Fishing for Dagaa with 5 mm and 10 mm mesh nets: A comparison of length-frequencies and biological characteristics

Abstract

Two mesh sizes (5 and 10 mm) usually used to harvest Rastrineobola argentea in Lake Victoria were assessed from April to September 2001 to determine their suitability. It was observed that 13.2% of fish caught in 5 mm and 11.2% caught in 10 mm for April, May, June and July were of a size below maturity (44 mm standard length, [SL]). Mean size of fish caught with the 5 mm mesh was 46.8 ± 1.2 mm and that of fish caught with the 10 mm mesh was 46.8 ± 0.5 mm (SL). Catches per unit effort (CPUE) from the two meshes were not significantly different, with Haplochromis laparogramma (50.1%) dominating the catch followed by R. argentea (48.9%). Juveniles of Nile Perch, Brycinus jacksonii, Brycinus sadleri, and Barbus spp. (0.9%) were caught in small numbers. About half of the females matured at 43.5 mm and the males at 46.6 mm SL. Fish caught with the 5 mm mesh had on average 1050 ± 400 eggs and those caught with the 10 mm mesh had 918 ± 281 eggs, but the difference was not significant. However, a significant difference was noted between non-infected fish (1050 ± 400 eggs) and fish infected by the cestode Ligula intestinalis (663 ± 316 eggs). Given the absence of differences in key parameters under investigation between the fish caught with the 5 and 10 mm mesh sizes, the two meshes can be used interchangeably.

Assessment of the effects of plerocercoid larvae of Ligula intestinalis (Cestoda) on Engraulicypris sardella (Cyprinidae) from northern Lake Nyasa/Malawi/Niasa

“…Paperna (1996), Van Dobben (1952 and Okedi (1981) reported that the tapeworm hamper the gonadal development and retarding maturation of the ovary of the host fish. Recently it has been reported by Nsinda et al (2013) that the tapeworm reduces fecundity of Dagaa fish Rastrineobola argentea in Lake Victoria.…”

Are the Solar and Battery-Powered Lights used for Dagaa Rastrineobola argentea Fishing a Threat to the Nile Perch Lates niloticus Fishery in Lake Victoria?

“…Both Dagaa and the Haplochromines have enormous potential for small-scale trading in local and regional marketplaces, acting as an affordable source of protein for both human and animal sustenance [3]. In addition, a sizable amount is transported to poultry factories to prepare animal feed [12].…”

“…The use of fabric materials as fishing nets was used at the beginning of the Dagaa (Rastrineobola argentea) fishery in Lake Victoria, followed by the introduction of lantern lamps (Karabai) [1][2][3]. The fishery is currently one of Lake Victoria's four commercial fisheries, the others being those for haplochromines, Nile perch (Lates niloticus), and Nile tilapia (Oreochromis niloticus) [4,5].…”