Qualitative assessment of Caspian kutum (Rutilus frisii kutum Kamensky 1901) (Rutilus frisii kutum Kamensky 1901)
2013
H. Fazli email | G.R. Daryanabard | R. Pourgholam | Sh. Abdolmalaki | A. Bandani | A. Pourgholami | S.A. Safavi
The main objective of the present study was qualitative assessment of Caspian kutum(Rutilus frisii kutum Kamensky 1901) stocks by using indicators of overfishing, conditionfactor 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% astarget 2) percent of specimens with optimum length, with 100% as target and 3) percentageof mega-spawners, with 0% as target, and if no upper size limit exists, 30-40% asrepresentative of reasonable stock structure. Over this period, the condition factor and relativeweight had a decreasing trend. The range of length with optimum yield was between 40 and48 cm. The mega-spawner measured as fish a size larger than 48 cm. According to these threeindicators, the percentage of mature (fork length>40cm), optimum size and mega-spawnerswere 62.0, 40.9 and 12.5% in 1991-92 which decreased less than 50, 38.2 and 8%, in theyears 1992-2011, respectively. The length structure is a matter of concern. Therefore, forreservation and rebuilt of kutum in the Caspian Sea, the target was to let all (100%) fishspawn at least once, using bigger mesh size in cod end (e.g. 35mm, during whole fishingseason). The aim was also to implement a fishing strategy that result no (0%) mega-spawnersbeing caught, and the main catch focus on optimum length.
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