THEORETICAL FOUNDATIONS OF AQUACULTURE - I.M. Sherman - 2011

3. THEORETICAL FOUNDATIONS OF FISH FARMING TECHNOLOGICAL PROCESSES

3.5. Theoretical components of commercial fish production

The theoretical components of commercial fish production in Water bodies of various origins and intended uses are primarily based on bioproduction potential, which consists of producers and consumers of different trophic levels. This potential includes aquatic organisms of PLANT AND ANIMAL origin, a significant portion of which can be utilized by certain cultivated fish species. In cases where a water body lacks fish species capable of efficiently consuming specific groups of aquatic organisms that form the bioproduction potential, these organisms are regarded as a food resource. It is well known that the food resource is an integral part of the bioproduction potential. Knowledge of the Qualitative and quantitative parameters of the food resource makes it possible to form an artificial ichthyocenosis of a limited species composition, yet represented by valuable fish species. Under such conditions, once the fish species within the artificial ichthyocenosis begin to consume these food organisms, the food resource is transformed into the food base.

The natural food base serves as the foundation of natural fish productivity—a vital component of the fish diet. This is related not only to the Abundance and biomass of food hydrobionts (flora and fauna), but also to providing fish with a physiologically balanced diet. This is of exceptional importance for fish health, overall condition, and their ability to respond properly to intensification measures under specific conditions.

Based on the foregoing, it is clear that in fattening ponds, the artificial ichthyocenosis should be viewed as a polyculture component capable of, on the one hand, utilizing the natural food base with maximum efficiency and, on the other hand, demonstrating an adequate response to amelioration measures and The stimulation of food hydrobiont development through organic and mineral fertilizers, alongside the feeding of polyculture species against the Background of ensuring appropriate water quality.

The commercial mass of individuals in warm-water and cold-water aquaculture is justified by subjective and objective components, which are established by current industry standards taking into account relevant soil and climatic zones.

At the same time, industry standards outline a general framework by linking the commercial weight of individuals to the initial weight of the stocking material, which largely determines the fish productivity of fishery water bodies, predominantly classic fattening ponds.

The starting weight of the stocking material and its significant compliance with standards when raising market-size fish is important, but far from everything. Despite having a high average weight, fingerlings or yearlings may possess poor genetics and, under intensification measures, exhibit low growth rates, fall ill, or show a low feeding response to Artificial and natural foods. This leads to high feed conversion ratios per unit of production and drives up other costs associated with modern intensification.

High-quality stocking material—characterized primarily by optimal body weight and linear dimensions, sound genetics, and appropriate vitality—combined with existing intensification tools that form an integral part of modern technologies, can ensure efficient fish production in water bodies of diverse origins and purposes.

When using organic fertilizers, It is important to remember that alongside Traditional Methods of applying them to ponds, preparing so-called liquid slurries (mash) is an effective practice. This ensures the uniform distribution of manure particles throughout the water Column, which contributes to a rapid increase in the abundance and biomass of zooplankton consumed by zooplanktivorous fish.

Classic commercial fish production in warm-water pond farms involves a two-year production cycle: growing stocking material in nursery ponds, transferring the resulting fingerlings to wintering ponds at the end of the vegetative season, and using the resulting yearlings in the spring to stock fattening ponds. A three-year cycle additionally utilizes secondary nursery ponds and wintering ponds.

Every technological cycle that involves draining nursery and fattening ponds is accompanied by the virtually complete destruction of producers and consumers across various trophic levels, which form The basis of the cultivated fish's food supply. This necessitates additional costs to restore the food base, which translates into lost time, an effectively shortened growing season, and reduced yields. Simultaneously, production costs rise due to the repeated filling and draining of water in various categories of ponds.

Alongside the aforementioned classic technology, There is a continuous technology that involves growing and wintering cultivated fish species in a single pond—specifically, raising fish from larvae to marketable size. In this setup, a stable natural food base is formed and maintained over a long period through the application of organic and mineral fertilizers, eliminating technological disruptions associated with water drainage during fish transfers between different pond categories. An essential role in this process is played by the accumulation of Metabolic waste products, which act as supplementary fertilizers.

Traditional and continuous commercial fish production technologies each have their objective Advantages and disadvantages. Based on this, and summarizing the objective factors, a specialist in each specific case—depending on real-world conditions—applies those fish-rearing principles that ensure maximum efficiency of fish production under concrete circumstances.

When discussing certain aspects of market-size fish rearing, we do not strictly equate stocking material solely with fingerlings or yearlings, and this is no accident. The fact is that alongside traditional stocking of fattening areas with yearlings, many enterprises carry out autumn stocking with fingerlings, which is driven by A number of objective circumstances and is undoubtedly appropriate.

The benefits of autumn stocking in fattening areas include the possibility of a longer feeding period before critical water Temperature drops occur, coupled with an earlier start to feeding in the spring as water temperatures rise. Furthermore, the technology is simplified by eliminating wintering ponds from the operational cycle, which require additional economic expenditures during the winter period. Along with this simplification of the general technological process—which is quite attractive—there is a loss of ability to effectively monitor the actual survival rate of fingerlings during wintering, coupled with uncertainty regarding the exact number of yearlings inhabiting the fattening water bodies. It also becomes impossible to subject the stocking material to preventative ameliorative treatments. Against this background, overall and species-specific stocking densities become problematic, calculations for intensification measures grow more complex, and it becomes impossible to sort and remove individual fish that exhibit exterior defects or signs of trauma.

In recent years, due to price disparities between market-size fish and the components required for its production, many enterprises have adopted an extensive fish-farming method known in recent years as pasture aquaculture.

The theoretical foundation of pasture aquaculture is based on selecting appropriate polyculture components for fattening areas with a well-substantiated ratio of individual species. This form of fish farming relies on determining stocking density and forecasted fish productivity parameters, which in turn are the result of the average individual weight and survival rate during the growing process.

A key condition for success in this case is the objective necessity, prior to forming the polyculture, to obtain accurate data on the abundance and biomass of food hydrobionts across key groups: phytoplankton, macrophytes, zooplankton, zoobenthos, and detritus.

Knowing the food conversion ratios of certain hydrobionts for specific fish species allows for simple calculations of potential fish productivity, taking into account that different fish species utilize up to 50% of the total biomass of food hydrobionts. Once these preliminary conditions are met, one can obtain information on potential total fish productivity as well as yields for individual species that consume corresponding groups of food organisms: phytophagous, macrophytophagous, zoophagous, zoobenthivorous, and detritivorous fish.

If organic and mineral fertilizers can be applied, fish productivity will increase significantly due to the boosted abundance and biomass of food organisms for the respective polyculture components. However, this approach moves beyond the boundaries of pasture aquaculture, which is the subject of the subsequent information in this section.

Each reviewed theoretical component of the technology is aimed at obtaining the maximum quantity of high-quality products with minimal costs, which are primarily associated with acquiring the stocking material.

Under pasture technology, The Need for supplementary feeding is eliminated, which represents a substantial share of production costs. By utilizing natural and artificial water bodies of various origins and purposes as fattening areas, expenses related to depreciation, repairs, and water supply are also excluded.

In total, products obtained via pasture technology have a minimal cost of production relative to current market prices, high consumer quality, and attractive environmental credentials. The total volume of harvested fish is relatively low because the fish feed exclusively on natural hydrobionts. The fish are produced almost entirely at the expense of the natural food Base of the respective water bodies, which ensures the high economic efficiency of pasture aquaculture.