Reproduction Strategy of Arabian Whipray Himantura randalli Last, Manjaji-Matsumoto & Moore, 2012 in Iraqi marine waters, northwestern Arabian Gulf

Abstract

Reproduction strategy of Arabian whipray Himantura randalliLast, Manjaji-Matsumoto & Moore, 2012 was studied in Iraqi marine water fromJanuary, 2014 to December, 2015. A total of 321 specimens (176 females and 145males) were collected by trawling net of Al-Bahith ship (related to Marine ScienceCentre). Results are pointed that there were five groups of disk width, with smallestfish of 70 mm disk width and 16 g in weight, while largest fish of 750 mm disk widthand 3834 g. Smallest fish appeared firstly at July concluding that birthing occurredduring this month. Relationship for both sex between disk width and weight wasrepresented by following equation: W=0.0006 x (DW) 2.449 . Results also appearedthat the disk width of smallest matured female was 385 mm and weight 1936 g, whilethe disk width of smallest matured male was 355 mm and weight 11249 g. Sex ratiowas differ during different months especially at reproduction period where ratio offemales 64.5% and males 35.5%, so overall sex ratio was 1:1.2 towards females. Thecycle of gonad maturation was divided into three stages: immature, maturing andmature for males and females. The GSI values were different during study period, andbirthing was considered during June to July. The ovary contain many eggs of differentsizes, while the uterus contain 2-5 embryos that surrounding by strong covers andthere wasn’t any placenta intelligence between embryos and female, so this fishconsidered as Ovoviviparous. Depending on histological inspections of gonads,spermatocytes were divided into seven maturing stages, while oocytes into fourmaturing stages.