Vismonitoring in het IJsselmeer en Markermeer in 2005

In dit rapport wordt een overzicht gegeven van de toestand van visbestanden en de visserij in het IJsselmeer en Markermeer in 2005. Deze monitoring geeft samen met het diadrome vissen programma en zeldzame vissen programma een beeld over de totale visstand in het IJsselmeer. De monitoring bestaat uit jaarlijkse routinebemonsteringen van de visstand in het najaar, aangevuld met gegevens over vis aangeland door de beroepsvisseri

Oeverbemonstering IJsselmeer - Markermeer: Pilot 2007

In 2007 is een pilot-project gestart dat loopt tot 2008, waarbij de oevers langs het IJsselmeer en het Markermeer bemonsterd worden op de samenstelling van de visstan

Vismonitoring in het IJsselmeer en Markermeer in 2006

Ten behoeve van het visserijbeleid, het integraal waterbeheer en het visstandbeheer wordt een jaarlijks geactualiseerde inventarisatie gemaakt van de visstand op basis van monitoring van de visbestanden en de visseri

Length–weight relationships of 216 North Sea benthic invertebrates and fish

Size-based analyses of marine animals are increasingly used to improve understanding of community structure and function. However, the resources required to record individual body weights for benthic animals, where the number of individuals can reach several thousand in a square metre, are often prohibitive. Here we present morphometric (length–weight) relationships for 216 benthic species from the North Sea to permit weight estimation from length measurements. These relationships were calculated using data collected over two years from 283 stations. For ten abundant and widely dispersed species we tested for significant spatial and temporal differences in morphometric relationships. Some were found, but the magnitude of differences was small in relation to the size-ranges of animals that are usually present and we recommend that the regression relationships given here, based on pooled data, are appropriate for most types of population and community analyses. Our hope is that the availability of these morphometric relationships will encourage the more frequent application of size-based analyses to benthic survey data, and so enhance understanding of the ecology of the benthic/demersal component of marine ecosystems and food webs

Length–weight relationships of 216 North Sea benthic invertebrates and fish

Size-based analyses of marine animals are increasingly used to improve understanding of community structure and function.However, the resources required to record individual body weights for benthic animals, where the number of individuals canreach several thousand in a square metre, are often prohibitive. Here we present morphometric (length–weight) relationshipsfor 216 benthic species from the North Sea to permit weight estimation from length measurements. These relationships werecalculated using data collected over two years from 283 stations. For ten abundant and widely dispersed species we tested forsignificant spatial and temporal differences in morphometric relationships. Some were found, but the magnitude of differenceswas small in relation to the size-ranges of animals that are usually present and we recommend that the regression relationshipsgiven here, based on pooled data, are appropriate for most types of population and community analyses. Our hope is thatthe availability of these morphometric relationships will encourage the more frequent application of size-based analyses tobenthic survey data, and so enhance understanding of the ecology of the benthic/demersal component of marine ecosystemsand food webs