Diversity, distribution and community composition of fish in perialpine lakes – “ Projet Lac ” synthesis report Author Alexander, Timothy Author Seehausen, Ole Eawag: Das Wasserforschungsinstitut des ETH-Bereichs Überlandstrasse 133, CH- 8600 Dübendorf text 2021 2021-11-12 Eawag: Swiss Federal Institute of Aquatic Science and Technology https://www.dora.lib4ri.ch/eawag/islandora/object/eawag:24051 book 2839 10.5281/zenodo.5779569 723c8018-f87a-440a-bed1-3d2fe2a46e42 978-3-906484-76-1 5779569

Table 1: Comparison of the objectives and information provided by Projet Lac and the catch statistics resulting from professional fisheries.

	Projet Lac	Professional fisheries
Objective	Precise, comparable estimates of	Maximise catches (biomass) of particular
	abundance and biomass for all species	species and size classes
(i.e. community composition) in all major
habitats
Methods	Combination of sampling methods:	Gillnets
gillnets, electrofishing, hydroacoustics
Habitats	Whole lake, all habitats	Particular parts of the lake, especially
		shallow
Distribution of	Random (CEN net protocol) and habitat-	Species-targeted.Targets locations where
effort	targeted (vertical net protocol and electro-	exploitable individuals of particular species
	fishing)	are thought to be in high abundance
Size of fish	Wide range of fish sizes. Gillnet mesh siz-	Size-targeted: larger fish only.
	es ranging from 5 mm to 70 mm. Electro-	Large gillnet mesh sizes only e.g.
	fishing somewhat biased towards smaller	> 24 mm
fish
Shape of fish	Gillnets over-represent deep-bodied and	Gillnets over-represent deep-bodied and
	spiny fish. Electrofishing less biased for	spiny fish among the targeted species
shape
Correction for	Catches are corrected for number and	Catches are generally only corrected
effort	area of nets and soak time	for lake surface area for comparisons
		between lakes. Catches could also be
		corrected by the number of licenses,
		permitted number/area of nets (number
		of net-nights not yet regularly recorded)
Effects of time	“Snapshot” in time of fish community i.e.	Annual statistics usually discussed. Catch-
	sampling generally conducted over one	es throughout the year influenced by fish
	or two weeks in late summer – early	growth and seasonal differences in rates
	autumn. (generating estimates of	of movement (e.g. relating to food availa-
	“relative standing biomass”).	bility). Long time series available in many
	No information on other seasons.	lakes
No time series available as yet