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Investigation on pearl oyster, Pinctada radiata growth and mortality parameters was carried out from September 2001 to October 2002 in west of Lavan Island using scuba diving method. Hinge length (H-LL) and Dorso-ventral measurement (D.Y.M) relationship was significantly (r2= 0.98) linear. Weight and dorso-ventral measurement relationship was shown to be W=0.0004 L 2.812(r2= 0.98). Asymptotic length (Loo) and growth rate (K) were estimated at 98 (mm) and 0.96 it respectively. More than 70 percent of the individuals were matured in April 2001. Mortality parameters including natural mortality (M), total mortality (Z) and fishery mortality (F) were estimated to be 1.21y-1, 1.68y-1 and 0.66y-1 respectively. Exploitation rate was estimated to be 0.27 in this survey.

As pearling has been banned since 2006 in Persian Gulf, growth and mortality rate of Mohar pearl oyster in its old habitats was surveyed in present research. For early survey and identification of habitats of Mohar pearl oyster Pinctada radiata, primary sea tours in coastal waters of Lavan Island, were done. Two habitats were identified and sampled seasonally from autumn 2011 to summer 2012, to investigate Pinctada radiata stock condition. Belt transects and random quadrates method was used in this sampling. Infinity length, L∞, in Lavan No. 1 (Dardoor) and Lavan No. 2 (Hedabad) habitats was 89.16 and 87.68 mm. Growth constant, K, estimated 0.34 and 0.44 year-1in that two habitats. The amount of t0 for oysters in Dardoor and Hedabad habitats was -0.36 and -0.28 year and tmax was estimated equal to 8.46 and 6.54 year respectively. Natural mortality constant, M, was 0.63 and 0.75 year-1 respectively. Analyses of growth constant, K, revealed that this figure has decrease in these habitats in recent years. Investigation of recruitment plots indicated semi continuous pattern of recruitment in pearl oysters, demonstrating that reproduction occurs in almost throughout the year although two peaks of reproduction were observed in summer and winter.

Mohar pearl oyster Pinctada radiata is the dominant economic species of pearl oyster in the Persian Gulf, particularly along the Iranian coastal waters. As pearling has been banned since 2006, stocks of pearl oysters has not been investigated during these years. For this purpose, conditions of natural habitats and stocks of Mohar pearl oyster in its old catch sites were surveyed in the present study. Shallow waters around the Lavan island were searched through diving and two habitats of Mohar pearl oyster, namely Lavan No. 1 (Dardoor) and Lavan No. 2 (Hedabad), were detected. Area of Dardoor and Hedabad habitats was calculated equal to 60 and 15 ha, respectively and Mohar pearl oysters had the highest distribution in depth ranges of 7 to 12 m and 5 to 11 m, respectively. Total stocks of Dardoor and Hedabad habitats was surveyed about 357000 and 61500 pearl oysters of which 11% and 17% of oysters were catchable, respectively. Catch per unit of area in Dardoor and Hedabad habitats was estimated equal to 0.6 N/m2 and 0.4 N/m2 and catch per unit of effort was calculated equal to 119 N/hr and 82 N/hr, respectively. Biomass rate in these habitats was obtained equal to 4620 and 1163 kg, respectively. Results of this research revealed that the area, the amount of stocks and catch per unit of area of habitats has decrease in the recent years. Although the pearling has been banned in this region in the past seven years, restocking has been conducted slowly.