ستراتيجية تكاثر نوعين من الاسماك الغضروفية في المياه البحرية العراقية == Reproductive strategy of two cartilaginous species from Iraqi marine water
Author name:
جنان حسن جاسم اللامي
Supervisor name:
ساجد سعد حسن النور | امجد كاظم رسن
General topic:
Agricultural sciences
Specific topic:
Zoology - Fish And Marine Wealth
Degree:
Master
University:
University Of Basrah - Faculty Of Agriculture - Department Of Fish And Marine Wealth
Language:
Arabic
University location:
Basrah
First pages:
31T1774 - p.pdf
Abstract:
Investigation of the reproductive strategies of Arabian carpetshark Chiloscyllium arabicum (Gubanov, 1980) and Arabian whipray Himantura randalli (Last, Manjaji - Matsumoto et Moor, 2012) were conducted in Iraqi marine water from January, 2014 to December, 2014. A total of 365 Arabian carpetshark (200 female and 165 male) with total length ranged from 141 - 750 mm and 321 Arabian whipray (176 female and 145 male) with disk width ranged from 70 - 429 mm were cached. Trawling nets of Bahith Ship (owned by Marine Science Center) or other fishing boats were used to cached these fishes.Sex ratios of these fishes were investigated during study period. The cycle of gonad maturation was followed - up throughout the period of investigation by defining stages based on colour, shape and size of gonads. Fecundity was estimated and spawning period detected depending on gonado somatic index (GSI), hepato somatic index (HIS), histological study and sonar inspection.The length frequency distribution of Arabian carpetshark was dominated by group of 300 - 399 mm that appeared in all months except October. Smallest fish (142 mm, 20 g) was during October and biggest fish (750 mm, 1668.5 g) during June. The length - weight relationship was represented by the following equations : Male W= 0.000007 ×L 2.88Female W= 0.000005 × L 2.93 Both Sex W= 0.000006 × L 2.91Values of HSI was differ depending on the maturing conditions of males and females, where highest value (11.906) of HSI for females was recorded at October and lowest value (6.908) was recorded at June, while highest value (12.5) of HSI for males recorded at January and lowest value (9.14) recorded at March. There were negative correlation between oil ratioof liver and maturing condition of females, while in males this relation was not clear.Distinguishing of sex was carried out according to presence or absence of claspers. Smallest matured female was 421 ml in total length and 785.23 g in weight, while smallest matured male was 401 in total length and 693.14 in weight. Females were dominant on males during all months except February, August and November with equal sex ratio during March, while overall sex ratio was 1 : 1.26 toward females.The cycle of gonad maturation was divided into three stages : immature, maturing and mature for males and females. Linear relationship was found between total length (TL) and clasper length (x) and it was represented by following equation : TL=211.3479 + 0.013883 x X, with significant (P<0.05) correlation (r= 0.899) between them.The GSI values were different during study period, where highest values (8.84 and 7.93) for females recorded during April and May respectively and lowest value (0.73) during June, while highest value (6.74) for males recorded during March and lowest value (0.66) during May. Monthly differences in GSI especially for females refers that spawning period extended from May to June. This result supported by the results of frequency occurrence of germ cells. Results appeared that ovary of Arabian carpetshark contain 44 - 52 eggs with diameters between 22 - 48 mm. Depending on histological inspection of gonads, spermatocytes cells for males are divided into eight maturing stages, while spermatocytes cells for females into four maturing stages.Disk width (DW) frequency showed fife groups for Arabian whipray with dominant of 300 - 399 mm group that appeared in all months except October, while group of 200 - 299 mm was appeared in all months. Group of0 - 99 mm appeared in July and August, so it was concluded that reproduction occurred in July. Smallest fish (70 mm, 20 g) was cached during July and biggest fish (490 mm, 3834 g) was cached during June. Relationships between disk width and weight were as follow : Male W= 0.00031 x DW2.59 Female W= 0.0031 x DW2.31 Both Sex W= 0.0006 x W2.4HSI differed according to maturing conditions of males and females, where highest value (11.85) for females recorded during January and lowest value (6.04) recorded during June, while highest value (11.66) for males recorded during November and lowest value (7.48) recorded at March. There were negative correlations between gonad weight and liver weight of females and also between oil ratio of liver and maturing condition of females.Smallest matured female was 115 ml in disk width and 1936 g in weight, while smallest matured male was 355 in disk width and 1249 g in weight. Sex ratio was differ from the ratio of 1 : 1 during different months and at reproduction period the ratio of females was 64.5% and of males 35.5%, while the ratio was 50% for each sex after reproduction period at August. Females were dominant on males during all months except September and December and overall sex ratio was 1 : 1.26 toward females.Maturing cycle were divided into three stages : immature, maturing and mature for males and females. For males the dividing depending on morphological characteristics (length, size and colour) of claspers. Linear relationship was found between disk width and clasper length (x) and it was represented by following equation : DW=92.4133 +0.2233 x X .GSI showed differences throughout study period for both sexes. The highest value (8.63) for females recorded during June and lowest value (0.81) during July, while highest value (7.59) for males recorded duringJanuary and lowest value (0.97) during March. It was concluded, according to GSI especially for females, that birthing occurred between June and July.Number of eggs in the Arabian whipray ovary was ranged between 10 - 35 eggs and diameters between 5 - 28 mm, while the uterus contain 2 - 5 embryos that surrounded by strong covers and there wasn’t any placenta intelligence between embryos and female, so this fish considered as Ovoviviparous. Depending on histological inspections of gonads, spermatocytes were divided into seven maturing stages, while oocytes into four maturing stages.
