Factors Affecting the Distribution of an Anguilla bicolor McClelland and Anguilla nebulosa McClelland (Anguilliformes; Anguillidae) in a River System of Southern Sri Lanka
Between 1990 and 1993, Anguilla bicolor bicolor and Anguilla nebulosa nebulosaMcClelland were captured using fyke nets, and physiochemical parameters were noted from the Malala Lagoon and five upstream reservoirs (Kuda Badagiriya, Badagiriya, Ranmuda Wewa, Pahalaandawa Wewa and Mahagala Wewa) of the Malala River System, Sri Lanka.
Catch per unit effort (CPUE) was higher for A. bicolor bicolor than for A. nebulosa nebulosa in all water bodies except for Kuda Badagiriya, from which lowest mean Secchi depth (22.7±8.1 cm) and water depth (1.10±0.27 m) and higher CPUE for A. nebulosa than for A bicolor were recorded. From Malala Lagoon, highest mean conductivity (4,082±2,331 µC cm-1), Secchi depth (93.0±32.4 cm) and CPUE for A. bicolor, smallest A. bicolor with the lowest condition factor (K), and silver A. nebulosa with the highest K, were recorded. Yellow eels were captured from all reservoirs but only yellow A. bicolor were captured from Malala Lagoon. Mahagala Wewa, the most upstream reservoir with low conductivity, recorded highest mean length and weight for yellow eels of both species, and the highest condition factor for A. bicolor.
Conductivity and turbidity of water could be suggested as the major factors which affect the distribution and condition of A. bicolor and A. nebulosa in river systems of Southern Sri Lanka.
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