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Title:	Some aspect of biological studies of the spotted scat, Scatophagus argus, in Malaysian waters
Authors:	Marina Hashim (P62656)
Supervisor:	Simon Kumar Das, Dr.
Keywords:	Estuarine ecology Fisheries -- Malaysia Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	29-Jul-2018
Description:	Scatophagus argus, the spotted scat, is a popular ornamental fish because of its attractive patterns and the high degree of resiliency which makes them highly desired in culture finfish and had a high value in the market. However, there are limited sources of literature regarding the biology of S. argus in Malaysian waters. Therefore it is important to document the detailed biology including length-weight relationship, condition factor, age, length-at-age, growth performance, stomach content analysis, trophic level, gastric motility, gastric emptying time, gastric emptying rate, pepsin activity, and reproductive biology of S. argus. A total of 1150 specimens were collected from Sungai Pulai, Johor coastal waters and Sungai Terus, Pekan Pahang. In the present study, the growth pattern of S. argus was estimated based on the length-weight analysis (W=aLb). S. argus displayed a positive allometric growth (3.1±0.03, b > 3). The growth pattern of male (3.2±0.1) and female (3.1±0.02) also display positive allometric growth (b > 3). The growth pattern of S. argus indicated that the fish increase in weight faster than in length. The mean Fulton condition factor (K) for S. argus ranged from 2.73 to 3.65 while the relative condition factor (Kn) ranged from 0.95 to 1.33. The age of S. argus was estimated using scales, and otolith analyses and estimated ages ranged from 1 to 10 years. The von Bertalanffy growth curve was fitted to the length at age of S. argus where the parameters were L∞ = 24.4 cm, K = 0.4 year-1. The estimated growth performance index (Φ') or phi-prime of S. argus was 5.47. Analysis of stomach content shows that the S. argus feed primarily on algae (Cyanophyceae) followed by detritus, prawn (Penaeus indicus), teleost and brown seaweed (Sargassum muticum). The overall mean trophic level for S. argus was 2.98±0.36 and analysis of the diet revealed it is an omnivorous fish. The stomach volume was measured as the total volume of water required to dilate the stomach until it burst where the volume=0.0000089W2.93. Gastrectomy observation of S. argus by using X-radiographic technique showed that the fish (200 g) completely evacuated the stomach within 32-36 hours (GET) post feeding. Digestion study of S. argus shows that the fish of various sizes emptying their stomach at the same phase (0.3 g.hr-1), with normalised GER around 0.0024 - 0.0026 g.hr-1.g-1bw. The pepsin activity in the stomach was studied by measuring the effect of meal size towards pepsin activity shows that the pepsin secretion increased with increasing meal size, but there were no significant changes observed between time intervals. Estimation of sex ratio of S. argus concludes that females dominate over males in the population with a sex ratio of 1 male:5 female. Histological observations of ovarian and testis development show that this species are most likely asynchronous spawners. This study also provides the findings of ovotestis in the ovary of S. argus, but more detailed studies needed to confirm the present results. The analyses of the macroscopic description of gonads, oocyte diameter and the GSI, have been able to determine the spawning season which suggested that the monsoon triggers oocytes maturation and spawning. Total fecundity estimates ranged from 57,000 - 1,312,000 eggs for female S. argus. The descriptive study of S. argus will aid in the management of wild stocks, commercial status and economic importance of S. argus.,Ph.D.
Pages:	162
Call Number:	QH541.5.E8M337 2018 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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