Synchronicity in southern hemisphere squid stocks and the influence of the Southern Oscillation and Trans Polar Index
Squid are short lived, with highly labile populations
that respond rapidly to changes in environmental
conditions. This makes them a good model for
studying the response of recruitment processes to
environmental signals. This study examines the
influence of the Southern Oscillation Index (SOI) and
Trans Polar Index (TPI) on the environment and
abundance of six species of commercially important
squid from the southern hemisphere, all linked to
major current systems connected by the Antarctic
Circumpolar Current: Dosidicus gigas (Southeast
Pacific), Loligo vulgaris reynaudii (Southeast Atlantic),
Nototodarus sloanii, N. gouldi (Southwest Pacific),
Illex argentinus and L. gahi (Southwest Atlantic). All
fisheries displayed a high level of inter-annual variability
and a degree of synchronicity was seen to occur
in the abundance of the three Pacific species. The
SOI signal was reflected in the environment of each
fishery, particularly in Pacific regions. Both indices are
correlated with squid abundance, particularly during
the early life history stages (SOI) and adult stages
(TPI), suggesting some degree of latitudinal separation,
with juveniles potentially influenced by environmental
variability at lower latitudes and adults at
higher latitudes.