Identification and distribution of mullets in the coastal water (intertidal zone) of Bushehr province northern Persian Gulf (2008-2009)
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AuthorNia Maymandi, Nassir
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AbstractThe distribution and stock assessment of edible bivalves were carried out in Bushehr shoreline areas (from 50֯ 38 - 29֯ 27 to 52֯ 41 - 27֯ 17 ) throughout the period of September 2008 - 2009. The objectives of this study were identifying the location of edible bivalves, biomass estimation, to estimate the growth parameters and natural mortality. Samples were obtained at roughly monthly or bimonthly from 7 areas and some of the at low tide during the year from 4 areas. Transects were selected at random direction and at the zigzag pattern in every area, so that is cover all of the shell beds. In each transects one or two sampling quadrat (0.25 m2) were placed randomly. Depending on the area size the number of the quadrat were different. After the removal of the stones and debries, the edible bivalves (empty and live bivalves) and some of the decoration shells were identified and numbered. Some of the samples were transferred to a bag and taken back to the lab for further identification and further analysis. In this study, the percentage of samples was used to show the distribution of the species in different areas. Faunal affinity between stations was calculated by Sorensen formula. For the purpose of the stock abundance, the mean number of the shells in each quadrat was regarded as an estimate of stock mean. The total stock in the investigated areas was obtained by multiplying the mean by the ratio of the stock area to the quadrat area (0.25 m2). Confident limits 0.95 % or 95 probility was given for precise the estimates. The length of some of the bivalves was measured from dextral to sinistral with vernier calipers to the nearest 0.1 millimeter. In some of the species the length frequency was used to estimate growth and natural mortality parameters. A subset of samples of Solen brevis was taken to the laboratory for the precise measurements, and relationship between body weights and total length. Surface sediment samples (5-20 cm) inhabited by some clam species were sampled in some areas. Water temperature and salinity were recorded during the survey in the sampled areas. A total of 45 species or species group was identified in the study area. The main area distributions for live edible bivalve, Solen brevis were located at Bupatil, Kaloo, Piazi and Bordekhoon. Other bivalve, Paphia cor was distributed in the Gassir, but empty bivalve shell was seen in the Bordekhoon shoreline. A limited tidal coastal area of Ganaveh has been covered by a pearl oyster species, Pinctada radiate that attached in the rocky beds. The empty shells of this species and other genus of the family were distributed in the other areas such as Golestan and Nayband. The most important areas for the decoration shells were located in the Golestan and Nayband. The empty bivalve shells, Trachycardium lacunosum were distributed in Lavar shoreline. The other species or species group were distributed in the shoreline of the study areas in different months with the low abundance. The growth parameters of two alive species, Paphia cor and Solen brevis were estimated. The Von Bertalanffy growth parameters for Paphia cor were estimated as K = 0.8 Year-1, L∞= 55 mm and t0 = -0.45 and for Solen brevis K = 0.7 Year-1, L = 120 mm and t0 = -0.35. . Estimated natural mortality rate for Paphia cor was M = 0.57 and for Solen brevis M = 0.26. The maximum ages (Tmax) calculated were 50 months for Paphia cor and 54 months for Solen brevis. The mean biomass of Solen brevis in Bupatil was 3.25 1.1 shells per quadrat with a maximum peak 4.6 shells per quadrat in October (Mehr) and minimum 1.5 shells per quadrat in Augest (Mordad). For the pearl oyster, Pinctada radiata in the Ganaveh this estimation was obtained in maximum peak in July (Tir) 60.5 shells per 100 m2 and minimum in March (Esfand) 3 per 100 m2. Mean biomass for this species was estimated 27.724.2 shells per 100 m2. The mean biomass of P. cor was 8.8 2.2 shells per quadrat and with a maximum in February (Bahman) and minimum in November (Abban).
Publisher or UniversityIranian Fisheries Science Research Institute
Series : Nr89.1306;