Lessons to Learn from 123 Years of Catch Data from a Small Scale Whitefish Fishery
Sandlund, O.T.; Diserud, O.H.; Næsje, T.F.
One hundred and twenty-three years (1885–2007) of catch statistics are available from the whitefish (Coregonus lavaretus) seine-fishery in the River Tufsinga, an inlet to Lake Femund, Norway. We describe the fishery and discuss factors that might influence the variation in annual catches. The fishermen developed their own locally adapted seine method to capture whitefish migrating upstream towards spawning areas during October of each year. Fishing has been carried out in the same manner during the entire 123 years of the fishery, and the annual catch statistics have been recorded by the well-organized, small group of fishing rights owners, ensuring accountability in the data set. There was a substantial between-year variation in both total catch per season (0–13000 fish) and in catch-per-uniteffort (CPUE, 0–745 fish per day). Three factors seem to play a substantial role in shaping the variation in the annual catches. Based on autocorrelation analyses of CPUEs, variation in year class strength is a significant factor shaping CPUE variation. Based on the positive correlation between CPUEs in River Tufsinga and the CPUEs of River Whitefish in Lake Femund 8–10 years later, a stock-recruitment correlation exists between the number of spawners in the river and stock in the lake. Lastly, there was a tendency for low fishery CPUEs in years with high rainfall and higher CPUEs in dry years, supporting the impression by fishermen that water flow is a major factor determining their fishing success.