caa a22 4500 397551223 CHVBK 20180308164750.0 cr unu---uuuuu 161202e199612 xx s 000 0 eng 10.1006/jmsc.1996.0146 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0146 Patterns of change in the size spectra of numbers and diversity of the North Sea fish assemblage, as reflected in surveys and models [Elektronische Daten] [Jake Rice, Henrik Gislason] Trends were analysed over two decades in the size spectra of numbers and diversity of the North Sea fish assemblage. In trawl survey data, the abundance spectrum was smoothly linear each year. Both slopes and intercepts increased significantly over the period, reflecting the effects of fishing. The diversity size spectrum was curvilinear, with diversity increasing among smaller sizes and decreasing linearly over larger sizes. The slope of the linear component of the spectrum varied with a multi-year pattern, but without an overall trend. The much greater stability of the diversity spectrum compared with the abundance spectrum suggests that the fish community structure has remained fairly stable over the period, despite significant increases in harvesting on component populations. To explore the hypothesis that the regulation of the com-munity structure arises from trophic interactions, the same community metrics were calculated from the output of a multi-species virtual population analysis of the major exploited fish predators and prey, parameterized with extensive catch data and feeding habits. Although many fewer species were included in the modelled assemblage than in the survey data, overall patterns were very similar. Annual abundance spectra were linear and slopes increased significantly and fairly smoothly over the 20 years, indicating significant effects of fishing on the size composition of the exploited fish assemblage. The annual diversity spectra were more dome-shaped than in the survey data. The shape showed no overall trend, but diversity of smaller size classes showed a different temporal pattern from the diversity of intermediate and large size classes. The patterns in modelled output are consistent with, but do not prove, the hypothesis that trophic interactions are an important factor in the fish community structure in the North Sea. © 1996 International council for the Exploration of the Sea Articles nationallicence diversity nationallicence ecosystem effects of fishing nationallicence fish community structure nationallicence multi-species VPA nationallicence size spectra nationallicence trophic interactions nationallicence Rice Jake Department of Fisheries and Oceans Pacific Biological Station, Nanaimo, BC, Canada, V9R 5K6 aut Gislason Henrik Danish Institute of Fisheries Research Charlottenlund Castle, DK 2920 Charlottenlund, Denmark aut ICES Journal of Marine Science Oxford University Press 53/6(1996-12), 1214-1225 1054-3139 53:6<1214 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0146 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0146 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Rice Jake Department of Fisheries and Oceans Pacific Biological Station, Nanaimo, BC, Canada, V9R 5K6 aut NATIONALLICENCE 700 1- Gislason Henrik Danish Institute of Fisheries Research Charlottenlund Castle, DK 2920 Charlottenlund, Denmark aut NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/6(1996-12), 1214-1225 1054-3139 53:6<1214 1996 53 icesjms Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford