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1.
Little is known about the biology and feeding ecology of Arctogadus glacialis (Peters, 1874), an endemic gadid fish species occurring circumpolarly in both ice-free and ice-covered Arctic seas. In this
study we analysed specimens sampled from bottom trawl and Agassiz trawl catches conducted at eight stations in water depths
from 115 to 490 m in the Northeast Water Polynya off Greenland in August 1990. Size composition and sex ratios were assessed
for 585 fish with standard lengths ranging from 7.8 to 34.5 cm. Median fish sizes at the stations ranged between 8.6 and 18.8 cm.
Quantitative stomach content analyses of a subsample of 175 specimens revealed that in the Northeast Water A. glacialis fed almost exclusively on pelagic prey. Truly benthic organisms were not found in the stomachs, and sympagic species were
rarely recorded. Overall, calanoid copepods were the major prey in terms of numbers. However, stomach contents varied considerably
between fish size groups. In terms of prey biomass, copepods dominated the diet of small fish (<12 cm), primarily occurring
at shallow stations (115–250 m), whereas amphipods and mysids were relatively more important for larger fish (>16 cm), which
dominated the catches at deep stations (360–480 m). The broad variety of diet composition indicated an opportunistic pelagic
feeding pattern.
Received: 6 November 1997 / Accepted: 11 May 1998 相似文献
2.
V. V. Napazakov 《Journal of Ichthyology》2010,50(1):100-104
On the basis of two trawl surveys made in the summer of 2005 and 2008 the diet of white-spotted greenling Hexagrammos stelleri, a widely distributed near-bottom sublittoral species, is investigated. The qualitative and quantitative characteristic of
its food spectrum is given, depending on its linear size. The principal food consists of crustaceans and fish, and secondary
food items are mollusks, polyhaetes, and echiurids. With growth, the composition of crustaceans in the food changes: gammarids
and mysids are replaced by shrimps, crabs, and hermit crabs. With growth, the significance of fish in the food of white-spotted
greenling increases. In the food of the largest specimens, over 30 cm long, fish are dominant. 相似文献
3.
Based on the data from six bottom trawl surveys carried out on the shelf of the Sea of Okhotsk in 1997–2007, the features
of the distribution, size and sex structure, and food composition of the notched-fin (east) eelpout Zoarces elongatus were analyzed. It was established that this species regularly occurs in trawl catches only in the eastern part of the sea
and that the density of its schools decreases with depth. It was recorded that females of the notched-fin eelpout are larger
than males. The sex ratio of the fishes varies from year to year. Females prevail at depths less than 25 m and males prevail
at depths greater than 25 m. 相似文献
4.
Although trophic cascades—the effect of apex predators on progressively lower trophic level species through top-down forcing—have
been demonstrated in diverse ecosystems, the broader potential influences of trophic cascades on other species and ecosystem
processes are not well studied. We used the overexploitation, recovery and subsequent collapse of sea otter (Enhydra lutris) populations in the Aleutian archipelago to explore if and how the abundance and diet of kelp forest fishes are influenced
by a trophic cascade linking sea otters with sea urchins and fleshy macroalgae. We measured the abundance of sea urchins (biomass
density), kelp (numerical density) and fish (Catch per unit effort) at four islands in the mid-1980s (when otters were abundant
at two of the islands and rare at the two others) and in 2000 (after otters had become rare at all four islands). Our fish
studies focused on rock greenling (Hexagrammos lagocephalus), the numerically dominant species in this region. In the mid-1980s, the two islands with high-density otter populations
supported dense kelp forests, relatively few urchins, and abundant rock greenling whereas the opposite pattern (abundant urchins,
sparse kelp forests, and relatively few rock greenling) occurred at islands where otters were rare. In the 2000, the abundances
of urchins, kelp and greenling were grossly unchanged at islands where otters were initially rare but had shifted to the characteristic
pattern of otter-free systems at islands where otters were initially abundant. Significant changes in greenling diet occurred
between the mid-1980s and the 2000 although the reasons for these changes were difficult to assess because of strong island-specific
effects. Whereas urchin-dominated communities supported more diverse fish assemblages than kelp-dominated communities, this
was not a simple effect of the otter-induced trophic cascade because all islands supported more diverse fish assemblages in
2000 than in the mid-1980s. 相似文献
5.
A. M. Tokranov 《Journal of Ichthyology》2008,48(9):759-769
According to materials of 1997–2002, the characteristic of the spatial-bathymetric distribution, size and age composition, size and sex structure, and feeding of the Korean flounder Glyptocephalus stelleri in the summer period in waters off Kamchatka in the Sea of Okhotsk (the site from 51°15′ to 57°20′ N, depths of 10–300 m) is given. It is shown that throughout the observation period, maximum catches of this flatfish were constantly observed at two sites of the western Kamchatka shelf (51°20′–53°00′ N and 55°00′–56°00′ N) in the zone exposed to the effect of anticyclonic gyres in the range of depths 101–200 m at the near-bottom temperature below 2°C. Unlike other habitat areas, off the coast of western Kamchatka, G. stelleri in the summer time is quite frequently found at negative temperature values, which is obviously determined by the specifics of thermal conditions of the eastern part of the Sea of Okhotsk. It was established that, in this species of flatfish, sex dimorphism is distinctly pronounced in sizes—males are considerably smaller than females whose relative number among individuals with a length larger than 50 cm reaches 100%. The main items of feeding of G. stelleri at the western Kamchatka shelf in the summer period are oligochaetes. 相似文献
6.
Information on the qualitative and quantitative characteristics of the feeding habits of two pandal shrimp—the humpy shrimp
(Pandalus goniurus) and the northern shrimp (Pandalus borealis) and one species of crangonids (Crangon communis) is submitted. The materials were collected in April–May 2006 and 2007 during complex surveys at West Kamchatka. The size
and sex composition of the shrimp, as well as the composition of their food were analyzed. The food of all the considered
species basically consisted of polychaetes, amphipods and, to a lesser extent, other shrimp. The daily ration (DR) of a shrimp
with a body length of 40–60 mm was calculated for the first time—it was 7.9% of the body weight. The DR of a northern shrimp
61–80 mm in length was 5.8% of its body weight. Individuals of the third species, Crangon communis, generally did not feed. 相似文献
7.
According to materials of trap, long-line, and trawl fishing, specific features of distribution of sablefish Anoplopoma fimbria and some of its biological characteristics in Pacific waters off the southeastern coast of Kamchatka, continental slope of the western part of the Bering Sea, Shirshov Underwater Ridge, and off the Commander Islands are considered. Maximum density concentrations according to data of trap fishing was noted along southeastern coast of Kamchatka and the data of trawl fishing indicated most frequent catches in the western part of the Bering Sea in the area of Koryak coast up to Cape Navarin. The pattern of vertical distribution in different areas considerably differs. The magnitude of trap catches in different areas is different and determined by the type of trap and the period of soaking. The size composition, fatness, and the sex ratio are different in catches of different fishing gear and differ between regions. On the whole, in Russian Far Eastern waters, females mature in mass at a body length of 71 cm and males at 57 cm. 相似文献
8.
New data on fecundity, sex ratio in different size groups, and the rate of sexual maturation of shortspine thornyhead Sebastolobus alascanus in the northwestern part of the Pacific Ocean are provided. Individual absolute fecundity of the studied females varies in
the range of 175 000–821000 (on average, 392500) eggs. In Pacific waters off the Kuril Islands and Kamchatka, among individuals
with a length to 41 cm, males dominate; in size groups of 42–59 cm, sex ratio is almost equal; among larger fish, females
prevail. In the western part of the Bering Sea among analyzed fish with a length to 44 cm, sex ratio is almost equal; among
larger individuals, females dominate. Half of males and females of shortspine thornyhead off the eastern coast of the northern
Kuril Islands and southeastern Kamchatka mature at a length of approximately 41 cm that can be recommended as a commercial
size for the given species in this area. 相似文献
9.
Complex trawl surveys were conducted in the upper epipelagic zone of the western Bering Sea and adjacent Pacific waters in
the summer and fall seasons of 2002–2006. The abundance of small nekton (micronekton) was estimated using two independent
methods: traditional trawling and a mathematical model of selective feeding by fish. According to the trawl data, total micronekton
density varied from 1 to 158 (average 40) mg/m3 on the northwestern Bering Sea shelf and from 6 to 151 (37) mg/m3 in deep-water areas of the southwestern Bering Sea and adjacent Pacific waters. According to model calculations, micronekton
density was higher—72–193 (141) mg/m3 on the shelf and 78–507 (228) mg/m3 in the deep-water part of the studied area. Both trawl and model data showed that small nekton on the northwestern shelf
mostly consisted of larval and juvenile walleye pollock, as well as small fish species, such as capelin and Pacific sand lance.
In the deepwater areas, mesopelagic fish and squid (northern lampfish, northern smoothtongue, and boreopacific gonate squid),
which migrate to the surface at night, juvenile Atka mackerel, and shortarm gonate squid dominated among micronekton. The
advantages and disadvantages of both the trawl and model methods for calculating the abundance of small fish and squid were
considered. Comparison of abundance estimates for mass fish species, obtained through trawl and model methods, enabled us
to analyze trawl catchability coefficients and propose a more differentiated division of micronekton into size classes than
had been done earlier. A function that characterizes the dependence of the catchability coefficient (CC) on body length was
offered for juvenile Atka mackerel. This equation can be also used for evaluation of CC for other fishes that have similar
size and behavior. 相似文献
10.
Tom Jza Jaroslava Frouzov Uwe Brmick Vladislav Dratík Tom Mrkvi
ka Jan Kube
ka 《International Review of Hydrobiology》2012,97(6):509-525
The fish stock of a deep temperate, mesotrophic lake was sampled at different depths using a fixed‐frame fry trawl, during two nights in mid‐September 2009. Additionally, horizontal and vertical hydroacoustics were used simultaneously to evaluate fish abundance and biomass estimates obtained by the trawl. Roach Rutilus rutilus and smelt Osmerus eperlanus were the dominant species of young‐of‐the‐year (YOY) fish in the trawl catches from the surface layers (0–9 m). Bleak Alburnus alburnus dominated the catch of older fish in the upper part of the surface profile (0–6 m). Around the thermocline (9–13 m) smelt dominated the catches of both the YOY and older fish. Beneath the thermocline (13–36 m) vendace Coregonus albula dominated the catch of YOY fish, and smelt was the only species of older fish in the trawl catches. Species composition, abundance and biomass of the YOY and older fish were heterogeneous throughout the depth profiles of the lake, but only abundance differed significantly between the layers. The hydroacoustics gave relatively similar estimates of abundance and biomass to those obtained by the trawl in all the depths sampled. Our results indicate that there is a clear separation of small fish of different species along the vertical profile of a deep temperate lake during the night, and an unequal vertical distribution of fish abundance and biomass. The similarity of the trawl and hydroacoustics estimates of abundances and biomass indicated that the trawl sampling did not cause important avoidance reactions of small fish during the night in this deep temperate lake (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
11.
The results of investigation are discussed on age and growth of the Pacific halibut Hippolglossus stenolepis, as well as size-age composition of its catches in three regions of the North-Western Pacific—in Navarin area of the Bering
Sea, in Pacific waters on the Northern Kurils and south-eastern Kamchatka, of the Southern Kurils—from the end of the last
century. The growth rate of Pacific halibut is similar in all three regions in spite of their considerable geographic remoteness.
No significant differences in the growth rate of males and females in these regions, as well as no significant interannual
differences in growth of specimens caught in Pacific waters off the Northern Kurils and south-eastern Kamchatka in 1996–2000,
are found. Comparison of the present-day size-age composition and that in the beginning-middle of the last century revealed
their considerable similarity. 相似文献
12.
In comparison with other bathydraconids, all species of the genus Bathydraco are poorly known from an ecological perspective. The diet of juvenile Bathydraco marri Norman, 1938 was studied for the first time in specimens collected in the southwestern Ross Sea during summer 1998. Fish
were collected in a single otter trawl catch at 330–340 m depth. The stomach content analysis showed that this species fed
exclusively on crustaceans. Overall, 20 prey taxa were identified to genus or species level. Mysids, amphipods and copepods
were the most important prey in decreasing order of importance. Other prey, such as Euphausia superba, isopods and tanaids were eaten occasionally and in very small amounts. A multivariate analysis was applied to feeding data
to assess ontogenetic or sex-related changes in diet. No difference was detected between sexes, whereas diet of small and
large fish differed in some degree. An ontogenetic shift from small and pelagic crustaceans such as copepods to benthic–benthopelagic
prey such as amphipods and mysids was observed. Relating present results with published data on physiological characteristics
of B. marri, it was possible to infer their feeding behaviour and mode of life. Like other bathydraconids, this species appeared to be
an inactive and sluggish fish, which relied on more or less motile benthic or epibenthic prey adopting a “sit and wait” feeding
strategy. On the other hand, smaller fish seem to be more active, feeding also on pelagic prey such as copepods that can be
seasonally abundant, thus reducing the intraspecific competition for food. 相似文献
13.
Quantative estimates of abundance of anadromous Kamchatka steelhead Parasalmo mykiss in the period of its maximum spawning migration in the shallow Utkholok River by the instrumental method using Didson dual-frequency
identification sonar are presented. Equipment and methods are described for the stationary observation of spawning run of
Kamchatka steelhead through the river cross section and mobile surveys of the water area of the Utkholok R. As a result of
stationary observations, the abundance and size composition of Kamchatka steelhead migrating to the upper reaches of the river
are determined. Peculiarities of the diurnal dynamics of migration of Kamchatka steelhead characterized by two sharp peaks
of run intensity in the morning and evening were revealed. During the period of observations from September 22 to October
20, 2007, in the seasonal dynamics of migration two peaks of intensity of run of Kamchatka steelhead depending on an abrupt
decrease in water temperature by 2°C were also registered. Mobile surveys supplied data on the abundance and size composition
of Kamchatka steelhead in the surveyed water area of the river, on its spatial distribution, and dynamics of accumulation
of fish in the river. The abundance of Kamchatka steelhead in the river almost doubled every three-four days and the spatial
distribution was aggregated, producing maximum concentration mainly in areas of increasing depth and channel meandering before
and after riffles. Comparison of the results of assessment of abundance of Kamchatka steelhead that arrived for spawning in
2006 and 2007 showed significant fluctuations in population abundance. 相似文献
14.
We test the hypothesis that size distribution of a Daphnia population reflects the vulnerability of each size category (instar) to predation by planktivorous fish. We hypothesize that
due to the different reaction distances from which separate prey categories can be seen by a foraging fish, each category
is preyed upon until its density is reduced and its size-specific apparent density level (number of prey within a hemisphere
of radius equal to the reaction distance) or encounter rate (number of prey encountered per time within a tube with a cross
section of radius equal to the reaction distance) become equal to those of other size categories. An experiment was performed
with populations of Daphnia hyalina and D. pulicaria grown at two Scenedesmus + Chlamydomonas food levels (0.2 and 0.05 mg C per liter) in outdoor mesocosms (1000 l tanks) with predation by invertebrates (phantom midge)
prevented by mosquito netting. Once the populations had become established, roach were added to the tanks at dusk each day
and allowed to feed for 3 h, while control tanks were kept fish-free. After 20–60 days, while D. pulicaria was at low density level, the densities of D. hyalina in fish tanks were high enough to see that the age structure and size distribution matched those from simulations with the
age-structured population model based on size-specific encounter rate. This match, however, remained only up to the point
of first reproduction when—in contrast to the size/age distribution predicted by the model—the percentage share of adult instars
in the total population decreased rapidly with age. This deviation from the predicted densities of adult instars suggests
that neither encounter rates nor apparent densities derived from instar-specific reaction distances are sufficient to explain
the instar-specific impact of a visual predator on planktonic prey. This implies that a foraging fish may temporarily change
its feeding mode from the typical low-speed harvesting of small but abundant prey from within its visual field volume, to
high-speed hunting for more scarce but larger ovigerous females when their abundance allows higher net energy gain. Shifting
from one feeding mode to the other may be responsible for damping population density oscillations in Daphnia. 相似文献
15.
On the basis of data on bottom trawl catches in Pacific waters off the northern Kuril Islands and southeastern Kamchatka (1992–2002), quantitative indices of occurrence of the smooth lumpsucker Aptocyclus ventricosus and the range of preferred habitation temperature are provided. Its spatial and vertical distribution are analyzed, and specific features of size composition and the relationship between the length and weight of the body and between the average weight and the capture depth are considered; the diurnal, seasonal, and long-term dynamics of occurrence and of the amount of average catches is presented; data on the species composition of fish present in catches parallel to A. ventricosus are cited. 相似文献
16.
V. V. Panchenko O. I. Pushchina D. V. Antonenko S. F. Solomatov P. V. Kalchugin 《Journal of Ichthyology》2011,51(3):217-226
It has been found, with reference to the data of trawl survey and literature, that, in the Sea of Japan, the Northern boundary
of the area of the elongated sculpin Alcichthys elongatus is the central part of the Tatar Strait. During the year, the elongated sculpin occurs at depths from 7 to 650 m. Its highest
concentration forms during the feeding period. At this time Alcichthys elongatus stays up to depths 253 m but prefers the range of 40–100 m. It winters below the 50 m isobath, mainly in the lower part of
the shelf and in the upper section of the continental slope. Being an eurythermal species, the elongated sculpin occurs in
a wide range of temperature (from −1.6 to 17.7°C). However, most specimens prefer waters with slightly positive temperature.
Juveniles prefer the warm water layers. Males are larger than females but the latter dominate in catches. According to the
kind of diet A. elongatus, it is a benthoichtyophage consuming predominantly decapods (mostly juveniles of Chionoecetes opilio) and small fish. In summer, the value of daily ration is 3.0% of the body weight. In the north-western part of the Sea of
Japan, A. elongatus may be characterized as a common species with a low but stable abundance. 相似文献
17.
The otolith microstructure of juvenile Scotia Sea icefish (Chaenocephalus aceratus) was analyzed from samples collected around Elephant and South Shetland Islands, with the aim to validate previous annual
ageing and to give new insight into its early life history timings. Fish were caught by bottom trawl fishing conducted on
the continental shelf between 100 and 500 m depth. To determine the timing and position of the first annulus on sagittal otoliths,
microincrements were counted on juvenile otoliths previously aged 1+ year old by counting annuli in sectioned otolith. Assuming
that microincrements were laid down daily, age ranged from 406 to 578 days in fish measuring 13–19 cm TL, thus corroborating
previous results. The relationship between fish size and otolith size/weight was estimated using the least square linear regression
method. The relationship between age and otolith size was also estimated to determine the otolith length in 1-year old fish,
which was approximately 1.58 mm. In all samples the otolith core was characterized by an evident strong check, assumed to
be laid down at the beginning of exogenous feeding of yolk sac larvae. The yolk sac duration estimated from hatch to the first
feeding check was longer than other channichthyids, lasting 29–45 days. Hatching dates were backcalculated from the date of
capture using the age estimates, indicating C. aceratus sampled off Elephant and South Shetland Islands hatched over a long period lasting from July to December, with a peak in
November. As a result, the potential larval dispersion driven by local oceanographic features is discussed. 相似文献
18.
Feeding habits of the Alaska greenlingHexagrammos octogrammus were studied in the coastal waters of Amurskii Bay in April–October 1997–1998. The greenling is characterized by a wide feeding
spectrum of no less then 56 fish and invertebrate species. Decapods predominate in the diets of all fish age groups. The feeding
spectrum ofH. octogrammus broadens as the fish grows. From spring to autumn, the stomach filling index of first-year fish rises, while that of the
other age groups decreases, reaching minimum values in the spawning period. 相似文献
19.
20.
V. V. Napazakov 《Russian Journal of Marine Biology》2008,34(7):452-460
The food spectra, trophic statuses, and feeding interrelations of three most abundant benthic carnivorous fish species inhabiting
the Shelikhov Bay—the Pacific cod Gadus macrocephalus, the great sculpin Myoxocephalus polyacanthocephalus, and the Okhotsk sculpin M. ochotensis—are considered based on materials collected during the complex survey of the RV Professor Kaganovsky of the TINRO-Center, in September 2004. It was found that these species were facultative predators with wide food spectra.
The significance of prey objects in the diet of the Okhotsk sculpin was as follows: crustaceans, fish, and mollusks. Great
sculpin and Pacific cod preyed mostly on fish, then on crustaceans, and mollusks. Pacific cod ate equal proportions of fish
and decapods. All the species had age-related variability of diet. The potential competition of great sculpin and Okhotsk
sculpin for food was mitigated by the difference in the depths of their ranges, as well as by morphological (body size) and
behavioral peculiarities in the areas where their habitats overlapped, and in microecosystems. The most probable competition
was among Pacific cod 30–60 cm long and Okhotsk sculpin 20–50 cm in length, as well as among cod and great sculpins of all
sizes. 相似文献