Vol 59, No 2 (2019)

A new species, Melanostigma meteori sp. n., is described from the Meteor Bank (southeastern Atlantic Ocean). The specimens of the new species were caught during the AtlantNIRO research expedition (1981) at the depths of 950–1000 m. The new species differs from other species of the Melanostigma genus by unique biological amplification of the lateral line of the body, which has four series of neuromasts (predorsal, dorsolateral, mediolateral, and ventral), and original combination of the features in the structure of the head canals of the lateral line, the axial skeleton, and coloration. The phenomenon of the lateral line polymerization, which is observed in a number of groups of higher Teleostei, including the Zoarcidae family, is considered in detail.

Landmark-based morphometrics are examined to evaluate the population status of Schizopyge niger (Heckel, 1838) from Dal Lake and Jhelum River. A total of 180 individuals are collected from the two locations, and a truss network is constructed by interconnecting 12 landmarks to yield 30 distance variables that are extracted from digital images of specimens using tpsDig2 and PAST software. Transformed truss measurements are subjected to Principal Component Analysis (PCA), where the first component explains 78.43% of total variance, while the second and third components explain 4.62 and 2.91% of total variance respectively. The high component loadings are from the characters which mostly contribute to anterior half of body depth, middle portion of body depth, and head region. The bivariate plot of PC1 and PC2 clearly indicates the separation of the two populations. The cross validation of this analysis reveals that the percentage of correctly classified fishes is 100% both in Dal Lake as well as Jhelum River.

Long-term data on spatial and bathymetric distributions, preferred bottom temperatures, length and weight of blue hake Antimora rostrata caught off the Atlantic coast of South America are presented based on published and unpublished materials. The species frequently occurred in waters of southern Argentina where catches were considerably higher as compared with Brazilian waters. The blue hake were captured at depths from 97 to 2162 m (average depth 1279 m). Most of the specimens (65.1%) were collected at depths from 700 to 1300 m, similar to depths in other parts of the species’ range. Bottom temperatures at sites of blue hake captures in Brazilian waters were 2.18–4.20°C (average 2.93°C). Specimens in bottom trawl catches were 9–61 cm in total length, averaging 34.84 cm. The bulk of the catches (85.5% of individuals) were fish of 25–45 cm. Body weight ranged from 70 to 1380 g (average 437.5 g). Frequency of occurrence decreased from southern Argentina to northern Brazil; complete absence of records in the Central Western Atlantic might relate to different means by which the blue hake colonized the Pacific and Atlantic coasts of South America.

The present study was undertaken to estimate age and growth of the spotted snakehead Channa punctata (Bloch, 1793) from the Ganga River, based on 390 fish samples collected during August 2016 to July 2017. Each of the 3 otoliths (lapillus, asteriscus and sagitta) were dissected out, cleaned and observed to identify the annual rings. Based on clarity of annuli and ease of reading, sagittae (whole as well as sectioned) were selected for age estimation. Standard procedures were followed to prepare and study the age structures viz., the otoliths and scales. The alternating opaque and translucent bands present on the ageing structures were interpreted as annuli. Amongst the 3 methods used for age estimation, the sectioned otolith exhibited highest percentage of agreement (92.4) between readers, and least values of average percent of error (2.68) and coefficient of variation (2.36). Age estimates from sectioned otoliths were taken to develop the von Bertalanffy growth equation [L_t = 31.5(1 – e^{–0.29(t+ 1.06)})] for the target fish species. The observed and calculated lengths in the fish did not vary significantly. Thus, the sectioned otoliths may be used for precise age estimation as well as calculation of various age-based population parameters of C. punctata inhabiting the river Ganga.

The results of the analysis of the bolus of the larval river lamprey Lampetra fluviatlis caught in the Chernaya River in May are presented. A quantitative analysis of the main food components is performed; the taxonomic composition of algae and invertebrates is determined. The content of the digestive tract consists mainly (>90% of weight) of sand and detritus as well as algae and invertebrates. A large amount of diatoms, other plankton, and periphyton unicellular algae and coenobia, as well as plankton rotifers, have been first found among food items. It is shown that organisms from the river flow may play a critical role in larval lamprey.

Analysis of previously published characteristics of the downstream migration of juvenile cyprinids (Cyprinidae) and percids (Percidae) from the Volga and Ivankovskoe, Volgogradskoe, and Tsimlayanskoe reservoirs is presented. In case of river damming, migrations of river fish are modified first of all due to transformation of the hydrophysical and morphological structure of the water course creating a different biotopic pattern influencing life activities of fish, including migratory behavior. In contrast to the natural river, where the conditions controlling the characteristics of the downstream migration change gradually from the upper reaches to the lower reaches, ecological barriers are formed in the dammed river—the water reservoir and the dam—which essentially change these conditions. A leading role in formation of these barriers and in regulation of the downstream migration is performed by the morphological complexity of a water body and by the intensity of water exchange. These factors act both on the scale of the whole water reservoir and on the scale of local biotopes where the downstream migration takes place and behavioral mechanisms act efficiently. The synergistic effect of these factors (a high ramification index of the reservoir at a low water exchange) may decrease the intensity of emigration of fish juveniles from a reservoir by several orders of magnitude.

The content of total moisture, dry matter, lipids, proteins, ash, and nitrogen-free extractive substances in the muscles, liver, and gonads have been analyzed for pike-perch Sander lucioperca and sichel Pelecus cultratus of Gorky Reservoir. In the muscles of the females of these fish species, the products of the lipid and protein metabolism accumulate more intensively than in males. In both pike-perch and sichel, the accumulation of lipids, proteins, nitrogen-free extractive substances in the liver, as well as protein and nitrogen-free extractive substances in the gonads, are similar in males and females. During the maturation of pike-perch and sichel, substances of various chemical nature are assimilated in the gonads. The nature of the accumulation of metabolic end products in the muscles and liver with age is similar. In the sichel muscles, a direct dependence of the lipid content on age is found, while it is the opposite in the pike-perch muscles, which may be due to the peculiarities of the fish nutrition.

Eustomias zygolampas sp. n. is described from the western Indian Ocean; it is characterized by the specific structure of the chin barbel. The new species belongs to the Dinematochirus subgenus. Species most similar to it are known so far only from the North Atlantic and the Central Pacific (Hawaii region).

The photographs of Hemitaurichthys polylepis in the natural environment of the coastal waters of Vietnam (Hon Noi) are given for the first time. The feeding of the representatives of the species on epibenthic organisms is registered on the slope of the reef. The data on the occurrence and depth distribution (6–35 m) of this rare (for the studied water area) species in the coastal waters of Vietnam are reviewed.

Transoceanic migration in lampreys is documented for the first time. 40 adult Pacific lampreys Entosphenus tridentatus were tagged with passive integrated transponder (PIT) tags in the western Bering Sea between 2012 and 2015. In September 2015, one of them was detected in the Columbia River basin. This testifies that Pacific lamreys are capable to perform lengthy transoceanic migrations from feeding grounds in the Bering Sea to spawning grounds in the U.S. and Canada rivers.