Contribution of obligatory and voluntary fisheries statistics to the knowledge of whitefish population in Lake Annecy (France)

Lake Annecy commercial and recreational fishermen are providing daily obligatory fish catch data since 1986. For the last 15 years, 20 volunteer anglers from Lake Annecy are also providing additional data regarding their own fish catch. These data are analyzed statistically to compare information from different sources and to check their accuracy. The results are published in the form of an annual report, which is presented annually at a meeting of fishermen to inform them about trends in Lake Annecy fisheries and to motivate them towards the sustainable management of the lake. From 1992 to 1997, the measured length distributions in the commercial fishery and the estimated length distributions from angler’s catches are filtered by a selectivity curve and are very similar: statistically the two distributions are the same. The CPUE calculated from both obligatory and volunteer angler data are also well correlated. Our results show that the volunteer’s catch can provide important information about population size and structure and are reliable enough to be a cost-effective option for fisheries management.