Spatial patterns and trends in abundance of larval sandeels in the North Sea: 1950–2005

Abstract Lynam, C. P., Halliday, N. C., Höffle, H., Wright, P. J., van Damme, C. J. G., Edwards, M., and Pitois, S. 2013. Spatial patterns and trends in abundance of larval sandeels in the North Sea: 1950–2005 – ICES Journal of Marine Science, 70: 540–553. Early recruitment indices based on larval fish data from the Continuous Plankton Recorder (CPR) have the potential to inform stock assessments of Ammodytes marinus in the North Sea. We evaluate whether the CPR data are reliable for sandeel larvae. Spatially, CPR larval data were comparable with catches by dedicated larval samplers (Gulf and bongo nets) during ICES coordinated surveys in 2004 and 2009. ICES data are also used to explore environmental influences on sandeel distributions. Temporally, CPR data correlate with larval data from plankton surveys off Stonehaven (1999–2005), with sandeel 0-group trawl data at the east Fair Isle ground (since 1984), and with recruitment data (since 1983) for the Dogger Banks stock assessment area. Therefore, CPR data may provide an early recruit index of relative abundance for the Dogger Banks assessment area, where the majority of the commercial catch of A. marinus is taken, and the Wee Bankie area that is particularly important for seabird foraging. While warm conditions may stimulate the production of sandeel larvae, their natural mortality is typically greater, in the Dogger Banks and Wadden Sea areas, when the larvae are hatched in warm years and/or with abundant 1-year-old sandeel that are likely to be cannibalistic.

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Maturity and growth population dynamics of Norway pout (Trisopterus esmarkii) in the North Sea, Skagerrak, and Kattegat

ICES Journal of Marine Science ◽

10.1093/icesjms/fsp153 ◽

2009 ◽

Vol 66 (9) ◽

pp. 1899-1914 ◽

Cited By ~ 12

Author(s):

Gwladys Lambert ◽

J. Rasmus Nielsen ◽

Lena I. Larsen ◽

Henrik Sparholt

Keyword(s):

Population Dynamics ◽

North Sea ◽

Stock Assessment ◽

Age Group ◽

Commercial Catch ◽

The North ◽

Stock Biomass ◽

Spawning Stock ◽

The North Sea ◽

Immature Fish

Abstract Lambert, G., Nielsen, J. R., Larsen, L. I., and Sparholt, H. 2009. Maturity and growth population dynamics of Norway pout (Trisopterus esmarkii) in the North Sea, Skagerrak, and Kattegat. – ICES Journal of Marine Science, 66: 1899–1914. The population dynamics of the Norway pout stock in the North Sea are investigated by statistical analyses, and GIS of ICES International Bottom Trawl Surveys (IBTS) and Danish commercial catch data from 1983 to 2006. The stock spawns mainly around mid-February along the northeastern English and Scottish coasts and between Shetland and Norway. Sex ratios indicate that males, which mature younger than females (age-at-50%-maturity, respectively, 1.2 and 1.5 years), migrate out of the Skagerrak–Kattegat to the spawning grounds before females. There is a decrease in the 2+-group maturity ratios as well as in weight and female length from before to after spawning. The results indicate spawning mortality. Only some 20% of the 1-group reaches maturity in the first quarter, which is higher than assumed in the stock assessment. Although the maturity ogives are variable over time, this difference should be taken into account when estimating spawning-stock biomass in routine assessments. Growth is also variable, with a tendency for male maximum length to be smaller than that of females, and immature fish to be smaller than mature ones in each age group. The juvenile growth rate is higher when the stock density is low and results in a reduced age-at-50%-maturity. Besides these intraspecific patterns, the growth rates show interspecific links to stock sizes of the important predators: cod, haddock, and whiting.

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Multivariate statistical approach to the temporal and spatial patterns of selected bioindicators observed in the North Sea during the years 1995?1997

Helgoland Marine Research ◽

10.1007/s101520050029 ◽

1999 ◽

Vol 53 (3-4) ◽

pp. 257-266 ◽

Cited By ~ 5

Author(s):

S. R. Schmolke ◽

K. Broeg ◽

S. Zander ◽

V. Bissinger ◽

P. D. Hansen ◽

...

Keyword(s):

Spatial Patterns ◽

North Sea ◽

Statistical Approach ◽

Multivariate Statistical ◽

Temporal And Spatial Patterns ◽

The North ◽

Multivariate Statistical Approach ◽

The North Sea ◽

Temporal And Spatial

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Gadoid dynamics: differing perceptions when contrasting stock vs. population trends and its implications to management

ICES Journal of Marine Science ◽

10.1093/icesjms/fsu075 ◽

2014 ◽

Vol 71 (6) ◽

pp. 1433-1442 ◽

Cited By ~ 16

Author(s):

Steven J. Holmes ◽

Colin P. Millar ◽

Robert J. Fryer ◽

Peter J. Wright

Keyword(s):

North Sea ◽

Stock Assessment ◽

Research Vessel ◽

Vital Rates ◽

The North ◽

Depth Contour ◽

Spawning Stock ◽

Population Structures ◽

The North Sea ◽

Local Pressures

Recent research suggests that ICES stock definitions for cod, haddock, and whiting of “west of Scotland” and “North Sea”, do not reflect underlying population structures. As population responses to different vital rates and local pressures would be expected to lead to asynchrony in dynamics, we examined trends in local spawning-stock biomass (SSB) among putative subpopulations of the three species. Delineation of subpopulation boundaries around spawning time was made based on genetic, tagging, and otolith microchemistry studies together with density distributions of species based on research vessel survey data. Subpopulation specific indices of SSB were derived using numbers-at-age and maturity observations from the same research vessel data and asynchrony was assessed by fitting a smoother to log SSB for each subpopulation and testing whether the smooths were parallel. Results for cod support the hypothesis of distinct inshore and larger offshore subpopulations and for whiting for northern and southern North Sea subpopulations with a boundary associated with the 50 m depth contour. In haddock, no difference in SSB trends between the North Sea and west of Scotland was found. For cod and whiting, subpopulation SSB trends differed substantially within current stock assessment units, implying reported stock-based SSB time-series have masked underlying subpopulation trends.

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Modeled larval fish prey fields and growth rates help predict recruitment success of cod and anchovy in the North Sea

Marine Ecology Progress Series ◽

10.3354/meps12615 ◽

2018 ◽

Vol 600 ◽

pp. 111-126 ◽

Cited By ~ 4

Author(s):

KB Huebert ◽

J Pätsch ◽

M Hufnagl ◽

M Kreus ◽

MA Peck

Keyword(s):

North Sea ◽

Growth Rates ◽

Larval Fish ◽

Fish Prey ◽

Recruitment Success ◽

The North ◽

The North Sea

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Numerical modeling of physical processes in the North Sea and Wadden Sea with GETM/GOTM

NCK-days 2012 : Crossing borders in coastal research : jubilee conference proceedings ◽

10.3990/2.197 ◽

2012 ◽

Author(s):

Meinard Tiessen ◽

Janine Nauw ◽

Piet Ruardij ◽

Theo Gerkema

Keyword(s):

Numerical Modeling ◽

North Sea ◽

Wadden Sea ◽

Physical Processes ◽

The North ◽

The North Sea

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Sources and Fate of PCBs in the North Sea: A Review of Available Data

Water Science & Technology ◽

10.2166/wst.1991.0278 ◽

1991 ◽

Vol 24 (10) ◽

pp. 77-85 ◽

Cited By ~ 16

Author(s):

J. Klamer ◽

R. W. P. M. Laane ◽

J. M. Marquenie

Keyword(s):

Adverse Effects ◽

North Sea ◽

German Bight ◽

Marine Mammals ◽

Wadden Sea ◽

Annual Basis ◽

The North ◽

Total Input ◽

Seal Population ◽

The North Sea

From literature data it is calculated that on an annual basis, 11 to 17 tonnes of PCBs enter the North Sea. Largest sources are the Atlantic Ocean and the atmosphere: together they account for 60-79% of the total input. Sources with greatest impact are the rivers, sewers and sludge. Highest concentrations are found close to the Dutch shore and in the German Bight. The PCB levels result in adverse effects on the seal population in the Wadden Sea. Of the total world PCB production, at least 57% is still in use and their future dispersal into the oceans cannot easily be controlled. If the increase in ocean PCB concentration continues, it may ultimately result in the extinction of fish-eating marine mammals.

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Opportunistically recorded acoustic data support Northeast Atlantic mackerel expansion theory

ICES Journal of Marine Science ◽

10.1093/icesjms/fsv243 ◽

2015 ◽

Vol 73 (4) ◽

pp. 1115-1126 ◽

Cited By ~ 11

Author(s):

Jeroen van der Kooij ◽

Sascha M.M. Fässler ◽

David Stephens ◽

Lisa Readdy ◽

Beth E. Scott ◽

...

Keyword(s):

North Sea ◽

Stock Assessment ◽

Detection Algorithm ◽

Trawl Survey ◽

Northeast Atlantic ◽

Acoustic Data ◽

The North ◽

The North Sea ◽

Northern North Sea ◽

Feeding Grounds

Abstract Fisheries independent monitoring of widely distributed pelagic fish species which conduct large seasonal migrations is logistically complex and expensive. One of the commercially most important examples of such a species in the Northeast Atlantic Ocean is mackerel for which up to recently only an international triennial egg survey contributed to the stock assessment. In this study, we explore whether fisheries acoustic data, recorded opportunistically during the English component of the North Sea International Bottom Trawl Survey, can contribute to an improved understanding of mackerel distribution and provide supplementary data to existing dedicated monitoring surveys. Using a previously published multifrequency acoustic mackerel detection algorithm, we extracted the distribution and abundance of schooling mackerel for the whole of the North Sea during August and September between 2007 and 2013. The spatio-temporal coverage of this unique dataset is of particular interest because it includes part of the unsurveyed summer mackerel feeding grounds in the northern North Sea. Recent increases in landings in Icelandic waters during this season suggested that changes have occurred in the mackerel feeding distribution. Thus far it is poorly understood whether these changes are due to a shift, i.e. mackerel moving away from their traditional feeding grounds in the northern North Sea and southern Norwegian Sea, or whether the species' distribution has expanded. We therefore explored whether acoustically derived biomass of schooling mackerel declined in the northern North Sea during the study period, which would suggest a shift in mackerel distribution rather than an expansion. The results of this study show that in the North Sea, schooling mackerel abundance has increased and that its distribution in this area has not changed over this period. Both of these findings provide, to our knowledge, the first evidence in support of the hypothesis that mackerel have expanded their distribution rather than moved away.

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