Reproductive biology and larval rearing of Hippocampus kuda, and the taxonomy of seahorses (hippocampus spp.) along the southern coast of India (TH 124)

Salin, K R (2003) Reproductive biology and larval rearing of Hippocampus kuda, and the taxonomy of seahorses (hippocampus spp.) along the southern coast of India (TH 124). PhD thesis, Central Institute of Fisheries Education, Mumbai.

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Abstract

An organised fishery and trade of seahorses exist in the Palk Bay and Gulf of Mannar coasts of India. Six species of seahorses namely Hippocampus borboniensis Dumeril 1870, Hippocampus spinosissimus Weber 1913, Hippocampus kuda Bleeker 1852, Hippocampus fuscus Ruppell 1838, Hippocampus trimaculatus Leach 1814 and Hippocampus guttulatus Cuvier 1829 were identified from the southern coast, and the total landing at the major fishing centre, Thondi was estimated as 18.25 MT or 26,48,179 numbers of seahorses during 2001 . The volume of seahorse trade from India was estimated as 9.75 MT of dried seahorses. A significant quantity of 1.6 MT (5,61,418 numbers) is also landed along the Quilon coast in Keraia, but it is not involved in any organised trade. H. borboniensis was found to be the major species (27.96%) at Thondi, followed by H. spinosissimus (22.14%). H. kuda (20.9%) , H. trimaculatus (14%) , H. fuscus (9%) and H. guttulatus (4%) . The major size classes represented in the fishery were 145-175 mm, 145-165 mm, 105-190 mm, 110-165 mm, 140-190 mm and 150-190 mm respectively for the six species collected from Thondi in 2001 . Crustaceans (88.85%) , consisting of cope pods (22.8%)' mysids and cumaceans (22.12%), amphipods and isopods (20.86%), decapod larvae and tiny caridean shrimps (20.67%) dominated the gut contents of H. kuda at Thondi. Ova diameter ranged from 0.5-0.8 mm and the mean fecundity was 56.8 g-1 body weight of the female. The length-weight relationships were obtained as W = 0.438615 (L 1.103592) for males, and W = 0.370531 (L 1.231822) for females of H. kuda collected from Thondi. The size at first maturity for males and -females of H. kuda was found to be 66.07 mm and 77.99 mm for males and females respectively. At Thondi H. kuda was fo_und to breed year round, the major breeding season extending from June to September with peak from July to August. The sex ratio remained almost the same, except during the breeding season when more males were seen in the catches. The captive rearing of the hatchlings of H. kuda using different feeds showed that a diet of enriched Artemia nauplii and mixed marine copepods was the best combination, which gave mean survival rates of up to 56% and growth of 49.4 mm and 0.316 g after 60 days of rearing. A stocking density of 3 juveniles per litre was found to be the optimum, which gave high growth increment in length (43.67 mm) and weight (0.313 g) as well as the highest mean production per litre of 1.51 during a rearing period of 60 days. The juveniles of H. kuda were found to grow equally well in salinities ranging from 15 %0 to 35 %0. The highest mean survival (60.56%). mean length (28.7 mm) and mean weight (39.1 mg) were obtained at 30 %0 while rearing for 14 days. Rearing tanks, which were partially covered to improve the feeding efficiency of Artemia nauplli registered the highest mean survival (91%) and mean length (36.2 mm) and weight (66.14 mg) of juveniles during a 14-day period. The juveniles of H. kuda were found to have reasonably high tolerance to extreme levels of salinity, pH and formalin. The LCso values were 4.62, 4.83, 5.43 and 5.56 for low pH and 11 .04,10.52,10.33 and 10.23 for high pH at 12, 24 48 and 72 h respectively. In the case of salinity, LCso values of 1.59, 2.92, 3.63 and 4.67 %0 for low salinity, and 58.08, 54.45, 51 .29 and 49.26 %0 for high salinity were obtained for 12, 24, 48 and 72 h respectively. The LCso for formalin was found to be 315, 296.48, 279.25 and 271 .02 ppm for 12, 24, 48 and 72 h respectively.

Item Type:Thesis (PhD)
Supervisor(s):Yohannan, T M
Uncontrolled Keywords:Reproductive biology; larval rearing; Hippocampus kuda; taxonomy; seahorses; hippocampus spp.; southern coast; India
Subjects:Theses
Demersal Fishes > seahorses
Divisions:CMFRI-Cochin > Mariculture
ID Code:7217
Deposited By:Dr. V Mohan
Deposited On:31 Jan 2011 15:42
Last Modified:21 Jan 2014 12:27

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