LL ) from May 2007 to January 2008. Hydro‐acoustic monitoring revealed that the cod in the NL cages were mainly distributed from 5 to 13 m depth at day while they were more dispersed and swam deeper at night. A clear ascent was observed prior to feeding events. The cod in the LL cages displayed a similar seasonal and daily pattern, but with a more dispersed vertical distribution range at both day and night. It is hypothesized that surface feeding motivation resulted in cod preferentially occupying the upper reaches of the sea cage, generally at depths < 13 m. This would also reduce the need for excessive alterations in swim bladder volume. Both the LL and the NL groups were exposed to LL the year before the study, resulting in first time sexual maturation (puberty) being delayed until the summer in both groups. However, while cod in the NL cages matured during the autumn 2007, the LL cod did not.