Catch Volume Research Articles

Development of new culinary products derived from black sea grey mullet

The increasing in tourist flow to the Republic of Crimea, as well as the acceleration of the pace of life of the population led to an increase in demand for finished fish culinary products. In this regard, there is a need to create a new fish culinary product of long-term storage from the raw materials of the Azov-Black Sea basin. The Black Sea mullet (Mugil cephalus) was chosen as fish raw material, the catch volume of which has been steadily increasing in recent years. Sous-vide technology - is a progressive technology, which is characterized by low-temperature modes of heat treatment, resulting in a product with unique organoleptic characteristics that are superior to traditional types of processing of fish raw materials. Fish and vegetables prepared using the sous-vide technology are distinguished by tenderness and juiciness, the aroma of the finished dish is enhanced. During the development of new product technology, the optimal technological parameters (temperature and process duration) were determined for heat treatment of fish fillet in vacuum based on mathematical modeling. The research was carried out on the equipment of the sector of technologies of processing of water biological resources of the department "Kerchenskiy" of the Azov-Black Sea branch of Russian Federal Research Institute of Fisheries and Oceanography. Heat treatment of samples was carried out in a water bath of LB-63 according to the plan of an experiment in the range from 55 to 70 ? with lasting from 15 to 30 min. For packing of a product the vacuum device Solis Vac Premium was used. A regression model was constructed consisting of the objective function determined by the microbiological index QMAFAnM. The software "STATGRAPHICS Plus Version 5.0" was used to plan the experiment and determine the optimal technological parameters of the fish culinary product..

Length-based indicators for the management of sport fishery in Yucatan, Mexico

Sportfishing is an activity of increasing popularity that involves a large number of users and high levels of fishing effort. In Yucatan, most of the target species in sport fishing are the same as those of commercial fisheries. However, there is no record of fishing effort or catch volumes. Thus the impact of sport fishing on these populations is unknown. This study analyzes the catches made by users of sport fisheries of nine species (Epinephelus morio, Haemulon plumieri, Seriola dumerili, Lutjanus synagris, Ocyurus chrysurus, Calamus bajonado, Sphyraena barracuda, S. guachancho and Mycteroperca bonaci) through length-based indicators. Samples of species’ sizes were obtained from the catches made during 10 fishing tournaments held in Yucatan's three-port towns (Sisal, Yucalpeten, and Telchac) between 2015 and 2016. The catch variables that were evaluated included: the number of mature individuals Pmat, optimal length Popt, and the number of mega-spawners Pmega. Length measures were derived from 1,252 individuals. Only H. plumieri, L. synagris, and S. guachancho exhibited sustainable indicator values, while E. morio and C. bajonado demonstrated extremely low values. In most species, sport fishing affects a high proportion of juveniles. The results suggest that sportfishing contributes to the fishing pressure of a species and commercial fishing, due to the capture of juveniles of economically important fish. It is essential to establish a systematic monitoring method of such activities and increase the priority level of the evaluation and management of this fishery.

FISHERIES DEVELOPMENT AND THE FORMATION OF THE FISH PRODUCTS MARKET IN UKRAINE AND IN THE CENTRAL AND EASTERN EUROPEAN COUNTRIES

FISHERIES DEVELOPMENT AND THE FORMATION OF THE FISH PRODUCTS MARKET IN UKRAINE AND IN THE CENTRAL AND EASTERN EUROPEAN COUNTRIES

History and status of sturgeon stock (Acipenseridae) in the Caspian pool

Analysis of materials from long-term studies characterizing the current state of sturgeon stocks in the Volga-Caspian fisheries basin, and the dynamics of commercial catches of beluga, sturgeon and stellate sturgeon in the XX - XXI centuries indicates that the Northern Caspian occupies the leading value in catch volumes, where more than 70 % of sturgeon fish are annually harvested. In the first half of the twentieth century sturgeon stocks were determined by the scale of natural reproduction in rivers and fishing volumes; in the second half, natural and anthropogenic factors began to intensively influence the formation of sturgeon stocks. The development of hydraulic construction on rivers, an increase in the withdrawal of freshwater runoff, a decrease in sea level to -29.0 mBS, pollution by industrial and agricultural runoff have necessitated the development of a set of measures for the reproduction, conservation and rational use of the Caspian’s aquatic biological resources. As a result of the studies, the response of the sturgeons to the changed conditions of reproduction has been determined in order to restore and increase their commercial stocks; high ecological adaptability of sturgeons to various living conditions within their range, their exceptional plasticity and pronounced intraspecific differentiation have been established. These indicators point to the possibility of creating conditions that meet the requirements for water quality for the life of sturgeons during migration and reproduction. In the course of the analysis of the obtained data, the influence of regulation of the Volga River flow on the efficiency of natural reproduction of sturgeons has been evaluated; the role of industrial sturgeon breeding in sturgeon stock formation has been shown; the abundance of juveniles in the North Caspian and adult individuals on feeding pastures of the sea has been estimated; trends in the number of sturgeon producers migrating in the Volga to spawning sites have been identified; the prospects for the restoration and rational use of sturgeons in the Volga-Caspian basin have been determined.

Güneydoğu Karadeniz’in Fatsa kıyılarında kullanılan dip uzatma ağlarıyla yakalanan avın miktarı üzerine derinlik ve mevsimin etkileri

The study was conducted along the Fatsa coasts of the South-eastern Black Sea, to investigate the effects of depth and season on catch volume of the bottom gillnet fishery. During the study, fishing was carried out using multifilament gillnets with mesh sizes of 32, 34, 36 and 38 mm in each of the four different depth strata (0-14 m, 15-29 m, 30-49 m and ≥50 m) three times per month between March 2013 and February 2014 (except for July and August), with a total of 30 gillnet hauls performed. The results of the study revealed that in all seasons whiting (Merlangius merlangus) was caught most in the 30 m and deeper water layers. However, whiting catch increased with increasing water depth. Most red mullets (Mullus barbatus) were caught in the 0-14 m depth waters during spring, winter and autumn periods, while its catch was the greatest in the 15-29 m during the summer period. Catch of this species decreased gradually with increasing water depth. Another fish species was pontic shad (Alosa immaculata) which was caught least in the shallow waters. However, during all seasons its catch increased gradually with increasing water depth up to the 30-49 m depth strata. Nevertheless, it was determined that catch volume for this species decreased in the ≥50 m level again. On the other hand, Mediterranean horse mackerel (Trachurus mediterraneus) was mostly caught in the shallow waters (0-14 m and 15-29 m) during all seasons. Especially in the ≥50 m waters, no Mediterranean horse mackerel was sampled during the study. This study presents that amounts of catch for the fish species sampled were affected especially by water depth and seasons.

Understanding Gender and Factors Affecting Fishing in an Artisanal Shellfish Fishery

Fishing strategies, effort and harvests of small-scale fishers are important to understand for effective planning of regulatory measures and development programs. Gender differences in fishing can highlight inequities deserving transformative solutions, but might mask other important factors. We examined fishing modes, fishing frequency, catch-per-unit effort (CPUE), resource preferences and perceptions of fishery stock among artisanal gastropod (trochus) fishers in Samoa using structured questionnaires and mixed effects models. The fishery has an extremely modest carbon footprint of 20.4 tonnes of CO2 p.a., as few fishers used motorised boats. Trochus (Rochia nilotica), an introduced gastropod, was the second-most harvested resource, after fish, despite populations only being established in the past decade. Daily catch volume varied according to gender and villages (n = 34), and was also affected by fishing effort, experience, assets (boat), and fishing costs of fishers. Boat users had much higher CPUE than fishers without a boat. Fishers who practiced both gleaning and diving caught a greater diversity of marine resources; effects that explained otherwise seeming gender disparities. Trochus tended to be ranked more important (by catch volume) by women than men, and rank importance varied greatly among villages. Local ecological knowledge of fishers informed the historical colonisation of trochus around Samoa and current trends in population abundance. Fishing efficiency, catch diversity and perspectives about stocks were similar between fishermen and fisherwomen, when accounting for other explanatory variables. Greater importance of these shellfish to women, and gender similarities in many of the fishing responses, underscore the need to ensure equal representation of women in the decision making in small-scale fisheries.

Comparison of the Catching Results of Mini One-Boat and Two-Boat Purse Seine in Bali Strait, Muncar, East Java Province

Mini purse seine has a major contribution in increasing production of small pelagic catches in Pelabuhan Perikanan Pantai (PPP) Muncar, because it has high productivity and the construction made according to catch schooling fish. This research aims to compare the catches composition and catch rate of mini one-boat and two-boat purse seine in Bali Strait, Indonesia. This research was conducted in Mei 2018 in Muncar, East Java, Indonesia. The method used in this research is survey. The primary data are total catch composition, fork length, individual weight of total catch and operation time of both fishing gears. Data were analysed by main catch and bycatch proportion, legal size proportion and catch rate. The results showed that the mini two-boat purse seine had a greater catch volume compared to the mini one-boat purse seine. The bycatch composition dominates in both fishing gear. The proportion of legal-size catching is 67% of the total. The fork length is not significantly different and for the total catches is significantly different. The catching rate of the mini purse seine one boat catch rate is lower at 4,048.67 kg/hour, compared to the mini two-boat purse seine which is 9,189.18 kg/hour.

Tuna trade‐offs: Balancing profit and social benefits in one of the world’s largest fisheries

AbstractThe western and central Pacific Ocean (WCPO) tuna fishery is one of the world's largest in terms of both catch volume and value, providing over half of global tuna catch with a landed value of US $5.84 billion in 2017. Fishing is conducted by both large‐ and small‐scale fleets, with fisheries subsidies disproportionately benefiting the former. The primary objective of this study was to determine the optimal distribution of effort between two large‐scale fisheries (LSF) and two small‐scale fisheries (SSF) in the WCPO under three scenarios: to maximize industry benefits, minimize subsidization or maximize food supply. The objective was approached using a bioeconomic game‐theoretic model. Results indicate opposite distributions of effort to maximize industry benefits (all fishing conducted by LSF) or to minimize subsidization (all fishing by SSF), with more balanced effort distributions to maximize food supply. Total value of capacity‐enhancing subsidies in optimal scenarios ranged from $1.4 billion when industry benefits were maximized to $0.2 billion when subsidization was minimized. Investigation of suboptimal scenarios reveals the flexibility of these results, with wide ranges in outputted state variables for a given goal. Difficulty was encountered in modelling the SSF sector due to data deficiencies, a well‐recognized issue in managing SSF. Investments towards “data equity” to help ensure that management decision‐making can properly account for the SSF sector would be useful. This study has implications for the objectives we set in fisheries management, and the potential trade‐offs, often value‐driven in nature, that we must make explicit in that management.

Особенности биологии и промысла плотвы (Rutilus rutilus L.) в некоторых водоемах Республики Карелия

The article summarizes the results of long-term observations of the status of roach stocks in the main fishing waters of the Republic of Karelia (Lake Onega, Lake Ladoga, Vodlozerо and Topo-Pyaozerо reservoirs, Lake Syamozero). New data on its biology (distribution, linear and weight indicators, abundance, biomass) have been presented. There has been shown the dynamics of roach catch for a long-term period (1950–2017). It has been found that the fishing capacity of the represented roach populations corresponds to the production capabilities of its mature part and to the value obtained by biomass growth. The results of observations showed that in the studied water bodies the number and stocks of roach allow for greater volumes of catch than it is currently available and the total catch can be increased up to the calculated values of the allowable catch subject to rational fishing in the water bodies. Roach should be commercially caught at the age of 4+ years old. Given the interspecific contradictions of roach and bream, intensive fishing is recommended during the period of spawning in the straits, bays and mouths of rivers. For catching roach, it is necessary to use coastal-type fishing gear (trap nets, seines). The intensity of fishing and the increase in catches in reservoirs should be considered as mandatory measures in terms of biological reclamation in water bodies. When allocating catch quotas, the priority should be given to the most productive roach suppliers. The accompanying factor for the wide distribution of roach, along with other spring-spawning carp species (blue bream, bream), in our opinion, is warming of the climate in the region. In this regard, it is necessary to take measures to force catching the above fish species.

Bycatch sea cucumber Holothuria scabra processing and the quality characteristics

Sea cucumbers are marine invertebrate animals that have high economic value. Indonesia is the main exporter of trepang over the world; however, this trepang export has not yet contributed to the improvement of community welfare. The low quality of trepang produced by Indonesia makes the economic value of trepang was still low. The low quality was caused by changes in processing stages due to decreasing the wild catch. Since the ban of the mini trawl use (cantrang), fishermen only process the bycatch sea cucumbers Holothuria scabra or sandfish. Trepang produce from sandfish is the most expensive one; the price can reach 3-5 million per kg. The study aims to analyze the quality and analyze the potential of developing the quality of trepang produce using sandfish. The decrease in sandfish catch volume after the Danish seine ban prohibits the stage changes in sandfish processing. Elimination of fumigation stage, the addition of storage in the refrigerator, addition of boiling, overcooking, and using excessive papaya leaves, were the main causes of less than the minimum value specified in SNI for appearance and odor characteristic. Although water, ash, protein, total plate count, Salmonella content, Lead, and Cadmium are in the decent range, the exporters still buy trepang at lower prices because exporters have to do reprocessing to improve the quality.

Does legislation affect elasmobranch conservation and research in Brazil? A case study from Paraná State

In Brazil, regulations for fishing for elasmobranchs are scarce, as well as insufficient monitoring and management. The first catch regulation for the group was published in 1998 (IBAMA No. 121/98). Despite the ban on finning, the legislation provides legal support for evisceration and decapitation prior to landing. Such practices have become particularly problematic for proper monitoring since decharacterization impairs the correct identification of species. In addition, processing is detrimental to research, as many studies rely on sampling of biological material (e.g., blood), posing an additional challenge for researchers using commercial fishing animals for scientific purposes. This study aimed to characterize the frequency of this practice in a representative artisanal fishing community in the fishing of elasmobranchs. The three years of monitoring show that landing patterns of gutted and beheaded animals are influenced by the species caught and the catch volumes of the day. In addition, endangered species protected by legislation were mostly landed already processed. We discuss the findings focusing on the need to revise the legal framework for the commercial landing of elasmobranchs and possible promising ways to address this challenge.

Links and Trade-Offs between Fisheries and Environmental Protection in Relation to the Sustainable Development Goals in Thailand

The fisheries sector significantly contributes to global food security, nutrition, and livelihood of people. Its importance for economic benefits, healthy diets, and nutrition, and achieving sustainable food systems is highlighted by several Sustainable Development Goals (SDGs), i.e., SDG 1 (No Poverty), SDG 2 (Zero Hunger), and SDG 14 (Life Below Water). However, due to unprecedented population levels, the contribution of the fisheries sector to fulfills these roles is challenging, particularly given additional concerns regarding environmental well-being and sustainability. From this perspective, this study aims to identify the links and trade-offs between the development of this sector and the environmental sustainability in Thailand via a critical analysis of their trends, current ecological impacts, and more importantly, their contributions to several individual SDGs. A time-series of Thailand’s fisheries production from 1995 to 2015 indicates a recent reduction from around 3.0 million tons in 1995 to 1.5 million tons in 2015 of wild fish and shellfish from marine and freshwater habitats. The maximum sustainable yield of these species has been exceeded. Conversely, Thailand’s aquaculture production has continued to grow over the last decade, resulting in a reduction of mangrove forest area, wild fish stocks, and water quality. While capture fisheries and aquaculture production significantly contribute to several SDG targets, there are potential trade-offs between their development and the achievement of SDGs within the planet dimension, i.e., SDG 6 (Clean Water and Sanitation), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), SDG 14, and SDG 15 (Life on Land). On the one hand, the mitigation of overfishing will be beneficial for the targets of SDG 14, leading to more sustainable resource management. On the other hand, it might cause a decrease in the volume of marine catches and economic and social profits. We conclude that the SDGs can serve as a framework for both policymakers and industrial workers to monitor and compromise on regulations that will optimize productivity in the context of sustainable development.

Fishery organization in the Lower Dniestr and in the Dnistrovsky liman (analytical overview)

According to official statistics, the long-term dynamics of catch of the main commercial fish species and invertebrates of the Lower Dniester, changes in the structure and variations in the volume of catches are shown. Fisheries in the lower Dniester basin are characterized by a very high level of exploitation of aquatic bioresources, which, along with other factors of anthropogenic impact, has led to changes in the structure of ichthyocenosis. The rapid increase in the number of prussian carp in the last five years indicates a significant imbalance of the ecosystem. Modern approaches to the organization and regulation of fisheries, including commercial, amateur, in the waters of the NRF are considered. The current regulatory documents governing the organization and regulation of fisheries are analyzed. The predominance of IUU fishing over the legal forms of fisheries activities was noted, which seriously threatens the state of commercial aquatic bioresources and makes their rational sustainable use impossible. The problem of reliability of statistical data on the catch volumes of aquatic biological resources is noted. Official fishery statistics provide not only significantly reduced catches but also a distorted catch structure. There are practically no reliable data on fishing by amateur fishermen. The low efficiency of measures taken for the artificial reproduction of aquatic biological resources is shown. The most promising route is the restoration of natural spawning areas downstream of the river and in the estuary, which can have a greater environmental and economic impact than artificial reproduction. Proposals to improve the protection and rational use of aquatic bioresources in the Dniester basin were considered.

Geopolityczne uwarunkowania rywalizacji o zasoby Arktyki

The aim of the study is to indicate the usefulness of game theory in the context of the effectiveness of geopolitical problem analysis in terms of improving decision-making in relation to Arctic areas. The article presents a series of significant global Arctic problems related to open fisheries, opening Arctic areas for the extraction of natural resources or creating new and more favorable sea routes for transporting goods. Key players in the Arctic area have been identified along with their conflicting claims. It was mentioned that cooperation leads to a reduction in social costs and the stimulation of economic development in the main areas of interest for individual countries. To verify the assumptions, an experiment based on a tragedy of the commons was carried out, in which the participants took the role of fisher-hunters and mining companies. The experiment took the form of a dynamic game, where in each round the participants decided on the volume of catches and resources extracted. The results showed that limiting the freedom of action extended the time of the game, and thus the functioning of the entities and the duration of resources. Leaving plenty of capacity led to agreement between the players and the self-introduction of limits. The experiment showed that the players were aware that only agreement led to gaining benefits in the long term. Thus the creation of an institution supervising disputed areas can lead to conflict mitigation, where entities with different goals and interests must reach agreement, especially when the key challenge is to avoid degradation of the resources and the environment.

Value Chain Analysis of Pen Shell (Baloko) in the Province of Sorsogon, Philippines

Sorsogon Bay is home to the pen shell (Atrina pectinata), locally known as Baloko. This study was designed to assess the existing value chains of pen shell and identify areas for improvement. The sites covered were the municipalities along Sorsogon Bay in the province of Sorsogon, Philippines. It employed the tracer methodology where only the processors and fisherfolks connected to the traders were selected as respondents of the study. Primary data were gathered through semi-structured questionnaires. Secondary data were used to establish a good understanding of the pen shell industry in the areas of the study. Results show that the adductor muscle or tinga is a substitute for scallops, thus, an export product. The other parts of pen shell or rambit are also of high demand. The highest volume of pen shell catch occur during October to April during the northeast monsoon (amihan) and gradually decline from May to September during the southwest monsoon (habagat) months. The value chain maps reflect the whole meat and semi-processed value chains, the two distinct marketing practices traced in the pen shell industry. The actors in the two value chains are the fisherfolks, processors, traders, and exporters. The enablers are the fisherfolks’ organization, local government unit (LGU), Bureau of Fisheries and Aquatic Resources (BFAR), City Fisheries and Aquatic Resources Management Council (CFARMC), microfinance institutions, Department of Trade and Industry (DTI), and Phil Export. There is uneven distribution of value added in both chains. More value is created and captured by the processors while the fisherfolks have negative gains. The value-added captured by the processors and traders are higher in semi-processed practice. There is the need to focus on the supply of pen shell, the effects of pollution of Sorsogon Bay, market information, technology to preserve the quality of products, industry association, and basic researches on pen shell under Sorsogon Bay condition.

Thresher sharks (Alopiidae) catch in the pelagic fisheries of Western Indonesia

Thresher sharks (family Alopiidae) are an evolutionarily distinct and globally endangered species group. Indonesia is the world’s largest shark fishing nation, and a global priority for reducing the capture of threatened shark species. Kutaradja port is one of Indonesia’s largest fishing ports, located in the capital of Aceh Province, Banda Aceh, Western Indonesia. Kutaradja is a large oceanic port serving a variety of fisheries, from small scale to industrial fleets. One of the main fisheries operating from Kutaradja port is an industrial purse seine fleet targeting valuable pelagic fish, particularly tuna. Pelagic sharks such as threshers are vulnerable to capture in these fisheries, due to their co-occurrence with stocks of valuable pelagic species. Here we describe the volume and composition of shark catch in Kutaradja’s purse seine fleet, based on daily landing monitoring conducted in January 2017 to May 2019. Our results show that the dominant species caught are thresher sharks (Alopiidae), which make up 51% of all shark landings. A total of 627 thresher sharks were landed during the monitoring period, consisting of 558 individuals of pelagic threshers shark (Alopias pelagicus) and 69 individuals of bigeye thresher shark (Alopias superciliosus). The catch is dominated by mature females, which could be particularly detrimental to the reproductive capacity of the population. Fishers in purse seine vessels often catch these threshers with hand-lines, which are used as a secondary gear while the main fishing gear is soaking. Based on these findings, we proposed recommendations for reducing thresher shark fishing mortality, including restricting the use of secondary fishing gears and releasing incidentally captured sharks.

Value Chain Analysis of Carpet Shell (Baduy) in the Province of Sorsogon, Philippines

The study was designed to assess the value chains of carpet shell and identify areas for improvement. The sites covered were the municipalities along Sorsogon Bay, in the province of Sorsogon, Philippines. It employed the tracer methodology. Only the traders and fisherfolks connected to the concessionaires and exporters were selected as respondents. Primary data were gathered through semi-structured questionnaires. Secondary data were used to establish a good understanding of the carpet shell industry. The highest volume of carpet shell catch occurred during December to April during the northeast monsoon (Amihan) and gradually declined from May to November during the southwest monsoon (Habagat) months. The Value Chain Maps reflected the fresh carpet for local market and for export market value chains, the two distinct marketing practices traced in the carpet shell industry. The actors in the two Value Chains are the fisherfolks, traders, concessionaires and exporters. The enablers are the fisherfolks’ organization, local government units (LGUs), Bureau of Fisheries and Aquatic Resources (BFAR), City Fisheries and Aquatic Resources Management Council (CFARMC), and microfinance institutions. More value is created and captured by the traders while the fisherfolks have least gains. The value-added captured by the traders were higher in fresh carpet shells for the local market than the export market. The areas of improvement will provide solutions to the problems on the supply of carpet shell, pollution of Sorsogon Bay, market information, technology to preserve the quality of products, industry association, and basic researches on carpet shell under Sorsogon Bay condition.

Современное состояние репродуктивного потенциала черноморского шпрота Sprattus sprattus phalericus (Risso, 1826) (Pisces: Clupeidae) в Крымском регионе и условия его формирования

Черноморский шпрот Sprattus sprattus phalericus (Risso, 1826) — один из наиболее массовых видов рыб в Азово-Черноморском бассейне. Благодаря своей многочисленности играет исключительно важную роль в экосистеме моря, являясь промежуточным звеном между зоопланктоном и представителями высшего трофического уровня ― крупными хищными рыбами, дельфинами и птицами. В то же время шпрот относится к числу важных промысловых объектов всех причерноморских стран, устойчиво занимая в последние десятилетия второе место по объёму вылова (после хамсы). Общий вылов достигает 100 тыс. тонн. Основные добывающие государства — Турция и Украина. Мониторинг и прогноз состояния популяции шпрота в условиях роста интенсивности промысла и изменения климата являются актуальными задачами. Предмет исследования данной статьи — многолетняя (2000–2016) динамика биологических (качественных) параметров, определяющих популяционную плодовитость черноморского шпрота в Крымском регионе, современное состояние репродуктивного потенциала и условия его формирования. В основу работы положены результаты собственных исследований. В числе параметров, определяющих популяционную плодовитость, изучены размерно-возрастная структура нерестового (родительского) стада, абсолютная индивидуальная плодовитость и половая структура нерестового стада (численное соотношение самок и самцов). В 2011–2016 гг. по сравнению с 2000–2004 гг. средняя длина нерестовых самок сократилась в 1,22 раза (с 7,36 до 6,03 см), что сопровождалось снижением абсолютной индивидуальной плодовитости в 2,39 раза (с 13 625 до 5690 икринок). Численное соотношение между самками и самцами уменьшилось в 1,23 раза (с 1,95 до 1,59). Одновременно величина запаса шпрота в северной половине Чёрного моря сократилась более чем в 2,5 раза (с > 500 тыс. т до < 200 тыс. т). В результате популяционная плодовитость шпрота в Крымском регионе уменьшилась более чем в 7 раз (2,39 × 1,23 × 2,5). Изучены условия промысла шпрота в северной половине Чёрного моря (от устья р. Дунай до Керченского пролива), которые показали 2-кратное снижение (с 251,9 тыс. тонн в 2000–2004 гг. до 129,1 тыс. тонн в 2011–2016 гг.) общего вылова и более чем 2,3-кратное (с 50,4 до 21,4 тыс. т) — среднегодового. На крымском шельфе, напротив, общий вылов в это время увеличился в 1,2 раза (с 76,9 до 92,2 тыс. т), а его среднегодовая величина осталась без изменения (15,4 тыс. тонн). Запас сократился в 2,5 раза, а значит, величина промысловой нагрузки на крымскую популяцию увеличилась в 2,5 раза, что даёт основание рассматривать фактор промысла в качестве главной причины её деградации. Справедливость данной версии подтверждает установленный ранее факт сопряжённости межгодовых колебаний между выловом и размерно-возрастными показателями шпрота в Крымском регионе в 2003–2013 гг.: выловы свыше 15–16 тыс. т сопровождались уменьшением средней длины шпрота в следующем году. Необходимым условием для предотвращения дальнейшей деградации, а также для восстановления и поддержания стабильного состояния популяции шпрота в Крымском регионе и её репродуктивного потенциала является регулирование промысла. Негативное воздействие природных (климатического и трофического) факторов на состояние популяции следует признать второстепенным. Локальный перелов косвенно указывает на структурированность промыслового запаса черноморского шпрота, его подразделённость на ряд пространственно-обособленных образований (единиц запаса), то есть на наличие внутривидовой дифференциации.

Properties and Some New Applications of Enzymes from Wastes of the Shrimp Pleoticus muelleri (Decapoda, Penaeoidea)

The shrimp Pleoticus muelleri (Bate, 1888) is an important fishing product from the Southwest Atlantic waters which is frequently captured as a bycatch and discarded. Wastes and by-products of shrimp are an excellent source of protein and enzymes. This review highlights the biochemical and catalytic properties of proteases from shrimp. Previous studies on P. muelleri enzymes have found different activities of alkaline proteases ranging from 0.01 to 0.78 Abs/min/mg of protein. These changeful results might be explained by the great influence that several biological and experimental factors, such as molting and developmental stages, type of diet, and culture conditions, have on the enzyme function. Regarding acid protease, it has been demonstrated that they have activities between 0.3 and 0.4 Abs/min/mg of protein. Processing Argentine red shrimp waste could offer many higher value products without increasing wild catch volumes; therefore, it is essential to conduct further studies that allow the development of more value-added products derived from the practical usage of shrimp processing waste.

CHARACTERISTICS OF FISH FARMING MANAGEMENT AT THE DANUBE LAKES AND PROSPECTS FOR ITS DEVELOPMENT

Problem. The Danube lakes have always been important water bodies both in terms of biodiversity conservation and restoration of water bioresources. The total area of the Danube lakes (Kahul, Kartal, Yalpuh, Kuhurlui, Katlabuh, Kytai), used as SCFFs, exceeds 44,000 ha. The exploitation of aquatic biological resources within the majority of the Danube lakes is carried out by special commercial fish farms (SCFFs). Unfortunately, the efficiency of using aquatic bioresources in this mode is not always effective.The purpose of the research was to study the current status of fishery at the Danube Lakes and prospects for its development under possible legislative changes.Material and methods. The research was carried out in the framework of the project “The Development of an Optimal Model for the Conservation and Sustainable Use of Aquatic Bioresources of the Danube Lakes Adapted to Climate Change” funded within the Programme for the Scientific-technical Projects of Institutions of the National Academy of Sciences of Ukraine for 2019. The analysis was based on the data of statistical reports relating to the catch volume of aquatic bioresources, SCFFs Regimes and field surveys at the Danube lakes.Main results of the research. Averagely, for the period 2014-2018, the planned indicators of the catch volume of aquatic bioresources (ABR) in the SCFFs, built on the Danube water bodies, were reached by 17-77%. Nowadays, the structure of commercial catches in the lakes includes only a low percent of artificially introduced fish species. According to the statistics, only in two SCFFs (Kahul and Katlabuh), their catches exceed those of indigenous species. In other fisheries their proportion constitutes approximately 30%, i.e. the catches are based on the exploitation of natural aquatic bioresources of the lakes. The research substantiates the necessity to reform approaches to functioning of the SCFFs on the large waterbodies.Conclusions. A current status and operation regime of SCFFs at the Danube Lakes is unsatisfactory and does not comply with the requirements of regulatory documents. Assignment of a “commercial fishing area” to a particular user of aquatic biological resources for a term of up 25 years may be applied as a possible form for the exploitation of fishing resources of such water bodies.