Population dynamics of an endemic and threatened Yellow Catfish Horabagrus brachysoma (Günther) from Periyar River, southern Western Ghats, India

G Prasad,Anvar Ali,Rajeev Raghavan,M Harikrishnan

doi:10.11609/jott.o2590.2333-42

Abstract

Based on the annual length frequency data collected from three major fish landing centres along the River Periyar, draining the southern Western Ghats, the von Bertalanffy growth function (VBGF) estimates of Horobagrus brachysoma were worked out as asymptotic length (La) = 422mm total length, growth co-efficient (K) = 0.55 yr-1 and growth performance index (ÃƒÂ¸) = 4.99. The total mortality rate (Z) was estimated at 5.64 yr-1, natural mortality rate (M) at 1.04 yr-1, fishing mortality (F) at 4.60 yr-1, and exploitation rate (E) at 0.82 yr-1. Yield per recruit (expected lifetime yield per fish recruited in the stock at a specific age) analysis showed an excessive fishing effort. Using the analysis of probability of capture of each length class, the length at first capture (Lc) of H. brachysoma was estimated to be 110mm. An indication of both growth and recruitment fishing is provided by the dominance of year 1 class in the exploited population and the capture of immature individuals below first maturity. Management of H. brachysoma fishing should include setting of a minimum mesh size limit of 160Ã¢Â€Â“180 mm for gill nets as well as a closed season starting from the month of May till August aimed at protecting the spawning stock. This study on H. brachysoma, an endemic and threatened catfish of peninsular India, provides hard evidence that species targeted by artisanal fishermen, in small-scale tropical riverine fisheries, are vulnerable to overexploitation.

Highlights

Small scale freshwater fisheries contribute an important source of food security and livelihood to billions of rural communities in the tropics
Data was collected following the methodology of Gulland & Rosenberg (1992) on the length based approaches to fish stock analyses published by the Food and Agricultural Organization (FAO)
‘b’ in H. brachysoma from Periyar River followed the cubes law indicating an isometric growth pattern, similar to the observations made by Kumar et al (1999) from Achenkovil and Ali et al (2008) from Pampa rivers

Summary

Introduction

Small scale freshwater fisheries contribute an important source of food security and livelihood to billions of rural communities in the tropics. In spite of being small-scale and artisanal in nature, the fishery of several important freshwater fish including mahseer (Bhatt et al 2000, 2004; Raghavan et al 2011) and catfish (Patra et al 2005) in India; major carps (de Graaf 2003) in Bangladesh; large cyprinids in the Mekong basin (Baird 2006; Dudgeon 2000) and sturgeons in China (Wei et al 1997) have shown a characteristic decline in the last decade. Unlike marine ecosystems, datasets on the Population of Yellow Catfish dynamics of exploited populations of economically important fish species in rivers, especially those in the developing countries are largely unavailable. This is mainly due to the lack of personnel and financial resources in such countries to undertake research programs (Maccord et al 2007). These deficiencies are a cause and consequence of the lack of attention that the sector receives from the government (Anonymous 2002)

Methods

Results

Conclusion