Management implications of the response of two tilapiine cichlids to long-term changes in lake level, allodiversity and exploitation in an equatorial lake

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Authors: Oyugi, D.O., Harper, D.M., Britton, J.R., Ntiba, M.J. and Kisia, S.M.

Journal: AMBIO: A Journal of the Human Environment

ISSN: 0044-7447

DOI: 10.1007/s13280-011-0139-3

This data was imported from PubMed:

Authors: Oyugi, D.O., Harper, D.M., Ntiba, J.M., Kisia, S.M. and Britton, J.R.

Journal: Ambio

Volume: 40

Issue: 5

Pages: 469-478

ISSN: 0044-7447

The tilapiine cichlids Oreochromis leucostictus and Tilapia zillii were introduced into Lake Naivasha, Kenya, in 1956. Previous studies on data collected to 1987 revealed they were persistent following establishment, despite environmental variability and exploitation. Recent data, however, suggest this persistence is under threat as data indicate some significant declines in aspects of their abundance since 1999. The influence of changes in lake level, allodiversity and fishing effort on this decline was tested and showed that a decline in lake level was a significant causal factor. The recent change in allodiversity, with the establishment and dominance of Cyprinus carpio in the fishery, was not significant on the catch per unit effort of O. leucostictus but was on T. zillii. Since 1999, catches of tilapiines in the fishery have been independent of fishing effort, contrary to between 1975 and 1987, suggesting their management through application of fishery models may no longer be applicable. As it was anthropogenic-mediated lake level changes that were mainly responsible for their decline, then lake management should focus on sustainable water utilization that maximizes lake levels in accordance with the basin-wide water balance.

This data was imported from Scopus:

Authors: Oyugi, D.O., Harper, D.M., Ntiba, J.M., Kisia, S.M. and Britton, J.R.

Journal: Ambio

Volume: 40

Issue: 5

Pages: 469-478

ISSN: 0044-7447

DOI: 10.1007/s13280-011-0139-3

The tilapiine cichlids Oreochromis leucostictus and Tilapia zillii were introduced into Lake Naivasha, Kenya, in 1956. Previous studies on data collected to 1987 revealed they were persistent following establishment, despite environmental variability and exploitation. Recent data, however, suggest this persistence is under threat as data indicate some significant declines in aspects of their abundance since 1999. The influence of changes in lake level, allodiversity and fishing effort on this decline was tested and showed that a decline in lake level was a significant causal factor. The recent change in allodiversity, with the establishment and dominance of Cyprinus carpio in the fishery, was not significant on the catch per unit effort of O. leucostictus but was on T. zillii. Since 1999, catches of tilapiines in the fishery have been independent of fishing effort, contrary to between 1975 and 1987, suggesting their management through application of fishery models may no longer be applicable. As it was anthropogenic-mediated lake level changes that were mainly responsible for their decline, then lake management should focus on sustainable water utilization that maximizes lake levels in accordance with the basin-wide water balance. © Royal Swedish Academy of Sciences 2011.

This data was imported from Web of Science (Lite):

Authors: Oyugi, D.O., Harper, D.M., Ntiba, J.M., Kisia, S.M. and Britton, J.R.

Journal: AMBIO

Volume: 40

Issue: 5

Pages: 469-478

ISSN: 0044-7447

DOI: 10.1007/s13280-011-0139-3

This data was imported from Europe PubMed Central:

Authors: Oyugi, D.O., Harper, D.M., Ntiba, J.M., Kisia, S.M. and Britton, J.R.

Journal: Ambio

Volume: 40

Issue: 5

Pages: 469-478

eISSN: 1654-7209

ISSN: 0044-7447

The tilapiine cichlids Oreochromis leucostictus and Tilapia zillii were introduced into Lake Naivasha, Kenya, in 1956. Previous studies on data collected to 1987 revealed they were persistent following establishment, despite environmental variability and exploitation. Recent data, however, suggest this persistence is under threat as data indicate some significant declines in aspects of their abundance since 1999. The influence of changes in lake level, allodiversity and fishing effort on this decline was tested and showed that a decline in lake level was a significant causal factor. The recent change in allodiversity, with the establishment and dominance of Cyprinus carpio in the fishery, was not significant on the catch per unit effort of O. leucostictus but was on T. zillii. Since 1999, catches of tilapiines in the fishery have been independent of fishing effort, contrary to between 1975 and 1987, suggesting their management through application of fishery models may no longer be applicable. As it was anthropogenic-mediated lake level changes that were mainly responsible for their decline, then lake management should focus on sustainable water utilization that maximizes lake levels in accordance with the basin-wide water balance.

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