Nutritional and anti-nutritional analyses of Azolla africana Desv. and Spirodela polyrrhiza L. Schleiden as feedstuffs for fish production

The chemical composition of Azolla africana and Spirodela polyrrhiza cultivated in earthen ponds were determined. Crude protein contents of the samples were 28.9~c0.6 and 25.6~c0.2% dry matter for A. africana and S. polyrrhiza respectively. Dry matter, crude fibre and lipid contents of A. africana were higher (P<0.05) than values obtained for S. polyrrhiza. Mineral analyses showed that S. polyrrhiza contained higher levels of Na, S, Ca, Mg and Fe than A. africana. Except for Ca content in S. polyrrhiza, heavy metals (Ni and Zn) accumulation in Azolla were very high. There were no wide differences in the individual amino acid indexes except for methionine. Some anti-nutritional factors were determined. Cyanide, tannin and phytin contents of fresh weed samples were higher than sun-dried samples. A. africana contained more cyanide and tannin than S. polyrrhiza both in fresh and sun-dried forms

Some aspects of the ecology and reproduction of the small pelagic cyprinid, Rastrineobola argentea in Lake Victoria

This study concentrated on the reproductive biology of the small pelagic cyprinid Rastrineobola argentea. The results indicate that this fish is an inshore spawning species, which agrees with other recent studies. It was also found that in areas where fishing intensity was likely to be relatively high, the size at first maturity of R. argentea was reduced, which is likely to be an effect of the fish altering its reproductive strategy according to life history theory. The CPUE results showed a general trend of decreasing with distance from shore, however areas less than one kilometer from the shore were not sampled. Evidence was also found suggesting that the cestode parasite, Ligula intestinalis had an adverse effect on the maturation and fecundity of R. argentea. Some management options concerning the findings in this study are also briefly discussed. (PDF has 82 pages)

Ecology and fishery in the Cross River Estuary - a research project

A literature review of 50 titles including nearly all relevant publications ensures adequate basis on the present level of knowledge. The proposal includes (a) the determination of the biozoenosis and selected environmental factors, and (b) of fishery and stock data of the main fish and shellfish species. The ecological research studies physical and chemical variables of the estuarine waters (flow velocity and direction, water temperature, conductivity, pH, dissolved oxygen, salinity, nutrients such as ammonium, nitrite, phosphate, silicate, pollutants such as hybrocarbons, pesticides and heavy metals, biochemical oxygen demand, chemical oxygen demand), plankton (bacterio-phyto-and zooplankton), benthos, sediment. The fishery biological and fishery investigations include: number of villages and fishermen, number of boats and gears by type, length and weight data of the main fishery objects with concentration on the shrimps, species and numbers of fish parasites. The ecological variables were monitored at fixed stations on sections in the Cross-River Estuary, Calabar and Great Kwara Rivers two times per month during spring and neap tides. The fishery biological and fishery variables were obtained during spring and neap tide too. For the determination of the detailed methodology the ecological and fishery part of the progeamme should be started with frame surveys based on a larger number of stations. These frame surveys should be repeated from time to time. Both parts of the programme are based on three years duration. It seems already appropriate to continue the work with selected representative stations, villages and variables in form of a long-term data chain

Studies on the nutritional value of cassava (Manihot utillisima) peels as energy source in the diet of Oreochromis niloticus fry fed in indoor glass aquaria

This study, though, has as its core objective cost reduction in aquaculture nutrition was equally designed to investigate the value of the peels of cassava (Manihot utillisima) as energy source in the diet of Oreochromis niloticus fry. Three levels of cassava peels diet and a control (100% yellow maize in the carbohydrate mixture) was prepared and tested on O. niloticus fry for ten (10) weeks. The fry with mean weight of 0.32g were grouped fifteen (15) in each of the glass aquaria measuring 60x30x30cm with a maximum capacity of 52 litres of water. The fry were fed twice daily at 10% biomass. Weekly, the fry were weighed to determine the weight increment or otherwise and the quality of feed adjusted accordingly. Water quality parameters like temperature, pH and dissolved oxygen (D.0) were monitored and found to be at desirable level. DT 3 (97 % cassava peels and 3% yellow maize) in the carbohydrate mixture gave the best growth performance. The fry fed, this diet gained mean weight of 1.18g for the period of the experiment. However, the poorest performance in terms of growth was from fry fed the control diet (100%yellow maize in the carbohydrate mixture) fry fed this diet gained mean weight of 0.80 for the duration of the experiment. Analysis of the various growth indices like SGR, PER, FCR and NPU shows that DT3 was the overall best diet with an SGR value of2.40 and FCR of 43.83. However, DT 1 (70% cassava peels and 30% yellow maize) gave the poorest SGR of 1.61 and FCR of 67.58. The difference in weight gain among the fry fed the three levels of cassava peels diet and the control was not statically significant (P>0.05)

A review of the biology, ecology and management of Scirpus Olneyi. Volume 1: An annotated bibliography of selected references

This annotated bibliography of selected literature on Olney's three7square (Scirpus olneyi Gray )compiled basically for two reasons: 1) to assist a task force in its pursuit of an explanation for the substantial reduction in marsh acreage at the Blackwater National Wildlife Refuge in Dorchester County, Maryland, and 2) to serve as the author's foundation for the initiation of ecological research on this species as partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Botany Department of the University of Maryland. Both purposes are directly related in that the Author's research will be of use to the task force, along I with its other technical information and research results, in under-standing and possibly correcting the marshland loss problem at the Refuge. (PDF contains 100 pages)

Feeding ecology and population characteristics of Oreochromis niloticus (L.) and trophic interactions in the fish community of Nyanza Gulf, Lake Victoria, Kenya

Oreochromis niloticus (L.) were caught by beach seining, hook and line and trawling from Nyanza Gulf, lake Victoria (Kenya) in order to study their feeding ecology and population characteristics. Collected fish were weighed and TL measured immediately after capture. Fish were dissected and sexed. Stomach contents were removed and preserved in 4% buffered formalin for laboratory analysis. In the laboratory items were sorted into categories such as three quarters, half and quarter and awarded 20, 15 and 5 points respectively. Main food items for O. niloticus from November 1998 to March 1999 were insects, algae, fish and plant material. Increase in insects in the diet of O. niloticus might be attributed to the lake infestation by water hyacinth which harbours different species of insects

Aspects of ecology of Owena reservoirs: implication on fish production

The article gives physical description of Owana reservoir, Nigeria. The reservoir was chemically and thermally stratified partial mixing of the water was observed during the rains. The concentration of major ions in the water showed distinct peculiarities. The captions (Na super(+), K super(+)Ca super(H),Ca super(Z), Mg super(++)) SO sub(4) super(2-) were relatively low. The water had high dissolved oxygen, it was acidic and also had low values of alkalinity, conductivity and total dissolved solids. About 61 plankton taxa belonging to 21 species were identified. The reservoir supports a commercial fishery of about fifteen fishermen with about fifteen species of fish caught daily with the aid of traps set and cast nets. Effective management of the lake will enhance fish production

Nutritional habits and food consumption pattern of fishing communities around Lake Kainji, Nigeria

The findings are presented of a nutrition survey carried out in the framework of the Nigerian-German Kainji Lake Fisheries Promotion Project in March/April 1995. The major aim of the study was to obtain closer information on the food habits and food consumption patterns of the fishing population, especially the quantification of fish and small fish in particular, consumed at the household level. A standardized questionnaire was used to collect relevant information on demographic, education and occupational profiles; the information was collected in 39 villages in the southern sector of Kainji Lake. (PDF contains 75 pages)

The nutritional status of pre-school children, Kainji Lake communities, Nigeria: a baseline survey

This survey was carried out to provide the Kainji Lake Fisheries Promotion Project (KLFPP), whose overall goal is the improvement of the standard of living of fishing communities around Kainji Lake, Nigeria, and an increase in the availability of fish to consumers, with nutritional status baseline data for long-term monitoring and evaluation of the overall project goal. In a cross-sectional survey, baseline anthropometric data was collected from 768 children, aged 3-60 months in 389 fisherfolk households around the southern sector of Kainji Lake, Nigeria. In addition, data was collected on the nutritional status and fertility of the mothers, vaccination coverage of children and child survival indicators. For control purposes, 576 children and 292 mothers from non-fishing households around Kainji Lake were likewise covered by the survey. A standardised questionnaire was used to collect relevant information, while anthropometric measurements were made using appropriate equipment. Data compilation and analysis was carried out with DATAEASE registered and EPI-INFO registered software, using NCHS reference data for the analysis of anthropometric measurements. The prevalence of stunted children in fishing households was high at 40%, while the prevalence of wasted and underweight children was likewise high at 10% and 29% respectively. Children from non-fishing households had a marginally lower prevalence of stunting, wasting and underweight with 37%, 7% and 25 % respectively, although these differences were not statistically significant. Considering the fact that the survey was carried out during a period of relative food abundance, the prevalence of wasting and underweight children is likely to be much higher during periods of food shortage. The prevalence of stunting, wasting and underweight was relatively high for children aged 3 to 23 months, suggesting an increased risk of malnutrition during this period, most likely associated with inadequate weaning practices. The prevalence of malnourishment amongst women of child-bearing age was relatively high, irrespective of occupation of the household, with an average of 11% undernourished and 6% wasted. Vaccination coverage was very low while infant and child mortality were extremely high with about 1 in 5 children dying before their fifth birthday. Based on the ethical obligation to maximise the potential benefits of the survey, recommendations for activities to improve community nutrition and health were made for communication to relevant authorities. (PDF contains 52 pages)

The nutritional status of pre-school children, Kainji Lake communities, Nigeria: a follow-up survey

This survey was carried out to provide the Kainji Lake Fisheries Promotion Project (KLFPP), whose overall goal is the improvement of the standard of living of fishing communities around Kainji Lake, Nigeria, managing the fisheries on a sustainable basis, with follow-up data for long-term monitoring and evaluation of the overall project goal. A similar survey, conducted in 1996, provided the baseline against which data from the current survey was evaluated. In a cross-sectional survey, anthropometric data was collected from 576 children aged 3-60 months in 282 fisherfolk households around the southern sector of Kainji Lake, Nigeria. In addition, data was collected on the nutritional status and fertility of the mothers, vaccination coverage of children and child survival indicators. For control purposes, 374 children and 181 mothers from non-fishing households around Kainji Lake were likewise covered by the survey. A standardised questionnaire was used to collect relevant data, while anthropometric measurements were made using appropriate equipment. Data compilation and analysis was carried out with a specially designed Microsoft Access application, using NCHS reference data for the analysis of anthropometric measurements. Statistical significance testing was done using EPI-INFO" software. The results of the follow-up survey indicate a slight increase in the percentage of stunted pre-school children in fishing households around Kainji Lake, from 40% in 1996 to 41% in 1999. This increase is however not statistically significant (p= 0.704). Over the same period, the percentage of stunted children in non-fishing households increased from 37% to 39% (p= 0.540), which is also not statistically significant. Likewise, there were no statistically significant differences between the 1996 and 1999 results for the prevalence of either wasted or underweight children in fishing households. The same applies to children from non-fishing households. In addition, vaccination coverage remains very low while infant and child mortality rates continue to be extremely high with about 1 in 5 children dying before their fifth birthday. There has been no perceptible and lasting improvement in the standard of living of fishing households over the course of the second project phase as indicated by the persistently high prevalence of stunting. The situation is the same for the control group, indicating that for the region as a whole, a number of factors beyond the immediate influence of the project continue to negatively impact on the standard of living. The results also show that the project activities have not had any negative long-term effect on the nutritional status of the beneficiaries. (PDF contains 44 pages)

Some ecological roles of Hippopotamus (Hippopotamus amphibious Linn. 1758) in fish production: possibilities for integrated fish-cum Agric production system

The common hippopotamus (Hippopotamus amphibious Linn. 1758) contributes to the productivity of aquatic systems where it lives. This paper reviews ecological roles of the hippo in this regard. Desk review of available literature information complemented with field observations were employed in the data collection. The ecological roles of the common hippopotamus being presented draw examples from East, West, Central and South African sub regions. The nutritional importance of the amphibious hippopotamus to rural communities was highlighted. In Southern Ethiopia, the Bodi, Bacha and Mura tribes eat hippo meat and this has led to severe hunting consequences on the wild populations of the animal. The important relationships between the hippopotamus and fish were presented. Hippopotamuses usually defecate in water and their excrements enrich the nutrients in the water resulting in favourable conditions for large fish populations. Some fish, including Labeo spp. were observed to feed on the micro-organisms and algae that grow on the skin of the hippotamus. A strong case was made for hippo-cum-fish integrated farm development in Nigeria based on ecological relationships so observed between the amphibious mammals and fish. This is one of the meeting points of fisheries and wildlife management that should be exploited for the benefits of the teeming Nigerian population

Social Organisation of the Short-finned Pilot Whale, Globicephala macrorhynchus, with Special Reference to the Comparative Social Ecology of Delphinids

As a contribution to the understanding of comparative social trends within the cetacean family Delphinidae, a 22-month study was conducted on the shortfinned pilot whale, Globicephala macrorhynchus, which has been suggested to have a unique social system in which males and females in the same group are related and mating occurs outside of the group. The individual identification of 495 pilot whales, analysed in daily group association patterns, allowed identification of 46 pods. They were classified as productive or non-productive based on the presence or absence of immature animals. Productive pods were a significantly larger, although 12% of them lacked adult males. Two classes of whales (residents and visitors) were defined by patterns of occurrence,suggesting differential patterns of habitat use. Resident pods occasionally travelled together (41% of all groups) and associations between age and sex classes showed that in mixed-pod groups, the highest ranked associations of the reproductive females were with males from other pods, while within pods, adult males and females associated less. During summer, the proposed peak conception period, pilot whale groups were significantly larger and contained individuals from a significantly greater number of pods. These findings support the hypothesis that males and females mate when associating with individuals from other pods. A comparative analysis of sexual dimorphism, brain size, and testes size, habitat, prey and group size within the 17 delphinid genera identified a correlation between sexual dimorphism and body size, but relative measures of brain size and testes size did not correlate with broad ecological or social classifications. However, a comparison of three delphinid societies identified two distinct male mating systems: males of the small, mono-morphic Tursiops truncatus live in age/sex segregated groups and mate with a number of discrete female communities. Males in the large sexually dimorphic Glob icephala spp. and Orcinus orca mate with associated female pods and yet remain with their female kin. This corresponds to the avunculate social system described in some human societies. It could evolve from a promiscuous mating system where there is little guarantee of paternity and where males that live with their kin increase their inclusive fitness.

The impact of varying nutrient regimes in earthen freshwater ponds on the comparative ecology of diurnally occurring candidate live feeds

The daytime composition and relative abundance of zooplankton species were studied in three treatments of two replicate earthen ponds each with nutrient sources and water replenishment regimes. Treatment -A (200m super(2) surface area supplied 900kgha super(-1) pig manure only). Treatment -B (200m super(2) surface area supplied 70kgha super(-1) month super(-1) pig manure, 50kgha super(-1) month super(-1) N.P.K. [15:15:15] and 30kgha super(-1) month super(-1) Urea) and Treatment-C (1500m2 surface area supplied 1150kgha super(-1) month super(-1) commercial grade 40% crude protein compounded feed). Water replenishment for Treatment A was daily tidal deluge from the New Calabar River while that for treatment B and C was from column-well and occasional rains. No zooplankton species were recovered from the pig-manure only treatment (A) while only Diffugia constricta and Difflugia urceolata were the two protozoans that occurred together in treatments B (combined fertilization) and C (compounded feed only) in contrast, Difflugia acuminate and three rotifers, Collurella uncinata, Diurella stylata and Keratella quadrata occurred only treatment B. similarly, Arcella arenaria, Arcella costata, Centropyxis aculeate, Difflugia pyriformis, Branchionus calyciflorus, Lepadella patella, Polyarthra trigla and Onchocanmptus mohammedi were recovered from treatment C. Arcella costata was the most abundant zooplankton in the entire experiment, while Arcella arenaria was very abundant in treatment C, Collurella uncinata was very abundant in treatment B. The inference is that combined fertilization of earthen freshwater ponds tend to be more suitable for the culture of rotifers such as Brachionus calyciflorus, popular in fish larva nursery, while those supplied compounded feed could be used to produce protozoans where desirable

Small Indigenous Freshwater Fish Species: their Role in Poverty Alleviation, Food Security and Conservation of Biodiversity, 23-25 February 2010, Central Inland Fisheries Research Institute, Barrackpore, Kolkata, West Bengal. Workshop report

This is the report on the workshop on “Small Indigenous Freshwater Fish Species: Their Role in Poverty Alleviation, Food Security and Conservation of Biodiversity”, organized by the International Collective in Support of Fishworkers(ICSF) in collaboration with the Inland Fisheries Society of India (IFSI). The workshop was a forum for exchange of views on the role of small indigenous freshwater fish species (SIFFS) in enhancing rural food supply and livelihood security, and in conserving biodiversity. The workshop also discussed the socioeconomic and cultural contexts for the culture and capture of SIFFS, and how to enhance access—especially for women—to better incomes, livelihoods and nutritional security, through appropriate policy spaces. This report provides a fresh focus on SIFFS, usually regarded as ‘trash’ fish. It urges scientists, researchers and decisionmakers to develop policy and legislative measures to ensure the conservation and promotion of SIFFS, both in capture- and culture-fisheries systems. This report will be useful for fishworker organizations, researchers, policymakers, fish farmers, members of civil society and anyone interested in fisheries and livelihoods. (PDF contains 86 pages)

Aquatic ecology, economy and society: the place of aquatic ecology in the sustainability agenda

This article explores aspects of sustainability and the importance of sustainable development, including the place of the crucially important resource of fresh water and of freshwater ecosystems. It examines the treatment of natural resources by the economic system that underpins global business, outlines some progress towards more sustainable approaches to business, and recommends steps to re-establish science as the driver of wise policies that contribute to sustainable development.