THEORETICAL FOUNDATIONS OF FISH FARMING - I.M. Sherman - 2011

1. THEORETICAL FOUNDATIONS FOR THE FORMATION AND UTILIZATION OF BIOPRODUCTIVITY IN VARIOUS TYPES OF WATER BODIES

1.3. Theoretical foundations of hydrobiont acclimatization as a method for managing and increasing the productivity of fishery water bodies

For a long time, the issue of acclimatization progressed through the accumulation of information on individual representatives of flora and fauna. Gradually, narrowly focused studies became incorporated into scientific monographs dedicated to various taxons of PLANT AND ANIMAL life, though excluding aquatic organisms.

Only In the second half of the 20th century did the prominent scientist and classic of the theory and practice of aquatic Organism acclimatization, A.F. Karpevich, publish a foundational monograph that remains modern and relevant today. The foundation and Structure OF THE text presented here are based on that monograph.

Global experience in acclimatization has a long history closely linked to the phylogenesis of flora and fauna and The Development of human civilization. Throughout history, specialists—guided by fairly arbitrary criteria—have divided this process into stages, phases, periods, and formations. Objectively, regardless of existing classifications, humans have always sought to maximize plant and animal production in accordance with their nature, thereby minimizing their dependence on the caprices of weather conditions in any given year.

The human desire to reduce dependence on the yields of wild plants and the fluctuating numbers of game gradually led from gathering edible plants to crop farming, and from hunting to livestock raising. This was accompanied by domestication processes—the development of plant varieties and animal breeds. This concept evolved across time and space, characterized by considerable Specificity and uniqueness shaped by the features of particular ethnic groups, religious orientations, and the characteristic climatic and natural factors of various regional settings across the planet.

For a long time, visible and predominantly spontaneous acclimatization focused on introducing the best available species within reach into the cultivation process. In some cases, this principle worked: plants and animals from other regions adapted to new natural and climatic zones, became new objects of cultivation, and contributed to the creation of new animal breeds and plant varieties.

At the same time, It is important to emphasize that the vast majority of spontaneous acclimatization attempts ended in failure, leaving humanity with numerous negative consequences. An analysis of spontaneous flora and fauna acclimatization has demonstrated not only its lack of Prospects but also its significant harm in many cases, leading to the deterioration of living conditions for native species and revealing profound contradictions in interspecific relationships.

This human activity, which practically demonstrated good intentions while yielding negative outcomes, was perceived by society as a "trial and error method," which logically fostered a negative attitude toward such practices during the 20th century. An objective need arose to establish a theory of acclimatization as a methodology for enhancing the bioproductivity of plants and animals under both natural and artificial conditions.

Modern research on flora and fauna predominantly focuses on terrestrial plants and animals; relatively little has been done regarding hydrobionts today, despite the vast potential offered by the total Water surface area of our planet.

The Development of the theory of acclimatization as a whole, and especially concerning hydrobionts, is impossible without defining specific terminology. Terminology forms the logical foundation of any science, and acclimatization is no exception.

In the vast majority of cases, adjusted for the lifespan of specific hydrobiont species, acclimatization is a relatively prolonged process that can be evaluated through certain parameters or the depth of the process itself across time and space.

According to A.F. Karpevich, acclimatization is a unified process of adaptation of introduced individuals and their offspring to new environmental conditions, as well as The formation of a new population of the species based on a limited Gene pool under METABOLISM/18.html">The Influence of natural Selection. Concurrently, natural selection induces Changes in the biology and morphophysiological status of subsequent generations of the settler's descendants.

Analyzing the views of leading scientists on the sequence and depth of the acclimatization process, one is struck by The Diversity of evaluations and the specifics of differentiation. This specific approach to the Theoretical components of acclimatization was summarized in A.F. Karpevich's foundational monograph and proposed in the form of phases based on quantitative and qualitative criteria.

Phase I demonstrates The ability to survive under new living conditions, or indicates that the individuals have successfully undergone physiological adaptation and acclimatization.

Phase II involves the option of reproduction under new conditions and the beginning of population formation.

Phase III is often viewed as a kind of "explosion" and is characterized by the maximum population size of the introduced species.

Phase IV is represented by the aggravation of contradictions between the introduced species and the biotic environment.

Phase V characterizes the achievement of naturalization.

Characteristically, Phases IV and V of acclimatization are closely intertwined with native species, whereas the preceding phases demonstrate the dominance of Abiotic factors in the acclimatization process.

The THEORETICAL FOUNDATIONS OF fish acclimatization require a consistent understanding and specification of specialized terminology. Guided by this postulate, we consider it appropriate to introduce the reader to modern, widely used terms and their concise Definitions adapted for hydrobionts.

In this regard, following N.A. Bazylevskaya, the term Introduction refers to the relocation of new species into an existing natural habitat system where these species have not previously occurred. Unlike introduction, acclimatization, according to L.A. Zenkevich, is the survival and development of a species that was previously absent in the niches of a new range. It is emphasized that acclimatization can occur in both natural environments and cultivation conditions, which is of particular importance for fish farming and implies adaptation. The process of acclimatization is logically understandable, but its constituent part certainly includes prior introduction, which involves transferring individuals of a species to a new environment that differs little from their previous habitat. In such cases, no Variability in the introduced organism is observed, which can be confirmed at The final stage of acclimatization.

The highest phase of acclimatization, or the final phase of hydrobiont acclimatization, according to renowned experts A.F. Karpevich and E.V. Burmakin, is naturalization. This occurs when the introduced species has adapted to new living conditions, its ecological niche and relationship with native species have been defined, a dynamic equilibrium has been established, and the possibilities for commercial utilization have been clarified.

During acclimatization efforts, situations sometimes arise where the naturalization effect is not achieved, remaining incomplete and requiring direct human intervention for completion. This state of acclimatization work is termed staged acclimatization. Human intervention in natural and artificial aquatic ecosystems leads in the vast majority of cases to direct or indirect impacts on abiotic and biotic environmental parameters. Although negative impacts can be cumulative, the specific Classification of the process is not critical; the negative consequences are definitively unfavorable. Under such circumstances, stenobionts are the first to disappear from their natural range due to their low ecological valence and narrow range of tolerance. In this context, alongside acclimatization, it is appropriate to consider the term "reacclimatization," which involves the introduction of individuals of a certain species to restore its population within its historical natural range from which it had disappeared for various reasons.

Among the existing terms in The Theory of acclimatization, THE CONCEPT OF autoacclimatization has gained some currency, referring to the spontaneous settlement of appropriate species without human intervention, which successfully acclimatize and naturalize in a given water body.

The vast majority of fauna in the Earth's aquatic ecosystems exist in highly specific conditions and depend largely on a heterogeneous environment, as clearly demonstrated by the spatial and temporal distribution of hydrofauna. Consequently, it is crucial to understand the action and interaction of abiotic and biotic environmental factors on The properties of aquatic organisms during their acclimatization. It should be borne in mind that human activity continually impacts natural hydroecosystems, either directly or indirectly, altering the Qualitative and quantitative parameters of water bodies. As a result, both flora and fauna are forced to exhibit genetically determined levels of tolerance and ecological valence, which define how aquatic inhabitants relate to stenobionts and eurybionts.

The concept discussed leaves no doubt as to The Importance of the external environment and the specific traits of hydrobionts during acclimatization. Given that acclimatization is the ADAPTATION OF ORGANISMS to new living conditions, It is worth emphasizing that the living component plays a leading role in this process—whether represented by an individual organism, a population, or a species with typical characteristics set against an environment characterized by specific quantitative and qualitative parameters.

It logically follows from the above that for both the theory and practice of ichthyofaunal acclimatization, the quality of selecting the translocation target and the thoroughness of assessing the suitability of new conditions for a specific species are of paramount importance.

As a rule, individuals for acclimatization projects are selected from small populations, which implies a Separation from their natural environment and

the establishment of new connections within the water body designated for the acclimatized species.

Acclimatizers enter an unusual, often fundamentally new environment, encountering unfamiliar qualitative and quantitative parameters. In such situations, the future ESTABLISHMENT OF THE species in the new range depends entirely on the survival of the introduced individuals. This success can only be realized if survival is underpinned by the correspondence of key environmental elements necessary for normal metabolism.

It is well known that the process of organic matter production is a general pattern based on the interaction of producers and consumers at various trophic levels. Green plants perform the function of producers, while animal organisms act as consumers. In this regard, it is appropriate to examine the Influence of Environmental elements on the metabolism of plants and animals. It is a well-established fact that green plants utilize Inorganic Components in their metabolic processes to produce primary organic matter.

Accordingly, Photosynthesis requires carbon (in the form of the respective gas), while Nutrition, biomass accumulation, and reproduction primarily require biogeochemicals—nitrogen, phosphorus, and A number of Trace Elements, among which iron, silicon, manganese, magnesium, and copper are predominant. During feeding, aquatic plants utilize dissolved chemical compounds (nitrites - NO₂, nitrates - NO₃, phosphates - P₂O₅, PO₄). To normalize osmotic pressure, plants require salts of sodium (NaCl), potassium (KCl), calcium (CaCO₃, CaSO₄), magnesium (MgCO₃), and many others. Element concentrations in water bodies are dynamic and exhibit a degree of astaticism, which may limit algal biomass accumulation, growth, reproduction, and Other Aspects of life. Animal organisms do not depend as strictly on the inorganic environment as plants do; at the same time, they are significantly more dependent than plants on the specific nutrient elements required for their metabolism.

Unlike warm-blooded animals, for which oxygen is sufficient, cold-blooded aquatic animals require not only dissolved oxygen to maintain Energy Metabolism, but also salts for osmoregulation; all other requirements are met through food, much like warm-blooded animals. However, unlike warm-blooded animals, fish and invertebrates can survive for extended periods without food, provided the dissolved oxygen content and thermal regime are appropriate for the species. A mismatch in these conditions leads to lethal consequences within a short timeframe. A similar situation occurs when water mineralization fluctuates significantly, leading to impaired osmoregulation processes.

Considering The chemical composition of food in terms of Metabolism and Energy, it must be emphasized that depending on the consumption of specific producers and consumers across various trophic levels, fish exhibit an exceptionally wide range of food organisms. This depends on species, age, concentration of forage hydrobionts, physiological state, season, and numerous abiotic environmental factors typical of poikilothermic animals.

Without disregarding the above, it is worth emphasizing that, other factors being equal, the Chemical composition of the diet has a dominant influence on the metabolism of hydrobionts. It is precisely the chemical COMPOSITION OF THE diet—comprising appropriate forage hydrobionts—that ensures energetic, plastic, and generative metabolism, including Respiration, growth, and reproduction.

In a broad sense, the food of hydrobionts is both a biochemical component that satisfies physiological needs and a biological component determined by the availability of forage hydrobionts. Naturally, when feeding on appropriate hydrobionts within their natural range, fish receive a complete diet that ensures normal protein, lipid, carbohydrate, and Mineral Metabolism. When translocated outside their natural range, the composition of forage hydrobionts must satisfy

the physiological needs of the introduced organisms. A forced change in the dietary chemical composition under new conditions can significantly affect PHYSIOLOGICAL AND BIOCHEMICAL processes, and consequently, the specific biological traits of the species in its new habitat.

Knowledge of the chemical composition of food in relation to metabolism and energy operates against the Background of environmental factors and can be substantially modulated by both abiotic and biotic factors.

The leading abiotic factors are primarily general physicochemical components, among which water Temperature, solar radiation, soil characteristics, currents, water level fluctuations, depth, water body area, and shoreline configuration are paramount. The key biotic factors affecting acclimatization success include the availability of forage hydrobionts, the level of food competition with native hydrofauna, predation pressure, parasite fauna composition, and infectious diseases.

The negative and positive factors discussed—encompassing both the abiotic and biotic COMPONENTS OF WATER bodies, without discounting anthropogenic risks—convincingly demonstrate that, on the one hand, the chemical composition of food is exceptionally important for the metabolism and energy of hydrobionts, and on the other hand, the actual intake of suitable food into the fish's organism depends on numerous components that must be taken into account during acclimatization operations.

Guided by objective necessity, it is advisable to define the terminology associated with adaptation during the acclimatization process.

The vast majority of theoretical and fish-breeding/biological justifications in the field of acclimatization rely to some extent on the realities of individual, population, and species adaptation, which largely ensures acclimatization success. Adaptations are closely linked to the capacity of individuals to exist within a specific range of relevant factors. The quantitative criteria for these factors vary across specific individuals, populations, and species, which in turn indicates the presence of eurybiont organisms. Alongside this, to fully grasp the adaptation process, it is useful to consider the ability of organisms to exhibit plasticity, or ecological plasticity—the capacity of certain organisms to survive under specific environmental changes.

In the course of phylogenesis, organismal plasticity served as the foundation of evolution and, driven by natural selection, was directed toward the refinement of speciation. As is well known, Components of the living world possess reproductive capacity, ensuring generation turnover.

At the same time, individuals of each species are capable of surviving within certain limits of dynamic environmental parameters thanks to plasticity, thereby adjusting or adapting to changing ecological conditions. The degree of individual adjustment is determined by their plasticity and limited at the genetic level, while the reaction of individuals is, in turn, constrained by the level of physiological plasticity.

To summarize the issue, it is practical to present a simplified Overview—a list of the main environmental factors that individuals interact with and adapt to during acclimatization: salt adaptations, thermal adaptations, adaptations to chemical Reagents, their modes of action and concentrations, and the adaptation of individuals to extreme values of environmental elements and factors. Based on this and building upon the foregoing, we emphasize that the adaptability of individuals, populations, and species depends on heredity, the level of conservatism, physiological plasticity, developmental stages and phases, as well as The Nature and concentration of the reagent.

In defining and summarizing The Essence of the term adaptation, it is necessary to provide a formulation that accurately describes the process while remaining concise.

Adaptation is the positive outcome of manifested adaptive traits resulting from interaction with an altered environment.

The theoretical components and practical aspects of adaptation discussed serve as Prerequisites for the fundamental possibility of acclimatization, whereas adaptation itself constitutes The First stage or phase of acclimatization as a whole and for hydrobionts in particular. Based on this, we may conclude that a smooth and gradual progression through the first stage indicates the compatibility of the physicochemical and hydrobiological environmental parameters with the biological traits of the introduced species.

In doing so, specialists actually obtain preliminary information regarding the probability of reproduction and survival of the first generation in new conditions, as well as the prospects for establishing a new population. Populations, in turn, can be represented by short-cycle and long-cycle species. It has been established that the shorter the biological cycle of a species, the higher The rate of adaptation to new conditions, the rate of variability, and the formation of a population of a new species outside its natural range. In the medium term, taking into account the biology of the species, this ensures successful acclimatization and naturalization. The formation of a population of species with a prolonged, long-cycle development period is considerably more complex. The process is slow, adaptation takes a long time to form, and variability can only be tracked across a series of generations.

Based on the biological characteristics of fish with short and long life cycles, the acclimatization process can be considered complete only after establishing the fact of regular reproduction of individuals in the new population, and—of paramount importance—the formation of a new population that has successfully withstood extreme fluctuations of relevant critical factors in the new habitat. It is worth emphasizing that cultivated individuals develop, to a certain extent, all the vital connections with their environment. At the same time, under conditions where there is even a single factor deviating from the norm, the introduced organisms exhibit new reactions and develop new adaptations, which in turn leads to an increase in the ecological, physiological, and morphological Variability of the individuals. Under such conditions, new populations of translocated organisms serve as material for natural selection.

The increase in species Abundance within a population across a series of generations generates tension between the acclimatized species and its biotic environment. Enemies, competitors, and diseases appear, while weak and unadapted individuals are eliminated or disappear. In fact, under the action of natural selection, a new population of the acclimatized species is formed in the new conditions, with natural selection acting as the driving force that directly influences the processes of adaptation and variability of the introduced species. The adaptations and variability of the new population, in turn, can lead to an increased intensity of physiological and biochemical processes, which will stimulate mass accumulation, linear growth, accelerate the attainment of sexual maturity, and contribute to higher condition factor coefficients, combined with improved commercial fisheries indicators.

When examining the adaptation and variability of species, it is appropriate to emphasize that, according to leading experts, the entire burden and danger fall directly on the new individuals that find themselves in novel environments and form the foundation of the emerging population. The species itself is practically excluded from the process, remaining within its natural range as a passive donor of acclimatization objects. At the same time, preliminary research prior to THE START OF acclimatization focuses on selecting individuals from promising populations within the natural range, which serve as the basis for establishing the young population outside the natural range. Notwithstanding the above, the passive role of the species in the acclimatization process is quite relative. When determining the choice of an object for translocation, its conservative traits are taken into account, which will allow the acclimatized species to retain the features and commercial qualities that justify the expansion of its range. In connection with acclimatization, especially under aquaculture conditions, Hybridization is of certain interest, which requires a corresponding Definition of the relative specificity of this phenomenon.

Given that a species carries a high level of conservatism—a feature that in a number of cases hinders or rules out acclimatization in principle—hybridization is of particular interest.

To mitigate or eliminate the factor of conservatism that hampers acclimatization, work with relevant species tends to favor individuals with a transformed genotype and weakened hereditary traits. Such individuals may be hybrid forms, driven by a higher level of eurybionticity based on enhanced adaptive capabilities. It is known that in natural conditions, hybridization is a fairly widespread phenomenon among ichthyofauna, as evidenced by natural hybrids of sturgeons, herrings, salmonids, cyprinids, and flatfishes. Returning to historical aspects, it is known that since ancient times, humans—both spontaneously and purposefully in the process of domestication—have practiced artificial hybridization, encountering both negative and positive results. However, through prolonged artificial selection, the opportunity arose to complete the domestication process and create breed groups and breeds of fish. Combining long-standing experience with modern theoretical foundations has shaped the concept of hybridization, which is represented by two classical directions. Today, the broad direction in the acclimatization process is considered to be natural hybridization in water bodies where sexually mature individuals of a certain species have been introduced and participated in spawning with individuals of native ichthyofauna. The second direction in acclimatization is artificial hybridization—purposeful human activity during domestication aimed at improving the aquaculture qualities of cultivated objects. Modern acclimatization is in some cases based on a synthetic principle, which involves combining components of the First and Second directions. With this approach, a potential acclimatized organism may undergo a certain period of acclimatization in artificial conditions, where, upon reaching sexual maturity, sex products are obtained from it using various fish species, and the progeny of such hybridization are used as introducers to stock artificial and, provided there is appropriate justification, natural water bodies for fishery purposes.

In the vast majority of acclimatization efforts in artificial water bodies, the process is actually associated with pasture-based fish farming and does not entail complete acclimatization and naturalization, merely yielding an economic effect. In contrast, when aiming for The Effect of naturalization in natural water bodies, a probable component in certain cases may be the short-term or long-term holding of the acclimatized organism in artificial conditions for the purpose of naturalization, prophylactic Treatment, stress reduction, and rearing to hardy stages. The formation of a group of sexually mature individuals with the subsequent introduction of their progeny into natural and artificial hydroecosystems is not ruled out. At the same time, it is possible that the effect of reproduction in new conditions may not be achieved.

Viewing the species from an appropriate perspective, it is advisable to proceed from the fact that a species is a unique product of evolution, formed in the process of prolonged phylogenesis against the background of the interaction between variability and conservatism. It is precisely this bipolarity that, figuratively speaking, drove the species during evolution, on the one hand, toward the maximum expansion of its range, and on the other hand—acting as a counterweight to this tendency—toward the preservation of a constant, stable range. At the same time, in nature, there are species in which the active component prevails, as well as those in which the passive component dominates, which determines the formation of certain species during phylogenesis.

A passive dominant is characteristic of endemics and native species, while an active dominant is represented by semi-migratory and migratory species. The colonization of large water bodies by certain species requires enhanced ecological plasticity, the ability to rapidly increase population numbers, and the formation of substantial biomasses of organisms of a given species. Summarizing this peculiar Introduction to the chapter, it is appropriate to emphasize that not all organisms possess an equal capacity for dispersal. Thus, it becomes clear that not all organisms have the same ability to spread, which affects the prospects for their acclimatization—a factor that must be taken into account based on modern theory and practice.

The theory and practice of fish acclimatization convincingly demonstrate the presence of certain intrinsic properties capable of promoting the rapid dispersal of species. Such features, or factors, include high fecundity and progeny survival, especially during early ontogeny. The presence of these specific traits quickly leads to a high density of individuals of a given species per unit of water volume or surface area of a water body. The consequence of such a situation is the creation of a shortage of food hydrobionts for the respective fish species. It is precisely this food deficit that drives individuals of specific species to search for new feeding grounds, stimulating and directing the process of colonizing new water body areas. Thanks to dietary plasticity, the transition of these species to new food hydrobionts is also possible. The foregoing explains, to a certain extent, the intrinsic properties of fish that facilitate the expansion of species ranges.

At the same time, it is necessary to account for variability and adaptability, which in turn stimulate the expansion of the species' range. Potential yet hitherto unrealized ecological and PHYSIOLOGICAL CHARACTERISTICS OF species facilitate their advancement into new areas and establishment in new locations.

The intrinsic properties of species can be considered stimulating in terms of limiting factors of dispersal, and conservatism is foremost among them. The genetically encoded conservatism of species manifests not only in the form of genetic but also physiological limitations, which ensure corresponding ethology. The contact of a species with a new qualitative and quantitative environment acts as a specific ecological barrier, which only species with sufficient ecological valence can cross.

Among the factors that significantly limit dispersal, it is appropriate to include the high requirements of many fish species regarding reproduction conditions, which is associated with the rather narrow adaptive traits of sexually mature individuals and juveniles in early ontogeny—a factor that must be considered when selecting a potential acclimatized organism.

Summarizing the above, it is clear that external factors promoting species dispersal can be classified by origin as abiotic and biotic. As already emphasized, abiotic factors may include the Physical and Chemical parameters of the environment, currents, wave action, soils, shoreline relief, astatic thermal and salinity regimes, and all other non-biological factors. Biotic factors may include the presence of empty ecological niches, low species population density in biocenoses, substantial reserves of food hydrobionts, a low level of competition or its complete absence, and the absence or scarcity of potential enemies. Under such conditions, acclimatized organisms do not encounter biological resistance and adapt relatively quickly to new environments.

Alongside this, there are anthropic or anthropogenic factors capable of directly or indirectly influencing the formation of both abiotic and biotic environmental factors.

EXTERNAL FACTORS AND barriers in the process of fish dispersal and acclimatization are identical to those that simultaneously stimulate this process, but their quantitative and qualitative indicators reach critical levels for specific fish species. These include physical-geographic, chemical, climatic, and biotic barriers, with geographic and climatic ones being dominant.

Of exceptional interest to the theory and practice of acclimatization are water bodies that have been in prolonged isolation. Such water bodies are characterized by limited representation, typical of ichthyofauna compositions dominated by endemics. As a rule, ichthyocenoses in such water bodies are impoverished, which, against the background of incomplete food chains, opens up significant opportunities for the acclimatization of individual species and the artificial formation of ichthyocenoses. Prior to initiating acclimatization work in such water bodies, it is important to have comprehensive information regarding THE ORIGIN OF isolation, the impoverishment of flora and fauna, and the direct species composition of the fish, which entails studying The impact of isolation on form- and speciation and The Role of "isolates" in the acclimatization process.

When examining The Emergence of a phenomenon such as isolation, it must be emphasized that historically this is primarily associated with planetary-scale geological processes that over a long period led to changes in the configuration of the aquatic environment of primary hydroecosystems against the backdrop of Earth's crust movement, resulting in the modern configuration of continents, oceans, seas, river systems, and lakes.

Under the Influence of the aforementioned factors, endemics—species unique exclusively to a given region or water body—emerged in many PARTS OF THE world, leading to the formation of peculiar biocenoses of which ichthyofauna is an integral part. In contrast to other regions, the European part of the world experienced a major corrective impact on the redistribution—predominantly impoverishment—of ichthyofauna and the formation of isolates due to processes associated with prolonged ice cover and subsequent glacial movement.

Planetary-scale geological processes, the movement of future continents, and changes in the configuration of water and land against the backdrop of shifting qualitative and quantitative environmental parameters actively, yet gradually over a long period, pushed species onto the path of divergence. Species that previously shared a single origin developed independently under conditions of isolation. Emerging in distant geological epochs, they found themselves isolated and demonstrated the ability to form new forms, subspecies, species, and other taxa adapted to altered living conditions.

When examining the impact of isolation on form- and speciation and The Significance of "isolates" for acclimatization, it is worth emphasizing that during acclimatization work, when searching for promising acclimatized organisms, it is advisable to thoroughly study the phylogenesis of prospective taxa. Based on objective criteria, individuals should be selected with regard to planetary-scale Evolutionary Processes, which ensured prolonged natural selection and laid the groundwork for artificial selection for acclimatization purposes.

The effectiveness of acclimatization largely depends on—and in certain cases is a dominant condition—the correct selection of recruits, taking into account their developmental stage when used for introduction. In this regard, the principles and Methods of selecting forms for acclimatization and aquaculture acquire exceptional importance.

The selection of a species should be considered the first stage of theoretical preparation, guided by the principles of acclimatization. The practical focus of the approach to selecting an introducer is determined by Modern views on the essence of introduction and the fishery goals expected and desired as a result. Depending on the objectives of the introduction—step-by-step acclimatization, domestication, or naturalization in a natural recipient water body—the requirements for the recruit will vary. Based on the outlined process, a certain system can be proposed, which can be modified depending on the goals of the acclimatization work:

- introduction for the purpose of naturalization may have different qualitative parameters depending on the Specific characteristics of the water bodies;

- acclimatization of species is possible in locations that do not differ in living conditions from the donor water body;

- species acclimatization is possible in a transformed environment and relies on the adaptive capacities of individuals, which as a result of acclimatization may lead to physiological and general biological changes in the organism and the population;

- acclimatization is fundamentally feasible, but it is a gradual, predominantly long-term process that can be traced across a number of generations through natural selection of individuals that have formed morphophysiological traits and characteristic features under the influence of the new environment, playing a decisive role in population formation.

Guided by the proposed theoretical concept, and depending on the Goals and Objectives, the method for selecting forms for translocation is chosen. In operations involving domestication, the approach to acclimatization takes on a somewhat different character.

Previously, a situation was considered where a recruit at a certain stage of development was introduced into a new water body and had to adapt at an appropriate level to conditions similar to, or varying to different degrees from, the native water body. When focusing on domestication, breed group hybridization, and breeding, specialists rely, on the one hand, on the adaptive potential of the acclimatized species and, on the other hand, anticipate the possibility of creating an artificial environment that will closely match the biological CHARACTERISTICS OF THE recruit.

Based on the foregoing, it is advisable to emphasize that there are General Principles of acclimatization as well as specific features that significantly influence the theoretical foundation and practice of acclimatization depending on its ultimate intended purpose.

Drawing on the theory and practice of acclimatization, it is appropriate to formulate classical provisions that summarize the presented information.

Industrial and commercial acclimatization. This involves full-cycle acclimatization of target fish species in natural water bodies followed by naturalization and commercial utilization.

Aquacultural acclimatization. Acclimatization for use as objects in pond fish farms, for rearing in natural water bodies up to certain Stages of development or life cycle phases.

In this regard, practice fundamentally considers the possibility, in certain cases, of combining classical acclimatization with aquaculture. Here, a certain degree of preparation for direct acclimatization is carried out by humans under artificial conditions. Upon completion of this preparation, the acclimatized organisms are released into natural or transformed environments, where the subsequent stages of acclimatization sequentially take place.

Acclimatization is largely a technological process involving specific working methods, and it is therefore appropriate to examine them.

Passive method. This focuses on a passive human role, where participation is limited to selecting the target organism and transferring it to a new water body. In certain cases, this essentially involves selecting individuals from fish hatcheries. Everything else in the acclimatization process relies entirely on the interaction between the introduced species and the environment.

Active method. This involves active human intervention in the survival and adaptation processes of the introduced species through cultivation, selection, hybridization, protection, feeding, and the careful selection of the release site and timing in respective aquatic areas.

Method of radial acclimatization. Fishery practice shows that positive acclimatization results are achieved by establishing broodstocks of the acclimatized species followed by their dispersal into appropriate water bodies.

Method of stepwise acclimatization. This involves the gradual transfer of fish from cold to warm waters or vice versa—from warm to cold waters. Stepwise acclimatization undoubtedly eases the passage of the Initial Stages of acclimatization for the introduced species, but obtaining a stable population while bypassing natural selection in subsequent generations remains problematic.

The composition of the native ichthyofauna in the vast majority of water bodies is represented by a peculiar polyculture—the result of natural selection throughout phylogeny—which, unlike human-created intentional polyculture, is the subject of artificial selection. Natural ichthyocenoses of water bodies essentially serve as the raw material base for fisheries and fall under The Scope of capture fisheries, whereas artificially created ichthyocenoses of various origins and purposes fall under aquaculture, which significantly brings the different branches of fisheries closer together.

The coexistence of various fish species and the stable state of their populations indicate that the limits of ecological valence and tolerance in many fish species are close in both qualitative and quantitative characteristics. At the same time, situations arise where several species share ostensibly identical requirements for physico-chemical regimes and similar feeding spectra, which generates interspecific food competition and hinders the development of respective populations. Meanwhile, this food competition

is quite specialized, and its intensity can be traced among specific groups of hydrobionts. Concurrently, certain groups of hydrobionts are not utilized by the native ichthyofauna. Based on the above, they constitute a component of the bioproductive potential of water bodies, but do not act as a food resource and are not transformed into a food base. In other words, they are neither utilized nor do they affect the fish productivity of natural or transformed aquatic areas where fishing is conducted, nor do they impact the fish productivity of classical pond aquaculture.

Regardless of the origin of a water body, its intended purpose, or the intentions of hydro-engineers, builders, and operators, every water body—with rare exceptions—develops its own bioproductive potential. The foundation of this bioproductive potential consists of producers and consumers of various trophic levels, which, in the absence of appropriate fish species, essentially remain untapped food resources. Only with the presence of specific fish species that begin to consume the flora and fauna of water bodies does the transformation of food resources into a fish food base occur.

Based on the foregoing and relying on practical experience, for the effective utilization of bioproductive potential in fisheries and fish farming, it is necessary to maintain a set of species in target water bodies capable of efficiently utilizing all components of the bioproductive potential and producing high-quality output through aquatic food organisms that are otherwise unused by the native ichthyofauna.

It is precisely this practical problem that acclimatization is capable of solving through the rational utilization of food resources. However, one should not oversimplify the objectively existing situation; it is quite complex and requires appropriate theoretical preparation. Achievements in the field of acclimatization are substantial, but one must also account for significant errors that have objectively occurred in the process.

In classical warm-water pond aquaculture, fish productivity has been increased two- to threefold through acclimatization without incurring costs for intensification components, accompanied by an expanded assortment and higher product quality. Acclimatization efforts are ongoing, their prospects are vast, and their possibilities are real. Conducting acclimatization makes it possible to introduce resource-saving technologies while eliminating negative environmental impacts.

When implementing acclimatization in natural and transformed aquatic areas, it is necessary to ensure the preservation of native ichthyofauna, with a particular emphasis on rare and endangered species. Given the above, it is clear that prior to initiating acclimatization work, a specific technology must be prepared—namely, a biological justification for the acclimatization of valuable hydrobionts, which is exclusively carried out by relevant research institutions and other fisheries-profile structures.

The biological justification for acclimatization can vary in content, depending directly on the water body considered as the recipient, the donor water body, and the target object of acclimatization. At the same time, we consider it appropriate to propose a standardized form defining the components of the biological justification, which significantly simplifies the formal aspect of the matter.

Indicative scheme of biological and economic justification

I. Basin characteristics

- Brief Description of the physicochemical and hydrobiological regimes, the state of the native ichthyofauna, and future prospects. Determination of the ecological capacity of the water body and its food supply in relation to the biomass ratio of valuable and low-value fish species, invertebrates, and plants.

- Justification of the expediency and necessity of acclimatization, as well as its compatibility with other methods aimed at increasing the commercial productivity of the given water body.

- Morphology/3.html">MAIN DIRECTIONS OF acclimatization measures: a) supplementing the native flora and fauna of hydrobionts with desirable species; b) replacing certain native species with more valuable ones from a biological and fisheries perspective; c) engineering the aquatic community so that a significant portion of the species is represented by acclimatized species, while ensuring the preservation of rare and endangered fish species; d) targeted Formation of the aquatic community focusing on the dominance of acclimatized species within the commercial and forage flora and fauna, establishing FOOD CHAINS AND coenoses; e) phased acclimatization.

II. Characteristics of Acclimatized Forms

- Full name and Origin of the introduced species.

- Bioecological characteristics of the introduced species, Assessment of the compatibility of its environmental requirements with the regime of the water body.

- Commercial and nutritional qualities of the introduced species.

- Prospects and possibilities for the naturalization of the introduced species, or necessary measures aimed at sustaining its population through relevant aquaculture practices.

- Main Pathways of impact of the introduced species on natives, including feeding and spawning grounds.

- Parasite fauna of the introduced species and potential risks to natives, and vice versa—risks posed by natives to the introduced species.

III. Biotechniques of Translocation

- Selection of the developmental stage of the introduced species most suitable for translocation.

- Location and time of obtaining the stocking material of the introduced species.

- Transportation methodology.

- Location for quarantine, release, or egg incubation, and the rearing of viable juveniles of the introduced species.

- Frequency of translocations for each species, sequence, and schedule for carrying out translocations of individual species.

IV. Probable Potential Efficiency

- Probable spawning and feeding range, and population size.

- Timing of entry into commercial fisheries and incorporation into the fish diet.

- Fishing locations and gear.

- Economic efficiency.

V. General outline of acclimatization measures for the water body, Implementation tactics.

We consider it appropriate to emphasize that data on the biology and ecology of hydrobionts provide only a preliminary basis for justifying the introduction and acclimatization of a particular species.

For a qualified and high-quality justification—except in cases involving unquestionably valuable fish species—it is necessary to conduct a preliminary series of in-depth studies performed by highly qualified experts.

Such studies should focus on engineering food chains, which is of paramount importance when forming the flora and fauna of water bodies comprising both native and acclimatized species, determining the carrying capacity of water bodies, and assessing the potential ecological and biological traits of the recruit both currently and in the future outside its natural range.

The findings of the reviewed studies should culminate in conceptual guidelines regarding the selection of introduced biotechnics, qualitative and quantitative parameters of planting material, the size of individual acclimatizer batches, and the stocking density of recruits in the water body, guided by appropriate methodologies that will facilitate the practical implementation of research results in acclimatization.

The information in the section dedicated to the theoretical foundations of hydrobiont acclimatization as a method for managing and enhancing fish productivity in fishery water bodies is largely general in nature, yet it simultaneously identifies existing challenges and requirements concerning both theoretical justification and practical execution

of acclimatization operations.

Acclimatization activities involve direct intervention in natural and artificial aquatic ecosystems. Therefore, one must be guided by the fundamental medical principle: first, do no harm.

Acclimatization is a powerful lever that can significantly influence—and already does influence—the substantial enhancement of water body bioproductivity. At the same time, the modern global perspective on this issue emphasizes the simultaneous need to protect flora and fauna resources, as well as to preserve rare and endangered species. While this somewhat complicates the practical aspect of the endeavor, it by no means excludes this promising direction in fisheries.

Self-Assessment Questions:

1. Theoretical Aspects of the formation, transformation, and utilization of food resources in fishery water bodies.

2. Define the difference between bioproductive potential and food resources.

3. Explain the primary essential differences between food resources and the food base.

4. Components shaping the fish productivity of water bodies in Artificial and natural ichthyocenoses.

5. The theoretical foundations of hydrobiont acclimatization as a method for managing and increasing the bioproductivity of fishery water bodies.