Fishing Research Articles

Backward swimming in elongated-bodied abyssal demersal fishes: Synaphobranchidae, Macrouridae, and Ophidiidae.

The deep-sea demersal fish fauna is characterized by a prevalence of elongated-body forms with long tapering tails. Using baited camera landers at depths of 4500-6300 m in the Pacific Ocean, we observed multiple instances of backward swimming using reverse undulation of the slender body in four species: the cutthroat eel Ilyophis robinsae, abyssal grenadier Coryphaenoides yaquinae, and cusk-eels Bassozetus sp. and Barathrites iris. Backward swimming was used as an escape or repositioning maneuver, reversing for up to seven tail beats before resuming forward swimming in a new direction. The eel I. robinsae reversed with a swimming wave frequency of 0.51-0.95 Hz, wavelength 0.6-0.75 of the body length (L), and large amplitude movements of the head from side to side. C. yaquinae reversed relatively slowly at 0.21-0.52 Hz and wavelength 0.5-0.7 L aided by propulsive movements of the pectoral fins and minimal lateral movement of the head. The ophidiids also used reversed propulsive body waves augmented by paddling with the pectoral fins but with some lateral movement of the head. Pectoral-fin movements in all species were in synchrony with the body movements. The elongated-body form enables backward swimming by reversal of the anguilliform propulsive wave and has the advantage that the fish automatically returns to safety along the path recently traveled. This maneuverability conferred by an elongated body may be a significant factor in selection for body shape in deep-sea fishes.

Taxonomic and molecular characterization of Pseudosteringophorusprofundis sp. nov. (Digenea, Fellodistomidae), a parasite of Macrourusholotrachys Günther, 1878 (Gadiformes, Macrouridae) from the deep sea southeastern Pacific Ocean.

Pseudosteringophorusprofundis sp. nov. a new species of deep-sea digenean, parasitizing the gallbladder of the "Bigeye grenadier" (Macrourusholotrachys Günther, 1878) in the deep waters of the southeastern Pacific Ocean is described on the basis of morphological and molecular (28S rRNA) data. The new species is distinguishable from Pseudosteringophorushoplognathi Yamaguti, 1940, the only other member of the genus, by its subterminal oral sucker, the position of the ovary and testes, the larger anterior seminal vesicle compared to the posterior one, and its larger eggs. In addition, the new species is a parasite of a deep-sea fish, whereas P.hoplognathi is a parasite of shallow-water fish. A phylogenetic tree, based on 28S rDNA sequences, indicates that this species is included in a clade of deep-sea fellodistomid species (Steringophorus spp.). We provide the first molecular data on the genus Pseudosteringophorus Yamaguti, 1940 and expand the molecular database for the family Fellodistomidae. Further studies, including sequences from other fellodistomid taxa, are needed to more precisely infer relationships within this family.

Уравнения, описывающие процессы эксплуатации траловых комплексов

Exploring deep-sea resources is an important step towards sustainable and efficient use of marine resources. Research may include analysis of biodiversity, ecosystem characteristics, and deep-sea fishing technologies and practices. Research in this area provides unique opportunities to advance understanding of the marine ecosystem for the development of deep-sea fisheries. This, in turn, helps to strengthen the sustainability and competitiveness of the Russian fishery complex in the long term. In the Russian Federation, the priority is to conduct scientific research in the field of deep-sea fishing, aimed both at developing the fishing of deep-sea objects and at studying them for the purpose of processing for the pharmaceutical industry. The development of innovative methods for catching mesopelagic fish and deep-sea aquatic organisms is an important task for the scientific community of the Russian Federation. The equations designed to describe various processes that occur during the operation of bottom and mid-depth trawl systems are discussed. The complexity of solving the above equations indicates the advisability of dividing exploitation processes into micro-level, macro-level and meta-level. The theory of multiphysics similarity allows you to simulate processes at various levels. Computer programs are presented that make it possible to recalculate the results of model experiments from a model of a trawl complex to a full-scale trawl complex.

The implications of climate change for New Zealand’s freshwater fish

Climate change is poised to reshape ecological communities globally by driving species into new environments and altering interactions between species. Conservation efforts should not only address current pressures but also plan for future pressures, such as sensitive species moving into degraded environments or arising problematic trophic interactions. This study sought to assess how climate change may affect the end-of-century distributions of New Zealand’s native and non-native freshwater fish, including consequences for the overlap between trout (a non-native sports fish) and native species vulnerable to trout predation. Random forest modelling was used to predict end-of-century distributions for New Zealand’s freshwater fish based on six hydrologically downscaled global climate models across four representative concentration pathways. Severe climate change impacts could drive nine native fish species to extinction or near-extinction and cause substantial declines in another eight native species. Seven non-natives are also predicted to decline substantially, including a 30-40% reduction in the extent of trout. To avert these potential extinctions, it is crucial to mitigate climate change severity and improve land use impacting freshwater ecosystems.

Possible New Focus of Diphyllobothriasis, Central Europe.

Diphyllobothriasis is a human parasitic infection that is widespread in the Northern Hemisphere. Popular sport fish such as pike and perch are the source of human infection. We document the autochthonous origin of diphyllobothriasis in a popular tourist destination in Central Europe, which likely marks recent colonization of the parasite.

Qualitative and Quantitative Composition of the Ichthyofauna of the Savica Lakes

Abstract The Savica significant landscape is the only wetland area within the boundaries of the city of Zagreb and as such is of great value. The lake comprises a small section of an old arm of the Sava River, and 13 interconnected lakes created by the expansion of old lake arms. In terms of its biological classification, it is a eutrophic lake and provides adequate conditions for the survival of fish populations. The aim of the study was to investigate the qualitative and quantitative composition of the ichthyofauna in Lake Savica, while determining biodiversity indices, the presence of nonnative species and species composition by trophic and ecological groups. Sampling was carried out by electrofishing at 11 sites in the important landscape of Savica. A total of 20 fish species were recorded, of which 7 were non-native species. These results were compared with previous surveys of the lake. Lake Savica is inhabited by fish from standing waters of the lowlands, and the species present are generally opportune, with some interesting species for sport fishing.

Acidentes com peixes durante pesca artesanal em comunidades florestais na Amazônia Ocidental

Introduction: Amazonian fish have great socioeconomic importance due to their potential for sport fishing, commercial and subsistence uses. However, accidents caused by fish (ichthyism) are very common and are considered a public health problem that receives little attention by public health managers, and epidemiological data is considered underestimated due to the low demand for hospital care. Objective: this research aimed to quantify and evaluate injuries related to fish during subsistence fishing activities in rivers, lakes and streams in forests in the state of Acre in the Western Brazilian Amazon. Methods: 233 residents who practiced artisanal fishing in three protected areas were interviewed. Results: among the fishermen interviewed, 155 (66.5%) reported having suffered at least one accident during this activity, 60.1% of whom were men. The majority of injuries were related to the ethnospecies known as “mandim” (Pimelodus spp.), with the fingers being the most affected region due to handling the fish while removing it from nets and hooks, resulting in pain, bleeding and hotness in the affected area in most cases. Conclusion: the need to produce relevant information on injury prevention and care was observed, which are essential measures to promote the health and treatment of injured fishers.

Development of a microhaplotype panel for steelhead/rainbow trout (Oncorhynchus mykiss) and application for phylogenetic analysis in California

AbstractAdvances in high-throughput sequencing and bioinformatic data processing have prompted a transition in wildlife and fisheries genetics from the use of allozymes, mtDNA, or microsatellites towards markers that are more amenable to genotyping by sequencing, increasing the amount of data obtained for a lower cost with less time-consuming techniques. Microhaplotypes are novel multi-allelic genetic markers that utilize a high-throughput genomic amplicon sequencing approach to genotype large numbers of individuals for parentage and kinship analysis and population genetic studies, including applications in monitoring and fisheries management. We describe the development of a panel of microhaplotypes for Oncorhynchus mykiss, a species of high cultural and economic importance throughout its native range and globally through introductions for aquaculture and due to its reputation as a prized sport fish among recreational fishers. The panel includes 124 loci presumed to be neutral, a marker for the sex determination locus (SdY), and 10 loci targeting previously identified adaptive genomic variants associated with important life-history traits in this species. We demonstrate that this panel provides high resolution for phylogeographic and other genetic analysis and on initial standardized reference population genetic baseline of California O. mykiss.

Swimming kinematics of deep-sea fishes.

Although the deep oceans represent Earth's largest habitat, the challenges of studying deep-sea organisms in situ have limited our understanding of adaptation, ecology, and behaviour in these important ecosystems. One fundamental trait of fishes that remains largely unexplored in the deep ocean is swimming, a vital process for movement, migration, and dispersal in marine habitats. Deep-sea conditions such as temperature, pressure, and food availability could each impact the speed and efficiency of swimming in fishes. To investigate swimming kinematics of fishes with increasing depth, we analysed in situ video of bony fishes across a 6000-m depth gradient. We compared open-source videos of fishes from National Oceanic and Atmospheric Administration (NOAA)Ocean Exploration with tank-based recordings of shallow-water relatives from Puget Sound, Washington, USA to understand how both habitat depth and phylogeny influence swimming in fishes. We analysed kinematics in four dominant demersal fish groups, the orders Anguilliformes, Gadiformes, Ophidiiformes, and Perciformes. Deep-sea fishes swam consistently slowly. Swimming kinematics varied across temperature, oxygen, body elongation, and depth. These results suggest that swimming kinematics do not change linearly with increasing habitat depth in fishes and that the impacts of deep-sea conditions such as low temperatures, high pressures, and low nutrient availability on swimming behaviour need to be considered independently of one another. These findings provide insight into the evolution of fish form and function in the deep ocean.

Variation in lanternfish (Myctophidae) photophore structure: A comprehensive comparative analysis.

The deep-sea open ocean habitat (below 200 m depth) is comprised of little-to-no light, near freezing temperatures, and vastly connected stratified waters. Bioluminescence is often linked to the success and diversification of fishes in these dark deep-sea habitats, which are host to many species-rich and morphologically diverse clades. Fish bioluminescence takes many forms and is used in a variety of behaviors including counterillumination, prey detection and luring, communication, and predator avoidance. This study focuses on lanternfishes (Myctophidae), a diverse group (252 spp. in 34 genera) of deep-sea fishes in which bioluminescence has played a critical role in their diversification. Using histological techniques, we provide new morphological analyses of the complex structure of the primary photophores of representative species from 17 genera in which photophore morphology has not previously been described. We combine this information with data from prior studies to compare primary photophore characteristics for species representing all 34 lanternfish genera. Although we find that lanternfish primary photophores are similar in many of their structural components, including the possession of a modified scale cup, photocytes, pigment, and reflector layers, we observe significant variation among species in other aspects of photophore morphology. Observed morphological differences include variation in pigmentation and in the calcification and thickness of the modified scale cup. We also find reflectors that are very thin or absent in gymnoscopeline and lampanyctine species, relative to the robust reflectors present in myctophine species. We find evidence of secondary reflectors and secondary pigment layers in six lanternfish species and observe major differences in scale-lens thickness and mineralization across the assemblage. Lastly, Scopelopsis multipunctatus is the only species analyzed lacking a photophore cup. Obtaining finer detail of light organ morphology across this species-rich lineage provides much-needed insight into the factors that have contributed to the remarkable diversity of lanternfishes in the deep open ocean.

"Anchoring Capture" Effect Mimicking Proline in Hardy Deep-Sea Fish to Stabilize the Zinc Anode with Lower Operating Temperature.

The low plating/stripping efficiency of zinc anodes, dendrite growth, and high freezing points of aqueous solutions hinder the practical application of aqueous zinc-ion batteries. This paper proposes a zwitterionic permeable network solid-state electrolyte based on the "anchor-capture" effect to address these problems by incorporating proline (Pro, a biological antifreeze agent) into the electrolyte. Extensive validation tests, Quantum Chemistry (QC) calculations, Molecular Dynamics (MD) Simulations, and ab initio molecular dynamics simulations consistently indicate that the amino groups in proline adsorb onto the Zn metal surface, stabilizing the zinc anode-electrolyte interface, suppressing side reactions from water decomposition, and homogenizing zinc-ion flux. This electrolyte demonstrates excellent reversibility in Zn-Mn2O3 cells and Zn-Zn half-cells, achieving a high coulombic efficiency of over 99.4% across 2000 cycles in Zn-Mn2O3 full cells, and delivering a discharge-specific capacity of 175.2 mAhg-1 at -35°C and 1 Ag-1. Additionally, an appropriate concentration of proline lowers the electrolyte's freezing point to -45°C through the network's solid-state effect, ensuring the stable operation of the solid-state battery at -35°C. This innovative concept of network solid-state electrolytes injects new vitality into the development of multifunctional solid-state electrolytes.

Diving deeper into the taxonomy of the Neoscopelus species complex (Myctophiformes: Neoscopelidae) with the description of Neoscopelus serranoi sp. nov.

Previous studies have highlighted possible cryptic biodiversity in the genus Neoscopelus. This hypothesis was tested using new morphological, molecular and biogeographical data on species of this genus caught in the north Atlantic between 2010 and 2022. The information obtained has been combined with available data in an integrative approach, including a review of morphological characters reported in the ichthyological literature and DNA-based species delimitation analyses. The main outcome of the present study is the description of Neoscopelus serranoi sp. nov. from the Atlantic and southwestern Indian Oceans. The new species is morphologically very similar to Neoscopelus microchir from which differs in having a shorter anal-fin base, a shorter pelvic fin, more dorsal and pectoral-fin rays, less anal-fin rays, fewer gillrakers and fewer isthmus and lateral photophores. They also differ in geographic distribution, with the new species occurring in the Atlantic Ocean and the near southwestern Indian Ocean, whereas N. microchir was originally described from Japanese waters of the Pacific Ocean. A literature review of available morphological data between geographic areas for Neoscopelus macrolepidotus and Neoscopelus microchir showed a large intraspecific overlap and no boundaries. However, molecular species delimitation based on the mitochondrial COI gene revealed the existence of cryptic diversity in both species, with eight to ten molecular operational taxonomic units (MOTU), compared to three valid species. Neoscopelus serranoi sp. nov. was considered an independent MOTU in all analyses performed, supporting the morphological identification as a new species. These results highlight that the taxonomy of Neoscopelus is far from settled and show that a greater sampling effort is needed to resolve the uncertainties and to describe unknown putative species. This also exemplifies the virtues of integrative taxonomy in delving into the systematics of deep-sea fishes.

Deep-sea fish reveal alternative pathway for vertebrate visual development.

Vertebrate vision is accomplished by two phenotypically distinct types of photoreceptors in the retina: the saturation-resistant cones for the detection of bright light and the highly sensitive rods for dim light conditions [1]. The current dogma is that, during development, all vertebrates initially feature a cone-dominated retina, and rods are added later [2, 3]. By studying the ontogeny of vision in three species of deep-sea fishes, we show that their larvae express cone-specific genes in photoreceptors with rod-like morphologies. Through development, these fishes either retain this rod-like cone retina (Maurolicus mucronatus) or switch to a retina with true rod photoreceptors with expression of rod-specific genes and transcription factors (Vinciguerria mabahiss and Benthosema pterotum). In contrast to the larvae of most marine fishes, which inhabit the bright upper layer of the open ocean, the larvae of deep-sea fishes occur deeper, exposing them to a dimmer light environment [4-7]. Spectral maxima predictions from molecular dynamics simulations and environmental light estimations suggest that using transmuted photoreceptors that combine the characteristics of both cones and rods maximises visual performance in these dimmer light conditions. Our findings provide molecular, morphological, and functional evidence for the evolution of an alternative developmental pathway for vertebrate vision.

STUDY OF TOURISM SUITABILITY AND CARRYING CAPACITY FOR FISHERIES-BASED ECOTOURISM DEVELOPMENT IN JATIGEDE RESERVOIR, WEST JAVA, INDONESIA

A reservoir is a multipurpose dam. The Jatigede reservoir in Sumedang Regency, West Java Province, Indonesia has excellent potential as a Fisheries-based Ecotourism (FbE) development due to its sufficiently wide inundation area, the availability of fish and marine resources, wealth of natural scenery and strategic location. Currently, Jatigede Reservoir is a well-known natural tourism destination and research study area; however, minimal studies have been conducted on the environmental aspects of tourism. This study aims to determine the ecological potential of Jatigede Reservoir as a Fisheries-based Ecotourism (FbE) destination and its suitability and carrying capacity. This research was conducted between 29th August 2022 and 30th June 2023 and consists of a preliminary survey and main research activity. The study area encompasses eight selected areas: (1) Tegal Jarong, (2) Naga Island, (3) Samiah Fishing Spot, (4) Sabeulit Boating Spot, (5) Jemah Island, (6) Buaya Island, (7) Curug Mas, and (8) Cibunut Fishing Spot. The Tourism Suitability Index (TSI) was calculated for two tourism categories: Fishing and boating. The TSI result for the fishing category is “Conditionally Appropriate” while for boating activity is “Very Appropriate”. The total Tourism Carrying Capacity (TCC) for all study areas is about 13.818 visitors/day.

Fish Species Assemblages and Diversity in Water Body Infested by Alien Species

Human is one of the mediators for non-native species invasion, especially in the aquatic ecosystem. Aquaculture and sport fishing activities are the main reasons for non-native fish introduction, especially in man-made habitats. In the present study, we determined the fish community between the invaded as opposed to pristine ecosystems in north Terengganu, Malaysia. The primary data was collected using hook and line, hand-held push net, cast net and gills net while secondary data were also utilised from published and unpublished data. The fish general information including functional traits and prey-predator relationship were obtained from literature and reliable online resources. The data were used to construct hypothetical diagrams and analyzed using taxonomic distinctness index. The fish community between the two habitats differ significantly in which the non-native fish invaded habitat has much lesser fish species richness than that of the pristine habitat. Taxonomic diversity between the two habitats also was markedly different. The non-native Cichla ocellaris added predation pressure to fish community in the lacustrine habitat as the apex predator and were proven to feed on the native fish fauna in the lake. We discuss the community structure in both habitats and explore the further impact of invasion by this invasive alien species on the native fish species. We conclude that the presence of Cichla ocellaris amplify pressure to native fish community in the man-made lake.

Hydrological and hydrochemical regime foothill rivers of the Almaty region

The hydrological characteristics of the foothill rivers Kaskelen, Aksai and Shamalgan are given, and the results of their hydrochemical studies are also presented. The purpose of this work is to characterize the current hydrological and hydrochemical state of the foothill rivers of the Almaty region, for applicability in the use of foothill rivers in fisheries (sport fishing, organization of aquaculture enterprises).

Lipidome and proteome analyses provide insights into Mariana Trench Snailfish (Pseudoliparis swirei) adaptation to the hadal zone

The hadal zone environment, characterized by extreme hydrostatic pressure, low temperatures, and limited food availability, presents substantial survival challenges for deep-sea fish species. In this study, we captured five deep-sea fish species (Bathysaurus mollis, Coryphaenoides rudis, Ilyophis sp., I. brunneus and Pseudoliparis swirei) from the Mariana Trench at depths ranging from 2027 to 7125 ​m, by employing China's “Exploration I and Exploration II”. By combining lipidomic and proteomic analyses, we aimed to explore the genetic basis of adaptive evolution to the hadal zone in fish. The results indicate several key findings: (1) P. swirei (Mariana hadal snailfish, MHS) may enhance energy storage and utilization during prolonged fasting periods by significantly increasing liver tissue levels of cholesterol ester (CE), ether-linked triacylglycerol (TG-O), coenzyme Q (CoQ), and ATPase content; (2) MHS could maintain membrane fluidity under high pressure by increasing the proportion of unsaturated fatty acids while reducing levels of cholesterol and phosphatidylethanolamine (PE) content. (3) The regulation of lipid types and ratios could increase the risk of lipid peroxidation. To counter oxidative stress, MHS likely elevates monounsaturated fatty acid content and enhances antioxidants such as transferrin and heat shock proteins. Overall, this study provides new insights into the adaptive mechanisms of MHS to deep-sea conditions through the lipidome and proteome analyses, thus broadening our understanding of its resilience in the hadal zone.

Invisible dynamics: exploring the genetic diversity of peacock bass in Brazil

In Brazil, the introduction of non-native species into freshwater environments, such as peacock bass (Cichla spp.), was driven by aquaculture and sport fishing. These Amazonian fish possess phenotypic plasticity and resilience that facilitate their invasion and establishment in new habitats. Due to the taxonomic complexity of cichlids, studies on intraspecific variation are essential to mitigate the impacts of biological invasions. This study aimed to analyze the genetic diversity of peacock bass, assessing how invasive populations have diversified over time and across different regions in Brazil. Samples were collected from different invasive populations in Maranhão, São Paulo, Paraná, and Goiás. DNA was extracted and the 16S and COX1 genes were amplified. Ninety-seven specimens of the genus Cichla Schneider, 1801 were identified as Cichla monoculus Agassiz, 1831 (n=12); Cichla kelberi Kullander and Ferreira, 2006 (n=75); and Cichla piquiti (Kullander and Ferreira, 2006) (n=10). Sixteen 16S haplotypes (445bp) were identified, with haplotype diversity and nucleotide diversity values of Hd: 0.830 and Pi: 0.03777, respectively. The results showed proximity between the invasive populations from Maranhão and São Paulo, with haplotype sharing among Parque Nacional dos Lençóis Maranhenses, Baixada Maranhense, and Ilha Solteira. This highlights the fragility of species delimitation and definitions within the group, based solely on morphological data. By evaluating the set of morphological and genetic data, we found significant intraspecific variations, despite expecting population homogeneity due to the founder effect and bottleneck commonly observed in invasive populations. This underscores the adaptive potential of these cichlids.

Omega-3 polyunsaturated fatty acids, especially DHA and EPA, remold gut microbiota to suppress inflammation in rabbits with atherosclerosis

Atherosclerosis (AS) caused by a high-fat diet becomes a critical cause of cardiovascular diseases, which has been regarded as an urgent public health problem. Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) have many beneficial effects on human health. However, in recent years, the critical role of gut microbiota in atherosclerosis has been gradually proposed, and the impact of omega-3 PUFAs on cardiovascular diseases via gut microbiota in rabbits remains unknown. Likewise, the role of omega-3 PUFAs in regulating endothelial lesions, visceral injury, and vascular inflammation caused by high-fat diet-induced trimethylamine-nitrogen oxide (TMAO) has not been reported. Here, we investigated the effects of omega-3 PUFAs administered orally on atherosclerosis via an atherosclerotic rabbit model induced by a high-fat diet. The results showed that omega-3 PUFAs obtained from deep-sea fish oil can alleviate high-fat diet-induced atherosclerosis by inhibiting the increase of plasma TMAO and the formation of liver foam cells, reducing inflammatory factors, fat deposition, and plasma lipid levels and suppressing organ damage. Furthermore, gut microbiota disrupted by a high-fat diet were remodeled in rabbits treated with omega-3 PUFAs. These results further confirm that omega-3 PUFAs are promising nutritional and medical health foods that can be supplemented daily to prevent cardiovascular diseases.

Emigration of Juvenile Tarpon Megalops atlanticus from Ephemerally Connected Coastal Ponds

Worldwide, coastal wetlands are threatened by disrupted hydrology, urbanization, and sea-level rise. In southwest Florida, coastal wetlands include tidal creeks and coastal ponds, which are the primary habitats used by juvenile Tarpon, Megalops atlanticus, an important sport fish. Coastal ponds can occur near uplands and are ephemerally connected to the open estuary, creating conditions of variable dissolved oxygen and salinity. Juveniles can tolerate wide-ranging abiotic conditions, but little is known about how they egress from their remote nursery habitats, which often requires them to cross > 1 km of mangrove forest to reach the open estuary. The objective of this study was to (1) compare Tarpon body condition among ponds close to the open estuary versus those ponds farther away on the Cape Haze peninsula of Charlotte Harbor, Florida, and (2) using acoustic telemetry determine what factors contribute to Tarpon emigration from the ponds to open estuarine waters. We tested the hypothesis that distinct groups of Tarpon occur in isolated ponds, leading to variation in fish length and body condition, and that opportunities for emigration from these ponds hinge on high water events. No pond stood out as having Tarpon of low body condition. Factors contributing to increased probabilities of Tarpon emigration were low barometric pressure, high-water level, and Tarpon body length. Tarpon emigrated from ponds near tidal creeks during summer king tides, while tropical cyclone conditions were needed to allow for movement from ponds farther in the landscape. The juvenile Tarpon were later detected at the mouths of large rivers 30 km up-estuary. The characterizations of water levels and event criteria needed for successful Tarpon nurseries should aid in habitat conservation and the creation of Tarpon nursery habitat in restoration designs.