Induced Breeding of Freshwater Fishes and Cost Benefit Analysis of a Selected Fish Hatchery in Jashore, Bangladesh

An investigation was carried out to know the induced breeding techniques of some firewater fish species such as rui (Labeo rohita), catla (Catla catla), silver carp (Hypophthalmichthys molitrix), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), bighead carp (Hypophthalmichthys nobilis), sharpunti (Puntius sarana) and bata (Labeo bata) at Ma Fatima Fish Hatchery in Chanchra, Jashore, Bangladesh. The cost-benefit analysis was also performed on this hatchery for three months from May to July, 2016. The brood fishes purchased from different local sources were used for spawning. The hatchery mainly practiced induced breeding by maintaining proper age and weight of brood stock during spawning. The ranges of fertilization and hatching rates of the experimental fishes were 80.04±1.44 % to 94.35±0.54% and 75.34±3.49% to 88.68±2.76%, respectively. Total spawn production was 960, 862 and 734 kg, and the total revenue income from spawn sell was BDT 2,883,500, 2,355,100 and 1,844,800 (BDT 85 = 1 US$) in May, June and July, respectively. Estimated capital cost was BDT 87,90,000, while the operating costs were BDT 1,810,650; 1,555,105 and 1,267,680 in May, June and July, respectively. The calculated cost-benefit ratios in May, June and July were 1.59, 1.51 and 1.46, respectively. The hatchery got the highest net profit of BDT (Bangladeshi Taka) 1,041,906 in May due to the highest production and higher price of spawn, and the lowest profit of BDT 546,176 was obtained in July. So, May was found to be the peak breeding month of Ma Fatima Hatchery. The estimated cost-benefit ratio indicated that the spawn production through induced breeding techniques was profitable for the hatchery owners.

Influence of Drying Techniques on the Physicochemical, Nutritional, and Morphological Properties of Bighead Carp (Hypophthalmichthys nobilis) Fillets

Different experiment analyses were performed to evaluate the influence of two drying techniques (oven drying and microwave drying) on the fillets of bighead carp fish (Hypophthalmichthys nobilis). The processed and fresh samples were subjected to the chemical analysis of (amino acids, minerals, volatile compounds, fatty acids, and vitamins) as well as scanning electron microscopy, thermal analysis, and color measurement, in order to identify nutritional components that can be additives or supplementary in food industries. The drying techniques increased the protein content significantly. Amino acids were identified, and the level of essential amino acid (EAA) was higher under the microwave treatment compared with the oven drying process. The Ca+2 and K+1 were presented in high values, followed by Na+1 and Mg+2. In addition, the drying techniques showed and released more volatile compounds in the processed samples compared with the unprocessed samples. Under the drying process, polyunsaturated fatty acids were increased in the processed fillets, whereas the level of saturated and monounsaturated fatty acids reduced. Thermal degradation occurred from 100 to 150 °C. However, the processed samples were subjected to an intensive endothermic response, but remained stable until 100 °C. Therefore, the microwave technique showed some enhancements in the nutritional value and has the potential to be applied as an effective preservation method of bighead carp fish. Furthermore, dried fillets could be an alternative source of bighead carp fish for the food industry.

Status of Chinese Carp Fisheries in Tunisian Freshwater Reservoirs: Threats and Opportunities

The current paper aims to diagnose the state of fisheries of three Chinese carp species whish have been introduced in Tunisian reservoirs since 1981: (silver carp Hypophthalmichthys molitrix, herbivorous carp Ctenopharyngodon idella and bighead carp Aristichthys nobilis) and seeks to study the benefits and risks associated with their introduction. Chinese carps cannot reproduce naturally in freshwater reservoirs. Eventually, artificial breeding operations and seeding of the dams with farm-produced fry are carried out by the Technical Centre of Aquaculture every year. Statistical analyses have shown a strong correlation between the landed quantity and the number of fries stocked each year. The impact assessment showed that the risks and benefits associated with the introduction of the three species are variable. Regarding their benefits, it was clear that the herbivorous carp has provided effective and sustainable control of the extensive development of aquatic vegetation in the eutrophic reservoirs and canal systems. The value of the other two species, though, remains less obvious, particularly for the bighead carp. The consequences of their introduction on ecosystems and native species seem to be negligible, especially when the densities are low. Eventually, it seems judicious to increase the stocking of the herbivorous carp, silver carp and bighead carp in Tunisian reservoirs.