Long-term trends in pelagic fish stocks of the North Sea and adjacent waters and their possible connection to hydrographic changes

Corten, A.

doi:10.1016/0077-7579(90)90024-b

Cited by 59 publications

(44 citation statements)

References 4 publications

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“…Similarly, Becker & Pauly (1996) noted that the spatial extent of the northern Atlantic inflow (characterised by the 35 psu isohaline) appeared to be limited in the northern North Sea during years with negative temperature anomalies (particularly in the late 1970s). Corten (1990) and Corten & van de Kamp (1992) suggested that most of the observed changes in the pelagic fish stocks in the North Sea (particularly the dramatic decline of herring in the late 1970s) could be explained by a reduction of Atlantic water and changes to the circulation of the North Sea during this period. For example, the spawning stock was 50 000 t in 1977 compared to an estimated 1 400 000 t in 1990.…”

Section: Resultsmentioning

confidence: 99%

“…Other evidence of chemical change was described by Dooley et al (1984) who reported that the different water masses passing through the Rockall Channel in the late 1970s had very different chemical properties (particularly silicate). Corten (1990) and Turrell et al (1996) suggested that the circulation changes in the North Sea, rather than the direct effect of variations in temperature and salinity, caused the ecological changes (particularly pelagic fish stocks) seen in the North Sea during the late 1970s.…”

Section: Resultsmentioning

confidence: 99%

“…The period in the late 1970s and early 1980s was anomalous in the North Sea, characterised by reduced salinities and temperatures caused primarily by the unusual hydroclimatic conditions and a change in the overall North Atlantic current dynamics. In the North Sea during the late 1970s, there was an initial reduction in inflow of Atlantic water, which was followed by a salinity anomaly and changes to the circulation of the North Sea (Corten 1990, Turrell et al 1992. A reduction in the inflow of generally warmer North Atlantic current waters and the arrival of the GSA in the North Sea would have conspired together to produce a cold-boreal climate within the North Sea.…”

Section: Discussionmentioning

confidence: 99%

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Ocean climate anomalies and the ecology of the North Sea

Edwards

Beaugrand²,

Reid³

et al. 2002

Mar. Ecol. Prog. Ser.

205

137

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Long-term changes in the plankton of the North Sea are investigated using data from the continuous plankton recorder (CPR) survey. During the last 4 decades, there appears to have been 2 large anomalous periods within the plankton data set, one that occurred in the late 1970s and the other in the late 1980s. These anomalous periods seem to be largely synchronous with unusual ocean climate conditions that have occurred episodically over a timescale of decades. The unusual ocean climate conditions prevailing at these 2 time periods appear to contain important hydrographical elements that involve oceanic incursions into the North Sea. This paper, using data from the CPR survey and providing evidence from other studies, focuses on the relationship between the long-term changes in the biology of the North Sea and these 2 exceptional hydro-climatic events. Here, we suggest that while atmospheric variability and associated changes in regional temperatures have a dominant effect on the marine environment, oceanic influences on the ecology of a semi-closed environment such as the North Sea may have been underestimated in the past.KEY WORDS: North Sea · Plankton communities · Long-term trends · Continuous plankton recorder · Great salinity anomaly · Ocean climate Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 239: [1][2][3][4][5][6][7][8][9][10] 2002 to such an extent they can take the form of notable biological shifts (Edwards et al. 2001a). In the North Sea, these biological irregularities appear to be largely synchronous with anomalous hydrographic events that have occurred episodically over the last 40 yr. In particular, 2 oceanographic anomalies stand out as exceptional periods. The first period, in the late 1970s, was associated with cold-boreal conditions, while the second period occurred in the late 1980s and was associated with a warm-temperate climate. The relationship between the long-term changes in plankton recorded by the continuous plankton recorder (CPR) survey in the North Sea and these 2 anomalous hydro-climatic events are discussed in this paper.The CPR survey, which was started in the North Sea in 1931, is one of only a few long-term biological monitoring programmes and the only one at a spatial scale that gives a systematic coverage of the North Sea in space and time. Using biological data recorded by the CPR survey, several planktonic time series were examined, including an assessment of phytoplankton biomass/structure, and components of the holozooplankton and meroplankton communities. This paper focuses predominately on the response of phytoplankton populations to the ocean climate anomalies. Other biological components of the ecosystem and independent studies from single-point stations are also discussed to corroborate and highlight the manifestation of this response through the various marine trophic levels. We found that although these studies also noticed an abrupt change in the North Sea ecosystem during these 2 periods, they did no...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Ocean climate anomalies and the ecology of the North Sea

Edwards

Beaugrand²,

Reid³

et al. 2002

Mar. Ecol. Prog. Ser.

205

137

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“…One explanation for the temporal Patterns Seen in the 2 Calanus species is that Atlantic influence and inflow (Corten 1990, Stephens et al 1998) into the North Sea were greater in the 1960s and more Calanus were imported: C. finmarchicus from overwintenng 1.ocations beyond the contmental shelf and C. helgolandicus from the north and West of Scotland via the Fair lsle Current (Backhaus et al 1994, Heath et al 1999. The waning of relatively warm Atlantic inflow left a signature of falling temperatures (See Fig.…”

mentioning

confidence: 99%

Temporal patterns in the surface abundance of Calanus finmarchicus and C. helgolandicus in the northern North Sea (1958-1996) inferred from Continuous Plankton Recorder data

Beare¹,

McKenzie²

1999

Mar. Ecol. Prog. Ser.

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Patterns in the temporal abundance of Calanus finrnarchicus and C. helgolandicus in 3 sub-regions of the northern North Sea are described from Continuous Plankton Recorder data, updating earlier studies with information from 3 more years (1994, 1995 and 1996). Abundances are considered using time-senes techniques that allow the annual seasonal cycles observed within each sub-region to change over the long term. It 1s demonstrated that, as lony-terrn trends of C finmarchicus and C. helgolandicus fluctuated in the northern North Sea between 1958 and 1996, simultaneous changes also occurred in the annual seasonal cycles of both species. The results are discussed in relation to local sea-surface temperatures and the North Atlantic Oscillation index.

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“…While the occasional occurrence of 'Lusitanian' fish species has been frequently documented (Aurich 1953;Corten 1990;Boddeke and Vingerhoed 1996;Scheffel et al 1996), this phenomenon has not significantly influenced the typical pelagic fish egg assemblage of the southern North Sea when considering the common community parameters. Although the presence of more 'Lusitanian' species may be regarded as an early indication of changes, the present southern North Sea ecosystem is still far from being strongly influenced by these taxa.…”

Section: Species Richness Abundance and Assemblagementioning

confidence: 99%

Species assemblages of pelagic fish embryos in the southern North Sea between 1984 and 2000

et al. 2002

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The occurrence and abundance of the pelagic eggs of southern North Sea spring-spawning fish were analysed between 1984 and 2000. Species number varied between six (1986) and 14 (1999) and was positively correlated with sea surface temperature. With one exception, dab eggs were always the most abundant and usually highly dominant. Ranking of species depended on temperature, but no significant differences in ranking between years was discernible. Although with the increase in temperature in the 1990s a change in species assemblage was evident [species belonging to the borealMediterranean (Lusitanian) group became more apparent in the species assemblage] this did not lead to an increased species diversity (Shannon Index) or a change in other community parameters. It appears that the recent developments regarding spawning stock biomass of commercial North Sea fish is reflected in the declining egg abundance of the respective commercial and larger species (i.e. cod, flounder, plaice) and an increase in abundance of the eggs of small species (i.e. long rough dab, rockling) over the years.

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Long-term trends in pelagic fish stocks of the North Sea and adjacent waters and their possible connection to hydrographic changes

Cited by 59 publications

References 4 publications

Ocean climate anomalies and the ecology of the North Sea

Ocean climate anomalies and the ecology of the North Sea

Temporal patterns in the surface abundance of Calanus finmarchicus and C. helgolandicus in the northern North Sea (1958-1996) inferred from Continuous Plankton Recorder data

Species assemblages of pelagic fish embryos in the southern North Sea between 1984 and 2000

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