Demersal fish populations in the coastal waters of the UK and continental NW Europe from beam trawl survey data collected from 1990 to 1995

Samples of the demersal fish fauna have been collected by beam trawl from the coastal waters of northwest Europe (49–57°N, 8°W–9°E) by the UK, Netherlands, Germany and Belgium, since 1990, during the third quarter of the year. Changes in community structure within small spatial scales were subtle as species compositions formed part of a continuum over the entire continental shelf. Populations of low diversity were particularly evident in the German Bight and on the North Sea continental coast, where dab Limanda limanda were abundant. In the Channel and to the west of the UK the demersal assemblages were more species-rich than in the North Sea and, although dab was still an important member of the underlying fish assemblage, the abundance of other species, especially poor cod Trisopterus minutus, solenette Buglossidium luteum, plaice Pleuronectes platessa, and the lesser weever, Echiichthys vipera, allowed a range of different groups to be identified. Despite the greater species diversity in this westerly region only eight out of a total nineteen flatfish species were found in abundance. The dominance of different species in different size classes was a key feature of the community structure. Flatfish were the largest group by weight in the smaller-length classes (<30 cm), and in western areas the elasmobranchs dominated the larger-size classes. Observed patterns in community structure were partly explained by the zoogeography of the region and the presence of the British Isles at the boundary between two faunal types. The additional influence on demersal populations of depth and substrate type, which may regulate the abundance of flatfish at key stages in their life history, was also discussed. In addition to these natural processes, recent increases in fishing effort are thought to have affected the structure of the demersal assemblage, and an examination of aggregated length-frequency distributions from these surveys tends to support this conclusion. Without further information on the distribution of fishing effort, it is not possible to separate the influence of natural faunal changes between regions from that of artificial changes caused by fishing activity.

[1]  S. Walsh.  Life history traits and spawning characteristics in populations of long rough dab (American plaice) Hippoglossoides platessoides (Fabricus) in the North Atlantic , 1994 .

[2]  H. Heessen,et al.  Long-term trends in ten non-target North Sea fish species , 1996 .

[3]  A. Rijnsdorp,et al.  Population biology of dab Limanda limanda in the southeastern North Sea , 1992 .

[4]  J. Ludwig,et al.  Statistical ecology: a primer on methods & computing , 1988 .

[5]  M. Kerstan.  The importance of rivers as nursery grounds for 0- and 1-group flounder (Platichthys flesus L.) in comparison to the Wadden sea , 1991 .

[6]  A. Magurran.  Ecological Diversity and Its Measurement , 1988, Springer Netherlands.

[7]  M. Hill.  Diversity and Evenness: A Unifying Notation and Its Consequences , 1973 .

[8]  A. Appenzeller,et al.  Diel and seasonal distribution of perch in Lake Constance: a hydroacoustic study and in situ observations , 1996 .

[9]  J. D. Riley,et al.  Recruitment of sole stocks, Solea solea (L.), in the Northeast Atlantic , 1992 .

[10]  Claude E. Shannon,et al.  The Mathematical Theory of Communication , 1950 .

[11]  M. Torchio.  Osservazioni sui Bothidae delle acque italiane (Pisces Pleuronectiformes) , 1962 .

[12]  Stephen J. Smith,et al.  Identifying Habitat Associations of Marine Fishes Using Survey Data: An Application to the Northwest Atlantic , 1994 .

[13]  R. Gibson.  Impact of habitat quality and quantity on the recruitment of juvenile flatfishes , 1994 .

[14]  S. Rogers,et al.  Factors affecting the annual abundance and regional distribution of English inshore demersal fish populations: 1973 to 1995 , 1996 .

[15]  P. Henderson,et al.  On the structure of the inshore fish community of England and Wales , 1989, Journal of the Marine Biological Association of the United Kingdom.

[16]  A. Rijnsdorp,et al.  Reproductive variability in North Sea Plaice, sole and cod , 1991 .

[17]  P. Henderson,et al.  On the factors influencing juvenile flatfish abundance in the lower Severn Estuary, England , 1994 .

[18]  A. Rijnsdorp,et al.  Changes in abundance of demersal fish species in the North Sea between 1906-1909 and 1990-1995 , 1996 .

[19]  G. J. Piet,et al.  On factors structuring the flatfish assemblage in the southern North Sea , 1998 .

[20]  R. Gibson,et al.  Piscine predation on juvenile fishes on a Scottish sandy beach , 1996 .

[21]  D. Pauly.  A framework for latitudinal comparisons of flatfish recruitment , 1994 .

[22]  A. Tyler,et al.  Sustainability of flatfish-dominated fish assemblages in Hecate Strait, British Columbia, Canada , 1991 .

[23]  Sven Ekman,et al.  Zoogeography of the sea , 1953 .

[24]  J. Hislop,et al.  Ecology of North Sea fish , 1990 .

[25]  R. May.  Patterns of species abundance and diversity , 1975 .

[26]  J. Diamond,et al.  Ecology and Evolution of Communities , 1976, Nature.

[27]  H. W. Veer,et al.  Nursery areas of solenette Buglossidium luteum (Risso, 1810) and scaldfish Arnoglossus laterna (Walbaum, 1792) in the southern North Sea , 1995 .

[28]  J. Steele,et al.  The ecology of 0-group plaice and common dabs at Loch Ewe I. Population and food , 1968 .

[29]  Jake C. Rice,et al.  Patterns of change in the size spectra of numbers and diversity of the North Sea fish assemblage, as reflected in surveys and models , 1996 .

[30]  Alec D. MacCall,et al.  Dynamic Geography of Marine Fish Populations , 1990 .

[31]  S. Rogers,et al.  The influence of spawning and nursery grounds on the distribution of sole Solea solea (L.) in the Irish Sea, Bristol Channel and adjacent areas , 1995 .

[32]  P. Walker,et al.  Long-term changes in ray populations in the North Sea , 1996 .

[33]  K. R. Clarke,et al.  A Comparison of some methods for analysing changes in benthic community structure , 1991, Journal of the Marine Biological Association of the United Kingdom.

[34]  C. E. SHANNON,et al.  A mathematical theory of communication , 1948, MOCO.

[35]  Stephen J. G. Hall,et al.  Fishing and the Ground-Fish Assemblage Structure in the North-Western North Sea: An Analysis of Long-Term and Spatial Trends , 1996 .

[36]  S. Groot.  On the interrelationships between morphology of the alimentary tract, food and feeding behaviour in flatfishes (pisces: pleuronectiformes) , 1971 .

[37]  L. Bolle,et al.  Nursery grounds of dab (Limanda limanda L.) in the southern North Sea , 1994 .

[38]  E. H. Simpson.  Measurement of Diversity , 1949, Nature.