Observations on the taxonomy and biology of Lates (Cuvier 1828) in Lake Albert

Both in terms of commercial landings and biological importance, the Nile Perch is one of the most prominent fish in Lake Albert. It can bear considerable further exploitation, is the source of stockings elsewhere, and it is, therefore, important to know whether more than one species is being dealt with, and, if so, what differences there are in the ecology of the different species.

Aquatic ecology monitoring: water quality, fish, fish catch, sanitation and disease vectors: monitoring No.7, 4-7th September 2010

The results reported on were from a monitoring survey No.7 undertaken between 4 th and 7th September 2010 during construction period of the Bujagali Hydropower Project (BHPP). Two pre-construction, baseline surveys in April 2000 and April 2006 were conducted and so far, during construction phase of the project, six monitoring surveys have been undertaken i.e. in September 2007, April 2008, April 2009, October 2009, April 2010 and the present one, in September 2010. Since 2009 biannual monitoring surveys have been conducted at an upstream and a downstream transect of the BHPP with emphasis on the following aspects: I. water quality determinants 2. biology and ecology of fishes and food webs 3. fish stock and fish catch including economic aspects of catch and 4. sanitation/vector studies (bilharzias and river blindness)

Aquatic ecology monitoring: water quality, fish, fish catch, sanitation and disease vectors: monitoring no.12, 25th-30th April 2013

Bujagali hydropower dam construction is now completed and a reservoir behind the dam has been created, extending all the way up to Kalange-Makwanzi, an upstream transects. During the 10th monitoring survey-April 2012, a third transect was established in the mid of the reservoir where it runs up to 30 m deep and sampled similarly as at the two original sampling transects, Kalange-Makwanzi and Buyala-Kikubamutwe for comparative purposes. This monitoring survey No. 12 undertaken between 25th and 30th April 2013 is the third one to be conducted after completion of construction of Bujagali Hydropower Dam. Two pre-construction baseline surveys in April 2000 and April 2006 were conducted and during construction phase, eight monitoring surveys (September 2007, April 2008, April 2009, October 2009, April 2010, September 2010, April 2011, September 2011) were conducted. Since 2009 biannual monitoring surveys have been conducted at an upstream and a downstream transect of the BHPP with emphasis on the following aspects: water quality determinants, biology and ecology of fishes and food webs, fish stock and fish catch including economic aspects of catch and sanitation/vector studies (bilharzias and river blindness). In the post-construction monitoring surveys, the assessments of algae, zooplankton and benthic macro-invertebrates which had been restrained since April 2008 were also included.

Aquatic ecology monitoring: water quality, fish, fish catch and parasites: monitoring no.4, 3rd-7th April 2009

The survey covered by this report was undertaken between 3rd and 7th April 2009 as a follow-up on the during construction surveys. Two pre-construction baseline surveys were undertaken in April 2000 and April 2006. During the construction phase which started in 2007, three surveys including the current one have been undertaken i.e. in September 2007, April 2008 and the present one, in April 2009. Unlike in all previous surveys in which monitoring was conducted at one transect upstream and three downstream transects, in the current survey, two transects, one upstream and the other,downstream of the BHPP were sampled with emphasis on the following aspects: 1. water quality determinants 2. biology and ecology of fishes and food webs 3. fish stock and fish catch including economic aspects of catch and 4. sanitation/vector studies (bilharzias and river blindness)

Observations on the biology of Nothobranchius guentheri (Pfeffer) (Cyprinodontidae), an annual fish from the coastal region of East Africa

Nothobranchius guntheri is found in seasonal pools and streams in the coastal region of Tanzania. A population recurring annually in a pond near Kilosa has been studied. Growth in length was rapid and maximum mean lengths were attained within 11-12 and 7-8 weeks of hatching by males and females respectively. Males grew larger and exhibited wider variation in length than females. N. guentheri shows clear sexual dichromatism. No significant inequality in the sex ratio was found. Females with ripe eggs were found 7-8 weeks after hatching. Spawning continued throughout adult life and fecundity increased markedly with increasing length. In laboratory aquaria, aggressiveness between adult males was noted and females were actively driven on to the substratum preparatory to spawning. The diet of the fish pond consisted chiefly of aquatic and terrestrial insects, of which midge larvae and pupae were the most common. N. guentheri is exploited by man in the aquarist trade and for the biological control of mosquitoes. An extended redescription of the species is appended which includes N. melanospilus (Pfeffer) as a synonym.

Improved facilities for marine biology in East Africa

In 1967 the then University College of Dar es Salaam built a small laboratory on the shore at Kunduchi, 16 km from the main campus and 24 km north of Dar es Salaam. This was used for undergraduate field courses, and as a base for staff from the University to carry out research. It soon became apparent that the urgent need for studies of the marine environment in the East African area, and the lack of existing facilities, necessitated the development of the Kunduchi Marine Biology station into a research establishment with its own staff of full time scientists. This operation began in 1970: necessary structural modifications have been made to the building, staff have been recruited, and the station has been equipped with an adequate range of field and laboratory apparatus. A varied programme of research is now actively under way.

Aspects of the biology of the Lake Tanganyika sardine, Limnothrissa miodon (Boulenger), in Lake Kariba

Juveniles of limnothrissa miodon (Boulenger) were introduced into the man-made Lake Kariba in 1967-1968. Thirty months of night-fishing for this species from Sinazongwe, near the centre of the Kariba North bank, from 1971 to 1974 are described. Biological studies were carried out on samples of the catch during most of these months. Limnological studies were carried out over a period of four months in 1973. Limnothrissa is breeding successfully and its number have greatly increased. It has reached an equilibrium level of population size at a lower density than that of Lake Tanganyika sardines, but nevertheless is an important factor in the ecology of Lake Kariba. The growth rate, size at maturity and maximum size are all less than those of Lake Tanganyika Limnothrissa. A marked disruption in the orderly progression of length frequency modes occurs in September, for which the present body of evidence cannot supply an explanation.