Patterns in the distribution of myctophid fish in the northern Scotia Sea ecosystem
The mesopelagic fish community of the northern
Scotia Sea was investigated during the austral autumn
using multi-frequency acoustics, opening and closing nets
and pelagic trawls fished from the surface to 1,000 m. The
Family Myctophidae (15 species in 5 genera) dominated
the ichthyofauna, with larval notothenids caught over the
South Georgia shelf and bathylagids and stomiids abundant
in deeper hauls. The biomass of myctophids was estimated
to be 2.93 g wet weight 1,000 m-3, with Electrona carlsbergi,
E. antarctica, Protomyctophum bolini, P. choriodon,
Gymnoscopelus braueri, G. fraseri, G. nicholsi and Krefftichthys
anderssoni, being the most abundant species.
Analysis of community structure indicated a high level of
depth stratification within the myctophids, with evidence of
diurnal vertical migration in some, but not all, species.
Length-frequencies of G. braueri, G. nicholsi, E. antarctica
and K. anderssoni were multimodal, suggesting that all
life stages may be present in the northern Scotia Sea. In
contrast, P. choriodon, P. bolini, G. fraseri and E. carlsbergi
had unimodal distributions despite having multi-year
lifecycles, indicating that they probably migrate into the
region from warmer areas to the north.
Authors: Collins, M A, Xavier, J C C, Johnston, N M, North, A W, Enderlein, P, Tarling, G A, Waluda, C M, Hawker, E J, Cunningham, N J