The abundance of wild salmon (Salmo salar) in the North Atlantic has declined markedly since the late 1980s as a result of increased marine mortality that coincided with a marked rise in sea temperature in oceanic foraging areas. There is substantial evidence to show that temperature governs the growth, survival, and maturation of salmon during their marine migrations through either direct or indirect effects. In an earlier study (2003), long-term changes in three trophic levels (salmon, zooplankton, and phytoplankton) were shown to be correlated significantly with sea surface temperature (SST) and northern hemisphere temperature (NHT). A sequence of trophic changes ending with a stepwise decline in the total nominal catch of North Atlantic salmon (regime shift in similar to 1986/1987) was superimposed on a trend to a warmer dynamic regime. Here, the earlier study is updated with catch and abundance data to 2010, confirming earlier results and detecting a new abrupt shift in similar to 1996/1997. Although correlations between changes in salmon, plankton, and temperature are reinforced, the significance of the correlations is reduced because the temporal autocorrelation of time-series substantially increased due to a monotonic trend in the time-series, probably related to global warming. This effect may complicate future detection of effects of climate change on natural systems.
- Climate change
- North Atlantic
- northern hemisphere temperature
- regime shift
- sea surface temperature
- REGIME SHIFT
- WATER TEMPERATURE
[Reid, Philip C.] Sir Alister Hardy Fdn Ocean Sci, Plymouth PL1 2PB, Devon, England; [Reid, Philip C.] Univ Plymouth, Inst Marine, Plymouth PL4 8AA, Devon, England; [Reid, Philip C.] Marine Biol Assoc UK, Plymouth PL1 2PB, Devon, England; [Beaugrand, Gregory] Univ Sci & Technol Lille, CNRS, F-62930 Wimereux, France
Reid, PC (reprint author), Sir Alister Hardy Fdn Ocean Sci, Plymouth PL1 2PB, Devon, England.