Abstract
High rates of body deformities is one of the most challenging problems in fish culture and is a common source of downgrading the product value of commercially raised fish. The aims of this study are explore the effects of xenic and axenic rearing conditions on the seabass larvae and check whether the rearing condition has a different effect as larvae grow older. The larvae of seabass larvae, Dicentrarchus labrax L. (Teleostea, Moronidae), were reared under xenic and axenic rearing conditions up to fourteenth day after hatching (DAH). The size and shape were analyses for specimens of three age groups: DAH zero, four and 12. The growth comparison was done based on length measurements. For specimens of DAH zero and four, the total length, gut length, predorsal fin length, yolk sac length and height were measured. For specimens of DAH 12 the total length, standard length, gut length, dorsal fin fold length and height, anal fin fold length and height, preanal fin fold length, predorsal fin fold length, eye diameter, head height, hind gut length and notochord diameter were measured. The average measurements for these metric variables were lower in axenic specimens than xenic ones suggesting better performance in xenic treatment. The variations in body shape were studied and quantified using geometric morphometrics. The results showed significant differences in shape between the xenic and axenic specimens at all age groups. Thus, the importance of larval rearing conditions in determining seabass shape and quality is evident. Key words/phrases : seabass, aquaculture, body deformity, geometric morphometrics
Highlights
The seabass, Dicentrarchus labrax, Linnaeus 1758, is primarily marine fish that sometimes enters brackish and freshwaters, tolerating wide range of environmental conditions: eurythermic (5-28°C) and euryhaline (3‰ to full strength sea water)
The disinfected ones were stored in incubation bottles for axenic rearing and the remaining eggs were kept in 20 liter tank for xenic treatment
The average value obtained for total length, gut length, yolk sac length and height are higher in xenically treated larvae whereas the average predorsal length was higher in axenically treated larvae at day after hatching (DAH) 0 and 4 (Table 1)
Summary
The seabass, Dicentrarchus labrax, Linnaeus 1758, is primarily marine fish that sometimes enters brackish and freshwaters, tolerating wide range of environmental conditions: eurythermic (5-28°C) and euryhaline (3‰ to full strength sea water). It was cultured in coastal lagoons and tidal reservoirs before the mass-production of juveniles started in the late 1960s (FAO, 2007). Various sources of body deformities have been identified: pollutants (Bengtsson et al, 1988; Nguyen and Jansen, 2002), temperature (Polo et al, 1991), water currents (Divanach et al, 1997), nutrition (Dedi et al, 1995; Takeuchi et al, 1998; Haga et al, 2002), diseases (Breinholt and Heckmann, 1976), and genetics (Campbell, 1995). Despite the impressive progress made in the rearing methods, nutrition and disease control, morpho-anatomical abnormalities continue to affect the hatchery production (Koumoundouros et al, 2002, Koumoundouros (http://creativecommons.org/licenses/CC BY4.0)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
