Advances in Aquaculture and Fisheries Management

Advances in Aquaculture and Fisheries Management ISSN 2756-3278 Vol. 9 (3), pp. 001-009, March, 2021. © International Scholars Journals

Key words: Fish distribution, seasonal variation, lagoon.

Advances in Aquaculture and Fisheries Management ISSN 2756-3278 Vol. 9 (2), pp. 001-006, February, 2021. © International Scholars Journals

Full Length Research Paper

The use of traps and the need for conservation of Synodontis fisheries in Asa Lake, Ilorin, Nigeria

P. A. Araoye

Department of Biological Sciences, Benue State University, Makurdi, Nigeria. E-mail: [email protected].

Accepted 16 April, 2020

Abstract

The basket conical traps are commonly used to catch Synodontis species by the fishermen in Asa Lake, Ilorin, Nigeria because these species are caught alive to attract higher market values. Fleets of these traps randomly set at the bottom shoreline by fishermen at three different locations around the lake from the dam site to the river source were examined for Synodontis catch in 12 months. The specimen of Synodontis schall and Synodontis gambiensis were encountered with the latter occurring in August to October corresponding only with the flood season around the lake. S. schall occurred throughout the seasons but more abundantly in the traps during the dry season. All the specimens of Synodontis caught were found alive with mean standard length ranging from 7.8 to 16.75 cm for S. schall and 16.8 to 22.48 for S. gambiensis. Their corresponding weights ranges are 12.50 to 77.45 g and 49.75 to 92.76, for S. schall and S. gambiensis, respectively. Gravid specimens of both species were caught between the months of June to August in both the fixed and the lost traps. A total of 18 lost traps were recovered during the 12 months of research particularly during the flood seasons. There were no lost traps in November to March. The period of low catch (October and November) also corresponded with the season when the juveniles of S. schall became abundant in the lake. The total fish catch in the wet and dry season was significantly different (P<0.05) in both species. ‘Ghost fishing’ a phenomenon that usually occurred when the set traps were lost due to high floods around the lake and the need for conservation of these valuable water resources are discussed.

Key words: Traps, Synodontis, ghost fishing, conservation.

Advances in Aquaculture and Fisheries Management ISSN 2756-3278 Vol. 9 (2), pp. 001-005, February, 2021. © International Scholars Journals

Full Length Research Paper

A profile of the introduced OREOCHROMIS  NILOTICUS (Pisces: Teleostei) populations in Lake Victoria Region, Uganda

Wilson W.  Mwanja¹*, Gregory C. Booton², Les Kaufman³ and Paul A. Fuerst²

¹Department of Fisheries Resources, P.O. Box 4 Entebbe, Uganda.

²Department of Evolution, Ecology and Organismal Biology, 1735 Neil Avenue, Columbus Ohio 43210, U.S.A. 3th Boston University Marine Program, Department of Biology, Boston University 5  Cunninng Street, Massachusetts.

Accepted 18 October, 2020

Abstract

Random amplified polymorphic DNA (RAPD) marker analyses were used to profile the ‘ecological explosion’ of the introduced OREOCHROMIS NILOTICUS in the basins of Lakes Victoria and Kyoga in comparison to its putative origin of Lakes Edward, George and Albert. O. NILOTICUS is currently the dominant tilapiine in Lakes Victoria and Kyoga basins following its introductions from the Lakes Albert and Edward starting in the 1920s. The populations from the Lake Victoria basin were more similar to the putative source population of Lake Edward, while the populations from Lake Kyoga were more similar to the Lake Albert population. Lake Kyoga basin populations were less diverse than those of Lake Victoria basin, consistent with the hypothesis that introductions into Kyoga were more recent and/or that a more diverse set of introductions contributed to those of Victoria basin. Wider differences between Lake George and Lake Edward populations relative to distant populations was attributed to the direct transplant of Albert strain into George by a fish processing establishment in the 1970s. RAPDs offered a quick and inexpensive molecular tool to discern fish populations that could be adopted for management of the fisheries given the recent volatile species/populations changes and/or losses in Lake Victoria Region.

Key words: RAPDs, Oreochromis niloticus, Lakes Victoria, Kyoga, Edward, Albert, George.

Advances in Aquaculture and Fisheries Management ISSN 2756-3278 Vol. 9 (1), pp. 001-007, January, 2021. © International Scholars Journals

Full Length Research Paper

Growth performance and nutrient composition of Bufo maculata (Linneaus) tadpole fed different practical diets as fish meal substitute

Sogbesan, Olukayode Amos¹* and Ugwumba, Alda Adhia Alex²

¹Department of Fisheries, Federal University of Technology, Yola, Adamawa, Nigeria.

²Department of Zoology, University of Ibadan, Ibadan, Nigeria.

Accepted 17 August, 2020

Abstract

One thousand and one hundred (1,100) Bufo maculata tadpoles of weight range 0.03 -0.05 g (mean = 0.04 ± 0.008 g) and length range, 1.2 - 1.6 cm (mean = 1.4 ± 0.018 cm) were collected from the breeding tanks using scoop net and stocked into the outdoor concrete culture tanks coded according to the experimental diet at the rate of one hundred and twenty tadpoles of known weights and lengths per tanks and cultured for 84 days. The growth performances, feed utilization and nutrient composition of the tadpoles (B. maculata) fed three experimental diets namely live zooplankton alone (D1), 40% crude protein National Institute for Freshwater Fisheries Research (NIFFR) crumb diet alone (D2) and mixed diet (50% live zooplankton and 50% of dry 40% crude protein NIFFR crumb (D3) were studied. They were harvested after culture and processed into meal. The best mean weight gain (3.65 g/tadpole), specific growth rate (2.34%/day) and feed conversion ratio (2.05) were from tadpole fed mixed diets.

Key words: Bufo maculata, tadpole, growth, plankton, nutrient composition.

Advances in Aquaculture and Fisheries Management ISSN 2756-3278 Vol. 9 (1), pp. 001-009, January, 2021. © International Scholars Journals

Full Length Research Paper

Trophic analysis and fishing simulation of the biggest Amazonian catfish

Ronaldo Angelini¹, Nídia Noemi Fabrè², Urbano Lopes da Silva-JR³

¹Postdoc Researcher Department of Zoology, University of Cape Town Private Bag, Rodensbosch 7701, Cape Town, South Africa.

Universidade Estadual de Goiás, campus de Anápolis CP 459 - BR 153- Km 98; 75001-197 Anápolis, GO- Brazil

²Universidade Federal do Amazonas, Departamento de Biologia, Av. Gen. Rodrigo Octávio Jordão Ramos, 3000 69077-000 - Manaus, AM – Brazil,

³WWF-Brazil. R. Senador Eduardo Assmar 37 Salas 01-04 69900-000 - Rio Branco, AC – Brazil.

Accepted 07 December, 2020

Abstract

Currently, it is unanimous the fact that the ecosystem approach gives important insights to support fisheries stock assessment and management and healthy sustain aquatic ecosystems. This work aims at the quantification of energy flows at várzea (Amazon floodplain) and the simulation of increase in the fishing effort regarding the biggest predators, the catfish, and decrease of flooded forest cover. It was used the Ecopath with Ecosim software to build BAGRES model, which could allow inferences on ecosystem stability. Results showed that: i) BAGRES model has high overhead (69.7%) and Production/Respiration rate very close to 1, showing that this floodplain system is sufficiently mature and capable to support disturbance; ii) Finn’s cycling index for BAGRES (14.6%) is high when compared to other worldwide system; iii) increasing the effort of the catch of three species of Brachyplatystoma (catfish) have positive effects on biomass and consequently catch and landing of their main preys; iv) in the simulation of deforestation of Floodplain Forest (with no natural regeneration), all species are prejudiced (no exception), including Brachyplatystoma groups that do not use flooded environment. Therefore, the indirect consequence of the deforestation is more intense over fish stocks than increasing fishing effort. The BAGRES model results have important implications for the current policy-making for inland fishing in Brazil, currently mostly based on “defeso” (fishing restriction season), suggesting the necessity of incorporate the impacts which drive the deforestation in Amazon Floodplain.

Key words: Brachyplatystoma sp; várzea, Amazon floodplain; fisheries; Ecopath with Ecosim.