Qualitative assessment of Caspian kutum (Rutilus frisii kutum Kamensky 1901) (Rutilus frisii kutum Kamensky 1901)

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Abstract

The main objective of the present study was qualitative assessment of Caspian kutum
(Rutilus frisii kutum Kamensky 1901) stocks by using indicators of overfishing, condition
factor and relative weight in Iranian waters of the Caspian Sea during a long period (1991-
2011). Three fisheries indicators in catch were: 1) percentage of mature fish, with 100% as
target 2) percent of specimens with optimum length, with 100% as target and 3) percentage
of mega-spawners, with 0% as target, and if no upper size limit exists, 30-40% as
representative of reasonable stock structure. Over this period, the condition factor and relative
weight had a decreasing trend. The range of length with optimum yield was between 40 and
48 cm. The mega-spawner measured as fish a size larger than 48 cm. According to these three
indicators, the percentage of mature (fork length>40cm), optimum size and mega-spawners
were 62.0, 40.9 and 12.5% in 1991-92 which decreased less than 50, 38.2 and 8%, in the
years 1992-2011, respectively. The length structure is a matter of concern. Therefore, for
reservation and rebuilt of kutum in the Caspian Sea, the target was to let all (100%) fish
spawn at least once, using bigger mesh size in cod end (e.g. 35mm, during whole fishing
season). The aim was also to implement a fishing strategy that result no (0%) mega-spawners
being caught, and the main catch focus on optimum length.
*Corresponding author

Keywords

Iranian Scientific Fisheries Journal
Volume 21, Issue 2 - Serial Number 79
March and April 2013
Pages 53-64

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