Fish Fauna and Fishery Evaluation of Sapanca Lake

Scientific data on fish communities in Türkiye’s lakes and rivers, particularly long-term studies with continuity, remain scarce. However, Sapanca Lake is an exception due to its strategic location in the Marmara Region, which has attracted significant research interest in its limnology, fish fauna, and fisheries. This review synthesises historical and contemporary changes in the fish communities of Sapanca Lake, integrating scientific articles, theses, books, and reports. The lake has undergone notable shifts in species composition, with some native species (Abramis brama, Alburnoides bipunctatus, Anguilla anguilla, Carassius carassius, Leuciscus aspius, Perca fluviatilis, Ponticola syrman, Salmo labrax) disappearing, while others (Gambusia holbrooki, Gobio sakaryaensis, Leucaspius delineatus, Phoxinus strandjae) have recently been recorded. These changes are attributed to eutrophication, habitat degra dation, overfishing, and the introduction of non-native species. Some non-native species, such as G. holbrooki, have established themselves in vegetated areas and slow-flowing streams, raising concerns about their potential effects on the lake’s biodiversity and food web. The review also highlights the role of fisheries regulations in shaping the lake’s ecological dynamics. Commercial fishing was banned in the late 1990s, and in 2003, the lake was designated as a drinking water basin, further restricting fishing activities. However, illegal fishing persists, posing ongoing threats to fish populations. Meanwhile, cyprinid species have become dominant, likely benefiting from the lake’s shifting trophic state and reduced predation pressure. Given these findings, the study underscores the urgent need for improved monitoring, conservation strategies, and adaptive management to mitigate further biodiversity loss and preserve the lake’s ecological integrity. Future efforts should prioritise long-term ecological assessments, targeted control of invasive species, and sustainable fisheries management to maintain the resilience of Sapanca Lake’s fish communities.