Changes in the fish community of Loch Leven: untangling anthropogenic pressures

• Published in: Hydrobiologia 2012-02, Vol.681 (1), p.73-84
• Main Authors: Winfield, I. J., Adams, C. E., Armstrong, J. D., Gardiner, R., Kirika, A., Montgomery, J., Spears, B. M., Stewart, D. C., Thorpe, J. E., Wilson, W.
• Format: Article
• Language: English
• Subjects: Anguilla anguilla; Animal populations; Anthropogenic factors; Aquatic ecosystems; Aquatic plants; Barbatula barbatula; Biomedical and Life Sciences; Climate change; Ecology; Esox lucius; Eutrophication; Fish; Fish populations; Fisheries; Freshwater; Freshwater & Marine Ecology; Gasterosteus aculeatus; Lakes; Lampetra planeri; Life Sciences; Limnology; Loch Leven Research; Marine; Oncorhynchus mykiss; Perca fluviatilis; Petromyzontidae; Phoxinus phoxinus; Platichthys flesus; Salmo salar; Salmo trutta; Salmon; Salvelinus alpinus; Species extinction; Water levels; Zoology
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-011-0925-8

Loch Leven, U.K., contains brown trout ( Salmo trutta ), eel ( Anguilla anguilla ), minnow ( Phoxinus phoxinus ), perch ( Perca fluviatilis ), pike ( Esox lucius ) and three-spined stickleback ( Gasterosteus aculeatus ), with brook lamprey ( Lampetra planeri ) and stone loach ( Barbatula barbatula ) also present in its tributaries. Arctic charr ( Salvelinus alpinus ), Atlantic salmon ( Salmo salar ) and flounder ( Platichthys flesus ) are now extinct. The brown trout population has supported a world-renowned recreational fishery for over a century, although a decline in fishery performance led to extensive stocking between 1983 and 2006, including with non-native rainbow trout ( Oncorhynchus mykiss ). This review combines historical information with contemporary gill-net and hydroacoustic surveys. In 2008, brown trout, perch and three-spined sticklebacks were abundant, but pike and stone loach were rare. The obstruction of migratory routes was probably responsible for the loss of Atlantic salmon and flounder, while a lowering of water level likely caused the extinction of Arctic charr and contributed to a reduction in pike abundance. Perch abundance has fluctuated markedly, being influenced by disease and eutrophication, although a reduction in nutrients and associated recovery of macrophytes are likely to have benefitted this species. Although the brown trout population has undoubtedly shown a long-term decline, individuals are currently in excellent condition.