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29-09-2010, 11:05 AM #1
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Detrimental effects of recent ocean surface warming on Atlantic salmon growth.
Having previously read this article in full, I was previously only able to pass on an abstract.
I found this full version earlier today: http://www.flyangler.co.uk/pdf/Detri...c%20salmon.pdf
I hope the Forum find it as interesting as I did.
Detrimental effects of recent ocean surface warming on
growth condition of Atlantic salmon
CHRISTOPHER D. TODD*, SARAH L . HUGHES, C. TARA MARSHALL, JULIAN C. MacLEAN§, MICHAEL E . LONERGAN* and E . MARTI N BIUW*
*Gatty Marine Laboratory, University of St Andrews, St Andrews, Scotland KY16 8LB, UK,
Fisheries Research Services, PO Box 101, Victoria Road, Aberdeen, Scotland AB11 9DB, UK,
School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, Scotland AB24 2TZ, UK,
§Fisheries Research Services, Freshwater Laboratory Field Station, Inchbraoch House, South Quay, Ferryden, Montrose, Scotland DD10 9SL, UK
Ocean climate impacts on survivorship and growth of Atlantic salmon are complex, but
still poorly understood. Stock abundances have declined over the past three decades and
1992–2006 has seen widespread sea surface temperature (SST) warming of the NE
Atlantic, including the foraging areas exploited by salmon of southern European origin.
Salmon cease feeding on return migration, and here we express the final growth
condition of year-classes of one-sea winter adults at, or just before, freshwater re-entry
as the predicted weight at standard length. Two independent 14-year time series for a
single river stock and for mixed, multiple stocks revealed almost identical temporal
patterns in growth condition variation, and an overall trend decrease of 11–14% over the
past decade. Growth condition has fallen as SST anomaly has risen, and for each yearclass
the midwinter (January) SST anomalies they experienced at sea correlated negatively
with their final condition on migratory return during the subsequent summer
months. Stored lipids are crucial for survival and for the prespawning provisioning of
eggs in freshwater, and we show that under-weight individuals have disproportionately
low reserves. The poorest condition fish (30% under-weight) returned with lipid stores
reduced by 80%. This study concurs with previous analyses of other North Atlantic top
consumers (e.g. somatic condition of tuna, reproductive failure of seabirds) showing
evidence of major, recent climate-driven changes in the eastern North Atlantic pelagic
ecosystem, and the likely importance of bottom-up control processes. Because salmon
abundances presently remain at historical lows, fecundity of recent year-classes will have
been increasingly compromised. Measures of year-class growth condition should therefore
be incorporated in the analysis and setting of numerical spawning escapements for
threatened stocks, and conservation limits should be revised upwards conservatively
during periods of excessive ocean climate warming.
In full: http://www.flyangler.co.uk/pdf/Detri...c%20salmon.pdf