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| The consequence of elevated ocean temperatures on
commercial fish stocks is addressed using time series of
commercial landings (1906–2004) and juvenile survey
catch data (1904–2006) collected around Denmark.
We analyze (i) whether warm-water sole (Solea solea)
has increased relative to Boreal plaice (Pleuronectes
platessa) and (ii) whether two related warm-water species
(turbot, Psetta maxima and brill, Scophthalmus
rhombus) show similar responses to increasing temperature
or, alternatively, whether turbot (which has a
broader juvenile diet) has been favored. Since the
early 1980s, both sole and turbot have constituted an
increasing part of the commercial landings and survey
catches, as compared with plaice and brill, respectively.
These changes in species composition were
linked to sea surface temperatures, Northern Hemisphere
temperature anomalies (NHA) and the North
Atlantic Oscillation. NHA was closely related and
explained 43% of the observed variation in sole survey
catches relative to the plaice catches and almost 38%
of the observed variation in the sole landings relative
to the plaice landings. For the less common species,
turbot and brill, none of the global change indicators
explained more than 15% of the variation, although
all showed a positive relationship. Survey catch per
unit effort increased significantly for both sole and turbot
around the early 1980s, whereas catch per unit
effort for plaice and brill remained constant. The
results indicate that the abundance of warm-water species
is likely to increase with increasing temperature
but also that species with similar life histories might
react differently according to degree of specialization. | |
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