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The ecology, fishery and stock assessment of Saurida tumbil in Iraqi marine waters, North West Arabian gulf.
بيئة ومصايد وتقييم مخزون أسماك أبو الهيل Saurida tumbil في المياه البحرية العراقية، شمال غرب الخليج العربي.

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Abstract

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 JuvenilesW = 4.7825× 10-5 L3.069 r2 = 0. 974 n = 176 malesW = 2.7580× 10-6 L3. 196 r2 = 0. 990 n = 195 femalesMonthly 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).

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Article
ANALYTICAL STUDY OF THE FISHERIES IN THE LOWER REACHES OF THE TIGRIS RIVER, NORTH QURNA, BASRAH, IRAQ
دراسة تحليلية لمصائد الأسماك في النهاية السفلى لنهر دجلة شمال القرنة، البصرة، العراق

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The fisheries of the lower reaches of Tigris river, north Qurna in Basrah Governorate have been analyzed during the period from January to December 2005. The fishing boats used there varied in lengths form 5 to 10m, of which 50% were motorized with 25-75 HP. Seine and drift gill nets are the main fishing gears used, their lengths ranged from 100 to 200m with mesh sizes of 14-100mm and 7-32mm for seine and gill nets respectively. The number of fishermen in each boat varied from 1 to 7. Twenty three fish species were recorded caught in the area, of which eight were marine species, belonging to twelve fish families, in addition to shrimps. The total catches ranged from 629Kg in January - march to 3335Kg in July- September with total catch of 7671Kg. Three species namely catfish Silurus triostegus, crucian carp Carassius carassius and khishni Liza abu comprised 86.93% of the total catches constituting 69.65%, 11.02% and 6.26%, respectively. The average catch per unit of effort was 19.8 Kg/hr/100m for seine nets and 2.42 Kg/hr/100m for gill nets. The diversity and evenness indices for biomass were 1.0 and 0.33, respectively, in July-September and 1.5 and 0.52, respectively, in October-December. The highest similarity index of species composition was between April-June and July-September (87%), and lowest between April-June and January-March (63%).

تم تحليل مصائد اسماك نهر دجلة شمال قضاء القرنة في محافظة البصرة خلال الفترة من كانون الثاني إلى كانون الأول 2005. تراوحت أطوال زوارق الصيد بين 5-10م، 50% منها مزوده بمحركات قوتها بين 25-75 حصان. كانت شباك الكرفة والشباك الخيشومية الهائمة وسائل الصيد الرئيسية في المصائد وتراوحت أطوالها بين 100-200م وحجم فتحاتها بين 14-100 ملم للكرفة و7-32 ملم للخيشومية. بلغ عدد الصيادين بالزورق الواحد بين 1-7 صياد. تم صيد 22 نوع من الأسماك، 7 منها أنواع بحرية، تعود الى 12 عائلة، أضافه إلى الروبيان. تراوحت كميات الصيد الكلية بين 629 كغم خلال فترة كانون الثاني – اذار و3335 كغم خلال فترة تموز - ايلول وبوزن إجمالي 7671 كغم. ساهمت ثلاثة أنواع هي الجري والكراسين والخشني، بـ 86.93% من الصيد الكلي وشكلت 69.65% و11.02% و 6.26% على التوالي. بلغ معدل كمية الصيد لوحدة الجهد لشباك الكرفة 19.8 كغم/ساعة/100م وللشباك الخيشومية الهائمة 2.42 كغم/ساعة/100م . تراوحت قيمتا التنوع والتكافؤ بالنسبة لوزن الأسماك بين 1.0 و 0.33 على التوالي خلال فترة تموز-أيلول و1.5 و 0.52 على التوالي خلال فترة تشرين الأول-كانون الأول، وكانت أعلى قيمة لمعامل التشابه (%87.0) بين الفترتين نيسان-حزيران وتموز-أيلول وأدنى قيمة(63.0%) بيـن الفترتين نيسان-حزيران وكانون الثاني-آذار.

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