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Vol.2 No.07 -4 : Morphological observations, length-weight relationships, and condition factors of the Whipfin fish, Gerres filamentosus (Cuvier, 1829) in the Hurghada Red Sea, Egypt.

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By : Taher M. Abu El-Nasr

Abstract

During the period from January 2010 to December 2010, the biometric studies of 669 (both sexes- 12:39 centimeters) the whipfin, silver biddy, Gerres filamentosus (Cuvier,1829) have been described to clarify the identity of the fish population in the Hurghada Red Sea, Egypt. The straight lines of the regression equations of twenty one morphometric measurements relative to the total length or the head length indicate the linear relationships of the different body parts. Significant curvilinear relationship existed between total length and other morphometric characters and between head length and other characters of the head. Relationships between total length and various body measurements of the fish were highly significant (p < 0.01) except the relationship between total length and 2nd spine dorsal fin length of fish (p < 0.05). The Meristic characters including the number of fin rays, lateral line scales and gill rakers were found to be more or less similar except slight differences. The length-weight relationships respect to the total or the gutted weight were also investigated. It is obvious that, the value of the exponent (n=2.9475) indicates the negative allometric growth of this species. The values of condition factors (kc) in the total length body-weight relationships for female , male and combined sexes were found to be 1.49 , 1.47 and 1.51, respectively. The mean values of relative condition factors (kn) were 1.03 , 0.97 and 1.00 for female , male and combined sexes, respectively. However, relative condition factor (Kn) of Gerres filamentosus computed for July was 1.116 ± 0.24 and for January was .934 ± 0.012, which suggest the specimens were healthy and in good condition due to spawning cycle or other physiological activities or environmental factors. In searching of new potential aquaculture marine species, Gerres filamentosus may play role for enhancement of fish production as well as upliftment of socioeconomic condition in Egypt.

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Vol.2 No.07 -6 : The Fecundity of the whipfin silver-biddy fish, Gerres filamentosus (Cuvier, 1829) In The Hurghada Red Sea, Egypt.

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By : Taher M.Abu El-Nasr

Abstract

Fecundity estimates were made on a total of 92 mature fish of whipfin Silver-biddy, Gerres filamentosus (Cuvier, 1829) of different lengths and weights, collected during the early June of 2010 to October 2010. Log-Log relationships were calculated between fecundity (either absolute or relative) and fish length, fish weight, ovary length and ovary weight. A linear relationship exists between the individual absolute fecundity and fish length or ovary weight. It was found that, absolute fecundity increased at a rate proportional to the power of 4.31115, 1.41549, 1.89836 and 1.122 of the total length, the body weight, the ovary length and the ovary weight, respectively. While the regression coefficients of the relative fecundity estimations for the total length, the body weight, the ovary length and the ovary weight were 3.31115, 0.41549, 0.89836 and 0.0.122, respectively. The observations of the present study showed that fecundity, either absolute or relative, depended mainly on body length and to a lesser extent on body weight, and ovary length. Therefore, fish length is the best expression for fish fecundity and can be used for the prediction of Gerres filamentosus (Cuvier, 1829) production in the Hurghada Red Sea, Egypt.

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