LAUSR

Abstract Vendace (Coregonus albula) is a small and rapidly reproducing planktivorous coregonid species that is known to endure very high fishing pressure. Catch levels of 10–25 kg ha−1 a−1 have been sustained for extended periods in several Finnish lakes without signs of fishery-related deterioration of recruitment or decline of spawning stocks. However, data from the lake Sakylan Pyhajarvi (SW-Finland) in the 1990s indicate an episode of recruitment overfishing of the vendace population. The combination of unfavourable spring weather and unusually high abundance of piscivorous fish led to poor vendace recruitment in two successive years (1990, 1991). In spite of the reduced stock, fishing effort remained high, which resulted in excessively high premature mortality, a depressed spawning stock, and markedly reduced catches. Fishing mortality remained high until the mid-1990s. Then, because of the impaired profitability of the fishery, part of the winter seine crews ceased fishing altogether. The ensuing reduced fishing pressure immediately brought about lowered mortality of vendace, and the spawning stock gradually recovered during the late 1990s. In the 2000s the year-class size stabilized to an average level about half of that in the 1980s. Concurrently, the importance of winter seine fishing diminished due to weakening ice conditions in the warming climate, resulting in a reduced overall fishing pressure on the vendace stock. This study shows that even small, rapidly reproducing freshwater planktivores can be overfished. In the case of Pyhajarvi, the fishery was self-regulating through economic forcing. A recovery from overfishing was possible because the biological features of vendace make it a highly resilient species.