Consumption Of Tilapia Research Articles

A PBTK/TD modeling‐based approach can assess arsenic bioaccumulation in farmed tilapia (Oreochromis mossambicus) and human health risks

A biologically based risk-assessment model of arsenic (As) exposure evaluated farmed tilapia (Orechromis mossambicus) and human health during tilapia consumption in an area of southwestern Taiwan where blackfoot disease (BFD) occurs. The risk assessment addressed exposures to city residents who lived in Taipei, Taichung, and Kaohsiung, as well as subsistence fishers living in the BFD area who consumed tilapia. The models implemented included a physiologically based toxicokinetic and toxicodynamic (PBTK/TD) model to account for As exposure and dose-response profiles in tilapia and a human health exposure/risk model that accounts for target lifetime risk (TR) and hazard quotient (HQ) for humans consuming farmed tilapia. Results demonstrated that 90th percentiles of TR ranged from 1.53 x 10(-8) to 1.62 x 10(-6) for city residents with farmed tilapia consumption rates of 0.41 to 1.37 g/d. The 90th percentiles ranged from 2.07 x 10(-6) to 7.89 x 10(-5) for subsistence fishers in the BFD area with farmed tilapia consumption rates of 16.80 to 59.15 g/d. All predicted 90th percentiles of HQ were less than 1 for city residents and subsistence fishers in the BFD area, indicating small contributions from farmed tilapia consumption. Critical variables included whole-fish body weight, water As content, and As level in tilapia muscle. Although bioaccumulation of As seems unlikely to result in toxicity to farmed tilapia and humans consuming tilapia, the theoretical human health risks in the BFD area are alarming, using a probabilistic risk-assessment model based on conservative assumptions.

Current status of production and consumption of tilapia in selected Asian countries

An assessment of the status of production and consumption of tilapia in five Asian countries was made to provide a baseline for the analysis of the potential benefits of the introduction of a new, improved strain of Nile tilapia. This paper provides a comparative analysis of the profile of tilapia fanners and their farming systems, costs, returns and productivity of tilapia production, and fish consumption patterns in Bangladesh, China, the Philippines, Thailand and Vietnam, using data from household surveys conducted by ICLARM and its partners in 1995–96. Farmers grow tilapia in varied farming environments depending on the nature of their farmland and on their investment capacity. Tilapia is cultured mainly in semi‐intensive systems on small and medium farms. The average farm size (pond area) of the surveyed pond operators varies from 0.60 ha (0.05 ha) in Bangladesh to 4.91 ha (1.56 ha) in the Philippines. In Asia, tilapia farming is very profitable. The productivity, costs of production and profitability of tilapia farms vary considerably among countries and production environments. Tilapia fanning is becoming increasingly commercial with a large proportion of production is marketed. Tilapia is consumed mainly by poor consumers because of its relatively low price compared to other fish species.

Safety Evaluation of Transgenic Tilapia with Accelerated Growth.

Recent advances in modern marine biotechnology have permitted the generation of new strains of economically important fish species through the transfer of growth hormone genes. These transgenic fish strains show improved growth performance and therefore constitute a better alternative for aquaculture programs. Recently, we have obtained a transgenic tilapia line with accelerated growth. However, before introducing this line into Cuban aquaculture, environmental and food safety assessment was required by national authorities. Experiments were performed to evaluate the behavior of transgenic tilapia in comparison to wild tilapia as a way to assess the environmental impact of introducing transgenic tilapia into Cuban aquaculture. Studies were also conducted to evaluate, according to the principle of substantial equivalence, the safety of consuming transgenic tilapia as food. Behavior studies showed that transgenic tilapia had a lower feeding motivation and dominance status than controls. Food safety assessment indicated that tilapia growth hormone has no biological activity when administered to nonhuman primates. Furthermore, no effects were detected in human healthy volunteers after the consumption of transgenic tilapia. These results showed, at least under the conditions found in Cuba, no environmental implications for the introduction of this transgenic tilapia line and the safety in the consumption of tiGH-transgenic tilapia as an alternative feeding source for humans. These results support the culture and consumption of these transgenic tilapia.

Ammonia Excretion and Oxygen Consumption of Tilapia Are Affected by Different Carbohydrate Ingestion

Ammonia Excretion and Oxygen Consumption of Tilapia Are Affected by Different Carbohydrate Ingestion

The influence of suspended silt on oxygen consumption by the redbreast tilapia, Tilapia rendalli (Boulenger,1896)

The routine oxygen consumption of redbreast tilapia, Tilapia rendalli exposed to silt from the Phalaborwa Barrage was investigated under controlled laboratory conditions. Exposure of adult fish to sublethal concentrations of silt did alter routine oxygen consumption by causing increased rates (53–77% from initial) of oxygen consumption. This indicates that sublethal levels of suspended silt concentrations results in an increase in oxygen consumption by the fish due to an increase in metabolic rate associated with increased activity and stress. From the laboratory experiments, it can therefore be predicted that sublethal releases from the Phalaborwa Barrage will stress the resident fish populations. However, the extent of the impact on the fish population will depend on factors such as frequency, duration and severity of exposure as well as the species in question. Long term monitoring of the fish population below the Phalaborwa Barrage is therefore essential.

Simulation of the effects of oxygen on food consumption and growth of Nile tilapia, Oreochromis niloticus (L.)

Fish need oxygen for aerobic generation of energy for body maintenance, locomotion, feeding and biosynthesis. The rate of oxygen uptake of most fish is limited by diffusion through the gills, and gill surface area grows at a slower rate than body mass. We hypothesize, therefore: (1) that the maximum rate of feed intake is related to the capacity to take in oxygen for processing of this feed; and (2) that the maximum rate of feed intake relative to body size decreases with increasing body size to a point where growth is zero. An oxygen limitation module based on this theory was incorporated into an existing dynamic simulation model for the Nile tilapia, Oreochromis niloticus (L.). The module calculates the maximum potential oxygen supply to the fish on the basis of Fick's law of diffusion and the allometric relationship between body weight and gill surface area. Total oxygen demand of the fish is computed as the sum of routine metabolism, feeding metabolism and energy needed for biosynthesis. In the module, the feeding rate is limited to a level where total oxygen demand does not exceed the potential supply. The model is used to simulate feeding and growth of O. niloticus. Simulation results provide strong support for the oxygen limitation theory. Hence, the model can be used for the analysis of fish growth as affected by feed amount, feed composition, as well as environmental conditions (temperature, dissolved oxygen concentration). It also explains differences in final size between fish species, and within species under different conditions.

Effect of Salinity on the Oxygen Consumption of Tilapia Fingerlings

Fingerlings of tilapia were used to compare the oxygen consumption rates at 0, 10, 20 and 30 ppt salinity. Oxygen consumption of tilapia at 0, 10, 20 and 30 ppt salinity was found 2.14, 0.71, 1.43 and 1.42 ml/liter/h respectively. Oxygen consumption rate thereafter decreased with increasing salinity, although the lowest consumption occurred at 10 ppt. Lower consumption at high salinities might be a result of reduced activity, which in itself was salinitymodulated. The fish in this study were in or near a resting state, and that differences in oxygen consumption rates probably were related to the energetic cost of ionic and osmotic regulation. Again, mechanism in the fill tissue might involve significant energy-consuming processes in different water salinities compared to fresh water.Keywords: Fingerlings; water salinities; Ionic regulation; osmic regulationsDOI: http://dx.doi.org/10.3329/diujst.v7i1.9581 Daffodil International University Journal of Science and Technology Vol.7(1) 2012 12-14