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Reproductive Characteristics of Liza Parsia (ham.) Inhabiting Southwest Coast of Bangladesh

M. Begum
Bangladesh Fisheries Research Institute, Brackishwater Station, Paikgacha, Khulna-9280, Bangladesh

M. A. Islam
Bangladesh Fisheries Research Institute, Brackishwater Station, Paikgacha, Khulna-9280, Bangladesh

H. K. Pal
Bangladesh Fisheries Research Institute, Brackishwater Station, Paikgacha, Khulna-9280, Bangladesh

M. J. Alam
Bangladesh Fisheries Research Institute, Brackishwater Station, Paikgacha, Khulna-9280, Bangladesh

Abstract/ Executive Summary:

In order to determine the reproductive characteristics of Liza parsia, a fish of commercial importance, the GSI, egg diameter, sex ratio and fecundity were examined in 331 specimens caught monthly for a period of ten months from September 2006 to June 2007. According to the GSI and egg diameter, the reproduction period of Liza parsia was determined to be in November to March with two peaks in the months of December and February. The maximum GSI values obtained for male and female were 1.49 and 14.71 respectively in the month of February. In December, the gonadosomatic index decreased in female (13.5) and in male (1.4). The average egg diameter of Liza parsia ranged from 0.35 to 0.50 mm. The sex ratio (Male:Female) of the investigated fish was 1:1.21. Fecundity of the fish ranged from 18,950 to 1,71,210 during the period of study. Linear relationships between fecundity and total-length, bodyweight, gonad-length and gonad-weight were found and fecundity was more related to the ovary length (r=0.8172) and ovary weight (r=0.8552) than the fish length (r=0.7538) and fish weight (r=0.7592).

Keywords: Reproductive characteristics, Liza parsia, GSI, Fecundity

Location: Brackishwater Station, Paikgacha, Khulna

Start Date: 00-09-2006

End Date: 00-06-2007

Program Area: Variety and Species

Commodity: Marine fish

Objectives:

To determine the egg productivity, gonadosomatic index, the reproduction period and age at maturity of L. parsia and also to establish a relationship between the fecundity and body-length, bodyweight, gonad-length and gonad-weight of the fish.

Methodology:

The experiment was conducted in Brackishwater Station, Paikgacha, Khulna for a period of ten months from September 2006 to June 2007. Thirty one mature fish were collected randomly during monthly sampling to determine the total length and weight. A total of 310 male and female Liza parsia were examined to determine the gonadosomatic index, fecundity and ova diameter. The collected specimens were brought to the laboratory and they were firstly cleaned, measured and weighed. In order to determine the sexual maturity and reproduction time, the male and female fish were separated and data were recorded after dissecting out the gonad of the individual fish. Then the gonads of fish were taken out very carefully and preserved in well labeled vials containing 5% buffered formalin for subsequent studies. Gravimetric method was followed to determine the fecundity of fish. In using this method, the external connective tissues were removed from the surface of the ovaries. Moisture of the ovaries was removed with the help of blotting paper. Weight of ovaries was recorded in gram with the help of a fine electric weighing balance. Then 0.01 g of each ovary was taken separately from anterior, middle and posterior regions of each lobe. The number of mature and immature eggs for each portion was sorted out and counted with the help of a needle and magnifying glass. The mean number of eggs in 0.01 g was determined and then multiplied by the total weight of the ovary, which gave the total number of eggs i.e., the fecundity of the respective fish. Gonadosomatic index (GSI) of the male and female fish of the collected samples was determined separately following the equation cited by Parameswarn et al. (1974). GSI = (Weight of gonad / Weight of fish) × 100 ova diameter at different stages of maturity was measured with the help of ocular micrometer. In this study, 12 ova were taken randomly from the mixed sample of eggs of three portions of each ovary. Measurements of ova diameter were taken along the longest axis of the ova. Sex ratio of the collected fishes was estimated. The relationship between the fecundity and total-length, body-weight, gonad-length and gonad-weight were determined with the help of a computer following MS Excel program.

Source of Information: J. Bangladesh Agril. Univ. 8(1): 173–178, 2010 ISSN 1810-3030

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The maximum GSI values obtained for male and female were 1.49 and 14.71 respectively in the month of February. In December, the gonadosomatic index decreased in female (13.5) and in male (1.4). The average egg diameter of Liza parsia ranged from 0.35 to 0.50 mm. The sex ratio (Male:Female) of the investigated fish was1:1.21. Fecundity of the fish ranged from 18,950 to 1,71,210 during the period of study. Linear relationships between fecundity and total-length, bodyweight, gonad-length and gonad-weight were found and fecundity was more related to the ovary length (r=0.8172) and ovary weight (r=0.8552) than the fish length (r=0.7538) and fish weight (r=0.7592). In accordance with the findings obtained, it was determined that the induced breeding of L. parsia should be done during November to March as it is the breeding period of this species. It was furthermore established that a prohibition on fishing should be put into effect during December and February since these months were observed to constitute the peak reproduction periods of L. parsia

Knowledge Management: Journal