Spawning of walleye pollock (<Emphasis Type="Italic">Theragra chalcogramma</Emphasis>) off the Southwestern coast of Kamchatka

The results of ichthyoplankton surveys conducted in 2007–2008 showed that waters off Southwest Kamchatka and North Kuril Islands were areas of mass spawning of walleye pollock. The peak spawning occurred during the last 10 days of April and in early May, which was much later than the peak at the main spawning site off West Kamchatka. The spawning activity of walleye pollock near the southwestern shores of Kamchatka is a regular event, as the analysis of archive materials shows. This gave us grounds to suspect the existence of a southern site that coincided well with the mass spawning in the Shelikhov Gulf in its timing and scale, but was missed during standard ichthyoplankton surveys conducted in early April. After analyzing the growth rates of spawners, the assumption was made that the southern spawning was performed by the East Kamchatkan walleye pollock population, whose mass spawning usually occurs in late April-early May. According to the data of 2008, the estimated biomass of walleye pollock spawning in the area of the Ozernovskaya basin in late April was nearly 600000 tons. Regular monitoring of the southern spawning is proposed by means of additional ichthyoplankton surveys south of 53° N, including the Okhotsk Sea waters of the North Kuril Islands, in late April—early May.     

The biochemical composition and calorie density of the walleye pollock <Emphasis Type="Italic">Theragra chalcogramma</Emphasis> in the Sea of Okhotsk

In tissues of the walleye pollock Theragra chalcogramma the dry matter content averages 18.5%. The lipid content of the raw material is 0.7%, the protein content is 15.3%, carbohydrates are 0.6%, and ash is 1.3%. The average calorie density is 940 cal/g wet weight and 5080 cal/g dry weight. The dry matter content of gonads varies within 14.9–28.0% in females and 14.5–17.0% in males. The lipid content of the raw material is 0.9–3.0% in females and 1.3–1.8% in males; the protein content is 10.2–21.5% and 10.7–13.4%, respectively. The calorie density of female gonads is 702–1537 cal/g wet weight and 4426–5482 cal/g dry weight; for the male gonads it is 760–960 cal/g wet weight and 4952–5641 cal/g dry weight. The dry matter content of the liver varies within 42.2–62.2% for females and 34.4–62.4 for males. The lipid content of the raw material is 25.6–44.5% for females and 16.6–41.3% for males; the protein content is 6.3–9.8% and 8.1–12.3%, respectively. The calorie density of the liver in females varies within 2918–4601 cal/g wet weight and 6370–7395 cal/g dry weight; in males it is 2291–4357 cal/g wet weight and 6392–7492 cal/g dry weight. The minimum calorie density of the liver is observed in juvenile pollock: 963 cal/g wet weight and 2045 cal/g dry weight. The dry-matter content of feces in different size groups varies within 15.0–18.4%. Values of the average lipid content of raw material range from 1.1 to 1.6%; the protein content is from 1.8 to 3.8% and carbohydrates are from 0.9 to 1.4%. The calorie density of feces from variously-sized walleye pollock varies within a narrow range, from 308 to 362 cal/g wet weight. The energy equivalent ranges, depending on body size, from 259 to 2377 cal. The share of energy concentrated in the somatic (muscle) tissue of variously-sized walleye pollock during ontogenesis constitutes 56.5–93.9%; in female gonads it is 0.9–26.6%; in male gonads it is 0.4–7.3%, in the female liver it is 7.9–27.2%, and in the male liver it is 5.7–26.9%. The amount of energy (cal), concentrated in the female liver and gonads is on average 1.5 and 3 times as high as that in the male liver and gonads, respectively. The maximum total energy loss (15–30%) in mature walleye pollock of various-sizes occurs in the spawning period, during the transition from the maturity stage 5 to stage 6. The total amount of energy accumulated during the lifecycle from small juveniles (<17 cm) to very large individuals (>60 cm) averages 1964 kcal for females and 1465 kcal for males. The difference in the amount of energy is explained by the fact that oogenesis requires more energy than spermatogenesis.     

Morphological and histological features of the gonad structure in hermaphroditic walleye pollock <Emphasis Type="Italic">Theragra chalcogramma</Emphasis> (Gadidae)

Morphology of hermaphroditic gonads is studied in the individuals of walleye pollock Theragra chalcogramma collected in different regions of the seas of the North Pacific from 1987 to 2014. Based on the external morphological characteristics of sexual glands of 17 fishes, the most frequent types of the structure of bisexual gonads are described. Histological analysis shows the absence of differences in the composition and condition of oocytes in the left and right-paired ovaries, and the testes and ovaries of each individual are at the same maturity stage. In the ovigerous lamellae of ovaries in the areas adjacent to testes the zones of oocyte resorption are observed. These zones are located exclusively near the joining of the female and male parts of the gonads. The development of ovaries and testes of bisexual gonads is similar to that in the majority of normally maturing males and females collected during the same period. The occurrence of hermaphrodites is 0.0003–0.0016% from the total number of investigated exemplars.     

An unusual localization of the parasitic copepod <Emphasis Type="Italic">Haemobaphes diceraus</Emphasis> Wilson, 1917 (Copepoda: Pennellidae) on the walleye pollock <Emphasis Type="Italic">Theragra chalcogramma</Emphasis>

During a study performed in April 2008 in the Pacific waters of the northern Kuril Islands, the parasitic copepod Haemobaphes diceraus was found localized on the isthmus of two specimens of the walleye pollock Theragra chalcogramma. In both cases, the parasite directly penetrated the heart, without entering the blood vessels.     

Winter energy allocation and deficit of juvenile walleye pollock <Emphasis Type="Italic">Theragra chalcogramma</Emphasis> in the Doto area,northern Japan

Seasonal energy allocation and deficits of marine juvenile fishes have considerable effects on their survival. To explore the winter survival mechanism of marine fishes with low lipid reserves in their early life, juvenile walleye pollock Theragra chalcogramma were collected along the continental shelf of northern Japan over a 2-year period, and energy allocation and deficit patterns were compared between wild and laboratory-starved fish. Contrary to expectations, wild fish generally continued to accumulate protein mass and concurrently tended to reduce lipid mass from late autumn through winter. The most plausible explanation for the continuous structural growth is that juvenile pollock give priority to reducing mortality risk from size-selective predators under quasi-prey-limited conditions. Exceptionally, inshore small fish reduced both constituents during a winter. The inshore fish consumed 2.5 times more lipid energy than protein energy in November–December, but protein was more important than lipids as a source of energy in December–January and in February–March. However, dependence upon protein reserves was lower for the wild fish than for the laboratory-starved fish, suggesting milder nutritional stress of the wild fish than that observed in the starvation experiment. Moreover, the lipid contents of mortalities in the starvation experiment were mostly <1%, whereas few wild fish had such lipid contents in the field. These results suggest that juvenile pollock are able to avoid both starvation and predation by accumulating protein reserves.     

Study of the filiform gonads of walleye pollock <Emphasis Type="Italic">Theragra chalcogramma</Emphasis> inhabiting the Sea of Okhotsk and the Bering Sea

The histological study of the adult specimens of walleye pollock Theragra chalcogramma carrying filamentous gonads evidenced that this group comprised males, females, and sterile fish. The specimens carrying the filamentous gonads have been found mostly in the elder age groups; no maturing of the oocytes or sperm cells has been registered. The frequency of occurrence of such specimens was relatively low: 0.07–0.13% in the Sea of Okhotsk and up to 0.25% in the Bering Sea. We conclude that these specimens have nearly no effect on the reproductive success of this species.     

Seasonal changes in the diel vertical migration of walleye pollock (<Emphasis Type="Italic">Theragra chalcogramma</Emphasis>) in the northern Gulf of Alaska

Walleye pollock (Theragra chalcogramma) perform diel vertical migration (DVM) as juveniles, but have an increasing tendency to be associated with the bottom with age. We studied the DVM of a local population of adult pollock in the northern Gulf of Alaska in August and November 2003. There was no relationship between the depth of pollock and the isolume (line of equal light intensity) necessary for visual foraging in August. Pollock passed through the thermocline at this time. In November there was a significant relationship between pollock biomass above/below the 200 m isobath and the isolume necessary for visual foraging. It is hypothesized that in August pollock ignore the isolume and thermocline, simply tracking the movements of their prey (euphausiids) to feed upon them near the surface at night. In November, relatively denser pollock shoals migrate up and down with the isolume necessary for visual foraging to feed on decapods.     

The dynamics of the abundance of the walleye pollock <Emphasis Type="Italic">Theragra chalcogramma</Emphasis> (Pallas, 1814) (gadiformes: gadidae) in the Sea of Japan

The biomass of the walleye pollock (Theragra chalcogramma) stock in waters of Primorskii krai, Sea of Japan, during the 1976–2015 observation period ranged from 48000 to 373000 tons; their number ranged from 99 to 1115 million fish. Four very strong year-classes born in 1975, 1981, 1997, and 2006 have been identified. It has been shown that the duration of the sexual-maturity period is determined by the periodicity of the dynamics of the year-class strength close to the 9-year cycle. According to the results of numerical modeling, an increase in the walleye pollock stock in Primorye is expected from 2017 to 2020.     

Population genetic structure of walleye pollock <Emphasis Type="Italic">Theragra chalcogramma</Emphasis> (Gadidae,Pisces) from the Bering Sea and Sea of Okhotsk

Walleye pollock Theragra chalcogramma Pallas occupies a central place in ecosystems of the North Pacific and is an important target species of fisheries. The species is characterized by daily vertical, spawning, feeding, and wintering migrations and spawning occurring under the sea ice. Since population structure estimation by the tagging with recapture is inefficient in walleye pollock, the pollock resources are difficult to estimate by conventional methods, requiring population genetic studies with molecular markers. The population genetic structure of five spawning aggregations from the Bering Sea was for the first time studied with ten microsatellite loci: Tch5, Tch10, Tch11, Tch12, Tch14, Tch16, Tch17, Tch19, Tch20, and Tch22. A spatially distant sample from the Sea of Okhotsk was used as a reference group. Polymorphism for the markers reached 100%, and heterozygosity of individual loci ranged from 41 to 95% in different populations. It was shown the aggregations of interest are in goodness-to-fit the Hardy-Weinberg equilibrium (HWE) at hole, while the Sea of Okhotsk sample demonstrated a sex bias: the heterozygosity at Tch16 in males was significantly lower than in females. The highest discriminative power was observed for Tch10, Tch20, and Tch22. F _ST genetic distances between populations were typical for marine fishes. A mixed composition was supposed for the sample from the region of the underwater Shirshov Ridge, which serves as a natural partial geographic barrier between the Olyutor-Karagin and Koryak walleye pollock stocks. With the Shirshov sample excluded, F _ST scatter plots and the spatial autocorrelation approach supported isolation by distance for the aggregations. An influence of abiotic factors on the population structure was assumed for walleye pollock of the Bering Sea.     

Reproductive conditions of walleye pollock <Emphasis Type="Italic">Theragra chalcogramma</Emphasis> (Gadidae) off the northeastern coast of Sakhalin Island,Sea of Okhotsk

The spatial distribution of eggs and larvae of the walleye pollock Theragra chalcogramma is considered in respect to dynamics of oceanologic processes, nutrients, chlorophyll а and zooplankton off the northeastern coast of Sakhalin Island in spring 2012. It is shown that the effect of severe temperature regime in the near-bottom horizons in the western Sea of Okhotsk during the spawning period of walleye pollock becomes milder due to specific features of water dynamics. The egg distribution is determined by mesoscale eddies in the region. The species survival depends on the effect of such environmental factors as freshwater discharge from the Amur River, eddy structure in waters of the Sea of Okhotsk, and dynamics of phytoplankton and zooplankton development.     

A mitogenomic approach to the taxonomy of pollocks: <Emphasis Type="Italic">Theragra chalcogramma</Emphasis> and <Emphasis Type="Italic">T. finnmarchica</Emphasis> represent one single species

Background  

The walleye pollock (Theragra chalcogramma) and Norwegian pollock (T. finnmarchica) are confined to the North Pacific and North Atlantic Oceans, respectively, and considered as distinct species within the family Gadidae. We have determined the complete mtDNA nucleotide sequence of two specimens of Norwegian pollock and compared the sequences to that of 10 specimens of walleye pollock representing stocks from the Sea of Japan and the Bering Sea, 2 specimens of Atlantic cod (Gadus morhua), and 2 specimens of haddock (Melanogrammus aeglefinus).     

<Emphasis Type="Italic">Ty</Emphasis>1<Emphasis Type="Italic">/copia</Emphasis>- and <Emphasis Type="Italic">Ty</Emphasis>3<Emphasis Type="Italic">/gypsy</Emphasis>-like DNA sequences in <Emphasis Type="Italic">Helianthus </Emphasis>species

Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.     

Revision of the <Emphasis Type="Italic">Serrulati</Emphasis> species of <Emphasis Type="Italic">Penstemon</Emphasis> section <Emphasis Type="Italic">Saccanthera</Emphasis> subsection <Emphasis Type="Italic">Serrulati</Emphasis>

A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations.     

<Emphasis Type="Italic">Galleria</Emphasis><Emphasis Type="Italic">mellonella</Emphasis> are Resistant to <Emphasis Type="Italic">Pneumocystis</Emphasis><Emphasis Type="Italic">murina</Emphasis> Infection

Studying Pneumocystis has proven to be a challenge from the perspective of propagating a significant amount of the pathogen in a facile manner. The study of several fungal pathogens has been aided by the use of invertebrate model hosts. Our efforts to infect the invertebrate larvae Galleria mellonella with Pneumocystis proved futile since P. murina neither caused disease nor was able to proliferate within G. mellonella. It did, however, show that the pathogen could be rapidly cleared from the host.     

<Emphasis Type="Italic">Agrobacterium</Emphasis><Emphasis Type="Italic">tumefaciens</Emphasis>-mediated transformation of callus cells of <Emphasis Type="Italic">Crataegus</Emphasis><Emphasis Type="Italic">aronia</Emphasis>

A genetic transformation system has been developed for callus cells of Crataegus aronia using Agrobacterium tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with 5 mg l⁻¹ Indole-3-butyric acid (IBA) and 0.5 mg l⁻¹ 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red colored callus was obtained on MS medium supplemented with 2 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l⁻¹ kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l⁻¹ hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this is the first time to report an Agrobacterium-mediated transformation system in Crataegus aronia.     

The <Emphasis Type="Italic">Caenorhabditis</Emphasis><Emphasis Type="Italic">briggsae</Emphasis> genome contains active <Emphasis Type="Italic">CbmaT1</Emphasis> and <Emphasis Type="Italic">Tcb1</Emphasis> transposons

The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.     

Differences in swimming and diving abilities between two sympatric species of water shrews: <Emphasis Type="Italic">Neomys anomalus</Emphasis> and <Emphasis Type="Italic">Neomys</Emphasis><Emphasis Type="Italic">fodiens</Emphasis> (Soricidae)

Swimming and diving abilities of two syntopic species of water shrews, Neomys anomalus and Neomys fodiens, were tested in aquaria using video recordings taken from three views (lateral distant, lateral close and dorsal). The frequency and total duration of diving, as well as the mean duration of diving and floating bouts, were significantly higher in N. fodiens than in N. anomalus. Frequency of paddling during surface swimming was lower in N. fodiens than in N. anomalus. N. fodiens dived mainly for long distances at the bottom of the aquarium and performed a wider range of dive profiles than N. anomalus, which preferred rather short and shallow dives. The two species differed also significantly in their fineness ratios (describing how streamlined their bodies are) when diving. When swimming, N. fodiens had a relatively wider body and performed narrower movements with its tail than N. anomalus. These results show quantitatively and qualitatively for the first time that N. fodiens is more proficient at swimming and diving than N. anomalus. The results also help to explain the inter-specific differences in efficiency of underwater foraging, and support the idea of segregation of ecological niches of these species based on their different foraging modes (diving vs. wading).     

The size composition of the pelagic eggs of walleye pollack <Emphasis Type="Italic">Theragra chalcogramma</Emphasis> in spawning areas of the northern Sea of Okhotsk

The data on the size composition of the pollack developing eggs of walleye pollack collected in the northern Sea of Okhotsk in 2001 during mass spawning are given. The eggs caught in western Kamchatka and in Shelikhov Bay had the greatest diameter; they were somewhat less in the northern Okhotsk Sea area; and the smallest eggs were found in eastern Sakhalin. The clinal variability of the size composition of walleye pollack eggs was observed in the northern Sea of Okhotsk, and in the western and eastern parts it had a local pattern. Parameters such as spawning female size composition, temperature, and salinity, as well their influence on the size composition of eggs, were considered.Original Russian Text Copyright © 2004 by Biologiya Morya, Ovsyannikov.     

New combinations and typifications in <Emphasis Type="Italic">Bistorta</Emphasis>, <Emphasis Type="Italic">Persicaria</Emphasis>, <Emphasis Type="Italic">Polygonum,</Emphasis> and <Emphasis Type="Italic">Rumex</Emphasis> (Polygonaceae)

New combinations are proposed in anticipation of the Polygonaceae treatment in the forthcoming volume of Intermountain Flora: Polygonum kelloggii var. esotericum, P. kelloggii var. watsonii , Rumex densiflorus var. pycnanthus , R. salicifolius var. utahensis, and R. occidentalis var. tomentellus. Typifications are proposed to facilitate ongoing studies in Polygonaceae and to maintain current usage.     

Prevalence,intensity and associated factor analysis of <Emphasis Type="Italic">Tropilaelaps</Emphasis><Emphasis Type="Italic">mercedesae</Emphasis> infesting <Emphasis Type="Italic">Apis</Emphasis><Emphasis Type="Italic">mellifera</Emphasis> in China

Tropilaelaps mercedesae is a serious ectoparasite of Apis mellifera in China. The aim of this study was to investigate the infestation rates and intensity of T. mercedesae in A. mellifera in China, and to explore the relative importance of climate, district, management practices and beekeeper characteristics that are assumed to be associated with the intensity of T. mercedesae. Of the 410 participating apiaries, 379 apiaries were included in analyses of seasonal infestation rates and 352 apiaries were included in multivariable regression analysis. The highest infestation rate (86.3%) of T. mercedesae was encountered in autumn, followed by summer (66.5%), spring (17.2%) and winter (14.8%). In autumn, 28.9% (93) of the infested apiaries were in the north (including the northeast and northwest of China), 71.1% (229) were in the central and south (including east, southeast and southwest China), and 306 apiaries (82.9%) were co-infested by both T. mercedesae and Varroa. Multivariable regression analysis showed that geographical location, season, royal jelly collection and Varroa infestation were the factors that influence the intensity of T. mercedesae. The influence of beekeeper’s education, time of beekeeping, operation size, and hive migration on the intensity of T. mercedesa was not statistically significant. This study provided information about the establishment of the linkage of the environment and the parasite and could lead to better timing and methods of control.