بيئة و مصايد و تقييم مخزون أسماك أبو الهيل Saurida tumbil في المياه البحرية العراقية، شمال غرب الخليج العربي

الملخص EN

The present study is considering some ecological and biological aspects and stock assessment of Saurida tumbil in Iraqi marine waters, NW Arabian Gulf.

Samples were monthly collected from August 1999 to July 2000 by trawl nets.

Air and water temperatures were ranged from 13.5 oC (in January) to 44.8 oC (in July) for the former and the letter was ranged from 12 oC (in January) to 38.7Co in July.

Water was less transparent (100cm) in March and more limpid (340 cm) in June.

Salinity concentrations ranged between 22.5 ‰ in March to 41.2 ‰ in August.

Mean annual catch per unit of efforts of total catch was calculated providing 22.75 kg/ h, S.

tumbil composed 1.13 kg/h.

Monthly variations in catches were detected.

The highest CPUE of S.

tumbil was 2.8 kg/h obtained in October and the lowest was 0.6 kg/h encountered in both January and February.

5535 individuals of S.

tumbil were collected.

Total length is ranging between 40- 484mm.

Length-weight relationships was calculated for juveniles and each sex of and yield the following equations: W = 2.6393× 10-6 L3.182 r2 = 0.976 n = 87 Juveniles W = 4.7825× 10-5 L3.069 r2 = 0.

974 n = 176 males W = 2.7580× 10-6 L3.

196 r2 = 0.

990 n = 195 females Monthly variations in mean values of relative condition factor were not detected.

Seven age groups (0- VI+) were determined.

The von Bertalanffy growth equation was: Lt= 510 [1-e-0.32 (t + 0.39)].

The total, natural and fishing mortalities were 2.48, 0.67 and 1.81 respectively.

The exploitation rate of S.

tumbil calculated to be is 0.73 slightly higher than optimum exploitation level (0.50).