High-Temperature Effects on Growth and Propagule Formation in Hydrilla Biotypes

In consecutive greenhouse studies, growth and propagule formation were examined first in monoecious hydrilla [Hydrilla verticillata (L.f.) Royle], then in dioecious hydrilla, at three temperature levels (25, 30, and 35 C) and contrasted over three periods of growth (8, 12 and 16 wks). Each biotype was grown under natural photoperiods, decreasing from 14 hrs (in Oct, Nov, and Dec). For both biotypes, total biomass and root-to-shoot ratios were significantly reduced at 35 C; greater biomass was produced both at 25 and 30C. Increases in growth period generally enhanced total biomass and shoot production; however, shoot length was unresponsive to growth periods beyond 8 wks. The 35C treatment strongly impeded tuber formation and eliminat4ed the production of axillary turions; the number and biomass of these propagules peaked at lower temperatures under short photoperiods after 12 to 16 wks. Shoot elongation was stimulated with increases in temperature and was especially pronounced in the dioecious biotype. Notably, in the monoecious biotype, the number of shoots as a potential source of fragments, and tuber production (although reduced) occurred at relatively high levels under unfavorably hihg-temperature (35C) conditions. These results suggest that monoecious hydrilla may be better adapted to high temperatures than previously shown, and that the distribution of both biotypes in the U.S. could overlap further in southern states.

Addressing technical, social and economic constraints to rice fish culture in Laos, emphasising women’s involvement: DFID Aquaculture Research Programme Project R6380Cb, final technical report

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Strategies for increasing freshwater fish production in the Green Revolution Programme

Sources of fish and fishery products in Nigeria were reviewed. The problems of various agencies involved in freshwater fish production in Nigeria were also analysed, such problems included shortage of manpower, inadequate training for personnel, shortage of funds, lack of infrastructures, among others

Lake Chad fisheries and its importance in the Green Revolution Programme

Lake Chad fisheries contributes about 13% of all fish produced by the inland and coastal states of the nation and supports a large population of fishermen and allied workers. The species of freshwater fish produced from the Lake such as Gymnarchus, Clarias and Heterotis are very popular with the fish consumers in Nigeria; hence Lake Chad processed fish is transported long distances to southern Nigerian markets. Lake Chad thus contributes significantly to the provision of fish protein and to the Green Revolution Programme

Developing a viable fish farming industry in Nigeria -- an alternative strategy to the strategy in the Green Revolution Programme

A study was embarked upon with the twin objectives of reviewing the Green Revolution Strategy for accelerating fish production in the country and proposing an alternative strategy, a private sector approach. Some of the programmes listed in the Green Revolution are very necessary for developing a viable - fish farming industry and that money spent under such programmes is money well spent. Programmes that are also desirable but need to be considerably expanded were identified. Other programmes have been criticised on the grounds that the method chosen to achieve the desired objectives is fraught with dangers if sufficiently long run view of fisheries development is taken

Polyculture: A boost to the Green Revolution Programme

Polyculture, as presently practiced in Nigeria, focuses interest mainly on finfish. This practice, apart from neglecting indigenous valuable species such as clams and water snails, does not make full use of existing biomass. This paper suggests possible deviations from normal practice. Inclusion of macroinvertebrates in a polyculture system and stocking, temporary bodies of water with seasonal species such as the fresh water crayfish are suggested. A final suggestion is to develop a polyculture of swamp rice and crayfish

Introduction of collection and distribution programme for the small-scale fisheries in Ondo State

Details are given of a programme for fresh fish collection and distribution in Ondo State, Nigeria. Collection centers, organization and managerial structure, collection scheme, trade system, price determination, management and distribution are described

Fishermen cooperatives in the Green Revolution Programme

The aim of this study was to examine areas in which fishermen cooperatives can become involved and then suggest operational guidelines in order to increase fishermen income and also to make the Green Revolution Programme a success through increased production of fish. The paper enumerated different areas in which fishermen cooperatives can participate. These include: thrift and credits, thrift and savings, consumers and building cooperative societies. It is the belief of the author that the expansion of fishermen cooperatives into the areas mentioned in this paper can enable members to process and market their products more economically, buy supplies and equipment in large quantities and obtain lower cost credit

An economic overview of the fish and shrimp production of the Nigeria fish trawling industry under the structural adjustment programme

Over the years, Nigeria have witnessed different government with different policy measures. Against the negative consequences of the past policies, the structural adjustment was initiated in 1986. Its aims is to effectively altar and restructure the consumption patterns of the economy as well as to eliminate price distortions and heavy dependence on the oil and the imports of consumer goods and services. Within the period of implementation, there has been a decreasing trend in yearly fish catch landings and sizes but the reverse in shrimping. There is also a gradual shift from fishing to shrimping, from the vessels purchased with 83.3% increase of shrimpers from 1985 to 1989. Decreasing fish catch sizes and quantity aggravated by the present high cost of fishing coupled with the favourable export market for Nigeria shrimp tend to influence the sift. This economic situation is the result of the supply measures of SAP through the devaluation of the Naira. There is also overconcentration of vessels on the inshore waters as majority of the vessels are old and low powers hence incapable of fishing on the deep sea. Rotterdam price being paid for automotive gas oil (AGO) by fishing industries is observed to be discriminating and unhealthy to the growth of the industry as it is exceedingly high and unstable thus affecting planning for fishing operation. Fuel alone takes 43% of the total cost of operation. The overall consequences is that fishing days are loss and therefore higher overhead cost. It was concluded that for a healthy growth and sustainable resources of our marine fishery under the structural adjustment programme licensing of new fishing vessels should be stopped immediately and the demand side of SAP should be employed by subsidizing high powered fishing vessels which can operate effectively on the deep sea

Embryogenesis of Heterobranchus longifilis (Curvier and Valenciennes, 1840)

Studies on development of H. longifilis (Curvier and Valenciennes, 1840) were conducted at a temperature of 25EC ( 1Ec) in aquaria tanks continuous development were monitored with the use of wild Heerbrugy photomacroscope and length of yolk and larva were monitored using Stereo Olympus microscope with ocular micrometer. The division into animal and vegetal poles was observed 22 minutes after activation. The first cleavage occurred 65 minutes after activation while the second division which was perpendicular to the first line of division occurred 74 minutes after activation. This was quickly followed by the third and fourth cleavage at 80th and 82nd minutes after activation respectively. Morular stage was reached at 4 hours 20 minutes with formation of optic bud at 14 hours 35 minutes. (DBO) Developing embryo hatched after 27 hours of activation at a mean length of 6.63 and mean yolk length of 2.17. Yolk size decrease at an average rate of 38.5 % till the 5th day of total absorption. Growth of larvae proceeded faster in tail-anus region than in anus-snout portion of the body. The rate of yolk absorption and larva development (survival) as monitored in this work gives important information in Research and development programme for H. longifilis larva - an important aspect of Research development and implementation of appropriate technologies in small scale fisheries

Food security and poverty alleviation under the National Special Programme for Food Security: a preliminary socio-economic assessment of Yamama Lake, Kebbi state, Nigeria

The World Food Summit in its meeting in Rome in 1999 estimated that 790 million people in the developing world do not have enough food to eat. This is more than the total populations of North America and Europe combined. Nigeria is one of the developing countries affected by hunger, deprivation and abject poverty by its citizenry inspite of its enormous natural and human resources. To reduce poverty and increase food supplies to the masses the Federal Government of Nigeria embarked on a programmed-tagged National Special Programme for Food Security (NSPFS) in the year 2002. The programme's broad objectives are to attain food security in the broadest sense and alleviate rural poverty in Nigeria. One of the areas of the programme's intervention is in the aquaculture and inland fisheries development because Nigeria imported 681mt of fish in 2003 with a total cost of about N50 million. The paper assesses the socio-economic conditions of one of the selected water bodies (Yamama Lake) with a view to introducing community-based fisheries management plan for the rational exploitation and management of the fishery and other aquatic resources of the water body thereby increasing fish supply and improving the living standard of the fisherfolk in the area. Data were collected using Participatory Rural Appraisal (PRA) tools and questionnaire administration

Some statistical aspects of the long-term gill net monitoring programme for pike Esox lucius in Windermere (English Lake District)

For more than 55 years, data have been collected on the population of pike Esox lucius in Windermere, first by the Freshwater Biological Association (FBA) and, since 1989, by the Institute of Freshwater Ecology (IFE) of the NERC Centre for Ecology and Hydrology. The aim of this article is to explore some methodological and statistical issues associated with the precision of pike gill net catches and catch-per-unit-effort (CPUE) data, further to those examined by Bagenal (1972) and especially in the light of the current deployment within the Windermere long-term sampling programme. Specifically, consideration is given to the precision of catch estimates from gill netting, including the effects of sampling different locations, the effectiveness of sampling for distinguishing between years, and the effects of changing fishing effort.

On the formation of ephippia in some Cladocera (Crustacea) [Translation from: Zoologicheskie Zhurnal 61, 1425-1427, 1982]

The determination of relative connections between families and genera of Cladocera, necessary for the construction of their natural systems, must be based on various criteria, among them on the structure of the ephippia. Of particular interest is the study of the process of formation and structure of the ephippium in Macrothricidae, different representatives of which differ significantly among themselves according to this criterion. In this article are presented the results of an investigation of the features of formation of the ephippium in seven species of Macrothricidae and in the moinid Moina weismanni Ishikawa (Moinidae).

Studies on the complex formation of iron with humic substances [Translation from: Vom Wasser 53, 243-247, 1979]

Most of the humic substances which occur in natural waters have an iron content of a few percent, indicated by the mg/1 content of organically-bonded carbon. This iron is apparently bound in a complex with the humic substances, for it quite plainly differs in its chemical and physico-chemical properties from what one would expect from the purely inorganic iron-water system. The deviations range from the solubility to the redox behaviour, and thus are frequently the basis of analytical and technical difficulties. The key to the solution of most of this problem lies in a better understanding of the aforementioned bonds between the iron and the humic substances. This paper studies the iron content of the humic substance concentration from a bog lake sample and the complexing of iron by humic substances from the surface of the bog lake.