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Length-weight Relationship and Growth Pattern Inference of a Small Indigenous Freshwater Prawn, Macrobrachium Lamarrei (h. Milne-edwards, 1837) in Bangladesh

Motia Gulshan Ara
Department of Fisheries Management, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Md. Noor Nabi
Department of Fisheries Management, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Zoarder Faruque Ahmed
Department of Fisheries Management, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Mst. Kaniz Fatema
Department of Fisheries Management, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Abstract/ Executive Summary:

The length-weight relationships (LWRs) of Macrobrachium lamarrei (H. Milne-Edwards, 1837) was studied to construct the generalized relationships of body weight to carapace length measurements for male, female and combined prawn population separately over a calendar year. A total of 1018 specimens were used for this study. The parameter values of the equation W = a Lb describing the relationships between body weight and carapace length for male, female and combined prawns. The parameter of equations, a varied from 0.00096 to 0.00333, 0.00059 to 0.00728 and 0.00081 to 0.00440 for male, female and combined prawn population respectively. On the other hand, the slope of equations, b varied from 2.4363 to 2.8229, 2.0761 to 3.0314 and 2.2915 to 2.8998 for male, female and combined prawn population respectively indicating isometric growth in females but negative allometric for males suggesting that female prawns were comparatively in better condition than males of the same population. The generalized length-weight relationship was fitted with the pooled data of all monthly samples for male, female and combined prawn separately which were BW = 0.0008 CL2.924, BW = 0.0012 CL2.783 and BW = 0.0010CL2.845 respectively indicating negative allometric growth as b varied from 2.783 to 2.924. The results further revealed that all length-weight relationships (LWRs) were highly correlated (r2 > 0.904).

Keywords: Freshwater prawn, Length, Weight, Growth pattern

Location: Bangladesh Agricultural University campus, Mymensingh, Bangladesh

Start Date:

End Date:

Program Area: Animal Health and Management

Commodity: Prawn

Objectives:

The aims of the present paper is to determine the length-weight relationships of monthly samples, to construct a generalized length-weight relationship of M. lamarrei for male, female and combined prawn separately over a calendar year and to evaluate the growth pattern of male, female and combined populations from L shaped pond at Bangladesh Agricultural University campus, Mymensingh, Bangladesh.

Methodology:

Sample collection: M. lamarrei prawn species was collected randomly using a fine-meshed push net from the Lshaped pond situated in Bangladesh Agricultural University campus, Mymensingh, Bangladesh once in a month over a calendar year. All specimens were preserved in 10% buffered formalin soon after collection. Sex determination: Male was identified observing second chelate legs which were extraordinary large, spiny and strong with naked eyes. Individuals confirmed as female with the presence of one pair of genital pore in the coax of third pairs of walking legs under a stereo microscope. Recording of carapace length and body weight Carapace length (CL) was measured from the tip of the rostrum to the posterior edge of the carapace with a slide calipers to the nearest 0.01 mm, whilst body weight (BW) was taken with a digital balance to the nearest 0.01 g. Length - weight relationship (LWR): The relationship between carapace length and weight was calculated using the equation, W = a CLb where coefficient ‘a’ is the intercept in the y-axis, and the regression coefficient ‘b’ is an exponent indicating isometric growth when equal to 3. This equation was converted into its logarithmic expression: ln W = ln a + b ln CL where the parameters ‘a’ and ‘b’ were calculated by linear regression, as was the coefficient of determination (r2). To test for possible significant differences in both slope and intercept, we followed the analysis of covariance (ANCOVA). All statistical analyses were considered significant at P < 0.05. Growth pattern inference: Growth pattern of individuals in monthly sample were determined on the basis of b value in the equation BW = a CLb. When ‘b’ is equal to 3, the growth was isometric resulting an ideal shape of prawn; when the value of b was less than 3.0, the growth was negative allometric and when the value of b was more than 3.0, the growth was positive allometric pattern. The growth pattern of the individuals in the population was evaluated judging the confidence interval of ‘b’ value at 95% confidence level.

Source of Information: Res. Agric., Livest. Fish. Vol. 1, No. 1, December 2014: 137-145

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Length-weight relationship (LWR) is an important fishery management tool (Bagenal and Tesch, 1978; Gonzalez Acosta et al., 2004). They are used for various aspects including estimation of weight from length observations, calculation of production and biomass in the assessment of fish populations, in addition providing information about body condition of specimens in stocks or populations (Lai and Helser, 2004; Gerritsen and McGrath, 2007). Information regarding any biological aspects of M. lamarrei prawn species from Bangladesh waters is quite insufficient. To the best of our knowledge, no references dealing with length-weight relationship (LWR) for M. lamarrei is available from Bangladesh waters. Therefore, this study presents the first attempt to describe this length-weight relationship for the M. lamarrei species from Bangladesh. In conclusion, this study has provided the first basic and baseline information on the LWR that would be beneficial for fishery biologists and conservationists to impose adequate regulations for sustainable fishery management and conservation of biodiversity for this species in Bangladesh. Further, the information provides a platform for future research into other growth and reproductive attributes of this fish species.

Knowledge Management: Journal