Publication Date:
2021-05-19
Description:
Kutum fish (Rutilus kutum) is an anadromous cyprinid species that spawns in adjusted rivers to the Caspian Sea.
Many million fingerlings were artificially produced and annually released in these rivers specifically in Sefidrud
River by Iranian Fisheries Organization. In this study were estimated the staying period of Kutum fingerlings in
Sefidrud River and its diet and growth. A small piece of the caudal fin was cut as a tagging method. About
50000 and 5200 individuals were marked during July and September 2013, respectively. The marked fish had an
average total length 53.2±5.6 mm and body weight 1.11±0.26 g and were released in river around two kilometers
of the estuary. The sampling of fishes had been earlier started from Feb. 2012 and continued until Feb. 2013 at
five stations. Four stations were along river from three Kilometer of estuary to estuary and one station was in
right side of estuary in the sea coast. The results showed that marked samples after releasing time were
distributed in all studied area from 3 kilometers of estuary to estuary but they migrate mainly toward Caspian
Sea in a short time. However the marked samples were observed in estuary and the sea coast after 6 and 24 hours
of their releasing time, respectively, Kutum fingerlings remained in Sefidrud river ecosystem in a longer time, at
least until end of our sampling period i.e. 105 days. The coefficient of vacuity index of the natural feeding study
was 0.0, 49.0 and 30.6 % for phytoplankton, zooplankton and benthos, respectively. The average of GastroSomatic
index, intensity of fullness and condition factor were calculated 6.30±3.25, 174.6±153.2 and 0.92±0.09,
respectively. A temporal and spatial variation on main food items were observed in gut content of fish
fingerlings from different locations and seasons. Gut contents were generally included 59 genera of
phytoplankton, 15 groups of zooplankton and 10 groups of benthos. Nitzschia, Navicula and Synedra were
dominated among phytoplankton genera with 45.83, 18.02 and 15.99 %, respectively. Among zooplankton
groups; the Rotaria, Moeina and Difflugia were dominated with 22.30, 20.86 and 15.83%, respectively.
Chironomidae and Gammaridae were the main food items among fed benthic animals with 83.67 and 11.15%,
respectively. Furthermore 48 phytoplankton genera, 32 zooplankton genera and 6 benthic families were
identified in ecosystem of Sefidrud river. Bacillariophyta phylum (with 23 genus), Rotatoria (with17 genus)
and Chironomidae family were dominated in each mentioned groups, respectively. It is concluded that the
Kutum fingerlings stay in Sefidrud River for a long time, although most of them migrate to Caspian Sea during
first month after releasing. However dietary indices were normal in studied samples, the condition factor index
seems to be low.
Description:
Iranian Fisheries Science Research Institute
Description:
Published
Keywords:
Rutilus kutum
;
Fingerlings
;
Kutum
;
Fish
;
Rotaria
;
Moeina
;
Difflugia
;
Phytoplankton
Repository Name:
AquaDocs
Type:
Report
,
Refereed
Format:
160pp.
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