Small pelagics are suitable candidates to identify regime shifts in fish
stocks. They respond rapidly to ocean climate changes, specifically with
a fast growth and early maturation in warm waters. This work examines
landings data of small pelagics over a 40-year period (1980-2019), and
auction and laboratory data of two species (Scomber colias and Trachurus
picturatus) from Madeira (NE Atlantic Ocean). Integrated data on Sea
Surface Temperature Anomaly (SSTA) and North Atlantic Oscillation (NAO)
is also discussed. General Additive Models (GAMs) showed that a regime
shift occurred in 2002, within a 2000-2003 transition period. SSTA and
NAO data explained up to 88.2% of the community shift.
Temperature-driven changes are not limited to a decrease of landings but
also to a low gonadosomatic index (GSI) and first maturity size, as well
as an increase in natural mortality of both species. This trend was
relentless despite the implemented stock management actions. An urgent
need to consider ocean warming in the management of fish stocks is
required.
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