Brucet, Sandra. 2016 . Density-dependent effects as key drivers of intraspecific size structure of six abundant fish species in lakes across Europe [in special issue: Size-based approaches in aquatic ecology and fisheries science: a symposium in honour of Rob Peters]. ABSTRACT 30 We studied fish size structure by using mean size, size diversity and the slope of linear size spectra of six 31 common European fish species and compared whether these variables responded to the same large-32 scale

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... tinental gradients. We also included relative estimates of abundance (catch per unit effort, 33 CPUE) as an indicator of density-dependent effects in order to assess whether they also modify the size 34 structure of fish populations. We found differences in the strength of main predictors of size structure 35 between the six species, but the direction of the response was relatively similar and consistent for most 36 of the size metrics. Mean body size was negatively related to temperature, for perch, roach and ruffe. 37 Lake productivity (expressed as total phosphorus concentration) and lake depth were also predictors of 38 size structure for four out of six species. Moreover, we found a strong density dependence of size 39 structure for all species, resulting in lower mean body size and size diversity and steeper size spectra 40 slopes. This suggests that density dependence is a key driver of fish size structure. 41