Distribution and abundance of fish in the southwest of Caspian Sea coastal waters

This study was carried out in southwestern Caspian Sea coastal area to elucidate demersal bony fishes distribution and abundance. Twenty two species were found in shore line, which belong to 6 families. In deeper waters down to 7 meters only 5 species of Gobiidae and 1 species of Syngnathidae were identified. Two species Neogobius caspius and N. pallasi were the main components of demersal fishes; however in some regions Rutilus caspicus, Rutilus kutum and Liza spp. were dominated. Most places were dominantly occupied by Atherina boyeri, which had the highest abundance among the pelagic fishes. Conversely, the Ponticola gorlap, N. melanostomus and Proterorhinus nasalis showed the lowest abundances (less than 1 ind./100 m²). Benthophilus stellatus and P. nasali had the lowest niche overlaps with other species. Both of these two species and P. gorlap are suggested to be classified as endangered or vulnerable species based on their low abundance. The distribution of Syngnathus abaster depends on algae, while algae grow up into the stony construction of the coastal line. A negative insignificant correlation was observed between pelagic and demersal fish abundances. The commercial fisheries data of 76 beach seines in our study area during 2002–2013 was compared with our results on fish abundance and species composition. More than 93% of total fish catch constituted Liza spp. and Rutilus kutum. The relationship between the abundance and distribution of the studied species, and the restocking activities performed by Iranian fisheries organization are discussed. The high abundance and distribution of small size fish in tidal zone could be related to the distribution of crustacean, which provide a good source of food for these fish species.     

Biological features of the common fish species in Olyutorsky-Navarin region and the adjacent waters of the Bering Sea: 4. family sculpins (Cottidae)

Based on the materials of investigations conducted for 20 years (1995?2015), the features of biology of the common fish species of the family Cottidae from the northwestern Bering Sea are studied. These species are found during summer and fall in the waters of the Olyutorsky-Navarin region. The size–age parameters of the fishes collected with different fishing gears, as well as the features of their body length and body weight dynamics, spawning time, and spawning conditions, are described. The largest exemplars of shorthorn sculpin Myoxocephalus verrucosus and staghorn sculpins, armorhead sculpin Gymnocanthus galeatus and G. detrisus, are recorded in the catches of snurrevads, while the fishes caught in trawls are characterized by smaller size. Interannual variability of the size composition of the fish is related to the abundance of certain generations or to the fishery directed to different associations of sculpins. In the coastal waters, comparatively low average body size is usual for the majority of common sculpin species (with the exception of lords, yellow Irish lord H. jordani and Gilbert’s Irish lord H. gilberti) because of the dominance of juveniles.     

An annotated list and molecular data on larvae of gryporhynchid tapeworms (Cestoda: Cyclophyllidea) from freshwater fishes in Africa

An annotated list of larvae (metacestodes) of gryporhynchid tapeworms (Cestoda: Cyclophyllidea) from freshwater fishes in Africa is provided with numerous new host and geographical records. Newly collected materials from Burundi, Democratic Republic of the Congo, Kenya, Madagascar, Namibia, Senegal, South Africa, Sudan and Zimbabwe practically double the total number of species reported from African fish so far. We confirm the occurrence of 16 species (five unidentified to the species level and most likely representing new taxa) belonging to the genera Amirthalingamia Bray, 1974 (1 species), Cyclustera Fuhrmann, 1901 (2 species), Dendrouterina Fuhrmann, 1912 (1 species), Neogryporhynchus Baer & Bona, 1960 (1 species), Paradilepis Hsü, 1935 (4 species), Parvitaenia Burt, 1940 (5 species), and Valipora Linton, 1927 (2 species). Additionally, metacestodes of four unidentified species of Paradilepis and Parvitaenia are reported from fish for the first time. Rostellar hooks of all species are illustrated and their measurements are provided together with a host-parasite list. The molecular phylogenetic analysis based on partial LSU rDNA sequences offers the first insight into the internal phylogenetic relationships within the family. Together with the morphological observations, the present study provides a taxonomic baseline for future studies on this largely neglected, but widely distributed and relatively frequent, group of parasites of African fishes, including economically important cichlids like tilapias and cyprinids.     

Fish length-weight relationships in the Weddell Sea and Bransfield Strait

Length-weight relationships are provided for 49 Antarctic fishes from 9 families. The fish were from three research cruises of 1996, 1998 and 2000 to the Weddell Sea and Antarctic Peninsula. Samples were collected by benthopelagic net, Agassiz trawl and bottom trawl at depths of 200–2,300 m. The exponent b in the length-weight relationship W=aL ^b ranged from 2.53 to 4.05. With a mean of 3.33, 50% of the values ranged between 3.157 and 3.480. In 31 species, the parameters were determined for each sex. For 64.5% of species, b was higher in females than in males. Exceptions were the Channichthyidae where b for six species was higher for males.     

A new gonad-infecting species of <Emphasis Type="Italic">Philometra</Emphasis> Costa, 1845 (Nematoda: Philometridae) from the marine fish <Emphasis Type="Italic">Terapon jarbua</Emphasis> (Forsskål) (Terapontidae) off the eastern coast of India

A new nematode species, Philometra terapontis n. sp. (Philometridae), is described from male and female specimens found in the ovary of the jarbua terapon Terapon jarbua (Forsskål) (Terapontidae, Perciformes) from the Bay of Bengal off the eastern coast of India. Based on light and scanning electron microscopical examination, the new species differs from most other gonad-infecting Philometra spp. in the length of the spicules (105–114 μm), a gubernaculum with dorsal, lamella-like structures and a distinct protuberance on its distal end, and a U-shaped, dorsally uninterrupted caudal mound in the male. From a few congeneric, gonad-infecting species with unknown males, it can be distinguished by morphological and biometrical features found in gravid females (i.e. length of body, length of first-stage larvae or oesophagus, and caudal structure), by the host type (fish family) and by the geographical distribution. Philometra terapontis is the first philometrid species reported from a fish belonging to the family Terapontidae. Philometra sawara Quiazon, Yoshinaga &; Ogawa, 2008 is considered a junior synonym of P. scomberomori (Yamaguti, 1935). A key to gonad-infecting species of Philometra parasitising marine and brackish-water fishes is provided.     

Impact of the Alien Species <Emphasis Type="Italic">Mnemiopsis leidyi</Emphasis> A. Agassiz, 1865 on Fish of the Caspian Sea

The data of long-term ecological studies (1999–2014) are used for assessing the impact of a new Caspian invader Mnemiopsis leidyi A. Agassiz, 1865 on marine and anadromous fish species. The introduction of the ctenophore and its massive development in the Caspian Sea have mainly affected planktophagous fish, especially the most abundant species anchovy sprat (Clupeonella engrauliformis Borodin, 1904) and sturgeons (Family Acipenseridae). Mnemiopsis leidyi is one of the main negative factors preventing the restoration of the populations of Caspian fishes, especially anchovy tyulka. The critical state of the resources of the spawning parts of sturgeon populations (Family Acipenseridae) has been reinforced as a result of the massive development of M. leidyi.     

Diapausing egg banks,lake size,and genetic diversity in the rotifer <Emphasis Type="Italic">Brachionus plicatilis</Emphasis> Müller (Rotifera,Monogononta)

The fish from the family Anostomidae represent one of the most important groups of freshwater ichthyofauna from South America, with species of high economical value. The migratory characteristic of some species, through the several Amazonian environments, takes them into waters with different physico-chemical characteristics. Cytogenetic studies on the Anostomidae demonstrate that these fishes have a conserved diploid number and karyotype macrostructure. So, to verify if this conservation occurs also in the genomic level, the current study aimed at a chromosomal comparative physical mapping, using 45S and 5S rDNA, of seven species of anostomids: Leporinus fasciatus, L. agassizi, L. friderici, L. trifasciatus, Rhytiodus macrolepis, Laemolyta taeniata, and Schizodon fasciatus, collected in different Amazonian environments. The results obtained corroborate the conservation of the karyotype macrostructure. However, significant differences were found in the distribution of heterochromatin and on the pair bearing the nucleolus organizer region. The staining of 45S and 5S rDNA by FISH highlighted, for four of the seven species, more than one chromosome pair bearing the site 45S. The 5S rDNA, although present in only one chromosome pair, varied in its chromosome and karyotype position. Thus, although the Anostomidae family has a conserved chromosomic macrostructure the use of molecular techniques revealed the presence of chromosomic translocation during the evolution of these fishes.     

Seasonal changes in blood cells and biochemical parameters in the Mongolian hamster (<Emphasis Type="Italic">Allocricetulus curtatus</Emphasis>)

It was shown previously that the Mongolian hamster (Allocricetulus curtatus) is a mammalian species with irregular short hibernation. The purpose of the present study was to determine how this status affects seasonal changes in the biochemical and hematological parameters in A. curtatus males under a natural temperature and light regime. It was found that a reduction in circulating white blood cells, specifically lymphocytes, neutrophils, eosinophils, basophils, and monocytes, occurred in winter and bilirubin levels increased in spring. These characteristics make Mongolian hamsters closer to the true hibernating species. At the same time, the character of seasonal changes in the number of red blood cells, glucose, total protein, creatinine, and albumin is closer to species with torpor.     

Diversity of fish species in suichuan river and shushui river and conservation value,China

Based on the data collected from the Suichuan and Shushui Rivers, both tributaries of the Ganjiang River between April and July of 2015, the fish species identified were classified into 68 and 46 species, 14 and 12 families in the Suichuan River and Shushui River respectively. Cyprinidae is the most common family that accounts for 52.9% and 58.7% in the total number of fish species in the Suichuan River and Shushui River, respectively. The dominant species were Pseudohemiculter dispar, Squalidus argentatus, Silurus asotus and Leptobotia elongate for the Suichuan River and Squalidus argentatus, Acrossocheilus parallens, Pseudohemiculter dispar, Silurus asotus, Pelteobagrus fulvidraco, Acrossocheilus fasciatus and Zacco platypus for the Shushui River. The diversity of fish species showed more abundant and diverse for the Suichuan River. The composition of ecotype of fish indicated the rich diversities of ecotype in both the Suichuan and Shushui Rivers. The tributary (Suichuan River) and main stream of the Ganjiang River demonstrated a highly fauna similarity and the fish resources indicated its significance to maintain the fish diversity in the middle of the Ganjiang River and its benefits to the existence of the fish species in mountain streams. Dam construction, sand excavation and heavy metal pollution are the most significant threat to fish diversity and ecosystem functioning in Ganjiang River basin. In order to protect fish diversity and fisheries more effectively, relevant laws should be strengthened and conservation areas should be established for the survival of freshwater fish species.     

Life history traits of two dwarf cichlids species in the white waters of the Amazonian floodplain

The reproductive parameters are among the most important life history aspects of fishes influenced by environmental variation. During recent years, the main life history strategies of Amazonian fish species were defined mostly by a set of reproductive parameters. In the present work, we sought to describe important life history parameters, in particular on reproductive characteristics of Apistogramma agassizii and Apistogramma bitaeniata, found in floodplain lakes of the Brazilian Amazonia. The species presented a positive sexual dimorphism, and males were significantly bigger than females. For both sexes, four developmental phase of gonad maturation were detected, and based on those it was possible to identify mature, reproductive specimens throughout the entire period of the study. From the ovaries of mature females, fecundity and spawning type were determined. Low fecundity, short spawning periods, possibly separated only by few months, and total spawning are all good indications that A. agassizii and A. bitaeniata evolved an opportunistic strategy in their life history.     

Estuarine fish behavior around slotted water control structures in a managed salt marsh

Estuaries are composed of multiple interconnected habitat types used by transient fish species during their period of estuarine residency. Structural marsh management restricts habitat connectivity and impedes the movement of fishes among these habitat types by limiting access via water control structures (WCSs) between the managed area and the rest of the estuary. While some general information on fish passage rates is available, species-specific information on passage through WCSs is lacking for salt marsh fishes. We monitored tagged fishes from March 2012 through November 2013 using passive integrated transponder antenna arrays at two identical WCSs in the Calcasieu Lake estuary, Louisiana, USA, to assess the effect of slotted WCSs on fish behavior. A total of 420 individuals of 15 species was tagged and released at the WCSs; of these, 145 individuals representing 11 species were later detected at the WCSs. Five species comprised most (93%) of the detected individuals: Elops saurus (n = 60), Mugil cephalus (n = 43), Sciaenops ocellatus (n = 20), Pogonias cromis (n = 7), and Ariopsis felis (n = 5). Passage rates were low, with most of the observed fishes (n = 80) passing only once through the structures. Other than E. saurus, which was only observed migrating out of the managed marsh, no clear pattern in swimming direction was observed for the other species. Detected species were all present primarily during the summer and fall, however, diel activity at the structures varied by species. The WCSs in our study area appeared to attract and congregate fishes, functioning more like ecological hotspots, rather than simply facilitating fish passage.     

Two new gonad-infecting species of <Emphasis Type="Italic">Philometra</Emphasis> Costa, 1845 (Nematoda: Philometridae) from <Emphasis Type="Italic">Trachinus</Emphasis> spp. (Osteichthyes: Trachinidae) in the Gulf of Hammamet,Tunisia

Based on light and scanning electron microscopical studies, two new gonad-infecting species of Philometra Costa, 1845, P. draco n. sp. and P. radiata n. sp. (Nematoda: Philometridae), are described from the marine perciform fishes Trachinus draco (Linnaeus) and T. radiatus (Linnaeus) (both Trachinidae), respectively, in the Gulf of Hammamet, off the northeastern coast of Tunisia. Philometra draco n. sp. and P. radiata n. sp. can be separated from other gonad-infecting species of this genus by the structures associated to the gubernaculum (e.g. dorsal protuberance, smooth field separating the dorsolateral longitudinal parts), as well as by the length of the body, spicules and gubernaculum. Philometra radiata n. sp. can be distinguished from P. draco n. sp. in having the dorsal side of the gubernaculum distal end provided with a median longitudinal smooth field demarcated by two dorsolateral lamellate parts. These two new species are the first philometrid species described from fishes of the family Trachinidae.     

Length-weight and length-length relationships of <Emphasis Type="Italic">Cirrhinus mrigala</Emphasis> (Cyprinidae) and <Emphasis Type="Italic">Xenentodon cancila</Emphasis> (Belonidae) from the river Ganga

Length-weight and length-length relationships are presented for two fish species collected during May 2015 to August 2016 from Narora site of the river Ganga. The parameters a and b of the length-weight relationships were estimated after the logarithmic transformation of the equation: W = aL ^b . The lengthlength relationships were also estimated using linear regressions. The coefficients of determination (R ²) values were >0.9 for both target fish species and linear regressions were highly significant (p < 0.001). Length-weight relationship indicated positive allometric growth pattern for Cirrhinus mrigala and negative allometric growth pattern for Xenentodon cancila. Length-length relationships for the selected fish species were also highly significant (R ² > 0.9, p < 0.001).     

Swimming abilities of juvenile estuarine fishes: implications for passage at water control structures

The capability of early life history stage fishes to access nursery habitat within managed salt marshes is dependent on their ability to negotiate water control structures (WCSs). Knowledge of swimming ability and hydrodynamic preferences is essential to assess the impact of WCSs on fish movement in managed marshes. These data, however, are lacking for many common estuarine fishes, and the utility of the data for the few species examined thus far is limited. We examined critical swimming speeds and derived linear relationships between fish size and swimming speed for juveniles of six common estuarine fish species of the southeast U.S. and northern Gulf of Mexico coasts. White mullet Mugil curema displayed the greatest swimming ability among these six species and was able to swim against currents ≥ 30 cm s^?1 higher than the other species examined at the same size. The remaining species displayed lower critical swimming speeds and were classified into groups of moderate (pinfish Lagodon rhomboides, striped mullet Mugil cephalus) or slow (silver perch Bairdiella chrysoura, spotfin mojarra Eucinostomus argenteus, spot Leiostomus xanthurus) swimmers. Our results suggest that high-flow conditions at WCSs would likely preclude the passage of all but the largest juvenile fishes, and passage for most juveniles would occur under low-flow conditions; these flows at WCSs are dictated largely by site-specific tidal and weather conditions.     

A new primer set for amplification of the cytochrome <Emphasis Type="Italic">b</Emphasis> gene in lantern fishes (Myctophidae)

New universal primers are offered for amplification of complete sequence of mitochondrial cyt b gene in lantern fishes of the family Myctophidae. Analysis of cyt b variability in the species of seven genera (Bolinichthys, Ceratoscopelus, Diaphus, Diogenichthys, Lampanyctus, Lepidophanes, Nannobrachium) demonstrates considerable divergence between species: an average of 18.2% (p-distances). Diversity (nucleotide diversity, number of segregating and phylogenetically informative sites, average number of nucleotide differences) and divergence significantly exceed those of another widely used mitochondrial marker, a fragment of cytochrome c oxidase subunit 1 sequence (cox 1). The mitochondrial cyt b gene amplified with the developed primers can be recommended as an informative tool for phylogenetic and population studies of lantern fishes.     

New host species and new distribution areas of <Emphasis Type="Italic">Salmincola lavaretus</Emphasis> (Copepoda: Lernaeopodidae): A parasite of coregonid fishes of Siberia

Data on the infestation of certain fish species by the parasitic copepod Salmincola lavaretus are presented for the first time. The infested fish species included Bauntovsky whitefish (Coregonus baunti), an endemic species from the Maloye and Bolshoye Kapylyushi lakes; Siberian whitefish (C. pidschian) and Siberian cisco (C. sardinella) from Bolshoye Kapylyushi Lake and Baunt Lake, which belong to the Tsypo-Tsypikan lake system (the Lena River basin, Transbaikalia); and Teletsky whitefish (C. lavaretus natio smitti) from Teletskoe Lake (the Ob River basin). Previously, S. lavaretus had been described as a parasite of Baikal omul (C. migratorius) and Baikal whitefish (C. baicalensis) from Baikal. The taxons of S. longimanus complex (S. longimanus, S. l. sibirica, S. svetlanovi, and S. lavaretus)—parasites of nasal fossae of grayling and coregonid fishes—were registered in the lakes of the Lake Baikal basin (Lake Baikal and Khovsgol Lake), the Lena River, the Yenisei and the Ob rivers (the largest rivers of the Arctic zoogeographic province), and the Kobdo River (the Western Mongolian province). It was assumed that S. longimanus complex is more widely distributed in the water bodies of the Arctic zoogeographic province of the Palearctic.     

The ultrastructure of the interstitial cells of the mesonephros in the teleost fishes of the Black Sea

The ultrastructure of cells that form mesonephros tissues in eight species of bony fish of the Black Sea, Gaidropsarus mediterraneus (L.), Lisa aurata (Risso), Trachurus mediterraneus (Staindachner), Diplodus annularis (L.), Spicara flexuosa (Rafinesque), Gobius niger jozo L., Mullus barbatus ponticus (Essipov) and Scorpaena porcus (L.), was studied. It was shown that the ultrastructure of agranulocytes and rodlet cells in the studied species is similar to that of cells in freshwater bony fish. The differences were observed in the number of ionocyte mitochondria, in the vesicle ultrastructure in the cells with radial vesicle array, and in the ultrastructure of the specific secondary granules of neutrophils and eosinophils.     

Chromosomal locations of U2 snDNA clusters in <Emphasis Type="Italic">Megaleporinus</Emphasis>, <Emphasis Type="Italic">Leporinus</Emphasis> and <Emphasis Type="Italic">Schizodon</Emphasis> (Characiformes: Anostomidae)

The U small nuclear RNA (U snRNA) genes comprise a multigene family and are required for splicing of pre-mRNA. In this paper, we aimed to study the chromosomal location of the U2 snRNA gene in Megaleporinus, Leporinus and Schizodon species, which constitute interesting models for the study of repetitive DNA and genomic evolution in fish once the group comprises species with and without heteromorphic sex chromosomes. The all six species showed 2n?=?54 chromosomes: Megaleporinus elongatus, Megaleporinus macrocephalus, Leporinus striatus, Leporinus friderici, Schizodon borelli and Schizodon isognathus. The U2 snDNA clusters were evident in only one medium-sized submetracentric pair in all analyzed species and this may represent a condition shared by Anostomidae family.