Cooling of cultured water can resist heart failure caused by collagen deposition and necrosis of cardiac fibers under chronic heat stress in sturgeon

Background Chronic heat stress (CHS) may threaten the survival of cultivated and wild sturgeon by jeopardizing heart function. Methods Therefore, we established a heart damage model for the Siberian sturgeon (Acipenser baerii) using varying degrees of CHS (24°C and 28°C) to explore its effect on the heart structure and function, and their mutual relationship. Results Our research showed that CHS caused systemic heart failure in A. baerii, clinically manifested as severely irregular ventricles, increased myocardial fibrotic in the interstitium of cardiomyocytes, and myocardial necrosis. Echocardiographic imaging of A. baerii revealed an accelerated heart rate, incomplete ventricular contraction, decreased cardiac output, and significantly reduced pumping efficiency under CHS. Generally, the contractility of the heart decreased and the afterload increased under CHS, which is typical of high-resistance and low-output heart failure. However, cooling of cultured water (20°C) can offset the adverse effects of partial or total CHS on tissue structure and function. Conclusion Our results systematically characterized the relationship between the effects of CHS on the heart structure and heart function in sturgeon. This work provides a preliminary reference for future summer breeding pond management and protection of sturgeon.

The Effect of Different Feeding Applications on the Swimming Behaviour of Siberian Sturgeon: A Method for Improving Restocking Programmes

Restocking programmes of different fish species have been implemented worldwide. However, the survival of hatchery-reared fish after release to riverine ecosystems is at a very low level. One of the reasons for the high mortality rate of post-released fish is their modified swimming behaviour due to the hatchery rearing practice. To investigate one of the possible causes for modified swimming behaviour, Acipenser baerii larvae were exposed to surface- and bottom-feeding applications with day and night light regimes in a factorial design. We also analysed the effect of 5 and 10 days of starvation after different feeding applications on sturgeon swimming behaviour. The surface-feeding application was previously expected to promote the frequent Siberian sturgeon swim up to the mid- and top-water layers in our rearing facilities. However, our results indicated that the modified behaviour of the Siberian sturgeon in our study was caused by fish starvation and a possible predator-free environment rather than by the method of feed application or the day/night light regimes. These results may be used to improve the implementation of restocking programmes either through modified hatchery rearing practice or the training of foraging skills with predator stimuli.

The results of growing young Lena sturgeon (Acipenser baerii Brandt) in the USV on various feed recipes

The effect of Aller Arrow S and Aller Trident S formula feeds on the growth, development and accumulation of fat in the muscles of Lena sturgeon juveniles raised in the conditions of ultrasonic testing for a repair herd was studied. The obtained results of cultivation indicate the effectiveness of the use of Aller Arrow feeds to reduce fat accumulation. It is shown that production feeds with a fat content of 14% and a higher (by 4%) energy-protein ratio contribute to an increase in the fatness coefficient and a decrease in the progonicity index, their use leads to an increase in liver weight by 48.5% (p≥0.05), and the gastrointestinal tract by 5.6%. The ratio of connective and adipose tissues, the density of muscle fibers indicates a more intensive accumulation of fat when using Aller Trident S, which indirectly indicates a higher energy (gastronomic) value of meat, due to an increase in its caloric content. According to the average final mass, mass accumulation coefficient, yield and growth of ichthyomass, relative growth rate, average daily growth, the best results were obtained in juveniles raised on production feed, the economic effect was 400 rubles/m3 of the pool.