Trends in invertebrates in the North Sea: a preliminary comparison of data sets
van der Veer, H.W.; Craeymeersch, J.A.; van der Meer, J.; Rijnsdorp, A.D. (1995). Trends in invertebrates in the North Sea: a preliminary comparison of data sets, in: [s.d.] Ocean Modelling (SCOR). 100: pp. 13-30
In: Ocean Modelling (SCOR WG Newsletter). Scientific Committee on Oceanic Research: Baltimore, more
Three data sets of trends in invertebrates of the North Sea were analysed: the NIOZ-archive, consisting of records of catches of landings over the period 1930-1990; the RIVO-DLO by- catches of beam trawl surveys over the period 1970-1991 and the NIOZ fyke catches over the period 1960-1991. The trends of the occurrence in invertebrates in the RIVO-DLO by-catch and the NIOZ fyke was compared with the records in the NIOZ-archive to evaluate the importance of these records as indicator of fishing intensity or abundance in the North Sea. In total 7 species could he compared, the whelk, the sea mouse, the sea urchin, the fiddler crab, the edible crab, the masked crab and the swimming crab. No definitive conclusion could he drawn. The time period over which the data sets could he compared (1970-1991) was too short, besides the distribution and occurrence of most invertebrates was too patchy. The trends in occurrence of some species (whelk and sea urchin) corresponded rather well with the trends in records in the NIOZ-archive. For other species (crabs) completely different patterns were found. It was concluded that the NIOZ-archive cannot he used for all species. It is suggested to extend the intercomparison by including fish species and by using techniques such as principal component analysis to reveal overall patterns in long-term occurrence of species.
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