Increasing fish production from wetlands at Lake Victoria, Uganda using organically manured seasonal wetland fish ponds

Abstract

The processes driving primary productivity and its impacts on fish production were investigated in field trials in eight seasonal earthen wetland ponds 'Fingerponds' (192 m 2 ) in Uganda between 2003 and 2005. The ponds were stocked by the seasonal flood with predominantly Oreochromis spp. at densities ranging from 0.1 to 0.5 fish m -2 . Chicken manure (521, 833 or 1,563 kg ha -1 ) was applied fortnightly. Results showed that primary productivity was enhanced with maximum average net primary productivity (±Standard Error) of 11.7 (±2.5) g O 2 m -2 day -1 at the Gaba site and 8.3 (±1.5) g O 2 m -2 day -1 at the Walukuba site. Net fish yields were higher in manured ponds with up to 2,670 kg ha -1 yield for a 310 day growth period compared to less than 700 kg ha -1 in unmanured ponds. Fish production was limited mainly by high recruitment, falling water levels, light limitation from high suspended solids and turbidity, and low zooplankton biomass. It was concluded that Fingerponds have a high potential for sustainable fish production and can contribute to the alleviation of protein shortages amongst the riparian communities around Lake Victoria. Production can be enhanced further with improved stock management.

A synthesis of past, current and future research for protection and management of papyrus (Cyperus papyrus L.) wetlands in Africa

“…Two EU-funded projects, Fingerponds (2002Fingerponds ( -2006 and Ecotools (2002Ecotools ( -2005 focused on enhancing fish production through integrated pond aquaculture (e.g. Denny et al 2006;Kaggwa et al 2009;Kipkemboi et al 2010) and on developing modelling tools for improved wetland management (Loiselle et al 2006). Various other projects focused on wetlands such as the Sudd (Mohamed et al 2004), Lake Naivasha (Boar et al 1999;Boar 2006), Yala swamp (Thenya et al 2006), northern Lake Victoria (Azza et al 2006), Rubondo Island in Lake Victoria (Mnaya and Wolanski 2002;Mnaya et al 2006Mnaya et al , 2007, wetlands in western Kenya (Gichuki et al 2001;Osumba et al 2010;Morrison et al 2012), and the Okavango Delta Ellery 1994, 1998;Ellery et al 1995).…”

Evaluation of nitrogen cycling and fish production in seasonal ponds (‘Fingerponds’) in Lake Victoria wetlands, East Africa using a dynamic simulation model

“…The fish that are trapped in the ponds can be farmed and cropped and provide protein for resource‐poor communities, particularly in the dry season. This has been demonstrated in experimental Fingerponds in the Rufigi floodplain, Tanzania and in the wetlands surrounding Lake Victoria in Uganda and Kenya (e.g., Denny, Kipkemboi, Kaggwa & Lamtane 2006; Kipkemboi, Van Dam, Ikiara & Denny 2007; Kaggwa, Van Dam, Balirwa, Kansiime & Denny 2009).…”

“…Four Fingerponds of 24 × 8 m were dug in each of the four sites located in the flood zone of Lake Victoria wetlands; Gaba (N 0°14′59.9″, E 32°28′14.4″) and Walukuba (N 0°25′58.2″, E 33°14′59.8″), Uganda; and Kusa (S 0°3′55.9″, E 34°53′21.3″ and Nyangera (S 0°3′55.9″, E 340 4′52.2″), Kenya. Water quality data, including temperature ( °C), dissolved oxygen (DO), total suspended solids, ammonium nitrogen, nitrate nitrogen (NO 3 ‐N), chlorophyll a (Chl a ) and secchi depth visibility were collected monthly between 10:00 and 14:00 hours over a full production cycle (Kaggwa 2006; Kipkemboi 2006; Kaggwa et al 2009) following standard methods (APHA 1995).…”

“…Fish growth is governed by external factors (such as climate, pond inputs and water level) and internal pond factors (water quality, primary productivity and fish reproduction). Most of these factors were investigated experimentally in field experiments with Fingerponds (Kaggwa, Kansiime, Denny & Van Dam 2005; Kaggwa, Kasule, van Dam & Kansiime 2006; Kipkemboi, van Dam & Denny 2006; Kipkemboi, Van Dam, Ikiara et al 2007; Kipkemboi, Van Dam, Mathooko et al 2007; Kaggwa et al 2009). Formulation of management strategies for these systems requires a proper understanding of the interactions between internal and external factors.…”

A Decision Framework for Integrated Wetland-River Basin Management in a Tropical and Data Scarce Environment

“…Hence, their major problems seem to be sewage discharges from nearby cities and soil erosion. In addition major challenges might be the increasing of fish production in the lake and wetlands and the use of papyrus as nitrogen retention agents (Kaggwa et al, 2008;van Dam et al, 2007). The European wetlands in consideration (e.g.…”