Journal Article

Integrated fisheries assessment and possible causes for the collapse of anchovy kilka in the Caspian Sea

Georgi M. Daskalov and Elchin V. Mamedov

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 64, issue 3, pages 503-511
Published in print April 2007 | ISSN: 1054-3139
Published online February 2007 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1093/icesjms/fsl047
Integrated fisheries assessment and possible causes for the collapse of anchovy kilka in the Caspian Sea

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Daskalov, G. M., and Mamedov, E. V. 2007. Integrated fisheries assessment and possible causes for the collapse of anchovy kilka in the Caspian Sea. – ICES Journal of Marine Science, 64: 503–511.

Anchovy kilka (Clupeonella engrauliformis) is the most abundant species of fish in the Caspian Sea. An integrated catch-at-age analysis based on commercial catch data and relative abundance indices from research surveys over the period 1991–2004 indicated two main periods. First, a period of high catches, from 1991 to 2000, sustained by relatively good recruitment and high spawning-stock biomass. At the end of this period, catches peaked at up to 271 400 t, fishing mortality reached 1.8 y−1 in 1999, and overfishing seems to have taken place. Over the next period, 2001–2004, the stock virtually collapsed, recruitment failing in 2001 and remaining very low thereafter. In 2005, total catches dropped to a historical minimum of 54 300 t. The most likely primary cause of the stock collapse is the invasion and spread of the ctenophore Mnemiopsis leidyi in the Caspian Sea. The dramatic recruitment failure from 2001 to 2004 is primarily attributed to competition/predation by this ctenophore, although other factors, including overfishing, likely contributed.

Keywords: age-structured stock assessment; anchovy kilka; Caspian Sea; ecosystem effects; fish stock collapse; invasive species; Mnemiopsis leidyi; overfishing

Journal Article.  5349 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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