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Abstract: — The rare species Icelinus pietschi Yabe, Soma et Amaoka, 2001 was first discovered in the Russian waters in the Sea of Japan (the Peter the Great Bay). The characters and description of the analyzed specimen are reported. The species I. pietschi inhabiting the Sea of Japan may be supposedly found from the Peter the Great Bay to the water region off the south coastline of the Sakhalin Island and along the continental coastline northward to the Vladimir Bay and southward to the northern part of the Korean Peninsula. PubDate: 2023-08-01
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Abstract: — Comparison of specimens of the Nile tilapia Oreochromis niloticus of two age groups did not show any significant differences. L-cysteine, L-lysine and citric acid have an attractive taste for juveniles (age 1.5 months, body length 6.5–7.0 cm, weight 5–7 g); L-cysteine and citric acid have an attractive taste for adult fish (4 months, 12–15 cm, 45–50 g). The other eight L-amino acids have an indifferent taste for fish of both age groups. Based on the data obtained and the results of other studies, a hypothetical scheme is proposed, according to which the fastest functional transformations of taste reception in fish ontogeny occur after the start of exogenous feeding of larvae and are completed before maturation. Fish of both age groups rarely re–grasp pellets flavored with taste substances, but juveniles spend much more time on pellets orosensory evaluation, up to 1.4–1.6 times. Regardless of the fish age, such an assessment requires more time if the testing of pellets ends with their ingestion. The differences may indicate an undeveloped stereotype of feeding behavior in juveniles of Nile tilapia. PubDate: 2023-08-01
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Abstract: Abstract The tactics of the reef needlefish Strongylura incisa while hunting for small schooling pelagic fishes is described and photographically documented for the first time. Small flocks of reef needlefish enter the lagoon of the mini-atoll through passages in the reef at the beginning of the tide to hunt small schooling pelagic fishes, which move over the reef into the lagoon of the mini-atoll. In the lagoon, needlefish spread, and part of the flock (only a few) enter the reef itself, while the main part of the flock continues to move along the edge of the lagoonal reef in the direction of schools of small pelagic fishes moving through the reef and cuts the schools into supra-reef and lagoonal parts. Then the reef needlefish move onto the reef and begin to solitary hunt prey at a depth of only 10–15 cm. At such an insignificant depth a school of small pelagic fish loses the ability to turn synchronously. When attacking by a reef needlefish, members of the former school make individual chaotic movements and thereby become easier prey for the needlefish. However, hunting in shallow reef waters poses risks of collision with coral branches on the bottom for the reef needlefish. PubDate: 2023-08-01
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Abstract: — Based on the expedition and literature data, the ichthyoplankton in the southwestern part of the Kara Sea is described. Larvae and pelagic fry of 22 fish species belonging to 19 genera, 10 families, and five orders were found in the study area from 1921 to 2019. Maps of the distribution of the most numerous species in 1981 and 2012–2015 are presented, as well as the data on the distribution density of species per unit volume and area in 2012–2015. It is established that over the past 38 years, the species composition of ichthyoplankton has not been replenished with any species and, first of all with representatives of the boreal complex, which indicates the absence of the processes of borealization of the ichthyofauna of this area observed in some other areas of the Arctic. PubDate: 2023-08-01
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Abstract: The genetic diversity of Pacific rainbow smelt Osmerus dentex from the seas of Okhotsk and Japan has been studied based on nine microsatellite loci and the control region of mitochondrial DNA (940 base pairs). The lowest values of all parameters of genetic diversity of mitochondrial DNA were observed in the group of samples from the northern coast of the Sea of Okhotsk. The highest value of the haplotype diversity was found in the sample from the Sakhalin Island and in rainbow smelt from the Sea of Japan. The star-shaped topology of the genealogical structures indicates a rapid expansion of the abundance and the origin of all populations of the species from a single common ancestor from the main refugium. Based on the results of analysis of nuclear markers, we have revealed a statistically significant genetic structuring of rainbow smelt within its Pacific range (the coefficient of genetic differentiation (FST) is 0.033), which is adequately described by the model of isolation by distance. The greatest genetic differences in two types of markers from the other samples have been found in rainbow smelt from the Shkotovka and Botchi rivers of the basin of the Sea of Japan and from the Naiba River (Sakhalin). The observed patterns of genetic differentiation of Pacific rainbow smelt by the nuclear and mitochondrial markers complement each other well and are most likely associated with differences in the distribution of smelt larvae from the spawning grounds, which are determined by the differentiation of oceanographic conditions. PubDate: 2023-08-01
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Abstract: — First information on the Arctoraja sexoculata frequency of occurrence, ecology, and biology, from the area off the middle Kuril Islands has been provided. It is estimated that the Arctoraja sexoculata is a common bycatch species in trawl fishing for the commander squid Berryteuthis magister in this water area. The locations of catch events for this species were localized off the Ketoy and Simushir Islands and in the Diana Strait at the depths of 250–490 m at a water temperature near the bottom of 1.8–2.5°С. It is supposed that the species belongs to the mesobenthal ichthyocene. In the catches, A. sexoculata represented by individuals of 26–90 cm length and 0.1–5.6 kg body mass. The species probably reaches the age of maturity for the first time at 8–9 years old and over. Its highest life expectancy is 16 years. The individuals of 50–90 cm length become predators consuming predominantly cephalopods and fishes, in the same time isopods and ctenophores among the food items were rarely recorded. PubDate: 2023-08-01
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Abstract: Overall, 85 fish species assigned to 56 genera, 27 families, and 13 orders were observed in the bottom net catches from the Kunashir Strait in 1998–2014. The highest number of species (18) represented the family Pleuronectidae, while the family Cottidae involved the lower number of species (14). Thus, 35 species were found in the Nemuro Strait (including the Kunashir Strait) for the first time. Considering the information in the literature, the total number of fish species in the strait separating the Southern Kuril Islands from the Hokkaido Island increased to 173. PubDate: 2023-08-01
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Abstract: Abstract The dynamics of aggressive behavior of the underyearlings of the rainbow trout Oncorhynchus mykiss infected with metacercariae of the trematodes Diplostomum pseudospathaceum has been studied in an experimental heterogeneous environment for 48 days. The fish competed for the dark area of the bottom by charges, biting, chasing, and frontal and lateral displays. The sharply increased aggressiveness of fish when the parasites became infective (1.0–1.5 months after infection), i.e., capable of infecting the final host (piscivorous birds), manifested itself in an increased frequency of bites (more than 20 times compared to the control) and charges (almost three times) and was accompanied by fast movements, sharp maneuvers, and low ability to compete for shelters. The share of comparatively slow displays and chasing was much smaller. The strategy of D. pseudospathaceum manipulation of fish behavior consists of two stages: (1) protecting the host from predators; (2) increasing the vulnerability of the host. At the first stage, the general level of aggression decreases sharply; at the second, on the contrary, aggressiveness rapidly increases, but the ratio of different categories of aggression changes. The share of categories that make the host more vulnerable to predators increases. High activity and low competitiveness of infected fish contribute to their rapid extermination by predators or moving to another habitat. Such migration of fish can increase the fitness of the parasite, facilitating its dispersal in the water body. PubDate: 2023-08-01
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Abstract: A new species of maurolicid hatchetfish of the genus Argyripnus from the Bonin Ridge in the northwestern part of the Pacific Ocean has been described. A. scharpfi sp. nov. is most similar to A. atlanticus, but differs in smaller and more numerous maxillary teeth, the absence of a noticeable gap between the last photophore of the lateral row and the first photophore of the ventroanal row, the anus close to the anal-fin origin, and, possibly, some meristic and morphometric characters, for the verification of which additional material is necessary. The genus Argyripnus was recorded for the first time on the Bonin Ridge. PubDate: 2023-08-01
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Abstract: Pelagic accumulations of fish are formed above the underwater mountains of the Whale Ridge in the evening and at night, but not observed during daylight hours. The study of such an accumulation above one of the mountains reveals its structure. The central part of the cluster consists of splendid alfonsino Beryx splendens, silver scabbardfish Lepidopus caudatus and oilfish Ruvettus pretiosus tend to keep on the periphery of the splendid alfonsino accumulation. Previously, it was found that food of splendid alfonsino, silver scabbardfish, rosefish Helicolenus mouchezi, Richardson’s boarfish Pentaceros richardsoni, and Cape bonnetmouth Emmelichthys nitidus consisted of organisms forming sound-scattering layers (SSL) above the underwater mountains. The composition of food and the daily dynamics of feeding of the listed commercial fish species indicate that they use two feeding tactics. In the first case, rosefish, Richardson’s boarfish, and Cape bonnetmouth forage for most of their food during the day at the bottom, when the SSL-forming organisms descend to the top of the underwater mountain during the diel migration. In the second case, splendid alfonsino, silver scabbardfish, and oilfish as part of a structured pelagic aggregation feed at night on the organisms rising into the upper layers of the water and forming sound-scattering layers. This tactic expands the possibilities for feeding fish that form pelagic aggregations in the dark hours of the day and allows the use of organisms both brought by the current to the mountain top and those that descended here earlier during the diel migration and then stayed until the beginning of the evening. PubDate: 2023-08-01
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Abstract: The body length and weight of the hatchery- and natural-origin chum salmon Oncorhynchus keta spawners (identified with the otolith marking technique) in the commercial stock in the Yasnomorka River and the Yasnomorskoe salmon stocking fish hatchery were analyzed in 2015–2019. The proportion of hatchery-origin fish comprised 65.5%, varying from 37.2 to 72.9% from year to year. In addition, 9.2% of specimens had the otolith marks provided by the adjacent salmon stocking fish hatcheries, such as the Sokolniki and Kalinin enterprises. The body weight of the natural- and hatchery-origin chum salmon spawners entered the river for spawning for each age group was not different with a few exceptions. However, the females and males spawn naturally tended to reach the sex maturity at the earlier age, on average, in all their generations for a five-year observation, when compared that to the hatchery-origin fish. Overall, the proportion of fish aged 2+ to 3+ among the hatchery- and natural-origin females comprised 25.1 and 61.5%, respectively. With respect to the hatchery- and natural-origin males, the proportions made up 32.2 and 69.0%, respectively. PubDate: 2023-08-01
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Abstract: Length-weight relationship was estimated for the deep-sea congrid eel species collected from the trawler landings at Kalamukku, of Kochi, Kerala and Colachel, of Kanyakumari, Tamil Nadu, Arabian Sea, southern India, between February 2021 and August 2022. The samples were obtained from the deep-sea trawlers, operated along the Exclusive Economic Zone of India, Arabian Sea with a cod end mesh size of 35 mm at 200–250 m depth. The estimated b values range from 2.80 to 3.19. Novelty of the study is providing length-weight relationship for two newly described eel species viz. Ariosoma indicum and A. maurostigma will help in the conservation and management of these species in the future. PubDate: 2023-06-19 DOI: 10.1134/S0032945223040112
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Abstract: Although possession of the large bucco-opercular cavity and its utilization in the feeding, breathing, egg brooding, and burrowing activities are quite obvious in mudskippers, the apparatus of this structure is little known. In the present study, we examined the anatomy of the bucco-opercular sealing apparatus of four oxudercine gobies, Oxuderces nexipinnis, Scartelaos histophorus, Boleophthalmus boddarti, and Periophthalmodon septemradiatus, showing different degrees of terrestriality. The results show that the morphological modifications including the short and restricted gill openings, the membranes on the gill opercular edge (except O. nexipinnis), and the developed hyohyoideus 3 could serve to seal the gill openings. The possible movement of the ceratohyal, the relative height of the urohyal, and the developed geniohyoideus could function to seal the mouth. Contraction of the hyohyoideus 1 to 3 could compress the opercular cavity generating strong mud spitting, whereas activation of the dilator opercula, levator opercula, and a portion of the geniohyoideus may serve to expand this cavity enable sucking mouthful of water at slow speed. These morphological modifications are presumable to facilitate vital activities of mudskippers as transition onto land. PubDate: 2023-06-19 DOI: 10.1134/S0032945223040197
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Abstract: Zona radiata is formed in vitellogenic oocytes between the plasmalemma and the follicular layer. Light microscopy, scanning electron microscopy, and transmission electron microscopy were used to study on the formation of oocytes and zona radiata. The morphological architecture of zona radiata is classified into four types: (1) villous structure-covered massive villi seen only in the genus Rhodeus (R. ocellatus, R. pseudosericeus, R. uyekii, and R. notatus); (2) mesh-shaped structures with porous shapes in Acheilognathus rhombeus and A. macropterus; (3) vine-like structure with longer and thicker materials in A. chankaensis; (4) smooth structure with no any structural modifications in A. yamatsutae, A. lanceolatus, A. koreensis, A. majusculus, A. signifier, and A. somjinensis. In all investigated species, the thickness, the number of pores, and other features of bitterlings zona radiata are species-specific. PubDate: 2023-06-19 DOI: 10.1134/S0032945223040021
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Abstract: The Atlantic bluefin tuna, Thunnus thynnus, is a fish of high economic interest. Nevertheless, its biology is not yet well understood. The objective of the study is to describe the age and the growth of the bluefin tuna collected from the tuna farm located in the East area of Tunisia (Salakta-Mahdia). The age is estimated by counting the annuli on the cross sectioned dorsal fin ray and the Von Bertalanffy growth equation is established: Lt = 390×(1 – exp(−0.07x(t + 1.23)). The estimated age ranges from 3 to 14 years. Most of the catch is composed of bluefin tuna of age class 4 to 7. A positive allometric growth is established for fattened bluefin tuna. The condition factor ranges from 0.98 to 2.63 with a mean value of 1.79 ± 0.26. The mean condition factor shows an increasing trend with age. PubDate: 2023-06-19 DOI: 10.1134/S0032945223040100
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Abstract: — The decorated ponyfish Nuchequula gerreoides and splendid ponyfish Eubleekeria splendens are two abundant leiognathid species in the Pranburi River Estuary, Thailand. However, information about their reproductive activity is still limited, preventing the implementation of effective conservative management. In this study, we investigated the sex ratio and the reproductive characteristics in relation to the size distribution of these polyfish species. Fishes were collected during February to November in 2017. The male to female ratios in N. gerreoides and E. splendens were 1.00 : 5.65 (χ2 = 55.2) and 1.00 : 4.65 (χ2 = 40.0), respectively. These ponyfishes shared similar morphology and histology of the reproductive system. All females were classfied as a juvenile because only undeveloped stage (stage 0) oocytes were found in the ovary. Males below 3.4 cm were all juvenile, but all males above 3.4 cm were mature having spermatogenic cells at spermatogenic stages. PubDate: 2023-06-19 DOI: 10.1134/S0032945223040070
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Abstract: The present work extends the distribution of Hypostomus uruguayensis to the upper Rio Paraguay basin. This species which was originally described from the Rio Uruguay in Southern Brazil and cited to Argentina and Bolivia is here reported for the first time within the Brazilian Midwest. Additionally, the new population was compared to the original description and the holotype of H. uruguayensis, providing a foundation for brief comments on a diagnosis of H. uruguayensis. PubDate: 2023-06-19 DOI: 10.1134/S0032945223040033
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Abstract: This paper is the second part of the “Ichthyofauna of the Fresh and Brackish Waters of Russia and Adjacent Areas: Annotated List with Taxonomic Comments”, which we started in 2022 based on a critical analysis of scientific publications of the last 200 years, and on the data of the author’s research. The current paper includes all currently known fishes of the order Cypriniformes of Russia and adjacent waters, represented by three suborders Catostomoidei, Cobitoidei and Cyprinoidei, comprising ten families, 64 genera and 177 species. The most specious families were the Leuciscidae (59 species/33.3% of all species), Gobionidae (35/19.8%) and Xenocyprididae (23/13.0%), which together represent just over 66% the total cypriniform species. Fourteen of the studied species (24.7% of all cyprinids in Russia) are introduced species, 21 species (11.9%) are endemic; 32 species (18.1%) are recorded from Russia for the first time. In relation to the habitat, 131 species live and breed exclusively in fresh waters, 31 species are of freshwater origin, but can also tolerate slightly brackish waters, ten species are represented by anadromous forms (all with residential populations), and three species are amphidromic, capable of live and reproduce both in brackish water and in freshwater. According to the IUCN criteria, the majority of fish are classified as Least Concern (135 species/76.3%), but two species, Cobitis taurica and Gobio tauricus, are Critically Endangered. PubDate: 2023-06-19 DOI: 10.1134/S0032945223040045
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Abstract: A report of the first occurrence of species Dysomma bucephalus Alcock in the Arabian Sea. The species first recorded outside its type locality in the Bay of Bengal. Dysomma bucephalus is described from three adult specimens collected in the Arabian Sea off the Laccadives at a depth of 193 m. The larval form of the species D. bucephalus was first found in the Bay of Bengal near the Nicobar Islands and is also described herein. These findings expand the known range species westward. PubDate: 2023-06-19 DOI: 10.1134/S0032945223040094
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Abstract: The hillstream loaches are a species-rich group that are well adapted to fast-flowing freshwater habitats. Loss of habitat owing to the construction of hydropower dams makes these fishes vulnerable. The phylogeny of the genus Beaufortia remains contentious according to previous studies. To help clarify the phylogenetic relationships of Beaufortia and related species, we sequenced and analyzed the complete mitogenome of B. pingi. The circular mitogenome is 16 565 b.p. long and contains 13 protein-coding genes (PCGs), 22 transport RNA genes, two ribosomal RNA genes, and one control region. The most-common codon in PCGs was leucine (16.66%), followed by alanine (9.32%) and threonine (7.71%). A phylogenetic analysis including 17 other species of hillstream loaches was performed using the maximum-likelihood method, based on the sequences of 13 mitochondrial PCGs. These species divided into two clades: Gastromyzontidae and Balitoridae, and some genera, including Beaufortia, appeared paraphyletic. Specifically, B. pingi grouped with Erromyzon kalotaenia, Yaoshania pachychilus, and Pseudogastromyzon fangi, followed by clustering with two other species of Beaufortia. PubDate: 2023-06-19 DOI: 10.1134/S0032945223040173
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