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Catch Per Unit Effort, Exploitation Level and Production of Hilsa Shad in Bangladesh Waters

S.M.N. AMIN
Institute of Marine Sciences and Fisheries University of Chittagong, Chittagong 4331 Bangladesh

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

G.C. HALDAR
Bangladesh Fisheries Research Institute Mymensingh-2201, Bangladesh

M.A. MAZID
Bangladesh Fisheries Research Institute Mymensingh-2201, Bangladesh

D.A. MILTON
CSIRO Marine and Atmospheric Research PO Box 120, Cleveland 4163 Qld Australia

Abstract/ Executive Summary:

Catch per unit effort (CPUE) and exploitation rates of hilsa shad (Tenulosa ilisha Hamilton 1822) were estimated from the Bangladesh waters to evaluate the productivity of the population. Adult T. ilisha was caught mainly by gill net (mesh size 10.6-19.1 cm) with a mean catch rate of 45.7 kgxboat-1xday-1 during the peak period (September-October) in the Ramgoti area of Meghna River, Bangladesh. Tempo hilsa (immatures) was caught by chandi current jal (monofilament net, mesh size 6-8 cm) with a mean CPUE of 33.5 kgxboat-1xday-1 and a mean fish weight of 152-235 g. The total catch of hilsa in Bangladesh was estimated to vary between 146,082 and 229,714 mt from 1984 to 2002, with jatka (juvenile hilsa) contributing 19,258 mt in 2000. The average weight of each jatka was 10 g and if 10 - 15% of these jatka were protected, an additional 150,000- 250,000 mt of adult hilsa could be harvested each year from the present fishery. Exploitation levels (E) of hilsa were very high during the years 1996-2003 and need to be reduced by decreasing the level of fishing effort or increasing the mesh size that can be used.

Keywords: Catch Per Unit Effort, Production of Hilsa Shad, Bangladesh Waters

Location: Bangladesh

Start Date:

End Date:

Program Area: Socio-economic and Policy

Commodity: Hilsa

Objectives:

The present study was undertaken to provide an estimate of the catch per unit effort, total annual production and exploitation level (E) of hilsa. These aspects will help in formulating management and conservation policies for hilsa in Bangladesh.

Methodology:

Several surveys were conducted to assess the number of fishing vessels and their gear with the F.B. Hilsa Research boat during 1998-2000. Surveys covered the freshwater and estuarine reaches of the Meghna River from Chandpur (23°10.75′ N and 90 °36.2′ E) to Hatia (22°26.95′ N and 90°53.86′ E). The number of boats fishing for hilsa was counted during each survey and their positions were taken with GPS. The total length of each fishing boat and net; mesh size and CPUE data were collected from 49 hilsa fishing boats during September-October 1998 and from 28 fishing boats during September-November 2000. To monitor the catch (landing) of hilsa, the landing data from 1984 to 2002 were collected from the Department of Fishery (DOF) of Bangladesh. Monthly length frequency data for hilsa were collected from the commercial catches at different landing sites (Gualanda, Chandpur, Barisal, Khulna, Chittagong and Cox’s Bazar). These data were collected from January to December in 2003. The hilsa fishery in Bangladesh uses a wide range of mesh sizes (6.0-13.0 cm) depending on the season. At each landing site, the catch of hilsa from different mesh sizes was subsampled. Total length (cm) and weight (g) of up to 50 fish from each daily catch were measured. The data were then pooled into monthly groups from different landing sites and subsequently grouped into 2.0-cm length intervals. Finally, the length-frequency data were analysed with FiSAT (Gayanilo et al. 2002) to estimate the population parameters such as asymptotic length (Lα), growth coefficient (K), natural mortality (M), fishing mortality (F) and exploitation level (E).

Source of Information: Asian Fisheries Science 21(2008):175-187

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The results clearly indicate that the problem of overexploitation of this species is mainly because of the heavy exploitation of juveniles. Therefore, measures need to be taken to minimize the juvenile Hilsa fishery. The exploitation rate of adults should be reduced either by decreasing the number of fishing boats or by mesh size regulations. Banning the use of nets that catch juveniles and increasing community awareness of the issue of juvenile catch among the fishers will also help. But in order for these measures to be effective, the government needs to provide alternative sources of employment for them during the period of juvenile fishing (December to April). This would greatly help to minimize juvenile Hilsa fishery in Bangladesh. This would substantially decrease the present overexploitation and help increase the fishable number of adults in subsequent years. A further increase in the existing fishing level/exploitation will probably result in a reduction in the yield-per-recruit and thereby threaten the viability of the population.

Knowledge Management: Journal