Further results from headline camera surveys in the North Sea

1984 ◽  
Vol 64 (2) ◽  
pp. 335-342 ◽  
Author(s):  
G. J. Cranmer ◽  
M. F. Dyer ◽  
P. D. Fry
Keyword(s):  
North Sea ◽  
Demersal Fish ◽  
The North ◽  
Biological Interest ◽  
Successful Series ◽  
The North Sea

A further series of North Sea demersal fish surveys was carried out during the summers of 1981 and 1982. The remote headline camera was used and the benthos trawled was recorded. At stations of special biological interest the camera was adjusted to take from one to three frames per minute throughout the 1 h duration of the trawl. A successful series of underwater photographs were obtained at 95 stations throughout the North Sea.

A series of North Sea benthos surveys with trawl and headline camera

1982 ◽  
Vol 62 (2) ◽  
pp. 297-313 ◽  
Author(s):  
M. F. Dyer ◽  
W. G. Fry ◽  
P. D. Fry ◽  
G. J. Cranmer
Keyword(s):  
North Sea ◽  
Local Population ◽  
Demersal Fish ◽  
Population Densities ◽  
The North ◽  
Sea Bed ◽  
Successful Series ◽  
The North Sea

During a series of North Sea demersal fish surveys, a headline camera was used to photograph the sea-bed at intervals of 1 min, throughout the duration of 60 min trawls. A successful series of underwater photographs were obtained at 119 stations throughout the North Sea. In addition, the benthos caught at 317 stations was recorded.A total of ca. 30 species could be identified on the underwater photographs, and of these ten species were sufficiently common or locally abundant for estimates of local population densities to be made. Distributions throughout the North Sea based on specimens trawled and specimens photographed were compared.

scholarly journals Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community

2012 ◽  
Vol 69 (1) ◽  
pp. 8-22 ◽  
Author(s):  
Simon P. R. Greenstreet ◽  
Helen M. Fraser ◽  
Stuart I. Rogers ◽  
Verena M. Trenkel ◽  
Stephen D. Simpson ◽  
...  
Keyword(s):  
North Sea ◽  
Fish Community ◽  
Size Structure ◽  
Demersal Fish ◽  
Community Size ◽  
The North ◽  
Management Objectives ◽  
The North Sea ◽  
Composition Structure ◽  
And Function

Abstract Greenstreet, S. P. R., Fraser, H. M., Rogers, S. I., Trenkel, V. M., Simpson, S. D., and Pinnegar, J. K. 2012. Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community. – ICES Journal of Marine Science, 69: 8–22. Broader ecosystem management objectives for North Sea demersal fish currently focus on restoring community size structure. However, most policy drivers explicitly concentrate on restoring and conserving biodiversity, and it has not yet been established that simply restoring demersal fish size composition will be sufficient to reverse declines in biodiversity and ensure a generally healthy community. If different aspects of community composition, structure, and function vary independently, then to monitor all aspects of community general health will require application of a suite of metrics. This assumes low redundancy among the metrics used in any such suite and implies that addressing biodiversity issues specifically will require explicit management objectives for particular biodiversity metrics. This issue of metric redundancy is addressed, and 15 metrics covering five main attributes of community composition, structure, and function are applied to groundfish survey data. Factor analysis suggested a new interpretation of the metric information and indicated that a minimum suite of seven metrics was necessary to ensure that all changes in the general health of the North Sea demersal fish community were monitored properly. Covariance among size-based and species-diversity metrics was low, implying that restoration of community size structure would not necessarily reverse declines in species diversity.

scholarly journals Different bottom trawl fisheries have a differential impact on the status of the North Sea seafloor habitats

2020 ◽  
Vol 77 (5) ◽  
pp. 1772-1786 ◽  
Author(s):  
A D Rijnsdorp ◽  
J G Hiddink ◽  
P D van Denderen ◽  
N T Hintzen ◽  
O R Eigaard ◽  
...  
Keyword(s):  
North Sea ◽  
Management Strategies ◽  
Demersal Fish ◽  
Time Interval ◽  
The North ◽  
The Status ◽  
Fisheries Conservation ◽  
The North Sea ◽  
The Impact ◽  
Trawl Fisheries

Abstract Fisheries using bottom trawls are the most widespread source of anthropogenic physical disturbance to seafloor habitats. To mitigate such disturbances, the development of fisheries-, conservation-, and ecosystem-based management strategies requires the assessment of the impact of bottom trawling on the state of benthic biota. We explore a quantitative and mechanistic framework to assess trawling impact. Pressure and impact indicators that provide a continuous pressure–response curve are estimated at a spatial resolution of 1 × 1 min latitude and longitude (∼2 km2) using three methods: L1 estimates the proportion of the community with a life span exceeding the time interval between trawling events; L2 estimates the decrease in median longevity in response to trawling; and population dynamic (PD) estimates the decrease in biomass in response to trawling and the recovery time. Although impact scores are correlated, PD has the best performance over a broad range of trawling intensities. Using the framework in a trawling impact assessment of ten métiers in the North Sea shows that muddy habitats are impacted the most and coarse habitats are impacted the least. Otter trawling for crustaceans has the highest impact, followed by otter trawling for demersal fish and beam trawling for flatfish and flyshooting. Beam trawling for brown shrimps, otter trawling for industrial fish, and dredging for molluscs have the lowest impact. Trawling is highly aggregated in core fishing grounds where the status of the seafloor is low but the catch per unit of effort (CPUE) per unit of impact is high, in contrast to peripheral grounds, where CPUE per unit of impact is low.

Plastic ingestion by pelagic and demersal fish from the North Sea and Baltic Sea

2016 ◽  
Vol 102 (1) ◽  
pp. 134-141 ◽  
Author(s):  
Christoph D. Rummel ◽  
Martin G.J. Löder ◽  
Nicolai F. Fricke ◽  
Thomas Lang ◽  
Eva-Maria Griebeler ◽  
...  
Keyword(s):  
Baltic Sea ◽  
North Sea ◽  
Demersal Fish ◽  
The North ◽  
The North Sea

scholarly journals Changes in the structure and function of the North Sea fish foodweb, 1973–2000, and the impacts of fishing and climate

2005 ◽  
Vol 62 (5) ◽  
pp. 847-868 ◽  
Author(s):  
Michael R. Heath
Keyword(s):  
North Sea ◽  
Secondary Production ◽  
Demersal Fish ◽  
Biological Data ◽  
Similar Species ◽  
The North ◽  
Production And Consumption ◽  
The North Sea ◽  
Vacant Niches ◽  
And Function

Abstract North Sea environmental and biological data were analysed to examine 30-year changes in production and consumption in the fish foodweb. The analysis revealed that the demand for secondary production placed on the ecosystem by fish declined from approximately 20 g C m−2 y−1 in the 1970s to 16 g C m−2 y−1 in the 1990s. Over the same period, the proportion of demand provided by zooplankton production increased from around 70% to 75%. The overall decrease was mainly due to a reduction in piscivorous demersal fish. Average secondary production by omnivorous zooplankton was estimated to be 35 g C m−2 y−1, and annual fluctuations were positively correlated with the gross production of planktivorous fish. The results suggest a “bottom-up” control of the pelagic foodweb. Individual planktivore species have been impacted by fishing, but the populations of other functionally similar species have expanded to fill the vacant niches, thus maintaining the planktivore role in the system. In contrast, the results indicate that benthos production was more “top-down” controlled. Overall, demersal fish species have been depleted by fishing, with no obvious species expansions to fill the vacant niche, releasing the benthos from predation pressure, and leading to an increase in benthic production and fisheries for invertebrates.

Coincident changes in four components of the North Sea ecosystem

1999 ◽  
Vol 79 (1) ◽  
pp. 183-185 ◽  
Author(s):  
K.F. Pearce ◽  
C.L.J. Frid
Keyword(s):  
Time Series ◽  
Species Composition ◽  
North Sea ◽  
Food Chain ◽  
Demersal Fish ◽  
North West ◽  
The North ◽  
The North Sea ◽  
Chain Links ◽  
Single Set

An analysis of species composition of the zooplankton, macrobenthos (two stations) and demersal fish from Northumberland (north-west North Sea) are reported. The four time-series show synchronous changes in species composition. While some of these changes coincide with changes in climateological variables, others do not. The degree of synchrony implies that either all the time-series are responding to a single set of extraneous forcing factors, or that food chain links, rapidly translate the signal through all ecosystem components.

scholarly journals Demersal fish biodiversity: species-level indicators and trends-based targets for the Marine Strategy Framework Directive

2012 ◽  
Vol 69 (10) ◽  
pp. 1789-1801 ◽  
Author(s):  
Simon P. R. Greenstreet ◽  
Axel G. Rossberg ◽  
Clive J. Fox ◽  
William J. F. Le Quesne ◽  
Tom Blasdale ◽  
...  
Keyword(s):  
North Sea ◽  
Demersal Fish ◽  
Species Level ◽  
Marine Strategy Framework Directive ◽  
The North ◽  
Fish Biodiversity ◽  
Environmental Status ◽  
The North Sea ◽  
Good Environmental Status ◽  
Species Specific

Abstract Greenstreet, S. P. R., Rossberg, A. G., Fox, C. J., Le Quesne, W. J. F., Blasdale, T., Boulcott, P., Mitchell, I., Millar, C., and Moffat, C. F. 2012. Demersal fish biodiversity: species-level indicators and trends-based targets for the Marine Strategy Framework Directive. – ICES Journal of Marine Science, 69: 1789–1801. The maintenance of biodiversity is a fundamental theme of the Marine Strategy Framework Directive. Appropriate indicators to monitor change in biodiversity, along with associated targets representing “good environmental status” (GES), are required to be in place by July 2012. A method for selecting species-specific metrics to fulfil various specified indicator roles is proposed for demersal fish communities. Available data frequently do not extend far enough back in time to allow GES to be defined empirically. In such situations, trends-based targets offer a pragmatic solution. A method is proposed for setting indicator-level targets for the number of species-specific metrics required to meet their trends-based metric-level targets. This is based on demonstrating significant departures from the binomial distribution. The procedure is trialled using North Sea demersal fish survey data. Although fisheries management in the North Sea has improved in recent decades, management goals to stop further decline in biodiversity, and to initiate recovery, are yet to be met.

The Epifauna of the Northern North Sea (56°–61°N)

1989 ◽  
Vol 69 (2) ◽  
pp. 387-407 ◽  
Author(s):  
D.J. Basford ◽  
A. Eleftheriou ◽  
D. Raffaelli
Keyword(s):  
North Sea ◽  
Regional Differences ◽  
Demersal Fish ◽  
Benthic Assemblage ◽  
Benthic Assemblages ◽  
The North ◽  
Composition And Structure ◽  
The North Sea ◽  
Northern North Sea ◽  
Fish And Shellfish

More than 65% of the demersal fish and shellfish caught by British vessels are landed at Scottish ports, most of the catch being taken from waters north of 56°, i.e. in the northern North Sea. The major resource supporting these fisheries is the benthos, but the distributions of both infaunal and epifaunal benthic invertebrates in the North Sea are poorly documented. Moreover, the environmental factors determining the composition and structure of North Sea benthic assemblages are not well understood. There have been several limited surveys of the benthos (Stephen, 1934; Ursin, 1960), and recently Dyer et al. (1982, 1983), Cranmer (1985) and Cranmer et al. (1984) attempted a more quantitative and systematic survey. Various schemes have been proposed to explain observed regional differences in types of benthic assemblage, usually based on the biological characteristics of water masses, and / or a limited and fragmentary knowledge of the sediments of the North Sea {e.g. Glemarec, 1973; Dyer et al, 1983).

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