Fisheries statistics of Kainji Lake, northern Nigeria, Nov. 1994 - Dec. 1998

Results are presented for the first 4 years data (1994-1998) of the Kainji Lake catch assessment survey, collected and analysed by the Nigerian-German Kainji Lake Fisheries Promotion Project. The following areas are covered: Methodology and alterations of the original sampling concept; Frame survey results - factors relating to the CAS; Catch assessment survey results - general; Gill net fishery; Drift net fishery; Beach seine fishery; Cast net fishery; Longline fishery; Trap fishery; and, Catch statistics from fisherwomen. (PDF contains 143 pages)

Toxicity of linear alkylbenene sulphonate (LAS) detergent, to Clarias gariepinus fingerlings

The acute toxicity of Linear Alkylbenzene Sulphonate (LAS) detergent to Clarias gariepinus fingerlings was investigated using static bioassays and continous aeration over a period of 96h. The 96h LC sub(50) was determined as 24.00mgL super(-1). During the exposure period, the test fish exhibited several behavioural changes before death such as restlessness, rapid swimming, loss of balance, respiratory distress and haemorrhaging of gill filaments amongst others. Opercula ventilation rate as well as visual examination of dead fish indicates lethal effects of the detergent on the fish. Water quality examination showed increase in pH from 6.55 to the alkaline, death point of 10.55. There was also a remarkabel rise of alkalinity from 20.00mgL super(-1) to 52.50mgL super(-1)

A survey of fisherfolk involved in artisanal fisheries in some selected areas of Ikorodu in Lagos State

The study focused on men and women involved in artisanal fisheries in some selected areas of Ikorodu Local government in Lagos State. The random sampling technique was used to select 50 fishermen each at Ibeshe and Baiyeku sites. The results revealed that majority of the fishermen were male, christian, semi-illiterate, and married. Data were collected on capital sources, labour used, income, gear techniques and type of fish caught. Analysis showed that the highest sources of capital were from personal savings (50%). Majority of labour used were hired labour, 44% at Ibeshe and 50% at Baiyeku. Highest monthly income ranged between N10, 000 - N25, 000 at both sites. Planks were mostly used at both sites for fishing boats as well as means of transport (Ibeshe 68%, Baiyeku 72%). Common fishing gear was the gill net, The fishes caught were found to be of various tyupes. Ethalmalosa fimbriata constituted the highest fish species caught by weight and number at both sites (50%). However, the problems of capital source were most peculiar coupled with high cost of fishing materials and labour scarcity

Impact assessment of Niger State fisheries legislation on fisheries conservation in Edozhigi local government area (L.G.A.) of Niger State

A preliminary survey was conducted among the fishermen in five selected villages in Edozhigi L.G.A. of Niger State. One hundred and fifty fishermen were randomly selected and interviewed to find out the impact of Niger State fisheries legislation on fisheries conservation resources in the area. The analysis of data collected using descriptive statistics indicated that undersized mesh of gill nets, beach seines and traps are being used unabated. Also, fenced barriers across the entrance of flood plain ponds and Ex-bow lakes from the main stream are in the area. The fisheries rules and regulations implementers are rarely seen or not seen at all in the area. The decreasing nature of fish catches was detected. It is observed that government policy on fish conversation is neglected due to inadequate or lack of funding for meaningful extension and implementation of the fisheries rules and regulations

Potential for sustainable floodplain fisheries development: a case study of Tatabu floodplain

This study presents evidence from a case study of an ecological appraisal of Tatabu flood plain aimed at formulation management approaches for the enhancement of the fishing communities social economic and cultural realities. Tabtabu flood plain is located north of Jebba and at high water the ecosystems cover about 700 hectares. Fishing constitutes the principal economic activity of natural fish food and flora (especially phytoplankton and zooplankton) which support and favour the growth of over 26 fish species that belong to 15 families. Among the commercially important species in terms of dominance on percentage weight basis are Mochokidae, Cichlidae, Claridae and Characidae with an overall average standing crop of 88.24kg/ha based on gill net experiment. The study based on the intrinsic ecological attributes and local people willingness for sustained contribution of fisheries to food supply indicates that with adequate management Tatabu flood plain ecosystems have tremendous fishery potentials that would enhance the economic well being of the communities. Several management options that are applicable to similar plain are discussed

Morphometric, meristics and comparative studies of Chrysichthys nigrodigititus (Lacepede) from Lagos Lekki and Badagry Lagoons, Lagos State, south west Nigeria

Morphometric measurements, meristic counts and comparative studies of Chrysicthys nigrodigitatus samples from Lagos, Lekki, and Badagry Lagoons was carried out to determine the amount of variation among the species from the different locations using seven meristic and two morphometric characters. Significant differences were observed only between the headlength (F==14.02; P<00.05), number of anal rays (F=19.9; P<0.05) and of gill raker counts (F=142.0, 160.94; P<0.05). The differences observed in the meristic characters could be attributed to environmental and climatic differences of the three isolated sites and therefore phenotypic rather than genetic. This study is valuable for the selection of quality strains of fish species for aquaculture production

Myxobolus aeglefini in Wittlingen (Merlangius merlangus)der Nordsee und der lrischen See

In June 1994 and 1995 stations in the North, Irish, Celtic Seas and the Channel were studied for the occurrence of Myxobolus aeglefini in whiting (Merlangius merlangus). The disease was visible externally as either white nodules of a few millimeters diameter in the upper mouth cavity, gill arches and the basis of pelvic fins and in severe cases also on the lower jaws or in the cornea and sclera of the eye. It was verified morphometrically in histological sections of infected eyes by size and shape of spores. Myxobolus aeglefini was present in low prevalences at two North Sea stations and high prevalences of up to 49 % in the Irish Sea (Solway Firth) during both cruises. Whiting between 23 and 55 cm were found to be infected. Neither length-age prevalences nor condition factors and gonado, spleen, liver somatic indices differed in diseased and healthy fishes.

The Windermere perch and pike project: an historical review

This paper is an attempt to set the background, provide a brief history, review some of the Windermere perch and pike project's scientific achievements, note current developments and hopes for the future, and comment on some aspects of such long-term projects. The project was originally started in 1939 in order to provide fish in freshwater lakes which might be harvested to enhance the supplies of food in a country subject to blockade. Pike traps and gill-netting were trialed as fishing methods. Catch statistics are available from 1939 which can be used to study population dynamics or for modelling purposes. The author provides an overview of changes in the population dynamics of perch and pike but covers briefly other species like arctic charr and brown trout. Also covered are several aspects of the basic biology and ecology of the principal species involved.

History, origins and importance of temporary ponds

In Europe, temporary ponds are a naturally common and widespread habitat occurring, often in abundance, in all biogeographical regions from the boreal snow-melt pools of northern Scandinavia to the seasonally inundated coastal dune pools of southern Spain. Ecological studies in Europe and elsewhere also emphasise that temporary ponds are a biologically important habitat type, renowned both for their specialised assemblages and the considerable numbers of rare and endemic species they support. They are, however, a habitat currently under considerable threat. Most temporary ponds are inherently shallow and the majority are destroyed even by limited soil drainage for agriculture or urban development. The paper gives an overview of definitions of temporary ponds and examines their formation and abundance. The authors also summarise a visit to the Bialowieza Forest in Poland to investigate the occurrence of temporary ponds.

Dangers and opportunities in managing temporary ponds

Although there is a growing awareness of the value of temporary ponds in Europe, there is still remarkably little information available to help guide their conservation and management. General principles which can be used to guide the management of temporary ponds as a whole have yet to be established. The aim of this article, therefore, is to give a broader overview of the main principles of temporary pond conservation, particularly by building on a number of general principles for managing ponds previously described by Biggs et al. (1994) and Williams et al. The authors emphasise the importance of surveys in order to get data on which to base management strategies. The main principles of temporary pond management are described, and examples of three case studies of ponds in England are given.

Fishing gear experiments in Finland

A comparison of some different European methods of estimating the numbers of fish in a lake using different fishing gear is described. The different gears used were 1. surface trawl used by night 2. bottom trawl used by day 3. trammel nets, set in the evening and lifted in the morning 4. surface seine net used by night 5. bottom seine net used by day 6. Fyke nets, emptied each morning and evening 7. gill nets, set in the evening and lifted in the morning. The most variable catches were from those gears used by day on the bottom and the least variable were those used by night at the surface. The work continued by examining the use of acoustic systems for pelagic fish stock assessment. This gear gave reasonable population estimates for pelagic fish 10m and more below the surface. The advantage of the accoustic method is that it is quick and requires little labour. Its disadvantage is that it is not possible to identify the species and so it must be supplemented by another, conventional method.

Fecundity estimates for Maryland Striped Bass

Contemporary striped bass population modeling efforts on coastal stocks point to a reduced population fecundity in Chesapeake Bay being partially responsible for declining reproduction (Anonymous 1985; Boreman and Goodyear 1984). Fecundity values used in these models were based on earlier work by jackson and tiller (1952), lewis and Bonner (1966), Hollis (1967) and Holland and Yelverton (1973). An important feature to the Boreman and Goodyear (1985) model (FSIM) is an accurate determination of the fecundity weight regression equation used to determine the rate of egg deposition over time. Egg deposition models in turn can be used to determine how reproductive potential is changing over time in response to various management actions, i.e. reducing fishing mortality rates. thus it is imperative to follow population stock structure in the Bay system and to develop a contemporary fecundity relationship for striped bass. This report deals with the gonadal material collected in 1986 and 1987 from a coordinated Maryland field program. Samples were obtained from drift gill net collections during the spawning season from four localities: Potomac Estuary, Upper Bay, Chesapeake and Delaware Canal, and the Choptank Estuary (Figure 1).

Estimativa da captura total de peixe e camarão das pescarias de emalhe e de arrasto da Baía de Maputo, em 1985

The most important fisheries of Maputo Bay (Mozambique) are the gill netting of the Hilsa kelee and the trawling of the shrimps Penaeus indicus and Metapenaeus monoceros . Data of capture and yields are presented and the number of artisanal fishing boats and semi-industrial fishing vessels is given.

Statistiques de pêche en Lagune Aby (Côte d'Ivoire): la pêche a l'epervier (1988)

Cast net fishing is a relatively important socio-economíc activity in Aby lagoon. About 516 fishermen practice this activity for an annual total production estimated at 336 millions CFA, which represents 54,000 CFA per month. The catches are essentially composed of Cichlidae (88,7 %) and Mugilidae (2,8 %). The annual production represents 15 % of that of other types of gears used (beach seines, syndicat seines and gill nets).

Statistiques de pêche en Lagune Aby (Côte d'Ivoire): évolution de l'effort et des captures de 1979 à 1990

Two kinds of fishing gears insure the exploitation in Aby lagoon: the individual gears are represented essentially by gill nets and collective gears by seines. The number of gill nets varies between 1500 in 1981 and 5600 in 1986. The beach seines, which number varies between 40 and 60, are regularly used. The purse seines (15-30) have been superseded by "syndicat" seines (15) in 1990.