Olga Isaeva
Biography
From 2024 to the present, she is Associate Professor of the Department of Biology and Earth Sciences of the Faculty of Natural and Technical Sciences of the Federal State Budgetary Educational Institution of Higher Education Vitus Bering Kamchatka State University, actively participates in the educational and scientific process in the bachelor's degree program (natural processes: biological and geological aspects), master's degree (biodiversity and biological resources), postgraduate program (ichthyology). She takes part in scientific work, has more than 100 published scientific papers, including in publications included in the international databases Web of Sciense, Scopus. She took part in a number of conferences and symposia, both Russian and international.
Research Interest
fish chemoreception, taste, marine chemical ecology, deterrents, attractants, marine hydrobionts
Abstract
Alternative food sources and orosensory attractive feeds in aquaculture
The current practice of using forage fish as a protein source in fish feeds is not sustainable and is one of the major bottlenecks in aquaculture. Many researchers have sought to find newer, less expensive and more readily available protein sources such as food industry by-products and other locally available raw materials. Echinoderms (sea stars, sea urchins and sea cucumbers) are common and abundant in shallow marine and intertidal waters, but only a few are harvested and cultured. We conducted an experiment with juvenile barramundi Lates calcarifer (7?9 cm TL) to investigate the palatability of several echinoderm species, including the crown-of-thorns starfish Acanthaster planci, which devastate living coral reefs during their mass breeding outbreaks. Feeding behaviour was assessed following the response of fish to agar beads flavoured with hydrophilic echinoderm extracts. Extracts from 5 of the 6 species (the starfish Linckia laevigata, A. planci, Culcita novaeguineae, Fromia milleporella, and the sea cucumber Holothuria atra) were found to be unpalatable to barramundi. In contrast, the sea urchin Diadema setosum extract was highly palatable. Our study showed that most of the echinoderms tested were unpalatable to barramundi and their use as an ingredient in barramundi feed is not recommended. The addition of natural feeding stimulants to commercial pelleted feeds formulated specifically for certain species is a promising method of stimulating feed intake in fish. Even cysteine or citric acid alone would be sufficient to act as an effective palatability stimulant for barramundi. However, mixtures containing these and other substances, such as alanine or another palatable substance, could certainly be more effective. Screening the palatability of carboxylic acids may help to find new taste stimulants. Another promising group of substances that may be taste stimulants are fatty acids, which play a variety of roles in physiological and biochemical processes in the body of aquatic animals. There is emerging evidence that fat is the sixth basic taste. Our research also shows that fatty acids can evoke strong taste sensations and improve food intake in fish. However, the taste preferences of fatty acids in fish have yet to be studied.
