نشریه علوم آبزی پروری پیشرفته
سال ششم شماره 1 (بهار و تابستان 1401)

Sturgeons are known as one of the most valuable fish species in the Caspian Sea and other water bodies across the world. These fishes are highly important both in caviar production and by-products such as leather from the skin. 17 out of 24 sturgeon species are categorized in critically endangered species based on the IUCN red list and all of the five available species in the Caspian Sea have this situation. The most important reasons for the sharp reduction of the sturgeons are illegal haunting for Caviar extraction, loss of nursery grounds, diminishing the water flow from the rivers and water pollution. Sex determination of these fish species is usually time-consuming and invasive, and genetic markers based on traditional methods were not able to solve this problem. Hence, the sex determination of sturgeons in early stages is possible now using the molecular markers obtained from modern techniques, which can be of great importance in terms of aquaculture management in sturgeon farms.

In the plan of developing aquaculture and increasing production in Soomeeholeya lake Dam in the East Azerbaijan, zooplankton studies were considered as basic studies and the possibility of increasing production in line with aquaculture and fish production in lake. In this project, 5 study stations were considered in the area of the dam lake and the river entrance.The studies started quarterly from the winter of 2010 and continued for one year until the fall of 2011. For zooplankton sampling, 30 liters of water was filtered by a 30-micron zooplankton hunting net. Finally, the samples were fixed with %4 formalin and in the laboratory, after preparation, they were identified and counted under an inverted microscope. In zooplankton studies, 5 Phyla and 19 genera were identified in this lake. In total, Rotifra with the genera of Polyarthra, Syncheata, Keratella and Cephalodella and an average of 240 per liter and 66.4% of the zooplankton population are the most abundant and Ciliphora with an average of 87 per liter and % 41.4 of the zooplankton population of the lake are in the next rank. Comparison of planktonic observations and environmental water factors has shown that, Vahdat reservoir dam is still young and has the talent and suitable species of zooplankton for feeding, breeding fish and their larvae, but the lake fauna need several years to complete the life cycle and adapt to the lake conditions.

In recent decades, the isolation of novel bioactive compounds from marine resources has attracted the great attention of many researchers. Seaweeds are a marine resource that contain various bioactive compounds such as polysaccharides, phenolic compounds, pigments, omega-3 fatty acids, proteins, and peptides. On these basses, they have been used in the different industries. Fucoidan is a sulfated polysaccharide extracted from brown seaweeds. Due to its suitable bioactive and functional properties, this polysaccharide can be used as functional ingredient in the formulation of functional foods and nutraceutical supplements. Conventional methods of hot water, acidic and alkaline, and novel methods such as ultrasound, microwave, enzymatic, supercritical fluid, and subcritical water can be used to extract fucoidan. The present study overviews the different steps of fucoidan extraction and also its applications, benefits, and effectiveness.

In order to investigate the status of Caspian Sea kutum ( Rutilus kutum) released to Khandaghlou dam reservoir in Zanjan province, a sample of fish fauna was carried out for one year. The Caspian Sea kutum was introduced to this reservoir in 2003 ( It is not clear that it was deliberate or accidental ). The results showed that the mean length of Caspian kutum caught in the Khandaghlou dam reservoir was 42.1 ± 3.1 cm with a minimum and maximum length of 38 and 46 cm, respectively. The average weight of this fish was 297 ± 1120 grams with a minimum and maximum weight of 667 and 1400 grams respectively. In the samples, the age range of this species was 3 and 5 years old, and the 4-year-old fish had comprised 67% of the catch (n= 6). In examining the contents of the stomach of caught fish there was a large amount of the shrimp of the lake (Macrobrachium niponnes) which was confirmed by Professor De Greev in samples transmitted to the London Zoology Museum. Also, the female gonads were in the fourth stage of sexual maturity. It seems that due to the high adaptability of Caspian Sea kutum, this species can be identified as one of the most suitable options for the aquaculture industry and culture-based fishery in dam reservoirs in the country.

The growing worldwide population has led to an increase in food query and aquaculture is one of the production sectors to supply feed required by the world. It is thought the aquaculture should be maintainable. However, the expansion of a sustainable aquaculture commerce has been hindered by the restricted accessibility of natural resources as well as its undesirable impact on the surrounding environment. The prime goal of aquaculture expansion must be to produce more product deprived of significantly increasing the usage of the basic natural resources of water and the land. The second goal is to develop sustainable aquaculture system that will not destruct the environment. The third goal is to built up systems providing an equitable cost/benefit ratio to support economic and social sustainability. Thus, there is a crucial need to search for better aquaculture production systems. All these three fundamentals for sustainable aquaculture development can be met by biofloc technology

Nowadays, sea foods are considered to provide more than 50% of the nutritional demands of ‎human communities. Therefore, with the development of the seafood market, the aquaculture ‎industry continues to grow day by day. Currently, some aquaculture food ingredients are made ‎from low price fishes (in the form of fish powder) and plants. But, the production of fish powder ‎cannot be increased due to disruption of the stability of aquatic ecosystems; Therefore, alternative ‎and environmentally friendly sources should be developed for aquaculture food ingredients. ‎Microalgae biomass suggests as a natural source instead of fish powder because the cellular ‎metabolites of these microorganisms contain a combination of essential amino acids, unsaturated ‎fatty acids, vitamins, and pigments. In addition to these unique properties and bioactive compounds ‎that are a major component of aquatic nutrition, microalgae can increase the survival of farmed ‎species, and improve the color and quality of fillets. Microalgae have the highest biomass productivity ‎among photosynthetic organisms, including forage crops, and therefore have high commercial ‎potential. Also, the production of microalgae does not require special arable land and freshwater ‎resources, which makes the feed based on microalgae contribute to environmental sustainability. ‎This article is a review of studies on the potential and application of microalgae in aquatic nutrition ‎to increase the productivity of aquaculture products.‎