نشریه ماهیان دریایی
سال پنجم شماره 1 (پیاپی 6، بهار و تابستان 1400)

Regarding the importance of aquaculture industry development, it is necessary to focus on inbreeding in artificial propagation to prevent genetic diversity reduction and problems arising from low genetic variation. Indeed, lack of facilities and the rules related to the responsible transportation of live aquatic animals, and carelessness on health- diseases control in farms has led to some diseases outbreaks which have imposed high costs for farmers, including huge losses or cure. Therefore, it is required to identify the species and population traits before initiating any culturing or breeding programs and evaluate them with molecular genetic methods to synchronizing study with biological characteristics such as reproductive potential, growth rate, and mortality. Achieving broodstocks and fry owning genetically relatedness is a principal issue in each hatchery. This article tries to discuss the significance of genetic diversity assessment by microsatellite marker for broodstocks' genetic relatedness, with an emphasis on Asian sea bass.Keywords: diversity, pedigree, Asian sea bass, marker

The use of antibiotics in the diet of farmed aquatic organisms is done to reduce infectious diseases or enhance growth function. in recent years, the preventive use of antibiotics has been criticized, which has ultimately led to a ban on the production and breeding of farmed organisms by many countries. given the current limitations on antibiotic use, there is a fundamental need to evaluate options. organic acids or their salts, a potential alternative to preventing the overuse and promotion of antibiotics as well as dietary supplements and antimicrobials, have recently been considered by many researchers and breeders. this study emphasizes the effects of organic acids on growth, use as nutrients, availability of minerals, improvement of intestinal flora and disease resistance in marine fish.many studies have reported that some organic acids can significantly increase the growth performance and health of fish, and these results, depending on the aquatic species, the type and concentration of organic acids and the conditions of the farming environment use depends.

Although fisheries production has increased dramatically over the last decades, the waste portion (such as skin, bones, intestines, and viscera) accounts for a significant part of yield. Marine fish are known as a rich source of bioactive compounds such as bioactive peptides. Recently, marine fish-derived peptides have obtained especial interest. The market size of fish protein hydrolysates is expected to grow of 4.5% between 2020 and 2026. Extraction of bioactive peptides is done by acid-alkaline hydrolysis, enzymatic hydrolysis and fermentation and depending on the structure and sequence of amino acids obtained, they have suitable biological properties suitable for the cosmetic-pharmaceutical industry. Furthermore, the production of marine bioactive peptides not only reduces environmental problems but also generates added value. The present article reviews the enzymatic hydrolysis and evaluated antimicrobial, antioxidant and anti-photoaging effects of peptides extracted from marine fish.

Cobia, Rachycentron canadum, is an important species for aquaculture worldwide. This species exhibits fast growth and can reach between 4 and 6 kg in 1 year. Cobia are carnivores and their protein and lipid requirements are 44.5 and 5.76 % respectively. In addition, to achieve optimal specific growth rate for cobia, a dietary carbohydrate supplementation of 21.1 is required. In environmental condition, fish is the predominant diet composition for cobia with 95.3%, followed by squid (3.1%), crab (1.5%), and shrimp (0.07%). The protein and lipid contents in cobia fillets were 20.3 and 6 % of wet weight respectively. The amount of total EPA + DHA in the cobia fillets was 0.2 g/100 g-1. Expenses related to feed, fingerlings and labor were the most important components of the operational costs in cobia cage culture. Therefore, cobia as a native species, is the candidate species for introducing to cage culture in Iran due to its fast growth.

Lactoferrin is an iron ion-binding glycoprotein belonging to the transferrin family, which is present in varying amounts in the milk of mammals, including cows. This glycoprotein was first isolated from cow's milk and was identified as milk red protein due to its iron content. Lactoferrin is considered an important host defense molecule and has a wide range of biological functions including a role in iron metabolism, cell proliferation and differentiation, and antibacterial, antiviral, and antiparasitic activity. One of the most important properties of lactoferrin is the iron absorption and transport. By absorbing free iron, lactoferrin deprives the environment of this element and thus deprives it of the pathogens that it needs to survive, thereby indirectly inhibiting the spread of infection by inhibiting the growth of harmful bacteria. The results show that although the use of lactoferrin in the culture of some species such as yellowfin seabream (Acanthopagrus latus) and Japonica eel (Anguilla japonica) has increased the growth and immune performance but use in the diet of some species such as sobaity fish (Sparidentex hasta) had different results (positive effect and no effect). Therefore, it seems that results will be varied for every species and different experimental conditions and more research is needed in this field.

In this research, trend catch and demographic characteristics and demographic characteristics of Longtail tuna (T.tonggol) were estimated by collecting information from 4 catchment areas on the coast of Hormozgan province including Kang, Salakh, Parsian and Jask. In this project, more than 14000 fish at the research stations were biometric and the growth parameters were infinite length of L∞ = 137 cm, growth factor K = 0.41 (yr-1), natural mortality M= 0.63(yr-1), mortality and mortality (yr-1), F = 0.49, total mortality (yr-1), Z = 1.12 ± 0.16 and exploitation coefficient (yr-1), E = 0.43, and the time zero was -0.26 for the years. Relative production per recruitment, relative biomass per recruitment, exploitation rate and average annual standing stock for kawakawa species were estimated Y '/ Rp =0.03, B' / Rp = 0.36, U= 0.38, respectively. This study showed that this species has moderate vulnerability and medium stock conditions, and also, exploitation ratio of this species stock is under fishing.