A total of 486 specimens of Scardinius erythrophthalmus caught in the Anzali lagoon, a large lagoon located in the southwest Caspian Sea (Iran), between March and June 2007 were
examined. Age determination showed that the maximum ages observed were 4+ in males and 5+ in females. Isometric growth was
identified from length-weight relationship in males, females and pooled data. There was no significant difference from parity
in the overall sex ratio of 252 males to 234 females. The fish spawn from mid April to late May, with peak spawning in mid
May with the highest average GSI value of 7.12 and 13.52 for males and females respectively. The absolute fecundity ranged
between 1482–59620 eggs with the mean of 9287.87 eggs while relative fecundity ranged from 127.8 to 1737.6 eggs/g with the
average of 709 eggs/g of body weight. Egg diameter ranged from 0.43 to 1.23 mm with a mean of 0.73 mm. The characteristics
of rudd in the stunted population from the Anzali lagoon differ markedly from those of other localities of its range.
Key wordsgrowth-fecundity-gonadosomatic index-length-weight relationship
The first capture in Russian waters of a spinulated specimen of Lobotes surinamensis with spinulation of opercular bones is reported. Morphology of two specimens is compared—with spines and without them. The
description is composed. There are no significant differences between them. With consideration of the original and published
data, we concluded that this character (spines) has no taxonomic value.
Keywords
Lobotes surinamensis
–description–taxonomy–the Sea of Japan
Comparative analysis of plastic and meristic characteristics of big-scaled redfin Tribolodon hakonensis from Sakhalin and southern Primorye has been performed. The considerable differences revealed are supported by results of
genetic studies. The results of comparison of morphology of big-scaled and Pacific T. brandtii redfins with the purpose of assessing the probability of the previously advanced hypothesis on the origin of the “southern”
form of big-scaled redfin are provided.
Key words
Tribolodon
-Far Eastern redfins-Sakhalin-Primorye
On the basis of morphometric analysis of our collections of pairs of spawning fish of the genus Neozoarces, development of prolarvae of fish, and a survey of museum collections, a conclusion is made in respect to only one of the
two species of the genus—tape blenny Neozoarces pulcher, Steindachner, 1880. Differences in morphometric characters and coloration of different fish are accounted for by a sharply
expressed sexual dimorphism. The reproduction and the egg and prolarvae development in N. pulcher are described.
A new species of eel cods Muraenolepis trunovi sp. nova (Muraenolepididae) from the Lazarev Sea is described. The type specimen is caught at the depth 730–860 m. The new
species differs from all known species in very elongated first dorsal and pectoral fins. With respect to the body proportions
and the number of rays in the second dorsal fin and the anal fin, it is related to M. marmorata but clearly differs from the latter in a greater number of vertebrae (73 vs. 67–69), in the reduced upper lateral line (to
one sensory tube), and in complete absence of the lower lateral line on the body. The lectotypes of Muraenolepis marmorata Günther, 1880 (British Natural History Museum, BNHM) and M. marmoratus microps (Lönnberg, 1905) (Naturhistoriska Riksmuseum, NRM) are redescribed.
A second finding of the right-eyed flounder Nematops microstoma in the equatorial part of the Pacific Ocean (two individuals from the Gilbert Islands), previously known only from type locality
near the Admiralty Islands, is reported. Illustrated descriptions of specific features of morphology of caught individuals
are provided, and their identification with N. microstoma is substantiated.
This study reviews the nominal taxa within the species “Nemachilus” stoliczkae and “N.” dorsonotatus, described by Herzenstein (1888). N. dorsonotatus, N. d. retropinnis, and N. plagiognathus are reviewed within the species Triplophysa stoliczkae; it is suggested that this species is represented by at least 5 subspecies. N. stoliczkae brevicauda, N. s. leptosoma (synonym, N. s. productus), and N. s. crassicauda are considered as valid species, the last 2 are related to the group including the species T. tenuis, T. choprai, T. tenuicauda, and T. yasinensis rather than with T. stoliczkae. It was shown that the “stoliczkae” species group (sensu Prokofiev, 2001) should be divided into three species groups: “stoliczkae” (s. str.), “tenuis,” and “robusta”; their diagnoses and the species composition are presented. A new species from the “stoliczkae” group is described (T. scapanognatha sp. nova), related to T. tanggulaensis (Zhu, 1982).
External morphology and osteology of Triplophysa alticeps, type species of the subgenus Qinghaichthys, is described. A detailed morphological comparison of this species with other species of the genus is also provided. The
characteristic traits of T. alticeps include: a short and deep head, neurocranium swollen in the postorbital part, significantly reduced seismosensory system,
absence of brushlike aggregations of tubercles on both sides of the head in males, three pectoral radialia, short ventroanal
distance, absence of manubrium, and several other features. Possibly, the subgenus Qinghaichthys should be recognized as valid, and should include the species with three radialia of the pectoral fin, a direct contact of
the swollen halves of the air-bladder capsule, short swollen head, and without brushlike aggregations of tubercles on the
sides of the head in males.
Juveniles of Leptoclinus maculatus diaphanocarus were observed in great numbers in netting of bottom trawl in the period from April 28 to May 7 2007 in the Tatar Strait.
Metamorphosis of juveniles reached its end at the body length from 8.5 to 11.0 cm. It was accompanied by change of coloration.
After transition to the bottom mode of life, the frequency of occurrence of specimens of this species in catches drastically
decreased. Principal counts are estimated, with consideration of additional material from far eastern seas of Russia. Two
groups of specimens which would correspond to the Pacific and the Atlantic subspecies sensu Andriashev are not found. It is
suggested that, for determination of the actual taxonomic status of intraspecies groups of the species L. maculatus, additional comparative material on morphology and genetics is needed from different regions.
Keywords
Leptoclinus maculatus diaphanocarus
–pelagic juveniles–distribution–counts–the Tatar Strait
The capture in waters off southeastern Sakhalin of a male of Hydrolagus TL 122 cm is described. It is tentatively identified as Hydrolagus cf. purpurescens, a new species for the fauna and the second representative of the subclass in far eastern waters of Russia. The captured
specimen is briefly described and its photographs are published. Unsolved problems of taxonomy of the group purpurescens complex do not permit to make a unanimous determination of this specimen. These problems are discussed and some items concerning
the nomenclature of this group are specified.
North Pacific Pseudoscopelus sagamianus (from the Kuroshio zone) are characterized morphologically in detail. The neotype is established. The North Pacific population
and the group of populations from the Atlantic and Indian oceans are compared in detail, significant differences are found
between them in coloration of the orobranchial cavity and in the pattern of photophores of series trf and prcf. In the author’s opinion, these differences are of the subspecies level. Potential areas of subspecies are discussed, and
the area of the whole species is verified. A possibility of validity of the name P. pierbartus Spitz et al., 2007, for the group of populations from the Atlantic and Indian oceans is considered. Additions and changes
to methods of investigations of Pseudoscopelus suggested by Melo et al. (2007) are critically discussed.
New findings of representatives of the endemic Sea of Okhotsk species—eelpout Lycodes semenovi Popov, 1931 (Perciformes: Zoarcidae)—previously known only from the type specimen are reported. The morphological description
of available individuals of this rare species is provided.
Sequencing of the fragment of control region in mitochondrial DNA in sculpin Cottus volki and the comparison of obtained data with homologous nucleotide sequences in the other species from genus Cottus demonstrated that C. volki occupies the basal position in the “poecilopus” group, which includes also typical sculpin C. poecilopus Heckel, 1837 from water bodies of Europe, sculpin C. szanaga Dybowski, 1869 from the Amur River basin, and sculpin Cottus cf. poecilopus from the Lena River basin. Early separation of C. volki line from common trunk of “poecilopus” group explains the presence in C. volki of several primitive (plesiomorphic for this group) morphological characters: long interior ray of ventral fin, practically
complete lateral body line, and well-developed dentition of palatine bones.
Morphology of a rare species—large-scale eelpout Lycodes macrolepis Taranetz et Andriashev, 1935—has been studied. It was shown that the main lateral line of this species has a ventrolateral
configuration rather than medial, as was considered previously. Large-scale eelpout is an endemic species of the Sea of Okhotsk;
evidence of its finding in the Sea of Japan is based on the erroneous classification of another eelpout species.
Key wordsLycodes-Sea of Okhotsk-lateral line-distribution
The first finding in the Sea of Japan of two specimens of Alectrias gallinus (Lindberg, 1938). Localities of captures, plastic characteristics, meristic characteristics and general habit of the investigated
fish are described.
A description of a rare representative of the family Gadidae—the Norwegian pollock Theragra finnmarchica Koefoed, 1956—is given. The Norwegian pollock caught in November 2004 in the Barents Sea off Nadezhda Island is the first
individual of this species officially recorded in Russia. At the present time, reliable information is available about 42
caught individuals of this species. A review was performed of evidence on the history of study and modern concepts of the
origin, biology, and distribution of Norwegian pollock.
Key wordsNorwegian pollock-amphiboreal distribution-morphology-ecological specific features-history of studies
The only known fossil representative of the genus Triplophysa, T. opinata from the middle-upper Miocene of Kirgizia is redescribed. It is suggested that this species is closest to the species groups
“dorsalis” and “labiata” (sensu Prokofiev, 2002, 2004a). The fossil finding clearly suggests that Triplophysa developed no later than in the middle of the Neogene.
It was determined on the basis of data on species composition and distribution that ichthyoplankton in the Sea of Japan within
the exclusive economic zone of Russia was represented in October 1995 and September 2001 by 13 species. Anchovy Engraulis japonicus and saury Cololabis saira were the most abundant and widely distributed. The area of distribution of anchovy larvae and juveniles was great, but was
restricted mostly to subtropical waters. The larvae and juveniles of saury were captured to the west of the frontal interface
in the waters of subarctic structure. The character of the distribution of early progeny suggests that the spawning of saury
in summer ran in the economic zone of Russia. The early progeny of saury was absent in the zone of Japan filled with subtropical
waters. Because of peculiarities of spawning strategy of the spawners, the regions of distribution and maximum concentrations
of their larvae and juveniles did not overlap and were associated with different water masses. The species composition of
larvae and young fishes collected with the Maruchi-Ami fry net was more diverse in comparison to the fish-egg net IKS-80.
The parameters of the catches of both nets on conversion to the filtered volume of water were comparable only in the regions
with increased concentrations of larvae and juveniles. The fry net was not very efficient for calculating recruitment in the
dispersed autumn aggregations.
In studying the variation of the taxa group Pseudopleuronectes yokohamae and P. schrenki from various areas in the Sea of Japan, significant differences in the combination of morphometric and meristic characters
were not revealed. It was found that typical characters such as fin coloration from the blind side of the body, number of
rays in the fins, number of scales in the lateral line, etc. that are used by most authors to distinguish P. yokohamae and P. shrenki strongly vary and are not adequate for assigning individuals to a certain taxon. A conclusion of the absence of differences
and, hence, the homogeneity of the group studied is supported by genetic-biochemical studies, as well as by analysis of the
lateral line system of these two groups of flatfish. Considering the results obtained and literature data on the morphology
and ecology of flatfish taxa considered in the paper, it is justifiable to consider the P. yokohamae + P. schrenki group as one polymorphic species Pseudopleuronectes yokohamae Günther, 1877. The second taxon, P. shrenki, as a later species, should be considered a synonym of the species P. yokohamae.
The state of the reproductive system of Tinca tinca—descendants of individuals that were exposed to radiation as a result of the catastrophe at the Chernobyl Nuclear Power Plant
in 1986 was studied. Material was collected in the postemergency period in radionuclide-polluted water bodies: in the Ukraine,
in Kiev Reservoir, the Teterev River, and Lake Glubokoe (1999–2005) and in Belarus, in Lake Svyatoe (1998–1999). It is demonstrated
that the total number and the extent of disturbances in the gonads of T. tinca are positively related to the levels of pollution in water bodies: in the cleanest water body, the Teterev River, the proportion
of fish with gonads without considerable deviations was about 93%; in Kiev Reservoir, 79%, and in Lake Svyatoe, only 18%.
Among the “postemergency” generations of T. tinca, the maximum number of disturbances in sexual cells and gonads was recorded in F3–4, which is evidently caused by a phenomenon of the “prolonged mutagenesis”. A relatively high species resistance of the reproductive
system of T. tinca to the radiation impact, in comparison with other cyprinids, was recorded.
The state of the reproductive system of the pike Esox lucius, descendants of individuals exposed to X-ray irradiation due to the catastrophe at the Chernobyl Nuclear Power Plant in 1986,
was studied. The material was collected in water bodies of Ukraine contaminated with radionuclides—Kiev Reservoir, the Teterev
River, and Lake Glubokoe in the postcatastrophe period 1999–2004. It was shown that the total number and the extent of disturbances
in the pike gonads are positively correlated with the levels of contamination of the water bodies: in the cleanest water body,
the Teterev River, the proportion of fish with gonads without considerable deviations was 70%; in the Kiev Reservoir, it was
45%; no individuals with normal gonads were recorded in Lake Glubokoe. The great number of anomalies in sexual cells and gonads
has led to a decrease in the reproductive capacity of the pike populations studied. A unique case was revealed of synchronous
hermaphroditism in a pike from the Kiev Reservoir that belonged to the fourth generation (F4) of fish that underwent emergency loads. Among postemergency pike generations, the maximum number of disturbances in sexual
cells and gonads was recorded in F2–4, which is possibly accounted for by the phenomenon of “prolonged mutagenesis.”
Based on complex epipelagic surveys in the western Bering Sea, a comparative analysis of food supply of Pacific salmon (Oncorhynchus spp.) was conducted in summer and fall from 2002 to 2006. Nine indirect indices of food supply used in the study were as
follows: feeding similarity, width of the feeding spectrum, diet feeding ration, diet feeding rhythms, fraction of accessory
food in the ration, growth rate of the fish, abundance of food resources, and abundance of salmon. The food supply of salmon
is lower in summer 2003 and fall 2006 in comparison to the food supply in other years of the study. However, well expressed
feeding selectivity, consumption of prey items of certain type, and small proportion of accessory food (copepods and chaetognaths)
prevailed in plankton, suggests the presence of sufficient food resources for Pacific salmon in the western Bering Sea.
KeywordsPacific salmon–food resources–food supply–feeding selectivity–growth rate–ration–feeding rhythms
The ichthyofauna of the narrow coastal zone of southwest Crimea in 2003–2004 was represented by 79 fish species belonging
to 36 families. The structure of the species composition of eggs, larvae, and adult fish in these years indicated to its restoration
in comparison with the late 1980s to early 1990s. The abundance of commercial fish increased: Engraulis encrasicolus ponticus, Trachurus mediterraneus ponticus, and Mullus barbatus ponticus. The quantity of migratory fish increased: Pomatomus saltatrix and Sarda sarda. The presence in winter catches of Trachurus mediterraneus ponticus and Pomatomus saltatrix indicated favorable conditions for their wintering off South Crimea. Appearance in catches of the fish of elder age groups
is evidence of the restoration of their age structure. The competitor for food Mnemiopsis leydyi still influences the food resources of the fish and, thus, their survival. If they appear in plankton simultaneously, the
abundance of larvae drastically decreases. The obtained data indicate to the vulnerability of coastal biocenoses to anthropogenous
impact and to the necessity of monitoring of fish resources and of their protection.
Data on the distribution of juvenile rock-nosed grenadier Coryphaenoides rupestris in the northern Atlantic are provided. The results of studies of the size and age composition are presented, and specific
features of vertical and horizontal distribution of juvenile individuals are analyzed. Directions of the subsequent study
of the species in early ontogenesis are determined.
In summer-autumn of 2003–2004, the ichthyoplankton of the Sea of Okhotsk comprised 35 species. In this period the most widely
distributed and numerous were larvae of the lord Hemilepidotus gilberti, the Pacific stout sand lance Ammodytes hexapterus, and the Sakhalin dab Limanda sakhalinensis. The maximum catches of fish larvae were attributed to coastal waters off eastern Sakhalin and to the shelf of the northern
part of the Sea of Okhotsk. In November of 2003, the ichthyoplankton of the Sea of Japan was represented by fish larvae belonging
mainly to the boreal ichthyocomplex. The catches consisted predominantly of larvae of the arabesque greenling Pleurogrammus azonus, the ronquil Bathymaster derjugini, and the rockfish Sebastes owstoni. Fish larvae and fry in the northwestern part of the Sea of Japan were caught principally within 43°–45° N and 137°–139°
E above the depth 1500–2000 m. The food spectrum of fish larvae in the Sea of Okhotsk and the Sea of Japan comprised over
20 plankters of various size belonging to seven taxa. Irrespective of fish species, the food items common of all fish were
copepods Pseudocalanus minutus and Oithona similis. The daily rations were calculated for mass species (Hemilepidotus gilberti, Ammodytes hexapterus, Hexagrammos stelleri, Pleurogrammus azonus, Bathymaster derjugini, and Sebastes owstoni). The larvae of all considered species in the Sea of Japan and in the Sea of Okhotsk fed predominantly in the light period
of the day.
Data on the numbers, species composition, and spatial distribution of ichthyoplankton, mesoplankton, and jelly-bodied microplankton
in the western sector of the Black Sea in October 2005 are presented. A decrease in the predatory impact of the comb jellyfish
Mnemiopsis leidyi on mesoplankton is recorded, which promoted the formation of favorable trophical conditions for larval fish survival. In
the 1990s in the study area, the proportion of larvae with empty stomachs reached 80–90%; in October 2005, all the studied
larvae were with food.
Key wordsichthyoplankton-mesoplankton-jelly-bodied microplankton-species composition-numbers-distribution-feeding of larvae-the Black Sea
Ichthyoplankton of Feodosiya bay in December 2006 was represented by eggs and larvae of winter-spawning fish species belonging
to three families. The average abundance of fish eggs and larvae was 62.1 and 5.5 pcs/m3, respectively, and was comparable with the values for the 1950s. The eggs and larvae of sprat Sprattus sprattus phalericus dominated. Most larvae of two winter-spawning species—sprat and smooth sand lance Gymnammodytes cicerellus—had food in their intestines. The species composition consumed by larvae of both species was similar. In comparison with
the 1950s and the 1980s, the food composition changed due to significant transformation of planktonic communities in the 1990s.
Ichthyoplankton of the Sea of Okhotsk from October to December 2007 comprised larvae and fry of eight fish species belonging
to five families. The larvae of lord Hemilepidotus gilberti, white-spotted greenling Hexagrammos stelleri, and Atka mackerel Pleurogrammus monopterygius were the most widespread and numerous in the study period. Fish larvae from October to December 2007 were seined over the
vast water area of the Sea of Okhotsk, maximum catches were made in waters of western Kamchatka. The food spectrum of larvae
of five fish species (H. gilberti, Hexagrammos octogrammus, H. stelleri, P. monopterygius, and Bathymaster signatus) included approximately 20 plankters. Irrespective of species belonging, copepods Pseudocalanus minutus and Oithona similis, eggs and nauplii of copepods, as well as juveniles of pteropods were common food items for all fish. Larvae of all considered
fish species in the Sea of Okhotsk fed mainly during the light hours of the day.
Key wordsichthyoplankton-the Sea of Okhotsk-distribution-size composition-feeding-index of stomach fullness
Results of the revision of black swallowers (Chiasmodon) made by Melo (2009) are reconsidered. It is shown that separation of species by this author is based on individually varying
characters investigated by this author on a limited number of fish, and some conclusions made in this study are based on factual
mistakes. Validity of C. lavenbergi Prok. is restored, and C. asper Melo is included to its synonymy. It is shown that C. pluriradiatus Parr, as all other nominal species of the genus Chiasmodon, should be place in C. niger s. lato. Variation of C. niger-complex by dentition of gill arches and by some other meristic characters is pointed out. By armament of the gill apparatus,
along with the typical form, forms α and β are discerned. The latter form is described in detail by two specimens from the
eastern part of the Indian Ocean. It is found that form β corresponds to characters of the holotype of C. braueri while form α does not correspond to neither of the nominal taxa, attributed to C. niger s. l.
Key words
Chiasmodon
-variation-nomenclature-systematics
The response of hydroxylase activity of cytochrome P-450 from the microsomes of fish liver depends on fish species and on
the kind of pollution. Differences in activity of the enzyme in whitefish Coregonus lavaretus and Pike Esox lucius depend on differences in ecology and in sensitivity of species to industrial effluents. Whitefish reacted to pollution by
decrease in the activity of cytochrome P-450. In pike the activity of the enzyme increased under the influence of industrial
wastewater. Males of both species are less resistant than females to the aforementioned pollutants. With consideration to
the obtained results, the determination of activity of cytochropme P-450 may be recommended as the indicator of pollution
level of the aquatic environment with industrial waste products, including those containing heavy metals.
Separate and complex effect of temperature, pH, and heavy metals (copper, zinc) is investigated on activity of carbohydrases
in the whole organism of juvenile fish (carp Cyprinus carpio, golden carp Carassius auratus, roach Rutilus rutilus, perch Perca fluviatilis, common kilka Clupeonella cultriventris, and rotan Perccottus glenii)—potential food objects of typical and facultative ichthyophages. Temperature of 0°C and low pH at separate and combined
action noticeably decrease the amylolytic activity in comparison with metals. Enzymes of golden carp, kilka, and rotan are
maximally stable to change of temperature and pH. As a rule, the combined effect of low temperature and metals, as well as
of low pH and metals, increases the level of separate effect. Maximum decrease of activity of carbohydrases (by two-seven
times) is noted under the complex action of temperature 0°C, pH 5.0, and heavy metals (especially copper).
Keywordstemperature–pH–heavy metals–copper–zinc–carbohydrases–fish
Thirty-eight specimens of the Mediterranean blenny Parablennius incognitus are collected near the eastern coast of the Black Sea. It is a common species in this area. These records of P. incognitus significantly extended the range of the species. A description, the distinctive characters, and certain information on habitation
are given.
The Khanka Sawbelly Hemiculter lucidus is characterized by a significant prevalence of females in catches of mature fish. By means of RAPD-analysis using 12 primers
and karyological investigations, the assumption on the presence of a unisexual gynogenetic form in this species was checked.
With consideration of the obtained data, the assumption on gynogenetic reproduction is rejected. Other causes of the shift
in sex ratio towards females are discussed.
Keywordsgynogenesis–unisexual form–Khanka sawbelly
Structure and dynamics of populations of bream Abramis brama inhabiting water bodies of Eastern Europe of different types are investigated. With the consideration of the original and
published data, the following issues are analyzed in populations from the southern part of the area (water bodies of Moldova)
and from the central and northwestern areas of the European part of Russia: age composition, sex ratio, males and females
growth in size and weight, and age of maturation. Over the area, all transitions from short-cycle populations to average-cycle
and long-cycle populations are observed. The maximum longevity of their specimens attains 9, 15, and 26 years, respectively.
The growth rate of bream is controlled by a combination of average temperature, duration of vegetation season, size of water
body, number of trophic niches for various size-weight groups, multiple change of the kind of feeding in ontogenesis, and
general availability of food for adults. From the north to the south the variation of maturation age and of the rate of size
and weight growth increase.
The study of feeding and defensive behavior in the two groups of bream (Abramis brama) differing in the peroxidase locus (presented by Po79 and Po100 alleles) has been performed. The A group bream (homozygous
by Po79 allele) exhibit higher locomotor activity and aggressiveness, actively feed in the presence of a predator, and adapt
quickly to experimental conditions. The B group bream (homozygous by Po100 allele) exhibit lesser locomotor activity and practical
absence of aggressiveness. These fish reject food in the presence of a predator, their behavioral characteristics after removal
of the predator recover after a long time and they adapt to experimental conditions slowly. Thus, the study revealed that
there really exists the intraspecies form of bream that is less reactive but more aggressive and agile in which conditioning
responses develop better. Presence in a population of reactive and nonreactive specimens serves as a basis for the mechanism
of regulation of acuteness of intrapopulation relations and range expansion. In the present case, this mechanism allows for
the efficient use of alternative resources having inconstant availability.
The feeding behavior of bream (Abramis brama) yearlings kept before the experiment (four months post hatch) under different conditions has been studied. Three variants
of conditions, varied in their levels of informational richness, were modeled for keeping young fish prior to the experiments:
1—minimal richness, mimicking conditions of standard commercial hatchery containers; 2—the conditions enriched by a water
current; 3—the conditions enriched by modeled impact of predation and feeding by live food. In the following experiments,
the conditions were similar for all three groups. It was revealed that the fish grown under the conditions of Variant 1 had
a lower learning ability, higher extent of schooling behavior, and lower efficiencies of feeding and defensive behaviors.
Similar traits were described in literature as being typical for the fish grown at standard fish farms. The Variant 2 fish
had the shortest adaptation period and most efficient feeding behavior but were lacking the skills of defensive behavior.
The fish from the 3rd variant had a medium duration of adaptation period and efficient feeding behavior and possessed well-developed
skills of defensive behavior. The results have shown that the level of environmental information richness during fish early
life stages plays a crucial role in further development of the most important adaptive forms of behavior. Maintaining the
young fish in containers with water current facilitates swimming performance and development of feeding behavior. However,
such fish, in fact, lack the skills of defensive behavior.
Experiments on the hormonal stimulation of oocyte maturation and ovulation of Abudefduf sexfasciatus (Pomacentridae) have been conducted. Both single and double injections of surfagon (LH-RH-a) are applied. Ovulation is registered
more often 40–48 h after injection I. The morphological changes of oocytes during final maturation are followed. The egg quality
is assessed after the storage of ovulated oocytes inside of the female’s body (in vivo) and in the external medium (in vitro)
at 25 and 5°C. The development of free embryos and larvae is described.
The embryonic-larval development is described and some data on the reproductive biology of Abudefduf sexfasciatus are provided. This species is characterized by an intermittent spawning. The egg membranes of ovulated oocytes are represented
by one-layered zona radiata and a shaggy chorion situated at the animal pole. Spermia have one flagellum with a length of
about 25 μm. The shape of the head resembles a bean. The duration of movements of spermia up to their complete stop is about
1 h at a temperature of 23–25°C. The drawings and morphological descriptions of the stages of normal development at a constant
temperature of 25°C are presented. The duration of the incubation period is about 120 h. By the moment of hatching, an almost
complete resorption of yolk takes place, and the larva is ready to pass to an exogenous feeding. Soon after emerging from
egg envelopes, A. sexfasciatus exhibit a clearly pronounced positive phototaxis.
Biology and seasonal (from May to November) population dynamics of big-head Far East goby Gymnogobius urotaenia from the Kolkhoznaya channel is analyzed (the estuary part of the Serebryanka River). This species attains length 145 mm,
weight 23.9 g, and age 5+. Males live one year longer than females. In both sexes, the highest growth rate is observed in
the first and second years of life, and that of weight growth is observed in the third and fourth years. It spawns from the
end of May until the end of June. The absolute fecundity does not exceed 4000 eggs. The base of the diet consists of mysids.
This is an abundant species. The annual life cycle of G. urotaenia comprises spawning migration, spawning, embryonic development, pelagic larval stage, the phase of transition to bottom mode
of life, feeding, and wintering migration.
Keywordsbig-head Far East goby–size-age composition–growth–sex dimorphism–fecundity–feeding–abundance–annual life cycle
This paper deals with the recovery process of ruffe helminth fauna following a catastrophic decrease in the fish population
of Rybinsk Reservoir. Mass mortality was observed in ruffe from 1997 to 1999. It led to a decrease in parasite species diversity.
However, two to three years later about 60% of the former parasitic species had recovered. The reasons for ruffe mass mortality
in a range of waterbodies are analyzed based upon literature data. Some regularities of such epizooties in ruffe are revealed.
It is suggested that epizooties are due to some unknown viral or bacterial infection, which may be facilitated by a specific
combination of several factors.
