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Vol.01-10
No.11-20
No.21-30
No.31-40 No.41-50
No.41 No.42
No.43 No.44
No.45 No.46
No.47 No.48
No.49 No.50
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Sci. Rep. Hokkaido Fish Hatchery
(50), 1996
- 50-1
The
pathobiology of ectoparasitic protozoans on hatchery-reared
Pacific salmon. Urawa, S. pp. 1-99. (In English with
Japanese
summary)
 (11,227KB)
Abstract
The present study was conducted to
determine the occurrence and geographical distribution of
external protozoan parasites on hatchery-reared Pacific salmon
(chum, pink, masu and sockeye salmon) in northern Japan, and to
clarify their potential impact on fish populations, and
host-parasite interactions such as the defense mechanism of host
fish. A flagellate Ichthyobodo necator, and two ciliates
Trichodina truttae and Chilodonella piscicola were
widespread in salmon hatcheries. Infection experiments indicated
that these three protozoan parasites were epidemic pathogens
capable of causing large economic losses both in hatchery and
wild conditions during the course of artificial salmon ranching.
Especially, I. necator infection has high potentials to
cause mass mortality among anadromous salmonids during their
initial marine life. The virulence of the ectoparasitic
protozoans is affected by the mode of attaching and feeding,
parasite intensity, host condition, and environments. The ideal
goal should be to control parasite infections in hatcheries on
the basis of these biological information.
- 50-2
Effects
of population density and habitat environment on life history
strategy and migration of juvenile sockeye (Oncorhynchus
nerka) and chum salmon (O. keta). Kaeriyama, M. pp.
101-111. (In English with Japanese summary)(569KB)
Abstract
Life histories of juvenile sockeye
and chum salmon show a conditional strategy with tactics of
residence and migration. They remain in lake or river when they
can sufficiently obtain their resources such as food and
habitat, but they migrate seaward in a case of scarcity of
resources for their energy metabolism. Their migration pattern
may be controlled by "prior residence" and "precedent
migration", involving a trade-off between the profitability of
resource acquisition and risks such as osmoregulation, energetic
demands of swimming, exposure to predators, and mobilization to
non-adaptable habitat by water current.
- 50-3
Allometric back-calculation of individual growth for chum salmon
otolith during early life. Fukuwaka, M. pp. 113-116. (In
English with Japanese summary)(306KB)
Abstract
Otolith growth and rate of
increment formation in juvenile chum salmon were examined to
determine whether the otolith could be used to back-calculate
body size of juveniles at various life stages. The sagittal
otoliths were firstly observed in newly hatched chum alevin. At
that time, the fish had an average total length of 19.5 mm and
their sagittae were approximately 0.312 mm long. As the fish
grew, the relationship between body length (L in mm) and sagitta
length (O in mm) was allometric and equaled: O = 0.312 +
0.0359(L - 19.5)0.790. An increment periodicity was
found to occur on a daily basis and was ascertained by
performing a fluorescent marking experiment. The results of this
work show that individual growth in juvenile chum salmon can be
estimated by features readily detected in their otoliths.
- 50-4
Effects
of starvation and refeeding on physiological condition of
juvenile chum salmon, Oncorhynchus keta. Ban, M.,
Hasegawa, H., and Ezura, M. pp. 117-123. (In Japanese with
English summary)(651KB)
Abstract
The growth of juvenile chum salmon
was reduced soon after the start of starvation. Total lipid and
serum protein of starved fish showed the lowest level after 10
and 20 days, respectively. The mortality of starved fish
increased after 20 days, reaching 100% within 45 days. The
starved fish lost their seawater adaptability after 30 days.
These fish recovered their growth and survival in fresh water
after refeeding, but the seawater adaptability was not improved.
- 50-5
Growth
pattern and age determination by scales of lacustrine sockeye
salmon in Lake Toya. Sakano, H., Kaeriyama, M., Ueda, H.,
Sakurai, Y., and Shimazaki, K. pp. 125-138. (In Japanese with
English summary)(919KB)
Abstract
The present study was conducted to
develop the age determination method using scale analyses, and
to determine factors responsible for growth variation of
different blood stocks of lacustrine sockeye salmon in Lake Toya.
Scale annuli seemed to form irregularly, because number of
circuli between two checks was significantly different among
individuals. Fish age was determined by the following method
after counting the number of circuli between two checks. One age
was added for fish with a large number of circuli between two
checks, whereas one age was reduced for fish with a few number
of circuli. Growth pattern was different between 1990 and 1991
brood stocks. Their growth variation among brood stocks may be
influenced by lacustrine environments.
- 50-6
Oncorhynchus masou
virus: serological relationships among salmonid herpesviruses
isolated from kokanee salmon, masu salmon, coho salmon and
rainbow trout. Sung, J. T., Yoshimizu, M., Nomura, T., and Ezura,
Y. pp. 139-144. (In English with Japanese summary)(401KB)
Abstract
Serological relationships of
herpesviruses isolated from salmonid fishes were investigated,
and salmonid herpesviruses were divided into two groups. One is
salmonid herpesvirus isolated from rainbow trout and steelhead
trout in USA (Salmonid herpesvirus; SaHV-1) and other is SaHV-2
isolated from sockeye salmon, masu salmon, coho salmon and
rainbow trout in Japan. The values of serological relationship
(1/R) among SaHV-2 isolates ranged from 0.51 to 1.53. Between
SaHV-1 and SaHV-2, the 1/R value was 3.16-5.69. These results
indicate that Japanese SahV-2 is apparently different from
SaHV-1 but similar among strains in Japan.
- 50-7
Oncorhynchus masou
virus: pathogenicity of salmonid herpesvirus 2 strains against
masu salmon fry (Oncorhynchus masou). Sung, J. T., Yoshimizu, M., Nomura, T., and Ezura, Y. pp. 145-148. (In
English with Japanese summary)(255KB)
Abstract
Pathogenicity of 6 strains of
salmonid herpesvirus 2 (SaHV-2) isolated from sockeye salmon,
masu salmon, coho salmon and rainbow trout in Japan was compared
by immersed artificial infections. The cumulative mortality of
masu salmon fry infected with SaHV-2 strains ranged from 50% to
71% during 60 days, while it was 4% in the control group. Thus
there was no apparent difference in pathogenicity among SaHV-2
strains.
- 50-8
Bibliography of salmonids published in Japan (9): 1994. Urawa,
S., and Azuma, T. pp. 149-159. (In English)(706KB)
Abstract
This current salmonid bibliography
covers scientific publications appeared in Japan in 1994. Titles
are given in English for all articles. An author's address is
shown in square brackets following the citation. This 9th issue
has included 99 papers, being divided into Aquaculture and
Propagation, Ecology-General, Distribution and Migrations,
Breeding and Reproduction, Feeding, Diets and Growth, Morphology
and Taxonomy, Physiology and Endocrinology, Biochemistry,
Genetics, Diseases and Parasites, Toxicology, and Economics, and
followed by Author Index.
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Sci. Rep. Hokkaido Fish Hatchery
(49), 1995
- 49-1
Variation in body size, fecundity, and egg size of sockeye and
kokanee salmon, Oncorhynchus nerka, released from
hatchery. Kaeriyama, M., Urawa, S., and Fukuwaka, M. pp. 1-9.
(In English with Japanese summary)(483KB)
Abstract
Reproductive variation was
examined for hatchery-released sockeye salmon. There was no
difference in egg size between lake-resident and age-1.1
anadromous sockeye salmon. In hatchery-released sockeye salmon
having a constant gametic effort without breeding competition
and parental care, the egg size may be stable within a cohort or
a population regardless of body-size variation, although the
fecundity is expressed by the function of body size affected by
environmental factors.
- 49-2
Prevalence of Myxobolus arcticus (Myxozoa: Myxosporea) in
five species of Pacific salmon in the North Pacific Ocean and
Bering Sea. Urawa, S., and Nagasawa, K. pp. 11-19. (In
English
with Japanese summary)(471KB)
Abstract
Five species of Pacific salmon
captured on the high seas of the North Pacific Ocean and Bering
Sea were examined for the freshwater brain myxosporean
Myxobolus arcticus. In the western North Pacific Ocean, the
prevalence of parasite was relatively high in chinook (57.5%),
sockeye (30.4%), and coho (18.8%) salmon, but low in chum (6.7%)
and pink (0%) salmon, being reflected by a mode of freshwater
life of host fish before their seaward migration. Distinct
regional differences in prevalence were observed in chinook
salmon: infected fish were frequently found in the western North
Pacific Ocean (especially west of 170ｰE),
but rarely in the eastern North Pacific Ocean and Bering Sea,
suggesting the restricted geographical distribution of M.
arcticus in chinook salmon. The parasite may be useful as a
biological indicator to separate the continental origin of
high-seas chinook salmon.
- 49-3
Histological changes in the digestive organ of chum salmon
Oncorhynchus keta at the early stages. Ban, M., Hasegawa,
H., and Abe, K. pp. 21-26. (In Japanese with English summary)(1,079KB)
Abstract
Histological changes were observed
in the digestive organ of chum salmon at the early stages. The
alimentary canal showed a simple, straight and tubular structure
at the early alevin stage. At the late alevin stage, the stomach
was composed of the muscle layer and cubical epithelium
including the glands, while the intestinal epithelium had a
columnar structure. After the early fingerling stage, the
epithelium of the stomach changed from cubical to columnar
structure, and the intestinal epithelium was characterized by
vacuolated supranuclear areas and a striated border. In the
liver, glycogen vacuoles appeared and nuclei enlarged after the
late alevin stage. Thus, chum salmon alevins could be divided
into two stages according to the development of the alimentary
canal. Rapid structural changes in the digestive organ after the
late alevin stage may be related with ecological and nutritive
transition in their early life.
- 49-4
Relationship between feeding rate and physiological quality in
hatchery-reared juvenile chum salmon, Oncorhynchus keta.
Ban, M., Hasegawa, H., and Abe, K. pp. 27-33. (In Japanese with
English summary)(1,077KB)
Abstract
Histological development in the
stomach, liver, kidney, gills and thyroid gland, and seawater
adaptability were compared among groups of chum salmon fry fed
at 1% (group A), 3% (group B) and 5% (group C) body weight per
day for 10 weeks. A significant difference in fork length was
present among the three groups. All groups showed almost same
increase trend in hepatosomatic index during the experimental
period. All groups showed a high survival rate (100%) and high
serum sodium excretion ability 24 h after seawater transfer
throughout the experimental period. Histological observations
indicated that glycogen vacuole accumulated into hepatic cells
of fry in group A was less abundant than in groups B and C at
the end of the experiment, but there were no structural
differences in the other organs examined among the groups. A
surge of the gill Na+-K+ATPase activity
was observed in groups B and C at week 8, but not in group A.
These results suggest that the physiological quality of
hatchery-reared chum salmon fry may not be affected by the
feeding rate between 1% and 5% body weight per day.
- 49-5
Occurrence of Myxobolus arcticus and M. neurobius
(Myxozoa: Myxosporea) in masu salmon Oncorhynchus masou
from northern Japan. Awakura, T., Nagasawa, K., and Urawa, S.
pp. 35-40. (In English with Japanese summary)(381KB)
Abstract
Adult masu salmon from seven
rivers in Hokkaido and northern Honshu were examined for the
geographical distribution of Myxobolus arcticus and M.
neurobius in northern Japan. Maturing masu salmon from
Japanese coastal waters of the Okhotsk Sea, Japan Sea, and
western North Pacific Ocean were also studied for the prevalence
of these freshwater myxosporeans. Myxobolus arcticus
occurred mainly on the Japan Sea coast of Honshu, whereas M.
neurobius was found in Hokkaido along the coasts of the
Okhotsk Sea and Japan Sea. Sea-caught masu salmon showed various
degrees of infections with M. arcticus and M.
neurobius. This indicates that masu salmon migrating in
Japanese coastal waters are a complex of mixed stocks that
originate in various rivers. Prevalence data support the
recently proposed the autumn migration route of maturing masu
salmon from the Okhotsk Sea to the Japan Sea.
- 49-6
Predation by fishes and seabirds on juvenile chum salmon (Oncorhynchus
keta) in coastal waters of Japan: a review. Nagasawa, K.,
and Kaeriyama, M. pp. 41-53. (In Japanese with English summary)(851KB)
Abstract
Over 90 fish species have been
reported to occur with chum salmon juveniles in coastal waters
of Japan. Among these species, fishes recorded as predators are
only 4 species: Japanese dace at estuaries, and Arabesque
greenling, Japanese flounder, and pink salmon at sea. The
release of hatchery-reared, large-sized juveniles possibly
reduces the mortality by fish predation. Rhinoceros auklets and
black-tailed gulls have been recorded as predators of juvenile
chum salmon. These seabirds breed abundantly in northern Japan,
and the impact of their predation on Japanese chum salmon
populations may be significant.
- 49-7
Reproductive characteristics of mature female chum salmon (Oncorhynchus
keta) in the Pinacheva River, Kamchatka. Ishida, Y., Ohkuma,
K., Bugaev, V. F., and Tochilin, V. A. pp. 55-59. (In Japanese
with English summary)(278KB)
Abstract
Over 90 fish species have been
reported to occur with chum salmon juveniles in coastal waters
of Japan. Among these species, fishes recorded as predators are
only 4 species: Japanese dace at estuaries, and Arabesque
greenling, Japanese flounder, and pink salmon at sea. The
release of hatchery-reared, large-sized juveniles possibly
reduces the mortality by fish predation. Rhinoceros auklets and
black-tailed gulls have been recorded as predators of juvenile
chum salmon. These seabirds breed abundantly in northern Japan,
and the impact of their predation on Japanese chum salmon
populations may be significant.
- 49-8
Bibliography of salmonids published in Japan (8) 1993. Urawa,
S., and Azuma, T. pp. 61-72. (In English)(810KB)
Abstract
This current salmonid bibliography,
distributed yearly since 1988, covers scientific publications in
Japan. The former seven issues were published in Technical
Reports of Hokkaido Salmon Hatchery (Fish and Eggs), No.
157-163. Titles are given in English for all articles, A reprint
of article may be available from the author. An author's address
is shown in square brackets following the citation. This 8th
issue has covered literature published in 1993, including 111
papers.
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Sci. Rep. Hokkaido Fish Hatchery
(48), 1994
- 48-1
A back-calculation method for estimating individual growth of
juvenile chum salmon by scale analysis. Fukuwaka, M., and
Kaeriyama, M. pp. 1-9. (In Japanese with English summary)(566KB)
Abstract
A back-calculation method was
proposed to estimate individual growth of hatchery-released
juvenile chum salmon during their early ocean life. The scale
pattern was examined for marked juvenile chum salmon reared at a
hatchery and those recaptured in the coastal water. A check
appeared on the scales just after release. Thus, the individual
growth rate could be estimated by using the individual fork
length at release back-calculated from the scale radius of
check.
- 48-2
Feeding selectivity of juvenile chum salmon in the Japan Sea
coast of northern Honshu. Suzuki, T., Fukuwaka, M., Shimizu,
I., Seki, J., Kaeriyama, M., and Mayama, H. pp. 11-16. (In
Japanese with English summary)(337KB)
Abstract
The present study evaluated the
relation between fish size and feeding selectivity in juvenile
chum salmon fed on pelagic zooplankton during their coastal life
in the Japan Sea coast of Honshu. Small juveniles fed small
preys and large juveniles fed selectively large preys. Juvenile
chum salmon emphasized selectivity for large preys at 50-60 mm
in fork length when they developed from fry to fingerling stage.
- 48-3
A parasitological survey of sockeye salmon (Oncorhynchus
nerka) and Dolly Varden (Salvelinus malma) from the
Ozernaya River System, Kamchatka. Nagasawa, K., Urawa, S.,
and Dubinin, V. A. pp. 17-21. (In English with Japanese summary)(952KB)
Abstract
Adult sockeye salmon from the
Ozernaya River near the outlet of Lake Kuril were infected with
Myxobolus arcticus (Myxozoa) in the brain and spinal cord
and with Philonema oncorhynchi (Nematoda) in the
peritoneal cavity. Some of these sockeye salmon were affected by
light visceral adhesions. This pathological condition was found
in male fish only. Myxobolus arcticus was also found in
the brain of adult Dolly Varden from a river flowing into Lake
Kuril. There was no substantial difference in spore measurement
of M. arcticus from salmonids among Kamchatka (Russia),
Hokkaido (Japan), and British Columbia (Canada). The Dolly
Varden carried Salmincola carpionis (Copepoda) on the
roof and floor of the buccal cavity and Anisakis simplex
(third-stage larvae) (Nematoda) on the viscera.
- 48-4
Existence of non-agglutinating Aeromonas salmonicida
subsp. salmonicida in strains isolated from salmonids in
Yamagata Prefecture, Japan. Nomura, T., Yoshimizu, M., Moki,
S., and Ezura, Y. pp. 23-29. (In English with Japanese summary)(960KB)
Abstract
Auto-agglutination, protein
staining of colonies and protein pattern of A-layer in 33
isolates of Aeromonas salmonicida from salmonids in
Yamagata and Hokkaido were studied. The strains isolated in
Yamagata did not showed auto-agglutination in broth, colony
color was mainly gray-white on TSA-C and NA-C medium, and there
was no 50kDa. major protein band in the A-layer with SDS-PAGE.
It was revealed from the results that non-agglutinating A.
salmonicida exist in the strains isolated in Yamagata. There
was no strain isolated in Hokkaido which were non-agglutinating.
We suspect that the reason for the existence of
non-agglutinating strains in Yamagata may depend on the
temperature at which this bacterium was isolated.
- 48-5
Optimum environmental condition for rearing juvenile chum salmon
(Oncorhynchus keta): a review. Nogawa, H., and
Yagisawa, I. pp. 31-39. (In Japanese with English summary)(712KB)
Abstract
Fish reared in intensive culture
are usually affected by various stressors such as handling,
crowding, chemical treatment, and unfavorable temperature and
water chemistry. These environmental stress predispose fish to
disease, and can result in reduced survival, growth, and food
conversion. This paper deals with the affecting factors on the
growth of intensively-reared juvenile chum salmon, especially
dissolved oxygen, fish loading, rearing density and ammonia.
- 48-6
Preliminary report on the observation method of water flow in an
alevin raceway-modeled aquarium using a flow visualizing
technique. Ohkuma, K. pp. 41-44. (In Japanese with English
summary)(312KB)
Abstract
A water flow observation method was
developed for improving salmon alevin incubation techniques.
This method is easily applicable to comprehend raceway flow
characteristics.
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Sci. Rep. Hokkaido Fish Hatchery
(47), 1993
- 47-1
The epidemiological study of furunculosis in salmon propagation.
Nomura, T. pp. 1-99. (In Japanese with English summary)(7,566KB)
Abstract
This study was carried out for
establishing the control measure of furunculosis. The author
attempted to determine the distribution and prevalence of
Aeromonas salmonicida in mature chum, pink and masu salmon
in Hokkaido that showed no apparent clinical signs of
furunculosis. The author concluded that the agent carrier state
in fish possess a serious problem in the prevention of
furunculosis and its reduction plays key role in salmon
enhancement. Both mature fish under conditions in low density in
pond, and disinfection of their eggs, are necessary to prevent
fish furunculosis during artificial enhancement of salmon.
- 47-2
A review of gastric evacuation rate of salmonids. Suzuki, T.
pp. 101-107. (In Japanese with English summary)(402KB)
Abstract
The gastric evacuation rate of
salmonids is affected by various factors such as water
temperature, food type, food size, and fish size. Use of wet or
dry weights of foods can lead to different conclusions for the
effect of meal size on the gastric evacuation rate. A relation
between the gastric evacuation rate and temperature is
classified into three patterns: (1) the gastric evacuation rate
increasing exponentially; (2) the gastric evacuation rate
reaching a plateau; and (3) the gastric evacuation rate with the
maximum value. High energy foods are evacuated more slowly than
low energy one. Several mathematical models have been proposed
for the gastric evacuation rate. The best-fit model may be
different depending on the food type and food size.
- 47-3
Copepods from waters around Ozerki Hatchery, Kamchatka, Russia.
Ishida, T., and Kobayashi, T. pp. 109-112. (In Japanese with
English summary)(218KB)
Abstract
Five species of Cyclopoida and 7
species of Harpacticoida were identified on the basis of
specimens collected from the Bolshaya River on the west coast of
the Kamchatka Peninsula. These species were common in Hokkaido,
but considerable morphological variations were observed in some
species.
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Sci. Rep. Hokkaido Fish Hatchery
(46), 1992
- 46-1
Studies on the freshwater life and propagation technology of masu salmon,
Oncorhynchus masou (Brevoort). Mayama, H. pp. 1-156. (In Japanese with
English summary)(10,164KB)
Abstract
Ecological studies on the
freshwater life of masu salmon were carried out in rivers, mainly of
southwestern Hokkaido. In addition, experimental releases based on the knowledge
obtained were carried out to establish the most efficient enhancement methods of
these resources. Comprehensive technology for producing masu salmon smolt and
improving adult returns was presented: fry release in the first spring at proper
body size to achieve higher survival and efficient dispersal, fingerling release
in the late autumn prior to the overwintering period, and yearling smolt release
at the time when wild smolts migrate to the sea. The enhancement technology will
combine various means, but no one method can be singled out for the increase of
masu salmon resources because of a diversity in their life pattern.
- 46-2
Anadromous sockeye salmon (Oncorhynchus nerka) derived from nonanadromous
kokanees: life history in Lake Toro. Kaeriyama, M., Urawa, S., and Suzuki,
T. pp. 157-174. (In English with Japanese summary)(1,780KB)
Abstract
Life history of sockeye salmon
derived from lacustrine sockeye salmon was investigated in Lake Toro of the
Kushiro River System. Juvenile sockeyes released in Lake Toro as underyearlings
(age 0.0) in late fall showed two life-history patterns: anadromous and resident
sockeye types. Their growth curves fit periodic von Bertalanffy's curves, but
anadromous type grew lineally more than the resident type. Seasonal changes in
the growth rate of anadromous type showed a constant periodicity, but that of
resident type showed an extreme fluctuation and gradually decreased with time.
Life history patterns of sockeye salmon may be influenced by genetic characters
of the original stock as well as by lacustrine environments.
- 46-3
Host range and geographical distribution of the ectoparasitic protozoans
Ichthyobodo necator, Trichodina truttae and Chilodonella piscicola on
hatchery-reared salmonids. Urawa, S. pp. 175-203. (In English with Japanese
summary)(1,273KB)
Abstract
The occurrence of Ichthyobodo
necator, Trichodina truttae, and Chilodonella piscicola was
investigated on juvenile Pacific salmon (chum, pink, masu and sockeye salmon)
reared at 204 hatcheries in northern Japan. These ectoparasitic protozoans were
widespread in the area at water temperatures between 2° and 15°C. I. necator
was most common among them, being recorded from all four salmon species. C.
piscicola was found on the former three fish species, and T. truttae
was encountered on only chum salmon. The percentage of positive hatcheries was
37.3% for I. necator, 15.2% for T. truttae, and 8.8% for C.
piscicola. The occurrence of Ichthyobodo infections was not related
to type of water supply, which implies that there are other mechanisms to spread
the parasite among host populations besides direct transmission. In contrast,
the majority of Trichodina and Chilodonella infections occurred at
the hatcheries supplied with river water, suggesting that wild fish may serve as
the reservoirs of infection.
- 46-4
Copepods from waters around Pilenga and Monetka hatcheries in Sakhalin.
Ishida, T., and Kobayashi, T. pp. 205-208. (In Japanese with English summary)(221KB)
Abstract
Five species of Cyclopoida and 9
species of Harpacticoida were identified on the basis of specimens collected
from fresh water on Sakhalin. A harpacticoid species, Bryocamptus umiatensis,
is the first record from Asia. Attheyella nordenskjoldii and
Bryocamptus hiemalisin may be dominant species among harpacticoids on
Sakhalin.
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Sci. Rep. Hokkaido Fish Hatchery
(45), 1991
- 45-1
Dynamics of the lacustrine sockeye salmon population in Lake Shikotsu, Hokkaido.
Kaeriyama, M. pp. 1-24. (In Japanese with English summary)(1,184KB)
Abstract
Population dynamics of lacustrine
sockeye salmon was investigated in Lake Shikotsu, Hokkaido. They appeared to
have two strategies of life history pattern: anadromous and lake-resident types.
The occurrence of two types was affected by population density and their
resources such as food and rearing environment within the lake. Sockeye salmon
usually coexisted with other fishes, however, a few juveniles were fed by
whitespotted charr (Salvelinus leucomaenis) and rosyface dace (Tribolodon
ezoe) when they dispersed from the nursery area to offshore in the lake.
Competitive interaction for food occurred between sockeye salmon and threespine
stickleback (Gasterosteus aculeatus). Population dynamics of sockeye
salmon indicated a population density-dependent mechanism: their individual
growth trended to reduce with an increase of population density. The recruitment
curve of sockeye salmon was fitted with the Ricker's formula, and the number of
adults for reproductive MSY was estimated about 7,200 individuals in Lake
Shikotsu.
- 45-2
Seasonal changes in seawater adaptability of the hatchery reared
juvenile sockeye salmon, Oncorhynchus nerka. Ban, M., and
Yamauchi, K. pp. 25-33. (In English with Japanese summary)(439KB)
Abstract
The seawater adaptability of
juvenile sockeye salmon reared in a hatchery was examined by
analyses of survival, serum sodium content, and gill Na+,
K+ -ATPase activity after one week of transfer to
seawater. They may develop the seawater adaptability in August for
age 0 and in June for age 1.
- 45-3
Differences in scale characteristics taken from various parts of masu salmon,
Oncorhynchus masou (Brevoort) and its scale development. Ohkuma, K. pp.
35-46. (In Japanese with English summary)(921KB)
Abstract
The scales of adult masu salmon caught in coastal
waters were examined to compare their characteristics among various body sites.
While the mean normal scale rate of the entire body surface was 55.9%, the rate
in the lateral tissue was low (40-50%). Focus radius was largest at the lateral
area below the adipose fin. The number of circuli during the seawater life
showed fewer differences among the various positions. The ratio of scale radius
during the freshwater life on entire scale radius was not different considerably
throughout the entire body area along the lateral line. This suggested that the
scales along the lateral line would be utilized for back-calculating the fork
length if the scales of the defined part (i.e., above the lateral line of the
body part between the dorsal and adipose fins) were missing or deformed. The
scale development began in the lateral tissues below the area between the
adipose fin and caudal peduncle, or slightly posterior than the area between the
dorsal and adipose fin as shown in previous reports.
- 45-4
Biological and chemical characteristics of chum salmon during their spawning
migration period. Shimizu, I., and Kaeriyama, M. pp. 47-56. (In Japanese
with English summary)(436KB)
Abstract
Chum salmon captured in the Chitose River and in
coastal waters around Hokkaido from June to November in 1985 were divided into 5
ranks: "keiji", "tokishirazu", "mejika", "ginke", and "buna". The proximate
lipid content of the muscle indicated 22-33% in "keiji", 11-35% in "tokishirazu",
7-12% in "mejika", 2-14% in "ginke", and 1-4% in "buna". Moisture contents of
the muscle indicated 61-73% in "keiji" and "tokishirazu", 72-77 % in "mejika"
and "ginke", and 76-83% in "buna". Thus the lipid content decreased but and the
moisture content increased in chum salmon muscle as their maturity increased
during the spawning migration.
- 45-5
New
records of the parasitic copepod Salmincola stellatus from Sakhalin
taimen (Hucho perryi) in Hokkaido, with a note on its attachment site.
Nagasawa, K., and Urawa, S. pp. 61-64. (In English with Japanese summary)(172KB)
Abstract
Salmincola stellatus,
a lernaeopodid parasitic copepod, was recorded from Sakhalin taimen (Hucho
perryi) in the Sarufutsu River (northern Hokkaido) and Otsu Fish Farm near
Kushiro (eastern Hokkaido). This is the first record from wild Sakhalin taimen
in Japan. The adult female S. stellatus showed a site preference to the
buccal cavity, not to the skin as reported by Kabata (1986).
- 45-6
Planktonic and benthic crustaceans of Lake Kussharo, in 1990. Ishida, T.,
Hashimoto, S., and Takada, Y. pp. 61-64. (In Japanese with English summary)(232KB)
Abstract
The fauna of planktonic and benthic crustaceans in
Lake Kussharo was investigated in 1990. The lake has been polluted by
mononuclear aluminum ion derived from hot spring water. Planktonic crustaceans
could not be observed. Although several benthic species of copepods and
cladocerans were collected, the size of these species was smaller than these in
other origotrophic lakes in Hokkaido.
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Sci. Rep. Hokkaido Fish Hatchery
(44), 1990
- 44-1
Number
of pyloric caeca of salmonids in the northern Japan. Kaeriyama, M., and
Urawa, S. pp. 1-9. (In Japanese with English summary)(411KB)
Abstract
Number of pyloric caeca was
examined for nine salmonid species collected from twelve rivers, one lake, and
four coastal areas in northern Japan. Chum salmon started to form the pyloric
caeca 20 days after hatching, and completed its formation by 120 days (about 80
mm in fork length) after hatching. There were no differences in the number of
pyloric caeca among chum salmon derived from northern Japan. The number of
pyloric caeca of "tokishirazu" and "keiji" chum salmon was extremely higher than
that of "akisake" derived from the northern Japan. Among salmonids, the number
of pyloric caeca was the highest in Hucho (203), while Oncorhynchus
(45-201), Salmo (51), and Salvelinus (23-28) followed in this
order. Among Pacific salmon, the species that are distributed widely in the
ocean, such as chum and pink salmons, have a greater number of pyloric caeca
than other species.
- 44-2
Some
aspects of the life of planted masu salmon, Oncorhynchus masou, as
determined by Acanthocephalan infections. Mayama, H. pp. 11-21. (In Japanese
with English summary)(624KB)
Abstract
Hatchery-produced juvenile masu
salmon were released in the Mena River, a tributary of the Shiribetsu River,
Hokkaido, and infections of an echinorhynchid acanthocephalan,
Acanthocephalus sp., in the intestine of these masu salmon were monitored as
biological indicator for some aspects of the freshwater life of released masu
salmon. The results suggested the following aspects: (1) although juveniles
dispersed soon after the release, they thereafter did not migrate widely in the
river in spring and early summer, (2) juveniles migrated to the places where the
intermediate host (Asellus hilgendorfi) were abundant in late autumn and
overwintering season. The level of infection was relatively higher in small
fish, indicating that juveniles used different feeding area by size. The
prevalence of parasite in hatchery-reared juveniles (1+) increased rapidly soon
after the release and apparently higher than that in wild fish, indicating that
the swimming ability of released fish was lower than that in wild fish.
- 44-3
Scale
formation of juvenile sockeye salmon reared under the different feeding levels.
Suzuki, T., and Kaeriyama, M. pp. 23-28. (In Japanese with English
summary)(389KB)
Abstract
Feeding levels of juvenile sockeye
salmon affected their scale growth. The higher feeding level resulted in the
higher body growth rate and the wider interval of circuli. The growth rate of
scale radius and the number of circuli in the fish reared at 3% feeding level
were larger than those at 1% feeding level. A check was observed on scales of
fish at the time when the feeding level raised. There was no significant
increase in the scale growth throughout the period of starvation.
- 44-4
Chemical conditions in Lake Abashiri during the seaward migration period of chum
salmon fry. Shimizu, I., Mayama, H., and Seki, J. pp. 29-38. (In Japanese
with English summary)(563KB)
Abstract
Chemical conditions in Lake
Abashiri were investigated from May to July in 1982. A thermocline formed in a
depth between 8 m and 9 m. A layer of oxygen-saturated water was observed above
the thermocline. Nutrients in the surface water decreased in July. These
observations may be a result of photosynthesis of phytoplankton. By contrast,
anoxic water was observed below the thermocline. Chloride ion, ammonia nitrogen,
and phosphate in the hypolimnetic water were remained higher than those in the
surface water.
- 44-5
Copepods in the mountain waters of Kyushu, Tsushima and Ryukyu Islands,
southwestern Japan. Ishida, T. pp. 39-51. (In Japanese with English summary)(554KB)
Abstract
Seventeen species of Cyclopoida
and 16 species of Harpacticoida were identified on the basis of specimens
collected from mountain waters in Kyushu, Tsushima and Ryukyu Islands. Nine of
the harpacticoid species were common in Hokkaido, and 13 species in Honshu. The
distribution and morphology of these species were reported.
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-
Sci. Rep. Hokkaido Fish Hatchery
(43), 1989
- 43-1
Copepods in the mountain waters of Honshu, Japan. Ishida, T. pp. 1-21. (In
English with Japanese summary)(989KB)
Abstract
Fourteen species of Cyclopoida and
26 species of Harpacticoida were identified on the basis of specimens collected
in mountain waters in Honshu. Four of them are the first record in Japan. The
distribution and morphology of all species were reported.
- 43-2
Copepods in the tidal reaches of the River Yoichi, west coast of Hokkaido.
Ishida, T. pp. 23-27. (In Japanese with English summary)(273KB)
Abstract
Two species of Calanoida, 6
species of Cyclopoida, and 11 species of Harpacticoida were identified on the
basis of specimens collected from brackish areas in the Yoichi River, Hokkaido.
Seasonal changes in abundance of these species were reported in this paper.
- 43-3
Environmental disruption by waste water from a hot spring-I. Toxicity of the
mononuclear aluminum -ion originated in the "Kawayu-onsen" on fish.
Hashimoto, S. pp. 29-38. (In Japanese with English summary)(1,137KB)
Abstract
This paper noted the toxicity of
mononuclear aluminum ion in the waste water of hot spring. The toxicity of
mononuclear aluminum ion against chum salmon fry depended not only on the pH of
water but also on the density of fish and volume of water supply. When chum
salmon fry were exposed to water including mononuclear aluminum ion, the fish
had white patches on the gill filaments, fins and body surface, showing a
symptom of suffocation. The TLM value of mononuclear aluminum ion was 0.130 ppm
for both 24 and 48 hours. These results suggested that mononuclear aluminum ion
caused moralities of chum salmon fry in the Kushiro River.
- 43-4
Environmental disruption by waste water from a hot spring -II. Effect of waste
water pollution of the "Kawayu-onsen"on fish in the "Kusirogawa-River Systems”.
Hashimoto, S. pp. 39-51. (In Japanese with English summary)(1,396KB)
Abstract
The author evaluated effects of
hot spring waste water on environments in the Kushiro River System including
Lake Kussharo. The acidification of Lake Kussharo was caused by the sulfate of
iron and aluminum originated in hot spring waste water from Kawayu-onsen. The
remarkable acidification in the upper Kushiro River and simultaneous outflow of
the toxic mononuclear aluminum ion into the river began after the third
exploitation of the hot spring in 1965. The density of mononuclear aluminum ion
in the river changed year by year.
- 43-5
Parasites as biological indicators contributing to salmonid biology. Urawa,
S. pp. 53-74. (In Japanese with English summary)(1,346KB)
Abstract
The present paper reviews the use
of parasites as biological indicators, which provide information on various
aspects of salmonid biology such as mode of life, feeding habits, population
dynamics, and phylogenetic development. Sixty-one species of parasites (3
Myxosporea, 1 Monogenea, 21 Trematoda, 13 Cestoda, 11 Nematoda, 7 Acanthocephala,
2 Mollusca, 3 Copepoda) have been proposed as indicators for the biological
studies of salmonids. Biological tag studies on the stock identification and the
homing have made good use of parasites acquired by juvenile salmonids in a
restricted freshwater area and persisting throughout the life of their hosts.
The migration of anadromous salmonids between marine and fresh water can be
traced by the presence of the parasites that have infected the fish outside the
area of capture. The coinciding evolution of parasites and their hosts yields
information about the phylogenetic development and separation of the host fish.
The life cycles of helminth parasites of Japanese salmonids are listed. This
table may be useful for estimating the hosts' feeding habits.
- 43-6
Reciprocal transplantation experiment of masu salmon (Oncorhynchus masou)
population 1. Comparison of biological characteristics between two masu salmon
populations, the Shari River on the Okhotsk Sea coast and the Shiribetsu River
on the Japan Sea coast, Hokkaido. Mayama, H. pp. 75-97. (In Japanese
with English summary)(1,207KB)
Abstract
Biological characteristics of masu salmon were
compared between two distinct populations from the Shari River along the coast
of the Okhotsk Sea, and the Shiribetsu River on the Japan Sea coast of Hokkaido.
Among the two masu salmon populations, there were significant differences in
water temperature at the returning time to the coasts near the natal river, the
body size of returning adults, and the spawning period. These characteristics
were almost stable in each river population for a long time
- 43-7
Reciprocal transplantation experiment of masu salmon (Oncorhynchus masou)
population 2. Comparison of seaward migrations and adult returns of local stock
and transplanted stock of masu salmon. Mayama, H., Nomura, T., and Ohkuma,
K. pp. 91-113. (In Japanese with English summary)(850KB)
Abstract
Exchange transplantation
experiments of masu salmon between the Shari River stock in the Okhotsk Sea
coast and the Shiribetsu River stock in the Japan Sea coast, Hokkaido, were
carried out to clarify the adaptability of non-native fish to the transplant
site. Two groups of smolts, one from the native stock and another from the
introduced stock were released at the same time into each river in 1986 and
1987. The recapture rate of adults of the introduced group was significantly
lower than that of the native group in both rivers. The seaward migration time
was apparently different among two groups, maybe it caused the low survival rate
of the introduced stocks. The results indicate that the conservation of native
stocks is the most important factor in their rehabilitation.
- 43-8
Sexual
difference in spatial distribution of hatchery-reared juvenile masu salmon,
Oncorhynchus masou, planted into stream (preliminary report). Mayama, H.
pp. 115-118. (In Japanese with English summary)(224KB)
Abstract
When a large number of masu salmon fry were released
in the upper portion of the stream, a degree of sexual difference was observed
in their migration patterns. Females showed a trend to migrate downstream, while
males did to remain in the release site. Consequently, the ratio of male around
the release site was considerably high. The sexual difference in the spatial
distribution of juveniles is thought to be an adaptation of masu salmon,
differentiating into the fluvial type and the sea-run type for efficient
utilization of limited productivity in a river.
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-
Sci. Rep. Hokkaido Fish Hatchery
(42), 1988
-
42-1
Incidence of fish pathogenic viruses among anadromous salmonid
in northern part of Japan (1976-1986). Yoshimizu, M.,
Nomura, T., Awakura, T., and Kimura, T. pp. 1-20. (In Japanese
with English summary)(1,060KB)
Abstract
From September 1976 to
November1986, a total of 5,058 ovarian fluid were collected from
salmonid fishes in northern Japan. Four virus, IHNV, OMV, CSV,
and IPNV were isolated during the course of this investigation.
IHNV has been recovered 9 times from the fish at 7 collection
sites and OMV was first discovered in 1978 from masu salmon at
Otobe Salmon Hatchery. Incidence of OMV has decreased since the
introduction of iodophore treatment for the eyed eggs. CSV was
isolated from the kidney of health chum salmon at Tokushibetsu
in 1978, but not isolated from the mature fish in other
investigation sites. Evidence for the presence of a fifth virus
was found in the erythrocytes of chum salmon and pink salmon
taken in water along the Okhotsk Sea coast, but this virus has
not yet been isolated in cell cultures.
- 42-2
Seaward migration and adult return of the marked masu salmon,
Oncorhynchus masou, released in late fall before wintering.
Mayama, H., Nomura, T., and Ohkuma, K. pp. 21-36. (In Japanese
with English summary)(922KB)
Abstract
In order to develop efficient
techniques for mass production of masu salmon smolts in natural
stream with a limited productivity, juveniles were released in
fall before overwintering in the Mena and Shubuto Rivers,
southern Hokkaido, in 1982 and 1985, respectively. The return
rate of fall-released juveniles as adult was considerable. There
was no significant difference in the body size of returning
adults between wild and fall-releases groups. The most effective
period for fall releases was when the river water temperature
was between 5 and 10°C. The fall release of masu juveniles whose
fork length was more than 9 cm was a prerequisite for a high
rate of smoltification in the next spring. Thus the fall release
method is expected to be a highly efficient technique in masu
salmon enhancement.
- 42-3
Sex ratio, age composition, and fork length of masu salmon (Oncorhynchus
masou), of the Shiribetsu River, Hokkaido, Japan. Ohkuma,
K. pp. 37-47 (In Japanese with English summary)(596KB)
Abstract
Sex ratio, age composition, fork
length, and scale pattern of mature masu salmon returning to the
Mena River, a branch of the Shiribetsu River, were investigated
from 1975 to 1985. The sex ratio was relatively stable
throughout the study period. Three (1.1) and 4 (2.1) years age
groups were observed, but the latter group was rare. There was a
significant difference in fork length between male and female. A
scale pattern analysis suggests that the growth of masu salmon
in fresh water rarely affects the following growth in the ocean.
- 42-4
Physiological studies of masu salmon (Oncorhynchus masou)
-II. Changes of total lipid in freshwater life. Nomura, T.,
Mayama, H., and Ohkuma, K. pp. 49-58. (In Japanese with English
summary)(515KB)
Abstract
Seasonal changes in total lipids of
masu salmon in fresh water was studied. The lipid content in
eggs was about 15% higher than that of chum, pink and sockeye
salmon eggs. Although the lipid content was stable through the
egg stage, it decreased one week before hatching. The total
lipid of hatchery-reared fry decreased gradually with their
growth. During the emerging period, the total lipid reduced to
60% of the initial level. The lipid content of juveniles
released in river increased.
- 42-5
On the early development and the occurrence of twin malformation
in chum salmon eggs and fry. Kuramoto, T., Arima, K.,
Kawakami, S., Shimizu, N., Nakawatari, A., Hasegawa, M., Hirama,
S., Moriyama, K., Yotsugi, K., Yasuda, F., Yasuda, M., and Hiroi,
O. pp. 59-73. (In Japanese with English summary)(11,776KB)
Abstract
The early development of chum
salmon eggs was examined at 15°C (high water temperature group,
HT), 8°C (ordinary water temperature group, OT) and 5°C (low
water temperature group, LT). Twin malformation of embryo was
observed only in HT group. The twin malformation showed some
types: symmetric twin embryo, great and small sized twin embryo,
and parallel twin embryo, Siam twin embryo, and three optic
vesicle embryo. The occurrence of twin malformation embryo might
be attributable to egg washing using high temperature water soon
after the insemination.
- 42-6
Optimum water temperature of fertilized water of chum salmon
eggs in the artificial fertilization-1. An influence of high
water temperature. Hiroi, O., Urawa, S., and Kuramoto, T.
pp. 75-79. (In Japanese with English summary)(304KB)
Abstract
Effect of water temperature on
fertilized chum salmon eggs was investigated. Chum eggs
inseminated by dry method at 10°C were washed for 2 hours by
water with various water temperatures at 10, 14, 16, 18 or 20°C.
The fertilized eggs after washing were kept in running spring
water at 10°C. Fertilized eggs treated by 2-hour washing at high
water temperatures (14-20°C) soon after their insemination died
mainly in the early stage. Embryonic malformations were found as
twin malformation embryo in the 14 and 16°C treated groups, and
spiral malformation embryo in the 18 and 20°C groups. The
present observations emphasized to use water under 13°C for the
fertilization of chum salmon eggs.
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-
Sci. Rep. Hokkaido Fish Hatchery
(41), 1987
-
41-1
A checklist
and bibliography of parasites of salmonids of Japan. Nagasawa,
K., Urawa, S., and Awakura, T. pp. 1-75. (In English with
Japanese summary)(3,920KB)
Abstract
Information on the parasites of
salmonids in Japanese waters that was published during the years
1889-1986 is assembled in the form of Parasite-Host and
Host-Parasite lists with accompanying bibliography. 94 named
species of parasites (18 Protozoa, 5 Monogenea, 21 Trematoda, 7
Cestoidea, 19 Nematoda, 15 Acanthocephala, 1 Hirudinoidea, 1
Mollusca, 1 Branchiura, 5 Copepoda, 1 Isopoda) have been
reported, and numerous other parasites not identified to species
level are also included. Although taxonomic revision is not the
aim of the checklist, the following three new combinations and
one new synonym are proposed: Microsporidium takedai (Awakura,
1974) n. comb. for Nosema takedai; Sterliadochona
ephemeridarum (Linstow, 1872) n. comb. for
Cystidicoloides ephemeridarum; and Salvelinema ishii
(Fujita, 1941) new synonym of S. salvelini (Fujita, 1939)
n. comb. for Metabronema salvelini.
-
41-2
Freshwater
harpacticoid copepods of Hokkaido, northern Japan. Ishida, T.
pp. 77-119. (In English with Japanese summary)(1,762KB)
Abstract
The distribution and morphology of 29
species of freshwater harpacticoid copepods from Hokkaido are
described with synonym list. Four species are the first record
from Hokkaido.
-
41-3
A falsepositive
reaction in the indirect fluorescent antibody test for
Renibacterium salmoninarum ATCC 33209 caused by a
Pseudomonas sp.. Yoshimizu, M., Rongxing, J., Nomura, T.,
and Kimura, T. pp. 121-127. (In Japanese with English summary)(349KB)
Abstract
An organism was isolated when the
screening was done for Bacterial kidney disease (BKD) antigen by
indirect FAT among the colonies grown on the KDM-2 which was
inoculated with the kidney tissues of pink salmon. The isolate
was classified as Pseudomonas sp., but showed a positive
reaction with antisera against R. salmoninarum by FAT.
The shape and size of the isolate were similar to these of R.
salmoninarum. The isolate did not show a positive reaction
in the coagglutination test and gel-diffusion test, and also did
not show a reaction with anti-serum against the different strain
of R. salmoninarum, and partially purified IgG of anti-R.
salmoninarum ATCC 33209 rabbit serum by FAT. The positive
reaction on the kidney smears of chum salmon and pink salmon
with FAT was judged to be a false positive reaction caused by
this isolate.
-
41-4
Seasonal
changes in seawater adaptation of sockeye salmon reared in the
freshwater. Kaeriyama, M., Shimizu, I., and Kakizaki, H. pp.
129-135. (In Japanese with English summary)(380KB)
Abstract
Sockeye salmon 1+ and 2+ juveniles
reared in fresh water were investigated for their seawater
adaptability by direct transfers from fresh water to seawater
and from seawater to fresh water. The Cl-
concentration of 1+ juveniles increased to175-180 mEq/l 3 days
after transfer from fresh water to seawater, subsequently
decreased and became constant (140-150 mEq/l) after 7days in
winter (January - February). Immediately after smoltification
from the middle to late of May, they indicated the maximum
osmoregulation ability, and their Cl- concentrations
reached the seawater-acclimated level (140 mEq/l) 10 hours after
transfer to seawater without showing any peak. In this time the
precocious males also adapted smoothly to seawater. In summer
(August) sockeye salmon were hard to adapt from fresh water to
seawater, and died when the Cl- concentration
increased over 200 mEq/l.
-
41-5
Ascending
behavior of juvenile masu salmon (Oncorhynchus masou) in
experimental fishway. Mayama, H. pp. 137-153. (In Japanese
with English summary)(962KB)
Abstract
Ascending behavior of juvenile masu
salmon under various hydraulic and light conditions was observed
in a small-scale experimental fishway (pool-and-overflow type).
The most successful passage of juveniles over weir occurred when
the water depth of pools was 10 cm, which was almost equivalent
with the body length of experimental fish. It was not evident
the relation between water flow supplied into the channel and
the ascend rate of juveniles. However, under the inadequate flow
condition (higher or lower discharge), the ascending style
changed from "swimming type" to "jumping type". Masu juveniles
showed a tendency to hesitate jumping from the shaded areas.
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