Pleurogrammus Azonus Research Articles

Nematodes of common Hexagrammidae species from the Far-Eastern Seas of Russia

Nematoda parasites of five greenling species from the Far-Eastern Seas ( Pleurogrammus azonus , P . monopterygius , Hexagrammos octogrammus , H . lagocephalus , H . stelleri ) are investigated. The family Hexagrammidae is endemic for the North Pacific. In total, 10 species of nematodes are found: Anisakis simplex l., Pseudoterranova decipiens l., Hysterothylacium aduncum , Contracaecum osculatum l., Ascarophis filiformis , A. curvicauda , A. pacifica , Cucullanellus minutus , Cucullanus heterochrous , and Paracapillaria helenae , all of them have wide geographical and hosts distribution. Anisakis simplex l. and Pseudoterranova decipiens l. are the most common for all investigated host species. The highest species diversity of nematodes (7 species) is registered for arabesque greenling P. azonus , particularly its females; Contracaecum osculatum l. and Cucullanus heterochrous are found for the first time for this host in the Japan Sea. The parasites are dispersed irregularly in muscles of all parts of fish body. Large-sized (i.e. elder) fish is higher infected by larvae of P. decipiens .

Life cycles and somatic production of hyperiids in the Okhotsk and Bering Seas

Hyperiid species Themisto pacifica , T. libellula , and Primno macropa are widespread in the Far-Eastern Seas. They are an important element of trophic web in pelagic communities of these seas. Their food spectra are very broad and include copepods, euphausiids, arrowworms, and fish larvae. On the other hand, the hyperiids play an important role in the diet of large-sized marine organisms as walleye pollock Theragra chalcogramma , mackerels Scomber japonicus , Pleurogrammus monopterygius , and Pleurogrammus azonus , and japanese squid Todarodes pacificus . Life cycles and production of these hyperiid species are described on the base of samples collected in complex surveys conducted by Pacific Fish. Res. Center (TINRO) in the Okhotsk Sea and the western Bering Sea in 1984-2011. All three species have similar life history though the maximal life span is 2 years for T. pacifica and T. libellula but 3 years for Primno macropa . They spawn twice in their life in the period from May to October with the peak in July. Their weight increments also increase twice, usually when their size is 7-10 and 10-12 mm for T. pacifica and P. macropa and 10-15 and 20-30 mm for T. libellula . The average specific daily production of hyperiids in the Okhotsk Sea is estimated as 0.0410 for T. pacifica , 0.0273 for T. libellula , and 0.0101 for P. macropa ; but in the western Bering Sea - as 0.0492 for T. pacifica , 0.0361 for T. libellula , and 0.0094 for P. macropa . The most favorable feeding grounds for hyperiids are located at Kuril Islands, at West Kamchatka, and in the Anadyr Bay. Their summary annual production is estimated as 30.235 mln t in the Okhotsk Sea and 21.370 mln t in the western Bering Sea.

Features of feeding for pacific herring <i>Clupea pallasii,</i> walleye pollock <i>Theragra chalcogramma</i>, and arabesque greenling <i>Pleurogrammus azonus</i> in Peter the Great Bay (Japan Sea) in summer season

Qualitative and quantitative indices of feeding and competitive relationships are investigated for pacific herring Clupea pallasii , walleye pollock Theragra chalcogramma , and arabesque greenling Pleurogrammus azonus on the data of bottom trawl surveys conducted over the shelf and upper continental slope of Peter the Great Bay in June-September of 2002-2009. Daily rations of these species in summer are estimated as 4.5, 3.0 and 4.3 % of body weight on average, respectively. The diet depends on their bathymetric distribution and structure of prey: generally, the portion of plankton and nektobenthos reflects the species ability to dwell beyond the bottom and changes from 66.9 and 32.1 % for herring and 45.2 and 46.9 % for pollock to 30.2 and 31.8 % for greenling. The rest of the greenling diet is presented by benthic invertebrates (24.8 %) and nekton (13.2 %). Mysids are the main common diet component for all three species, their portion in the herring and pollock diets is extremely high in Peter the Great Bay comparing with other habitats of these species, obviously because of high abundance of mysid shrimps and low concentrations of large-sized zooplankton (particularly euphausiids) in the Bay. Role of the considered species in demersal ichthyocenosis of Peter the Great Bay is not high enough for food competition between them, taking into account their active seasonal migrations and low stocks of herring and pollock in recent times.

Occurrence of hexagrammidae fish at early stages of ontogenesis in open waters of the northwestern part of the Pacific ocean

Hexagrammidae are endemics of the northern Pacific widely spread in marginal seas and coastal parts of the Pacific Ocean from the East China Sea in the west and California in the east to the Bering Strait in the north (Rass, 1962; Rutenberg, 1962; Shinohara, 1994). Almost all greenlings are nearbottom fish inhabiting coastal areas, and only lingood Ophiodon elongatus and Atka mackerels of the genus Pleuro� grammus lead a semipelagic mode of life and perform migrations to considerable distances into open waters (Gorbunova, 1962; Rutenberg, 1962). Hexagrammi� dae spawn in coastal areas in shallow water where incubation of bottom eggs takes place. The hatched out larvae are carried out by currents into open waters, sometimes to considerable distances from the coast, and they pass the first several months of life in the pelagial. Despite rather considerable number of publi� cations on the biology and ecology of greenling, the early stages of ontogenesis of these fish have not been adequately covered in literature, and were most com� prehensively considered in the paper of Gorbunova (1962) according to material of the 1950s. The distri� bution of juveniles of arabesque greenling Pleurogram� mus azonus and Atka mackerel P. monopterygius in the epipelagial of far eastern seas and the northern part of the Pacific Ocean is described in papers of Mel'nikov et al. (1996a, 1996b); Mel'nikov and Efimkin (2003); Mel'nikov and Loboda (2003). In the suggested paper, the occurrence in ichthy� oplankton and distribution of Hexagrammidae at early stages of ontogenesis in the northwestern part of the Pacific Ocean are considered.

First finding of the Okhotsk Atka mackerel Pleurogrammus azonus (Scorpaeniformes: Hexagrammidae) in Tauy bay (northern Sea of Okhotsk): Description of the specimen and the justification of its species definition

The first finding of an adult specimen (TL = 385 mm) of the Okhotsk atka mackerel Pleurogrammus azonus (Scorpaeniformes: Hexagrammidae) is reported for the northern coast of the Sea of Okhotsk (mouth of western Tauy Bay). This is the northernmost finding of this species in the Sea of Okhotsk. The detailed description of the external morphology of the specimen is given. The mtDNA COI gene fragment is compared to GenBank data, and the molecular genetic analysis justifies the species definition significantly.

ホッケ柱（ばしら）：渦形成によるホッケ魚群の摂餌戦略

ホッケ柱（ばしら）：渦形成によるホッケ魚群の摂餌戦略

Vortex flow produced by schooling behavior of arabesque greenling Pleurogrammus azonus

Arabesque greenling Pleurogrammus azonus form schools of 30,000–60,000 individuals to feed on mesozooplankton near the sea surface. The fish need to be close to the surface where mesozooplankton production occurs, but the food is not sufficiently dense there for the fish to grow optimally while avoiding predation by sea birds. Arabesque greenling use a unique method to optimize their feeding conditions while avoiding staying on the sea surface. When the school swims upward, water is pushed downward. Upward swimming of a school of 30,000 individuals generates a downward stream of about 0.8–1.1 m/s, resulting in a convergent flow near the surface. This convergence concentrates the mesozooplankton on the sea surface and transports them into deeper layers with a strong vortex about 3.0 m in diameter and 10–20 m long. Thus, schooling of this fish induces vortex flows that provide a rich feeding environment.

Anisakis simplexLarvae: Infection Status in Marine Fish and Cephalopods Purchased from the Cooperative Fish Market in Busan, Korea

The infection status of marine fish and cephalopods with Anisakis simplex third stage larva (L3) was studied over a period of 1 year. A total of 2,537 specimens, which consisted of 40 species of fish and 3 species of cephalopods, were purchased from the Cooperative Fish Market in Busan, Korea, from August 2006 to July 2007. They were examined for A. simplex L3 from the whole body cavity, viscera, and muscles. A. simplex L3 were confirmed by light microscopy. The overall infection rate reached 34.3%, and average 17.1 larvae were parasitized per infected fish. Fish that recorded the highest infection rate was Lophiomus setigerus (100%), followed by Liparis tessellates (90%), Pleurogrammus azonus (90%), and Scomber japonicus (88.7%). The intensity of infection was the highest in Gadus macrocephalus (117.7 larvae per fish), followed by S. japonicus (103.9 larvae) and L. setigerus (54.2 larvae). Although abundance of A. simplex L3 was not seasonal in most of the fish species, 10 of the 16 selected species showed the highest abundance in February and April. A positive correlation between the intensity of L3 infection and the fish length was obvious in S. japonicus and G. macrocephalus. It was likely that A. simplex L3 are more frequently infected during the spring season in some species of fish. Our study revealed that eating raw or undercooked fish or cephalopods could still be a source of human infection with A. simplex L3 in Korea.

Structural properties of trypsin from cold-adapted fish, arabesque greenling (Pleurogrammus azonus)

A cDNA clone encoding trypsin (AG-T) was isolated from the pyloric ceca of cold-adapted fish, arabesque greenling (Pleurogrammus azonus). The cDNA was composed of 892 bp with an open reading frame of 729 bp at nucleotide positions 25–753. Similar to all the known trypsin, the AG-T seemed to be synthesized as preproenzyme that contains a hydrophobic signal peptide, an activation pentapeptide and a mature trypsin of 222 amino acid residues. The AG-T also completely conserved the major structural features common to trypsin such as the catalytic triad (His57, Asp102, and Ser195), the obligatory Asp189 and twelve Cys residues. On the other hand, the AG-T possessed the deletion of Tyr151 and substitution of Pro152 for Gly in the autolysis loop when aligned with the sequence of tropical-zone fish and bovine trypsins. In addition, Val75 concerned in a combination with calcium ion was exchanged for Ala in the AG-T, and the content of positively charged amino acid residues at the calcium-binding site of the AG-T was three times higher than those of tropical-zone fish trypsins. Moreover, the ratio between charged and hydrophobic amino acid residues in the N-terminal region of the AG-T was also higher than those of temperate-zone fish and tropical-zone fish trypsins. Such structural properties of the AG-T would contribute to its low thermostability.

Collagens from the skin of arabesque greenling (Pleurogrammus azonus) solubilized with the aid of acetic acid and pepsin from albacore tuna (Thunnus alalunga) stomach

Due to the low extraction efficiency of collagen from fish skin by the typical acid solubilization process, pepsin has been widely used to aid further extraction of collagen from the residue. The aim of this study was to characterize collagen from the skin of arabesque greenling extracted with the aid of albacore tuna pepsin, in comparison with collagen obtained from the acid solubilization process. Acid-solubilized collagen (ASC) from the skin of arabesque greenling was extracted with acetic acid. Pepsin-solubilized collagen (PSC) was further extracted from the skin residue with the aid of pepsin from albacore tuna. The yields of ASC and PSC were 303 and 140 g kg(-1) (dry weight), respectively. Both collagens contained alpha- and beta-chains as their major components and were characterized as type I collagen. Both collagens contained glycine as a major amino acid and had imino acid content of 157-159 residues per 1000 residues. The degradation induced by lysyl endopeptidase and V8-protease was more pronounced in PSC compared with ASC. Maximal transition temperatures of both collagens were in the range of 15.4-15.7 degrees C. Fourier transform infrared spectra revealed some differences in molecular order between ASC and PSC. Nevertheless, the triple-helical structure of PSC was still predominant. Based on zeta-potential, pI of ASC and PSC was estimated to be 6.31 and 6.38, respectively. Isolation of collagens from the skin of arabesque greenling could be achieved by acid or albacore tuna pepsin solubilization. However, there was a slight difference in properties between ASC and PSC.

동해 임연수어, Pleurogrammus azonus (Jordan and Metz)의 성숙과 산란

Maturity and spawning of the atka mackerel, Pleurogrammus azonus, was investigated based on the samples collected by gill net and set net in the East Sea from January 2006 to March 2009. Gonadosomatic index (GSI) began to increase in October, and reached a maximum between November and December. After spawning GSI began to decrease from January. The spawning period was from October to January, and main spawning period was from November to December. Annual reproductive cycles of this species could be divided into five successive stages in females; early growing stage (June), late growing stage (July to August), mature stage (September to October), ripe and spent stage (November to January), and recovery and resting stage (January to May). Males showed four successive stages: growing stage (June to August), mature stage (September to October), ripe and spent stage (October to December), and recovery and resting stage (January to May). P. azonus could be one of polycyclic species spawning two times or more during one spawning season. Number of total and mature eggs in the fecundity were proportional to fork length. The fork length at 50% group maturity was estimated to be 26.9 cm.

Seasonal and inter-annual oceanographic changes induce diet switching in a piscivorous seabird

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 393:273-284 (2009) - DOI: https://doi.org/10.3354/meps08192 Seasonal and inter-annual oceanographic changes induce diet switching in a piscivorous seabird Motohiro Ito1,*, Hiroshi Minami2, Yuzan Tanaka1, Yutaka Watanuki1 1Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato, Hakodate, Hokkaido, 041-8611, Japan 2National Research Institute of Far Seas Fisheries, 5-7-1 Shimizu, Shizuoka, 424-8633, Japan *Email: m-ito@fish.hokudai.ac.jp ABSTRACT: The structure of a marine food web can change quickly within seasons as well as inter-annually in response to physical oceanographic changes. In this study, we examined the relationship between temporal changes in the marine ecosystem of northern Hokkaido, Japan, and diets of rhinoceros auklets Cerorhinca monocerata breeding in this region. To obtain an integrated measure of changes in diet composition on short (days) and inter-annual (2004 and 2005) time scales, we used a 2-pronged approach. We examined (1) the diets of adults using stomach contents and stable isotope signatures in tissues, and (2) chick diets using the composition of bill-loads delivered to chicks. During the incubation period, the diet of adults comprised euphausiids (Thysanoessa longipes and T. inermis). During the chick-rearing period, the diet of adults was age 0 Japanese sandlance Ammodytes personatus and age 0 Japan Sea greenling Pleurogrammus azonus in the early period, but switched quickly (<10 d) to warm-water-preferring Japanese anchovy Engraulis japonicus when the warm Tsushima Current intruded into their foraging range. Adult blood plasma stable isotope ratios reflected these seasonal changes in stomach content. Diets did not differ between age categories. Furthermore, the timing of diet switching to anchovy differed inter-annually, and was about 10 d later in 2005 than 2004, reflecting a difference in the timing of the intrusion of warm water. We conclude that rhinoceros auklets respond sensitively to current-related rapid marine food web changes. KEY WORDS: Prey switching · Stable isotope signatures · Rhinoceros auklets · Anchovy · Tsushima Current Full text in pdf format PreviousNextCite this article as: Ito M, Minami H, Tanaka Y, Watanuki Y (2009) Seasonal and inter-annual oceanographic changes induce diet switching in a piscivorous seabird. Mar Ecol Prog Ser 393:273-284. https://doi.org/10.3354/meps08192 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 393. Online publication date: October 30, 2009 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2009 Inter-Research.

Observations of food falls off the Shiretoko Peninsula, Japan, using a remotely operated vehicle

Sinking carcasses deposit highly concentrated organic matter in benthic ecosystems. Numerous studies have simulated natural food fall and have used time-lapse cameras to examine the response of scavengers to the bait [1–3]. The few studies of natural food falls include a description of an aggregation of amphipods on a shrimp body [4], a shot of a fish skeleton [5] in the deep sea, and aggregations of ophiuroids around giant jellyfish carrion [6]. Here, we report observations of natural scavenging on fallen fish carrion that was found by chance on the sea floor. A survey was conducted in the Nemuro Strait off the Shiretoko Peninsula (Fig. 1), Hokkaido, Japan, from 21 to 23 January 2008, using a remotely operated vehicle (ROV; Expert Nova System, Kowa, Japan; Fig. 2). The ROV was equipped with three cameras and 100-mm parallel lasers, and was maneuvered from a ship by controlling two pairs of thrusters for vertical and horizontal movement. The free movable range was about 20 m from a ca. 70 kg weight that was attached to the ROV cable with an angle frame to keep the ROV near the target depth, as the vehicle was neutrally buoyant. Images from the ROV were monitored on the ship in real time and were recorded with a video recorder (AK-V100, Toshiba). In 11 runs, we observed fish (e.g., walleye pollock Theragra chalcogramma, Okhotsk atka mackerel Pleurogrammus azonus, sculpins, flat fish, and rockfish, benthic invertebrates (e.g., echinoids, ophiuroids, and ivory shells), and plankton (e.g., Sagitta and euphausiids). Generally, the fish did not respond notably to the ROV, except when the vehicle approached them quickly. In contrast, the plankton aggregated near the ROV’s lights, especially when it moved slowly or stopped. In this survey, we observed two food falls of walleye pollock, which are abundant in the strait [7]. The first carcass was found at Sta. 1 (43 57.980N, 145 10.810E, depth 228 m). Its total length was ca. 33 cm, and numerous ophiuroids were aggregated around it (Fig. 3). The second carcass, discovered at Sta. 2 (43 58.000N, 145 10.830E, depth 234 m), ca. 50 m away from Sta. 1, was ca. 45 cm long, and some echinoids and ophiuroids were attached to it (Fig. 3). No accumulations of amphipods, which typically appear rapidly after bait reaches the sea floor, [3] were visible on the carrion. In this area, pollock is considered one of the key species that shift energy from lower to higher trophic levels through predation (Matsuda et al., unpublished data, 2008). Our footage showed benthic scavengers consuming the pollock carrion, suggesting that pollock does not only act as an agent for the one-way transfer of energy but is also a food source for benthic scavengers. We could not determine what killed the pollock (e.g., natural death or fisheries activities). Nevertheless, scavengers lead to faster transfer of organic matter to the food web than decomposition by micro-organisms [8]. This may enhance secondary J. Yamamoto (&) T. Iwamori Field Science Center for Northern Biosphere, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan e-mail: yamaj@fish.hokudai.ac.jp

Summer-autumn ichthyoplankton of the Sea of Okhotsk and the Sea of Japan and special traits of feeding of fish larvae and fry in 2003–2004

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.

Glands in the olfactory epithelium of marine fish

Specific features of the morphohistochemical and ultrastructural organization of the secretory system of olfactory organs in marine fish from the Pacific region were studied. Multicellular alveolar and tubular glands were revealed in the olfactory epithelium of Pleurogrammus azonus, Myoxocephalus yaok, Enophrys diceraus, Alcichthys elongatus, Gymnocanthus pistilliger, Hemilepidotus gilberti, Hemitripterus villosus, Podothecus veternus, Liparis dubius, Clupea pallasi, as well as in salmonids (Oncorhynchus nerka, O. keta, O. gorbuscha, O. masou, O. kisutch, O. tschawytscha) and in tetraodontids (Takifugu rubripes). The morphofunctional characteristic of the described glands is close to the Bowman’s glands of land animals. The structure, localization, and density of location of olfactory glands are determined by specific features of the ecology of the species. These structures are most numerous in bottom and near-bottom representatives of marine ichthyofauna.

New species of myxosporean (Myxozoa: Myxosporea) parasites of Ceratomyxa from fishes of Peter the Great Bay (Japan Sea).

Four new species of Ceratomyxa were found during parasitological studies of fish caught in shallow areas of Peter the Great Bay, Russia. Two of them (C. aspera n. sp. and C. durusa n. sp.) were found in the gall bladders of the flounders Limanda aspera and L. herzensteini. The third species (C. azonusi n. sp.) infected the gall bladder of the greenling Pleurogrammus azonus, and the fourth (C. lianoides n. sp.) was found in the gall bladder of Stichaeus grigorjewi. Ceratomyxa spp. have not been previously described from P. azonus or S. grigorjewi.

Importance of the Japanese anchovy ( Engraulis japonicus ) to breeding rhinoceros auklets ( Cerorhinca monocerata ) on Teuri Island, Sea of Japan

Temporal variation in the diet and chick growth of rhinoceros auklets (Cerorhinca monocerata), on Teuri Island, Sea of Japan, was studied to understand how local marine environmental changes affect the reproduction of this piscivorous seabird. The food delivered by parents to chicks was sampled every 1–2 weeks from late May to July, 1994–1998. Overall, the diet of nestling rhinoceros auklets consisted of (by mass) 61% Japanese anchovy (Engraulis japonicus), 18% Japanese sand lance (Ammodytes personatus), 18% Japan Sea greenling (Pleurogrammus azonus), 2% other fish and 1% squid. Among years, the contribution of anchovy ranged from 16% to 93%. Once anchovy occurred in the diet, it dominated (80% on average) thereafter. Accordingly, when anchovy appeared in the diet early in the chick-rearing season (1994, 1998), the contribution of anchovy overall was large. The first appearance of anchovy in the diet of auklets late in the summer of 1997 was possibly related to negatively anomalous sea-surface temperature. Food loads composed of anchovy (34.0 g) were heavier than those of sand lance (22.5 g) and greenling (28.5 g). The energy density of anchovies also was higher: 6.3 kJ g–1 wet mass compared to 0+ greenling (4.78 kJ g–1) and 0+ sand lance (3.78 kJ g–1). Thus, a high proportion of anchovy in the diet resulted in high food load mass, high daily growth rates of chicks and high fledging success. This study highlighted the importance of the time of arrival of migratory high-lipid prey, which is influenced by local oceanographic conditions, to the reproductive performance of a piscivorous seabird.

Partial Purification and Characterization of Six Transglutaminases from Ordinary Muscles of Various Fishes and Marine Invertebrates

Six transglutaminases were prepared from ordinary muscles of scallop (Patinopecten yessoensis), botan shrimp (Pandalus nipponensis), squid (Todarodes pacificus), carp (Cyprinus carpio), rainbow trout (Oncorhynchus mykiss), and atka mackerel (Pleurogrammus azonus), and their physicochemical and enzymatic properties were compared with each other. The Km value of carp transglutaminase for monodansyl cadaverine, a kind of primary amines, was 0.33 mM, while the other enzymes had Km values of 0.01–0.03 mM. The Km values for succinylated casein of scallop, botan shrimp, squid, carp, rainbow trout, and atka mackerel enzymes were 1.2, 0.3, 1.8, 0.3, 0.2, and 0.1 mg/ml, respectively. In the presence of 0.5 M NaCl, the activities of scallop, botan shrimp, and squid transglutaminases were further enhanced about 11-, 2-, and 6-fold, respectively. There was no effect of NaCl on the activities of fish enzymes. These increment in the activities were dependent of NaCl concentrations and could be exhibited by using KCl instead of NaCl. To date there are no reports on types of transglutaminases whose activities are stimulated by salts. These findings suggest there exist a novel type of TGase in marine invertebrate muscles in which the osmotic pressure is isotonic to sea water.

Winter Feeding of Thick-billed Murres in Coastal Waters Off the Shakotan Peninsula, Hokkaido.

Thick-billed Murres, Uria lomvia, were obtained as an incidental catch during commercial gillnetting for Japan Sea greenling (Pleurogrammus azonus) off the Shakotan Peninsula, Hokkaido, in winter. Stomach content analysis revealed only Japanese sandlance, Ammodytes personatus (Pisces). In winter Japanese sandlance migrate to waters off the Shakotan Peninsula for spawning, where they are preyed upon by species such as Japan Sea greenling, masu salmon (Oncorhynchus masou) and walleye pollock (Theragra chalcogramma). It is apparent that the Thick-billed Murres compete with the above predatory fishes for the Japanese sandlance resource.

カラフトマスの胃中から得たホッケの稚魚について

The authors obtained young Atka fishes, Pleurogrammus azonus JORDAN et METZ from the stomach contents of Pink salmon, Oncorhyncus gorbuscha (WALBAUM) which were caught by salmon gill-nets in the offshore of the Sado Island during the 3-5, May, 1958 (Fig. 1). These specimens were measured from 93 to 124mm. in total length (Table 1 and Fig. 2) and the largest one (124mm.) may be a new recored in size which have been found in the Japan Sea of the north Main Island.