Inland Fisheries Research Articles

Length‐Based Assessment of Hovsgol Grayling (Thymallus nigrescens), Lenok (Brachymystax lenok), and Burbot (Lota lota) Population Status in Lake Hovsgol, Mongolia

ABSTRACTDespite the global importance of inland fisheries, data available for stock assessment is often limited. Data‐limited methods that use length composition data offer a potential approach to assessing more inland fisheries. We assessed the population status of three fish species in Lake Hovsgol, Mongolia through length‐based spawning potential ratio (LBSPR) analysis and evaluation of trends in eight length‐based indicators of population status, catch‐per‐unit‐effort (CPUE), and body size. Hovsgol grayling (Thymallus nigrescens) were not yet overfished, but CPUE and body size declined due to targeting of large, mature fish. Lenok (Brachymystax lenok) were experiencing overfishing, especially of small, immature fish, which contributed to size–structure truncation. The burbot (Lota lota) population was healthy according to most indicators, but the lack of local life history information exacerbated already large uncertainties. Continued monitoring and improved coordination among fishers, managers, and scientists will be critical to enhancing the sustainability of these fisheries.

Indigenous Inland Fisheries Development and Management in India

This paper provides a comprehensive review and analysis of indigenous inland fisheries development and management practices in India. Drawing on extensive literature review and case studies, it examines traditional ecological knowledge, community-based management systems, and the integration of indigenous practices with modern scientific approaches. The research highlights the diversity of inland fisheries across India's varied ecosystems and the critical role of indigenous communities in sustainable resource management. Key challenges including overfishing, habitat degradation, and socioeconomic pressures are analyzed. The paper proposes policy recommendations to support and scale indigenous management practices while addressing conservation needs. Findings underscore the importance of participatory, culturally-appropriate approaches that leverage local knowledge for inland fisheries development in India.

A brief review on effect of heavy metals in fish fauna

The variety of fish species is essential for the well-being and stability of aquatic environments. Fishes are one of the most important aquatic creatures that are directly or indirectly related to human health and wealth. With thousands of different species inhabiting various water bodies around the world, each fish contributes to the overall biodiversity and sustainability of these environments. Humans have long relied on aquatic resources for food, medicines, and materials. Fish species are adapted to a variety of environments such as freshwater lakes, rivers, reservoirs, oceans, and estuaries. The diversity of habitats available allows a variety of fish species to thrive in different environments. Fish diversity is a vital component of aquatic ecosystems, supporting ecosystem stability, economic value, and cultural significance. India's inland water resources are abundant and diverse, including reservoirs that play an important role in the country's inland fisheries sector.Biodiversity and its conservation are considered one of the key issues to enable sustainable use of natural resources. Protecting ichthyophan diversity in its natural habitat is essential and the need of the hour. By understanding the factors that influence fish diversity and the importance of preserving biodiversity, we can work towards protecting and protecting these priceless resources for upcoming generations.

Assessment of Ecosystem Characteristics and Fishery Carbon Sink Potential of Qianxiahu Reservoir Based on Trophic Level and Carbon Content Methods

Optimizing biological carbon sequestration has become a primary strategy in global low-carbon-emission initiatives. Freshwater fisheries in reservoirs play an important role in aquatic biological carbon sequestration. However, a standard method for evaluating the carbon sink capacity of inland fisheries has not been developed. Therefore, this study aimed to assess and compare the carbon sequestration potential of the Qianxiahu Reservoir’s fisheries using the trophic level and mass-balance methodologies. The Ecopath model was employed to determine the trophic levels of aquatic organisms within the Qianxiahu Reservoir ecosystem, with input parameters sourced from in situ surveys and the literature on reservoirs. The model includes 21 functional groups, with trophic levels ranging from 1.000 to 3.281. The key species identified are silver carp, bighead carp, and crucian carp. The indices of Finn’s cycling index (FCI), connectivity index (CI), system omnivory index (SOI), and total primary production/total respiration (TPP/TR) for the Qianxiahu Reservoir are 11.35, 0.27, 0.196, and 1.540, respectively. These values indicate a high degree of material recycling and complex interconnections among functional groups. The fishery carbon sink potential of the Qianxiahu Reservoir, calculated using the trophic level and carbon content methods, yielded values of 261.8362 tons/km2 and 66.6818 tons/km2, respectively. The trophic level method showed a notable increase of 195,1544 tons/km2 compared to the carbon content method, underscoring significant differences in results between the two methods. The study concludes with recommendations for research on methods to assess the carbon sink capacity of freshwater fisheries, aiming to establish a scientific framework for this evaluation.

Per-recruit analysis and proposed sustainable harvest strategy for rednose labeo Labeo rosae and Mosambique tilapia Oreochromis mossambicus in Flag Boshielo Dam, Olifants River, South Africa

Inland fisheries development in South Africa has been proposed to improve rural livelihoods and food security. However, inland fisheries are susceptible to collapse through overfishing. Therefore, establishing biological reference points for these fisheries is essential for long-term sustainability. Here, spawner-biomass-per-recruit (SBR) analysis was used to set biological reference points for a gillnet fishery targeting the rednose labeo Labeo rosae and Mozambique tilapia Oreochromis mossambicus at Flag Boshielo Dam on the Oliphants River in Limpopo Province, South Africa. Both species are currently exploited at the impoundment by subsistence fishers that keep their entire catch. The current yields are estimated at 59 and 172 g yr−1 for L. rosae and O. mossambicus, respectively. The per-recruit analysis showed that age-at-first-capture for both species should be 4 years, at minimum lengths of 280 mm TL and 250 mm TL for L. rosae and O. mossambicus, respectively, with fishers using a minimum mesh size of 100 mm to reduce the risk of stock collapse. To maintain a SBR value greater than 25% of a pristine population, the L. rosae yield could be increased to 98 g yr−1, while the O. mossambicus yield could be increased to 176 g yr−1, following implementation of the recommended mesh size and size limits. A per-recruit analysis for O. mossambicus that includes recruitment variability and error to accurately calculate the biological reference points is recommended.

Estimates of life-history and growth parameters of exploited fish species in lakes Edward and George: Implications on exploitation status, population dynamics, management, and conservation of native species.

Adequate knowledge is essential for responsible inland fisheries. However, many inland fisheries lack monitoring, and therefore, decision-making for fisheries management is not reliable. In this paper, we used data from surveys and literature to estimate the life-history and growth parameters of 16 exploited fish stocks in the Ugandan part of Lake Edward and Lake George (East Africa). The estimated parameters are pivotal indicators of fish stock status, particularly in data-poor fisheries. The estimated parameters included maximum length (Lmax) and mean length (Lmean) as indicators of size structure in experimental and commercial catches, coefficients of length-weight relationships, length at 50% maturity (Lm50), fecundity, von Bertalanffy parameters, total mortality (Z), and natural mortality (M). These parameters were estimated using empirical formulae, statistical methods, and analyses of length frequencies. Only two stocks of semutundu Bagrus docmak exhibited significant and increasing trends in Lmax (Lake Edward) and Lmean (Lake George). The estimates for the remaining parameters were consistent with those in FishBase and other literature resources, either for the same species or related species. This consistency indicates their reliability for application in decision-making and further assessments. Some parameters showed evidence of unsustainable fishing. For example, estimates of Lm50 for four of the assessed stocks belonging to two species (Nile tilapia Oreochromis niloticus and marbled lungfish Protopterus aethiopicus) were lower than baseline estimates in the studied waterbodies. Furthermore, the Lmean in catches for all the stocks were less than the optimum lengths (Lopt), which maximize catches with a minimal impact on biomass and size structure. No significant changes in Lmean, length-frequency distributions, and size at maturity could be attributed to the management changes implemented in 2018, probably because it is too early to observe changes in these parameters. However, there are positive signs attributable to the changes in management as shown by a high proportion of mature individuals in commercial catches for most of the stocks for which the proportion was calculated, and an increase in Lmean and Lmax for some stocks, such as B. docmak, in commercial or experimental catches. New estimates from this study will enhance decision-making and further assessments of fisheries. Routine monitoring is recommended to update and improve the estimates.

Comparative Effect of Fish Feeds on the Initial Growth and Survival Rate of Juvenile Redbreast Tilapia (Coptodon rendalli) under Early Hatchery Conditions

This study compared the effects of three supplementary diets—egg yolk, Artemia, and commercial pellets with 48% crude protein—on the growth performance and survival rate of redbreast tilapia (Coptodon rendalli) under intensive culture conditions at the Kamutjonga Inland Fisheries Institute in the Kavango East region of Namibia. The study was conducted from December 2023 to January 2024 using a complete randomized design replicated thrice. Results showed that fish fed with commercial pellets exhibited the highest specific growth rate (1.39 ± 0.80%) compared to egg yolk (0.94 ± 0.54%) and Artemia (0.33 ± 0.19%). Commercial pellets also had the best survival rate (76.19 ± 43.099), compared to egg yolk and Artemia (70.47 ± 40.69; 33 ± 19.05), respectively. However, egg yolk had the best feed conversion ratio (0.20 ± 0.05) compared to the commercial pellets (0.22 ± 0.04) and Artemia (0.26 ± 0.07). Critical water quality parameters were maintained within acceptable survival ranges for C. rendalli across all treatments. These findings highlight the importance of dietary protein content in optimizing the growth and survival of C. rendalli under intensive culture conditions and provide insights for effective feeding strategies. However, commercial pellets are expensive and inaccessible to small-scale fish farmers. As an alternative, egg yolk emerged as a viable and affordable feed option, promoting fish growth and supporting the establishment of small-scale farming practices in the region.

Constraints in Production and Marketing in Perception of Fish Farmers and Market Intermediaries of Inland Fisheries in Khammam District of Telangana State, India

The study focuses on Khammam district in Telangana, a significant region for fish farming. Using primary data collected through personal interviews with fish farmers (60) and market intermediaries. The present study aims to identify the constraints in fish production and status of marketing using Garrett’s ranking technique. The major constraints in fish production were identified include high feed costs (Garrett score- 71.41), lack of market facilities (68.55), and inadequate capital (68.15). For marketing, addressing the key issues include high price fluctuation (60.4) in the fishes, high transportation costs (56.13), and lack of market infrastructure (53.53).These results point to important issues that must be resolved in order to increase the productivity and sustainability of fish farming and marketing. The most significant difficulties are those concerning infrastructure, such as lack of market facilities and high transportation costs, along with financial limitations like high feed costs and insufficient money. Addressing these challenges is essential for enhancing the fisheries sector contribution to food security and economic development, particularly in the regions of Khammam District in Telangana

Present status and future prospects of fisheries of Tehri dam reservoir

Fisheries in India are a burgeoning industry with immense potential and opportunities. Ironically, because of its enormous but untapped potential, reservoir fisheries are called as "a sleeping giant". The average productivity from these reservoirs in India is about 30 kg/ha compared to the production potential of 250 kg/ha. Inadequate management leads to low rate of fish production in Indian reservoirs. A major impediment to science-based fish productivity in reservoirs is the lack of authentic data on target stocks. Inland fisheries, like those in reservoirs, are particularly affected. Investigators generally rely on simple catch statistics and hypothesis statements to assess fish production and potential yields due to inadequate resources, population data, and experts in the area. The present paper emphasizes the quintessential 44sq km huge Tehri hydro-power dam reservoir, located in the Bhagirathi and Bhilangana valleys of the lesser Himalayas in the Garhwal hills. On average the fish productivity from Tehri reservoir in the year 2021-2022 is reported as 13.75 kg/ha but, this is significantly lower than its actual productivity. Thus, the current technical paper addresses this issue by condensing and synthesizing the current status of fisheries in the Tehri Dam reservoir with past status in terms of fish species diversity. It provides baseline information on fish production and various data shortfalls in fisheries activity management. The paper also describes the ecological and economic aspects that affect fish catch to utilize the reservoir resources and mired the cold-water fishery management in the Tehri reservoir.

Factors influencing fish migration in one of the world's largest inland fisheries

Fish from Cambodia's Tonle Sap Lake are economically, culturally, and nutritionally significant for people in the Lower Mekong Basin, providing income, livelihoods, and protein. Fish in this system generally migrate toward upstream Mekong River in dry season and return in early wet season. However, drivers of fish migration from Tonle Sap Lake to the Mekong River are not well-understood. In this paper, we utilized Mixed Effects Random Forest to predict the catch weight of six fish species migrating from the Tonle Sap Lake to the Mekong River using precipitation, lunar cycle, and hydrologic conditions like river stage, streamflow, flow magnitude, and timing as predictors. As a surrogate for fish migration, we used daily fish catch weight from 2002 through 2008 at the bagnet, or Dai, fisheries along Tonle Sap River, a migration corridor connecting Tonle Sap Lake to the Mekong River. We found that migration of large fish was mainly cued by streamflow and flow magnitude, while smaller fish migrate depending on the combination of streamflow and flow timing. Streamflow less than average cumulative flow was the most important driver for migration of Pangasianodon hypophthalmus, and Cirrhinus microlepis. Migration of Cyclocheilichthys enoplos and Osteochilus melanopleurus was highly dependent on the number of low- and minimum-flow days. Cumulative flows, period of high flow and water level were the main predictors of the small mud-carp Henicorhynchus entmema's migration, while individuals of Labiobarbus leptocheilus migrated out of the Tonle Sap Lake depending on the number of days after 7-, 30-, and 90-day minimum flows. These results suggest that flow characteristics can be used to aid conservation and adaptive management of Cambodia's Dai fisheries.

A Comprehensive Review on Heavy Metal Toxicity in Coastal Sediments

Abstract Heavy metal toxicity is becoming a growing environmental concern worldwide. The estuary’s surface waters and sediments are finally being transported to the coastal areas. During this transportation, the water and sediments carry numerous elements. The essential elements like nutrition are nitrates, phosphates, silicates, and sulphates, which are required for aquatic life, and non-essential elements contribute to pollution. The input of these essential and non-essential elements is being contributed by nature and anthropogenic activities. Due to the increase in urbanization and anthropogenic activities like agricultural, industrial, thermal power plants, dye factories, inland fisheries, small and significant scale industries, as well as recreational activities, are the sources of heavy metal toxicity. The toxic heavy metals, including mercury, cadmium, chromium, and lead, are leading to biological toxicity. Environmental standards are being modified due to increasing concerns. However, naturally occurring heavy metals and metalloids are drawn from parent rocks and absorbed by aquatic organisms, such as benthic organisms, which fix some heavy metal ions. Flora and fauna also absorb these ions, reducing their concentration. However, due to climatic factors like temperature and pH, these metal ions get adsorbed on the surface of the sediments. During hydrodynamic forces, they get released back into the water and vary seasonally.

Sorting grid usage to reduce the catch of undersized narrow‐clawed crayfish (Pontastacus leptodactylus Eschscholtz, 1823) in fyke net fisheries

AbstractSustainability of natural stocks of crayfish is critical because of their economic and ecological importance. Crayfish (Pontastacus leptodactylus), one of the most important species in Turkish inland fisheries, has been facing serious threats recently. One threat the species faces is high landed bycatch of undersized crayfish because of selective fishing gear, such as fyke nets. We estimated size‐selectivity of sorting grids with various bar spacings for crayfish to reduce bycatch. Six bar spacings (15.0, 17.5, 20.0, 22.5, 25.0, and 30.0 mm) were tested alongside commercial crayfish fyke nets. Mean selectivity (L50) (±95% CI) was 6.90 (6.63–6.99) cm for 15.0 mm bar spacing, 7.52 (7.16–8.02) cm for 17.5 mm, 8.52 (8.32–8.71) cm for 20.0 mm, 9.70 (9.28–9.90) cm for 22.5, 10.75 (10.34–11.17) cm for 25.0 mm, 11.80 (11.31–12.24) cm for 30.0 mm, and 8.79 (8.05–9.29) cm for commercial fyke nets. The proportion of undersized specimens caught be reduced from 32.27% for commercial fyke nets to as low as 2.46% by using sorting grids. The codend of 22.5 mm bar spacing was more selective, with significantly lower discard rates, and more effective for individuals above the minimum conservation reference size than commercial fyke nets.

Sustainability of fishing cooperatives in the Gulf of Mexico: A case study

Small-scale fishing, characterised by small groups of people working with basic technology and little investment, is an important economic activity in regional and global contexts. In Latin America, inland fisheries play a very important socio-economic role, providing food and income to local families, alleviating poverty, and contributing to social well-being. They are often structured as a social cooperative, as a way to ensure productivity. Cooperatives tend to be sustainable, and their performance can be judged from the impact they have on the social, economic, and environmental spheres. The aim of this study was to measure the sustainability of inland fishing cooperatives in Mexico from these three viewpoints. Though cooperatives generally show a medium-high level of sustainability, on account of their historical background and their contribution to social and economic indicators, our results revealed some weaknesses in terms of environmental indicators, which are locked in a negative relationship with economic ones. Social indicators, however, were positively related with the other two. The sustainability of fishing cooperatives today faces various challenges, as political decision-making tends to favour the social and economic dimensions over the environmental one.

Outlay of inland fishery cooperatives for fishery resource enhancement in Japan

Outlay of inland fishery cooperatives for fishery resource enhancement in Japan

Unraveling Greek Inland Competitive Fishing: Historical Insights, Angler Profiles, and Motivations through Limited Data Integration in Recreational Fishing Research

This study delves into the realm of competitive sport fishing in Greece’s inland waters, where recent years have witnessed a notable surge in such activities. Despite the absence of official records, insights into the sport’s trend and the motivations and socio-demographic characteristics of anglers participating in fishing competitions were gleaned from digital data sourced from online platforms and interviews with anglers. Our findings illuminate the growing popularity of sport fishing in Greece, evident in the increasing number of fishing competitions and the burgeoning angling community. Predominantly male, anglers exhibit a strong dedication to catch-and-release practices, citing relaxation and socialization as primary motivations, with competitive aspirations also shaping their involvement. Moreover, the study highlights legislative gaps in inland water fisheries regulations, underscoring the need for updates to ensure sustainable management and to mitigate illegal activities. Additionally, there exists an opportunity to bolster anglers’ ecological awareness through targeted education initiatives. Ultimately, addressing these conclusions holds the potential to foster responsible fishing practices and contribute to the long-term sustainability of inland water fisheries.

Impact of antiparasitic used in livestock: effects of ivermectin spiked sediment in Prochilodus lineatus, an inland fishery species of South America.

Ivermectin (IVM) is a widely used antiparasitic. Concerns have been raised about its environmental effects in the wetlands of Río de la Plata basin where cattle have been treated with IVM for years. This study investigated the sublethal effects of environmentally relevant IVM concentrations in sediments on the Neotropical fish Prochilodus lineatus. Juvenile P. lineatus were exposed to IVM-spiked sediments (2 and 20µg/Kg) for 14days, alongside a control sediment treatment without IVM. Biochemical and oxidative stress responses were assessed in brain, gills, and liver tissues, including lipid damage, glutathione levels, enzyme activities, and antioxidant competence. Muscle and brain acetylcholinesterase activity (AChE) and stable isotopes of 13C and 15N in muscle were also measured. The lowest IVM treatment resulted in an increase in brain lipid peroxidation, as measured by thiobarbituric acid reactive substances (TBARs), decreased levels of reduced glutathione (GSH) in gills and liver, increased catalase activity (CAT) in the liver, and decreased antioxidant capacity against peroxyl radicals (ACAP) in gills and liver. The highest IVM treatment significantly reduced GSH in the liver. Muscle (AChE) was decreased in both treatments. Multivariate analysis showed significant overall effects in the liver tissue, followed by gills and brain. These findings demonstrate the sublethal effects of IVM in P. lineatus, emphasizing the importance of considering sediment contamination and trophic habits in realistic exposure scenarios.

Establishing a Freshwater Turtle (Emydura subglobosa) Laboratory Line (FTLL) as a novel model species for research and education

<b>The Jardine River turtle (Emydura subglobosa) was selected as a potential model species for studies on freshwater turtles and general reptile physiology. Attempts to establish a freshwater turtle laboratory line were made when an adult pair of E. subglobosa was received in 2016 by the Laboratory of Inland Fisheries and Aquaculture (Poznań University of Life Sciences). The first generation of offspring was obtained in 2017, and the second generation in 2023. In each generation, unrelated specimens were added to the animal cohort to avoid inbreeding. Husbandry regimes were established, and a basal diet for nutritional experiments was developed and manufactured by two methods, producing extruded feed and a gelatine-solidified variant. The establishment of the Freshwater Turtle Laboratory Line (FTLL) provides an opportunity to improve the development of husbandry techniques, increase knowledge of reptile physiology, and use laboratory-raised animals as model species for research and education.

Evolution and Prospects of Freshwater Fish Species and Aquaculture in Colombia: A Historical Perspective

Since the 1970s Colombia has been aware of the importance of aquaculture and inland fisheries in the future of its economy due to the constant increase of a population that is increasingly in need of protein of animal origin. In 1972, a joint project between the Government of Colombia and the Food and Agriculture Organization of the United Nations was approved and aimed at studying inland fishing and developing aquaculture in the country. The work of the project is described, as are the fish culture and fisheries research activities starting with the situation in the 1970s but comparing it with recent findings. A list of the main capture and culture fish species is given. Colombian fishing production has had great variations, but first inland water fishing was more important than marine. For instance, in 1972 total fish catch was 104,390 tons and 79% of that originated from inland waters. After the continental fisheries went down, the marine fisheries accounted in 2019 already 78 per cent of the total catch of the country. Mean standing fish crop estimates in 1975‒76 from the bay, open water and vegetation habitats in four floodplain lakes were 118, 12 and 251 kg/ha indicating clearly that the fish productivity on the Magdalena floodplain was relatively low. The aquaculture sector has been growing rapidly, reflecting global trends, and producing more than capture fisheries. Aquaculture produced 88,000 tons in 2013, which was a three-fold increase from the mid-1990s. Again twofold increase took place before 2020 when the production was almost 180,000 tons. Future development prospects of inland fisheries and aquaculture are discussed and a mention is made of the present situation of ornamental fish cultivation and trade in Colombia.

Potential for a commercial inland fishery or just another water storage facility at Spring Grove Dam, KwaZulu-Natal, South Africa?

South Africa's inland fisheries are generally undervalued, though there is developing interest in the sector. Spring Grove Dam in the KwaZulu-Natal Midlands became operational as a water storage facility in 2013 to provide water to the growing urban population in the province. We assessed whether the impoundment could potentially support commercial fisheries as had been proposed during its design and construction. We conducted seasonal fish community surveys from 2020 to 2021 at sites along the impoundment and in the mainstem of the Mooi River which feeds into the impoundment. We recorded a total of nine fish species, including six non-native fishes with invasive characteristics. Only three of 10 expected native species were found, namely the KwaZulu-Natal yellowfish Labeobarbus natalensis, chubbyhead barb Enteromius anoplus and African longfin eel Anguilla mossambica. Catch per unit effort (CPUE) was low in the sampling surveys using mostly gillnets and fyke nets, and relatively low yields (14.97 tonnes yr-1) were subsequently calculated for the impoundment, making commercial fisheries unviable. However, the existing subsistence and recreational fisheries for non-native salmonids and the native L. natalensis would benefit by controlling the distribution range and abundances of non-native centrachids Micropterus spp. We offer recommendations and suggestions for management plans for Spring Grove Dam in the context of local fish diversity, a changing climate, further construction of water storage facilities on east-flowing rivers in the province, and a nationally neglected inland fishery industry.

Pattern and Dynamics of Genetic Stock of Freshwater Fishes Using Various Molecular Markers for Their Conservation Management Concerns in the Indian Riverine System

India has a world's richest, most abundant and most promising inland fisheries resources with variety fishes in tributaries, streams, canals, lakes, ponds, and reservoirs. There are several significant river systems in India, including the Cauvery, Tapi, Narmada, Krishna, Indus, Brahmaputra, Ganga, Mahanadi, and Godavari which showing shrinkage of fish fauna because of environmental disturbance, human interference and human threats. In order to conserve the fish diversity, the molecular markers are helpful in determining genetic diversity, gene polymorphism and gene flows from generation to generation. The topic experienced a surge in interest due to the introduction of strong statistical analysis tools and the accessibility of DNA fingerprinting, DNA sequencing techniques and consequently population genetic studies. Some molecular markers, Microsatellite markers, RAPD, Allozymes and mitochondrial (cox1, cytob, ATPase6/8) implications have been discussed in this review which will provide an overview that have been used by scientists to studied population genetic structure and genetic variations at various levels.