Dr. Hooman Rahmati-Holasoo completed his Ph.D. at the age of 28 years from the University of Tehran. He is an associate professor of aquatic animal health. He has published more than 50 international papers in reputed journals and has been serving as a reviewer of many international journals. His main research is on ornamental and sturgeon fish diseases.
Sturgeons have been referred to as ‘primitive fishes’ among the bony fishes because their morphological characters have remained relatively unchanged. Farming sturgeons is an economically important profession in a number of countries in the world. Based on the nutritional value and demand for caviar and meat production, sturgeons are considered one of the most high-valued food fish. Siberian sturgeon (Acipenser baerii Brandt 1869) is a marine acipenseriform food fish, which has been classified into the Acipenseridae family. Due to the interest of several fish farms in culturing sturgeon in Iran and the lack of sufficient relevant data, this study investigated parasite, fungus, and bacteria-related health problems of an acipenseriform food fish species, the Siberian sturgeon (Acipenser baerii) from five fish farms between November 2018 and November 2021 in central Iran. Mortality of Siberian fish was reported in 5 sturgeon farms. The different types of pathogens found in these fish were investigated until the fish reached about 3 kg of weight (2+ years). A number of parasitic disease pathogens (monogenean Diclybothrium armatum and protozoan Trichodina sp.), fungus Saprolegnia sp., and bacteria Aeromonas sp. were identified in the moribound fish. Samples for histopathology were taken and studied under light microscopy. Then treatment of alive fish was performed according to the identified pathogens. And mortalities were stopped. In conclusion, due to the relatively large variety of these pathogens, consideration of few applied measures including full observance of the quarantine period, setting up an appropriate filtration and ventilation system, periodic use of efficient disinfectant compounds, and use of cement and fiberglass ponds as an ideal alternative for the earth ponds, are recommended to promote the fish health condition and prevent the development of infectious diseases in sturgeon fish farms.
Esraa E. AbouElMaaty, National Institute of Oceanography and Fisheries, Suez, Egypt
Increasing fishing potential on edible sea urchins causes significant depletion in sea urchins’ populations worldwide. This evinced that aquaculture is required to fill the gap between supply and demand. Induce spawning and larval rearing of the sea urchin T. gratilla was studied. Four induction agents were tested on 4 groups of 10 individuals each of T. gratilla with same sizes. The treatments included: injection with 0.5 and 1.0 M KCL, drying under direct light for 4 hours, and mechanical shaking. The fecundity (oocytes released per female) and responding times to induction agents varied significantly according to the treatment. The highest fecundity was estimated for the group treated with drying under direct light, while the lowest fecundity was recorded for the group treated with mechanical shacking, being 18.6±1.1 and 0.94 ±0.0039 million oocytes/female respectively. In addition, the quickest respond (less than a minute) was recorded for the group treated with 1M KCL, compared with 2-5 minutes for groups treated with other induction agents. It was also noticed that the lower abundance the higher survival, i.e. higher survival of larvae was recorded at a density of 3 larvae/ml compared with the other tested densities of 9 and 6 larvae/ml, all fed with the alga Nanochloropsis species. Embryonic development, larval metamorphoses, and morphometric parameters were followed and measured.
Rivara Michael Patricio, Cornell University Cooperative Extension, Southold, New York, USA.
One of the major challenges for commercial shellfish aquaculture operations has been the seasonal fluctuation in the availability of seed stock. Unsuccessful spawns, diseases, and the seasonal nature of bivalve hatcheries present obstacles to locally-sourced fresh shellfish for the seafood industry. It would be of great advantage to shellfish hatchery operations if they are able to store larvae for an extended period of time in order to bridge between spawns (weeks to months) and seasons. In addition, since fewer spawns are needed, algal production that would normally be devoted to broodstock conditioning would become available for feeding post-set, at a time of year when hatchery demand for algae is at its highest. Traditional cryopreservation of juvenile bivalves in liquid nitrogen using proven cryoprotectants and protocols has been attempted many times with limited results, particularly for species currently in high demand in the northeastern United States (e.g. eastern oyster & bay scallops). Our project involves subzero C stasis using optimal cryoprotectants and temperature ramps. Funded in part by New York Sea Grant, NOAA, DOC.
Mohamed Y. M. Aly National Institute of Oceanography and Fisheries, Cairo, Egypt
This review provides a summary of the toxic effects of heavy metals on fish. In the aquatic environment, these metals are important pollutants and are found in all ecosystems and are found in large quantities. Some heavy metals such as Cadmium, iron, copper, zinc, and lead have the advantage of accumulating in tissues and poisoning fish. These minerals can effectively affect biological processes, and fish reproduction, impair the immune system, and cause pathological changes. Therefore, heavy metals play an important role as a vital predictor of pollutants affecting the health and life of fish environments. These minerals cause organ damage even at low levels of exposure, so they have recently been classified as carcinogens. For all the above-mentioned reasons, this review has been written to contribute to the role of heavy metals in the environment, the toxic mechanism, the toxic effects on fish, and the health of the human consumption of fish. Also, this article reviews the Histopathological change and biomarkers when exposed to heavy metal contamination.
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