Exploitation potential of sturgeon fish and sustainable harvesting in Iranian water of the Caspian Sea.
2009
Moqim, Mahdi | Ghani Nezhad, Davud | Taqavi, Amin Ol-Lah | Par AFkandeh, Farrokh
In the present research experiments were conducted to evaluate the exploitation potential of sturgeon fishes in south part of the Caspian Sea (Iranian side) by measuring different parameters such as CPUE, length, age, weight, sex, caviar weight. The biological sampling was collected from 14 commercial landing centers and bottom trawl survey during 1380-82. Although catch composition varied in different seasons, Persian sturgeon comprised the largest proportion of trawl catch. Persian sturgeon consisted 45.2% of the total catch of spring survey and 62%, 70.3%, 62.2% respectively of summer, autumn, winter surveys. Stellate sturgeon showed different seasonal distribution pattern.42% in spring, 45% in summer, 26% in autumn and 36% in winter. Few specimens of Russian sturgeon, beluga and ship sturgeon was captured. The relative catch of sturgeon in the considered area of Iranian water of the Caspian Sea was 1.3 specimens per trawl in spring, 13.5 in summer, 1.69 in autumn, 1.01 in winter survey. Related abundance for Persian sturgeon was higher than other Sturgeons and showed more fluctuation. The biomass amount of sturgeons in spring, summer, autumn and winter surveys were 6218.7, 140.6, 14.9 and 3.9 thousand tones, respectively. Major part of these fishes was immature Persian sturgeon. Catch and CPUE of all five spices showed descending trends in commercial catch during 2001-2003 and Sturgeon stocks descending trend is continued yet. For Persian Sturgeon in which was in a different stock situationmeanwhile the resources of juveniles and youngest ones are in a reasonable condition, but the amount of adults have been significantly decreased. Due to decrease of natural and artificial breeding during the decade of 1990 and increased exploitation of the sturgeon stocks (legal and poaching), , consequently the decrease of sturgeon stock is continued and it is assumed that this ascending trend is continued within next years. According to the present situation of sturgeon resources and regarding to prevent the destroy of this resources, it is proposed to ban any fishing on sturgeons and only to collect few brood stocks for artificial propagation and research studies.
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