Hieromin Lamtane | Sokoine University of Agriculture (original) (raw)

Papers by Hieromin Lamtane

Aquaculture international, Feb 8, 2024

World Journal of Food Science and Technology

Histamine (scombrotoxin) food poisoning is a community health risk associated with consumption of... more Histamine (scombrotoxin) food poisoning is a community health risk associated with consumption of some marine fish species and it has been proposed that some anaerobic bacteria contribute to this form of food poisoning. However, histamine levels and histamine producing bacteria in fish marketed in Tanzania have not been appraised. This study was conducted to determine histamine levels and histamine-producing bacteria in the E. affinis (tuna) value chain in Tanga and Mtwara regions. High-performance thin-layer chromatography (HPTLC) was used to determine histamine levels, Bacteriology and biochemical tests were employed to determine histamine-producing bacteria. A total of 64 tuna fish samples were collected from deep sea fish market and Sahare Tanga and ferry market, Mtwara coasts. The mean level of histamine was found to be 86.4±43.9 in Tanga and 64.8±47.5 in Mtwara and the overall mean was 77.1±46.4. All fish 64 samples were positive for histamine; however, the mean level was within the recommended limit for consumed fishery products according to European Union regulation of 200 mg/kg (m) to 400 mg/kg (m) (EC, 2005). Klebsiella spp, pseudomonas spp, and proteus spp were isolated and confirmed as histamine-producing bacteria based on bacteriology and biochemical characteristics. It concluded that although within the recommended levels, all fish samples were positive to histamine and three bacterial species associated with its production isolated. To prevent raising histamine to concern levels, maintenance of hygiene and low temperature along the production chain should be observed.

Innovation in the Food Sector Through the Valorization of Food and Agro-Food By-Products, 2021

Animal and crop production throughout the world generate high amounts of wastes or by-products an... more Animal and crop production throughout the world generate high amounts of wastes or by-products annually that may possess added value compounds with high functionality. These wastes and by-products may cause negative environmental impacts and significant expenses if not well managed and or controlled. Much of these wastes and by-products is valuable and cheaper source of potentially functional compounds such as proteins, lipids, starch, micronutrients, bioactive compounds, and dietary fibbers. In aquaculture, feed is expensive, and the existing body of literature has shown that animal manure and its extracts can be successfully incorporated into fishpond to increase fish production at a low cost. In addition, crop residues such as rice bran, maize bran, and seed cakes are commonly used as pond inputs in small-scale aquaculture. Animal waste and crop residues are added in a fishpond that filter-feeding fish can use directly as feed, and these may form a major proportion of the detritu...

Impacts of Climate Change on Agriculture and Aquaculture, 2021

Over the last century, water temperatures in Lake Tanganyika have risen due to climate change, wh... more Over the last century, water temperatures in Lake Tanganyika have risen due to climate change, which increased thermal stratification and reduced the magnitude of nutrient availability. A rise in temperature increases the C:N:P ratio resulting in a poor algal diet. In addition, lake littoral habitat is experiencing increased sediment load due to deforestation of the watershed caused by anthropogenic activities. Sediments cover benthic algae and reduce its nutritional value, consequently affecting the foraging behavior, distribution, and growth performance of algivorous fish. Algae and algivorous fish are an important link in the lake food chain; therefore, if the rise in temperature will continue as predicted, then this may have a cascading effect for the rest of the community in the food chain including human being. This, in turn, may contribute to food insecurity at local and regional levels. To counteract this adaptation and mitigation measures such as environmental monitoring sy...

BMC Evolutionary Biology, 2020

BackgroundAfrican annual killifishes (Nothobranchiusspp.) are adapted to seasonally desiccating h... more BackgroundAfrican annual killifishes (Nothobranchiusspp.) are adapted to seasonally desiccating habitats (ephemeral pools), surviving dry periods as dormant eggs. Given their peculiar life history, geographic aspects of their diversity uniquely combine patterns typical for freshwater taxa (river basin structure and elevation gradient) and terrestrial animals (rivers acting as major dispersal barriers). However, our current knowledge on fine-scale inter-specific and intra-specific genetic diversity of African annual fish is limited to a single, particularly dry region of their distribution (subtropical Mozambique). Using a widespread annual killifish from coastal Tanzania and Kenya, we tested whether the same pattern of genetic divergence pertains to a wet equatorial region in the centre ofNothobranchiusdistribution.ResultsIn populations ofNothobranchius melanospilusspecies group across its range, we genotyped a part of mitochondrial cytochrome oxidase subunit 1 (COI) gene (83 indivi...

Journal of Information, Communication and Ethics in Society, 2019

Purpose This paper aims to examine the challenges facing fish farmers in the use of information a... more Purpose This paper aims to examine the challenges facing fish farmers in the use of information and communication technology (ICT) in information sharing on fish farming. Design/methodology/approach This study used both quantitative and qualitative methods. It involved 240 fish farmers who were randomly selected. Questionnaires, focus group discussions (FGDs), observation and key informant’s interviews were used as methods of data collection. Both descriptive and inferential statistics were used to analyse quantitative data, while content analysis was used for qualitative data. Findings It was found that the most frequently used ICTs by fish farmers in sharing agricultural information were mobile phones, radio and television. Also, the study revealed that major challenges facing fish farmers in sharing information include unfavourable radio or television broadcasting time, high cost of acquiring and maintenance of ICT facilities, lack of training on ICT, poor network connectivity an...

African Journal of Biological Sciences, 2019

Mariculture has recently been adopted in many parts of coastal East Africa as a source of income ... more Mariculture has recently been adopted in many parts of coastal East Africa as a source of income and employment to many women and heartbroken fishermen who are the main victim of dwindling wild stock of aquatic resources. The sea cucumber (Holothuria scabra) has for long time been collected and sold as export marine product. Macroalgae (Eucheuma denticulatum and Kappaphycus alvarezii) are the common cultured seaweed species that provide hope for future increase in mariculture production. An experiment was conducted along the intertidal lagoon of Unguja Ukuu village in Zanzibar to assess the survival and growth performance of sea cucumber (H. scabra) in two separate pens under co-cultured systems with E. denticulatum and K. alvarezii. Juvenile sea cucumber H. scabra with mean weight (± se) of 67.18 ± 2.06 were integrated with the two common commercial seaweed in pen system for 10 weeks. The results revealed that the growth rate and survival of H. scabra, E. denticulatum and K. alvarezii were better under integration system. The growth of H. scabra was higher (1. ) in pen systems co-cultured with K. alvarezii compared to 0.898 gd -1 in pen systems co-culture with E. denticulatum. Survival rate of H. scabra was higher (76%) in the pen systems co-cultured with E. denticulatum compared to that (70%) observed in pen systems co-cultured with K. alvarezii. The results suggest that the best integration of sea cucumber and macroalgae is between H. scabra and K. alvarezii. However, reliable source of H. scabra juvenile is essential for the future expansion of pen co-culture system.

Journal of Applied Aquaculture, 2019

In an Artemia survey conducted along the coast of Tanzania between March and July 2017, 32 salt p... more In an Artemia survey conducted along the coast of Tanzania between March and July 2017, 32 salt pans in Tanga, Dar es salaam, Pwani, Lindi, and Mtwara were assessed. Of all visited salt pans, 16 (50 %) had either Artemia biomass or cysts or both. Body length ranged from 4.0 mm to 9.5 mm, while the mean and modal lengths were 6.2 mm and 6.0 mm, respectively. Temperature ranged from 27.2 °C to 48.7 °C, salinity from 20 g L -1 to > 140 g L -1 , pH from 5.8 to 7.8, dissolved oxygen (DO) from 3.1 mg L -1 to 4.9 mg L -1 , water depth from 10 cm to 75 cm and conductivity from 42.0 ms cm -1 to 176.6 ms cm -1 . A bisexual population of Artemia franciscana is suggested. Observed cyst states included concave, biconcave, spherical and cracking cysts. This is the first to report on the occurrence of Artemia in Tanzania.

Aquaculture Research, 2018

The use of medicinal plants to control reproduction in aquaculture have recently received conside... more The use of medicinal plants to control reproduction in aquaculture have recently received considerable attention because they are biodegradable, safe, effective and locally available. However, information on their effects on gonadal characteristics and histological features in fish is currently limited. The present study evaluated the gonadal characteristics and histological changes of Nile tilapia, Oreochromis niloticus gonads fed on Aspilia plant, Aspilia mossambicensis and Neem tree, Azadirachta indica. Juvenile fish were fed diets supplemented with four doses (1.0, 2.0, 4.0 and 8.0 g/kg diet) of A. mossambicensis or A. indica leaf powders at 3% of their body weight daily for 90 days to examine absolute fecundity (AF), relative fecundity, gonadosomatic index (GSI) and histology of gonads. The antifertility phytocompounds in the two plants were quantified by using standard methods. Results indicated that, all doses of A. indica and A. mossambicensis used reduced significantly AF and GSI values (p < 0.05). Dose-dependent histological alterations of gonads were noticed in both plants starting from doses of 2.0 g/kg in males and 4.0 g/kg in females. The highest percentages of total flavonoids (23.7%) and alkaloids (14.2%) were obtained from A. indica ethanol extract (p < 0.05). Taken together, dietary supplementation with A. mossambicensis and A. indica leaf powders alter gonadal characteristics of O. niloticus and histology triggered by alkaloids and flavonoids. Farmers interested in using the two plants to control prolific breeding should limit the dose inclusion to 2 g/kg to avoid severe effects on fish testis and ovaries. K E Y W O R D S antifertility, Aspilia mossambicensis, Azadirachta indica, histology, Nile tilapia, phytocompounds 1 | INTRODUCTION Nile tilapia, Oreochromis niloticus is among the top ten farmed species in the world due to its hardiness, tolerance to varying degrees of physical and chemical environmental factors (Watanabe, Losordo, Fitzsimmons, & Hanley, 2002) among other attributes. Under natural conditions, O. niloticus starts to reproduce at a size of 20 to 30 cm (Lowe . However when cultured in earthen ponds, it starts at a much smaller size of about 8 to 13 cm at which it undergoes successive reproductive cycles at intervals of three to six weeks ). As a result, ponds become overcrowded

SpringerPlus, 2016

The majority of fish farmers in developing countries practise semi-intensive culture of Nile tila... more The majority of fish farmers in developing countries practise semi-intensive culture of Nile tilapia (Oreochromis niloticus L.) by feeding them with on-farm made feeds due to unavailability and high cost of commercial feeds. In Tanzania, over 95 % of fish farmers practise semi-intensive mixed-sex culture of O. niloticus in earthen ponds (Kaliba Abstract Unaffordability of commercial feeds to semi-intensive Nile tilapia, Oreochromis niloticus farmers has led to reliance on supplemental feeding and fertilization for nutrition of their fish without a scientific basis. This study compared the growth, survival, condition factor and yield performance of O. niloticus fed on mixed ingredients (MI) and rice bran alone (RB) diets reared in fertilized earthen ponds in small scale farmers' ponds. The study also determined phytoplankton composition, biomass and abundance in the experimental ponds. Quadruplicate ponds were stocked with O. niloticus and African sharptooth catfish, Clarias gariepinus at a stocking ratio of 1:3. The initial mean weights of O. niloticus and C. gariepinus were 14.62 ± 0.61 and 20.34 ± 1.44 g respectively. The fish were fed on MI and RB diets with protein content of 184.74 and 126.06 g kg -1 respectively for 270 days. The results showed that growth performance, survival rate and condition factor of O. niloticus were not affected by either feeding with MI or RB diet (p > 0.05). Moreover, there were no significant differences obtained in phytoplankton biomass and abundance in O. niloticus ponds fed on the two diets (p > 0.05). Furthermore, feeding O. niloticus either on MI or RB diet did not affect the net and gross fish yields (p > 0.05). The study revealed that the use of either MI or RB diet does not significantly affect the performance of O. niloticus cultured in semi-intensive earthen ponds where natural food organisms are an integral part of the culture system. Rice bran could be used for semi-intensive culture of O. niloticus in fertilized ponds to boost the production based on its availability and low cost.

Developments in Aquaculture and Fisheries Science

Abstract The abundance of macrofauna, size structure of predominantly gastropods and environmenta... more Abstract The abundance of macrofauna, size structure of predominantly gastropods and environmental variables were examined in Pangani and Ruvu mangrove forests to assess the effect of mud crab (Scylla serrata) fattening on mangrove forest biodiversity. Ruvu mangrove forest was used as a control site since there is no crab fattening activity. Benthic macrofauna were sampled in both study sites using quadrats of 0.25 m x 0.25 m. The substrate within the quadrat was dug out and sieve through a 1.0 mm mesh size to separate macrofauna. The size of the predominant gastropods, noteby Terebralia palustris and Cerithidea decollata were measured using callipers. Salinity, temperature, pH, organic matter and sediment particle size were Five environmental variables measured. Three predominant groups of benthic macrofauna were recorded, namely; crabs, polychaetes and gastropods. Generally, the results revealed that there was significant lower total benthic macrofauna in Pangani than Ruvu mangrov...

Aquaculture International, 2015

Abstract Uncontrolled breeding and precocious maturity in Nile tilapia, Oreochromis niloticus can... more Abstract Uncontrolled breeding and precocious maturity in Nile tilapia, Oreochromis niloticus can be avoided by using all-male population. This study compared the growth performance, survival rate, condition factor and final fish tank biomass (yield) of mixed-sex and hormonal-sex-reversed O. niloticus and hybrids (O. niloticus × O. urolepis hornorum) cultured in tanks. Sex-reversed males were produced by feeding newly hatched fry with a diet containing 60 mg of 17α-methyltestosterone for 28 days. Fourteen O. niloticus with initial mean weight (±standard error) of 0.50 ± 0.04, 0.48 ± 0.06 and 0.46 ± 0.01 g for mixed-sex, sex-reversed and hybrids, respectively, were separately stocked in triplicate tanks at a density of two fish m−2 and fed a 300 g kg−1 crude protein diet for 12 weeks. Results showed that hybrids had significantly higher final mean weight (31.41 ± 0.33 g) than hormonal-sex-reversed (25.82 ± 1.51 g) and mixed-sex O. niloticus (19.50 ± 1.26 g; p < 0.05). Similarly, sex-reversed O. niloticus had significantly higher final mean weight than mixed-sex (p < 0.05). The condition factor of hybrids (1.71 ± 0.05) was significantly higher than that of sex-reversed (1.46 ± 0.01; p = 0.001) and mixed-sex O. niloticus (1.43 ± 0.01; p = 0.001). Survival rate was not significantly different among treatments (p = 0.445). The final fish tank biomass was significantly higher in hybrids (535.24 ± 31.67 g tank−1) and hormonal-sex-reversed (486.52 ± 33.70 g tank−1) than mixed-sex O. niloticus (330.05 ± 17.08 g tank−1; p < 0.05). This study demonstrates that hybrids have superior growth performance and condition factor than sex-reversed and mixed-sex but have similar yields to hormonal-sex-reversed O. niloticus. These results suggest that O. niloticus farmers can improve growth rate and yield by rearing hybrids without affecting survival rate.

Western Indian Ocean Journal of Marine Science, 2009

The reproductive biology of Gerres oyena (Forskal, 1775) (Gerreidae) along the Bagamoyo coast was... more The reproductive biology of Gerres oyena (Forskal, 1775) (Gerreidae) along the Bagamoyo coast was studied from January to December 1999 using samples from monthly commercial catches. Size at first maturity was 12.8 and 13.9 cm TL for males and females respectively. The sex ratio was found to be 0.98:1 (m:f) and was not significantly different from 1:1. G. oyena spawns throughout the year with two peaks: one in March and the other between October and December, which coincide with the northeast monsoon. Ova-diameter frequency distributions indicated that G. oyena is a multiple spawner. They may spawn in three successive batches within the same prolonged spawning season. On an average, the numbers of mature ova produced were 148,138 per fish. For management purposes, a focus should be on the size of maturation relative to length-body depth or capture size. This would reduce harvesting of prereproductive individuals.

Natural Science, 2014

Out of the 48 fishes examined, 40 (83.3%) were infected by 759 parasites, which comprise of trema... more Out of the 48 fishes examined, 40 (83.3%) were infected by 759 parasites, which comprise of trematodes, monogeneans, crustaceans and acanthocephalans. Acanthocephalans and strigeid trematodes were the majority, 23 (47.9%) of all the parasites, while crustaceans, Ergasilus was the minority (20.8%). Fish with length size greater than 160 mm were infected (prevalence 100%). Strigeids showed the highest prevalence (83.3%) and mean intensity (24.7) in fish of total length 160 -189 mm while those greater than 219 mm had the least prevalence (20%) and mean intensity (2). Acanthocephalan showed the highest prevalence (87.5%) and mean intensity (15.7) in fish of total length 190 -219 mm and least prevalence (30.4%) and mean intensity (5.6) in those with 130 -159 mm in total length. Generally male fish had higher prevalence (88.5%) and mean intensity (21.6) than female fish. However, statistically these were not significant (P > 0.05). A total of 9 parasite taxa were recovered; 5 from Oreochromis urolepis, 4 from Citharinus congicus, 2 from Clarias gariepinus and Synodontis maculipinna. Three groups of parasites were common in Oreochromis urolepis, these include Dactylogyrus, Acanthocephala, and strigid. Ergersilus lamelifer was common in Citharinus congicus and Clarias gariepinus. Nematodes, Procamalanus laevionchus and Oxyuridae were common in Synodontis maculipinna and Citharinus congicus respectively.

Aquaculture Research, 2016

This study explored the yield and economic benefits of African sharptooth catfish, Clarias gariep... more This study explored the yield and economic benefits of African sharptooth catfish, Clarias gariepinus, and Nile tilapia, Oreochromis niloticus polyculture, reared in earthen ponds for 270 days integrated with Chinese cabbage, Brassica rapa chinensis, farmed for 45 days to small-scale farmers in Tanzania. An integrated aquaculture-agriculture (IAA) system involving fishes and vegetables resulted in three and 2.5 times higher net yield than the culture of fishes alone and farming of non-integrated vegetables respectively. Vegetables irrigated with pond water resulted in 1.8 times higher net and annual yields than those irrigated with stream water. The practice of fish-vegetable integration and growing of vegetables irrigated with pond water produced 14 and 13 times higher net annual yield, respectively, than the culture of fishes alone. The integrated system produced 20 and 150 times more net returns compared with vegetables irrigated with pond and stream water respectively. Integrating fishes with vegetables resulted in significantly higher annual net cash flow than the farming of fishes and vegetables separately. The study revealed that integrating fishes with B. rapa chinensis increases yields, income and food production to small-scale farmers. Thus, small-scale farmers can adopt IAA technology to meet the increasing demand of fish and vegetables, stabilize their incomes and diversify food production, consequently improving food security. These benefits will be realized by providing proper training in IAA technology and management skills to small-scale farmers.

International Aquatic Research, 2015

Prolific breeding and production of high percentage of recruits are main problems in mixed-sex Ni... more Prolific breeding and production of high percentage of recruits are main problems in mixed-sex Nile tilapia (Oreochromis niloticus) culture in earthen ponds. The current study assessed the efficiency of different sizes of African sharptooth catfish (Clarias gariepinus) in controlling recruitment in mixed-sex Nile tilapia cultured in tanks and its effect on growth performance, percentage survival and yield. Three treatments consisting of triplicate ponds stocked with mixed-sex Nile tilapia in monoculture and in polyculture with large (62.50 ± 3.26 g) and small (40.00 ± 2.68 g) African sharptooth catfish were fed on a 297.50 g kg-1 crude protein diet for 126 days. Results showed that, the number of recruits was significantly lower in larger African sharptooth catfish predator than smaller ones and monoculture of Nile tilapia. Polyculture with larger African sharptooth catfish resulted in significantly higher growth performance of Nile tilapia. Large African sharptooth catfish in polyculture reduced the amount of small, low-value recruits, while the yield of large and high value Nile tilapia was increased. This study revealed that fish farmers can reduce prolific breeding, obtain higher growth performance and produce larger size of marketable Nile tilapia by predominantly stocking ponds with large African sharptooth catfish predator of at least 60 g.

Uncontrolled breeding and precocious maturity in Nile tilapia, Oreochromis niloticus can be avoid... more Uncontrolled breeding and precocious maturity in Nile tilapia, Oreochromis niloticus can be avoided by using all-male population. This study compared the growth performance, survival rate, condition factor and final fish tank biomass (yield) of mixed-sex and hormonal-sex-reversed O. niloticus and hybrids (O. niloticus × O. urolepis hornorum) cultured in tanks. Sex-reversed males were produced by feeding newly hatched fry with a diet containing 60 mg of 17α-methyltestosterone for 28 days. Fourteen O. niloticus with initial mean weight (±standard error) of 0.50 ± 0.04, 0.48 ± 0.06 and 0.46 ± 0.01 g for mixed-sex, sex-reversed and hybrids, respectively, were separately stocked in triplicate tanks at a density of two fish m−2 and fed a 300 g kg−1 crude protein diet for 12 weeks. Results showed that hybrids had significantly higher final mean weight (31.41 ± 0.33 g) than hormonal-sex-reversed (25.82 ± 1.51 g) and mixed-sex O. niloticus (19.50 ± 1.26 g; p < 0.05). Similarly, sex-reversed O. niloticus had significantly higher final mean weight than mixed-sex (p < 0.05). The condition factor of hybrids (1.71 ± 0.05) was significantly higher than that of sex-reversed (1.46 ± 0.01; p = 0.001) and mixed-sex O. niloticus (1.43 ± 0.01; p = 0.001). Survival rate was not significantly different among treatments (p = 0.445). The final fish tank biomass was significantly higher in hybrids (535.24 ± 31.67 g tank−1) and hormonal-sex-reversed (486.52 ± 33.70 g tank−1) than mixed-sex O. niloticus (330.05 ± 17.08 g tank−1; p < 0.05). This study demonstrates that hybrids have superior growth performance and condition factor than sex-reversed and mixed-sex but have similar yields to hormonal-sex-reversed O. niloticus. These results suggest that O. niloticus farmers can improve growth rate and yield by rearing hybrids without affecting survival rate.

In Africa there is a need to increase food security especially in the dry season when livelihoods... more In Africa there is a need to increase food security especially in the dry season when livelihoods are most at risk. The fingerpond concept is designed to exploit fringe wetlands sustainably for food production whilst conserving swamp integrity and biological diversity. The concept is a marriage of natural wetland phenomena with the historic activities of riparian peoples and more recent agro-piscicultural practices. These are summarized to highlight the main principles of fingerpond systems. Fingerponds exploit the richness and productivity of the wetland ecotone at the land/water interface and the seasonal flooding thereof. They are dug at the swamp edge in the dry season and the excavated soil is spread around their perimeters. The ponds are stocked naturally during the seasonal floods with fish migrations: they become cut-off as the waters recede and the land between is cultivated. Manure and waste from village compounds are used to fertilize the ponds. With co-funding from the EU INCO-DEV programme, experimental fingerponds co-managed by local communities were established in East Africa in 2002/03. We shall present our preliminary observations and discuss some strengths and pitfalls of our systems.