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Some Aspects of Population Dynamics of Juvenile Hilsa Shad (tenualosa Ilisha Ham.) from the Meghna River, Bangladesh

M.S. Miah
Bangladesh Fisheries Research Institute, Riverine station, Chandpur-3602,Bangladesh

M.A. Mazid
Bangladesh Fisheries Research Institute, Riverine station, Chandpur-3602,Bangladesh

G.C. Haldar
Bangladesh Fisheries Research Institute, Riverine station, Chandpur-3602,Bangladesh

M.A. Rahman
Bangladesh Fisheries Research Institute, Riverine station, Chandpur-3602,Bangladesh

Abstract/ Executive Summary:

Population dynamics of the juvenile hils a shad (Tenualosa ilisha) in the nursery ground of the Meghna river have been studied on the basis of the length cohort analysis of 8023 specimens. The growth parameters viz; asymptotic length (L ), curvature character (K) and initial time(t₀) were found to be 30.69 cm, 1.2 yr^·1 and 0.45 yr^·1respectively. Curvature parameter indicate that jatka is a fast growth performer. The natural, fishing and total mortality were found to be 1.37 yr^{· 1}, 1.41 yr^·1 and 2. 78 yr^·1respectively. Survival rate (S) was found to be 6.2%. A small difference was found between the;age at first capture (T J and the recruitment age (Tr). Stocks of jatka seems to be overexploited and need to be conserved.

Keywords: Juvenile hilsa, Population dynamics, Meghna river

Location: Meghna river, Chandpur

Start Date: 00-12-1993

End Date: 00-04-1996

Program Area: Animal Health and Management

Commodity: Hilsa

Objectives:

To understand the impacts of juvenile hilsa population as a capture fishery.

Methodology:

Length-frequency data collection - Length-frequency data of 8023 individuals of jatka were collected from the nursery ground of the Meghna river in and around Chandpur during December 1993 through April1996. Length-frequency data were collected both by experimental fishing as well as from commercial catches. In each month adequate number of length-frequency data were randomly collected. Total length (em) was measured from the tip of the snout to the posterior most margin of the caudal fin. Experimental fishing was done by a beach seine net (150m x 18m, 0.75cm mesh) manually hauled by 12 people. Commercial catches were done by a large seine net (400m x 30m, 0.75cm mesh) employing about 60 fishermen for hauling. Data analysis - Length-frequency data were analyzed by using the Microstat and Excel-statistica computer software packages program. Growth parameters of jatka fishery viz; asymptotic length (L.,J, curvature parameter (K) and initial time (t0 ) when jatka begins to grow just after hatching, were estimated on the basis of the Von Bertalanffy growth analysis by using the growth equation model. Natural and fishing mortality - Natural mortality (M) for jatka fishery was calculated by Pauly's empirical formula through various combinations of L, K and average annual temperature(T⁰ c). Here annual temperature was considered only for the period of November to April when jatka is available in the riverine nursery ground.

Source of Information: Bangladesh J. Fish. Res., 4(1): 75-81, 2000

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The growth parameters viz; asymptotic length (L), curvature character (K) and initial time(t₀) were found to be 30.69 cm, 1.2 yr^·1 and 0.45 yr^·1respectively. Curvature parameter indicate that jatka is a fast growth performer. The natural, fishing and total mortality were found to be 1.37 yr^{· 1}, 1.41 yr^·1 and 2. 78 yr^·1respectively. Survival rate (S) was found to be 6.2%. A small difference was found between the;age at first capture (T J and the recruitment age (Tr). Stocks of jatka seems to be overexploited and need to be conserved.

Knowledge Management: Journal