共查询到20条相似文献,搜索用时 0 毫秒
1.
Tamaki Shimose Maki Fujita Kotaro Yokawa Hirokazu Saito Katsunori Tachihara 《Fisheries Science》2009,75(1):109-119
We studied the spawning seasonality and gonadal development of blue marlin Makaira nigricans using specimens captured around Yonaguni Island in southwestern Japan between February 2003 and February 2006. The mean (±SD)
lower jaw–fork length of females (234 ± 24 cm) was greater than that of males (191 ± 12 cm). The smallest mature female and
male were 183 and 160 cm, respectively. Most of the 717 females had immature ovaries. However, in March and from May to September,
the ovaries of 26 females contained oocytes with yolk globules, hydrated oocytes, or postovulatory follicles. Most males had
testes with a large amount of spermatozoa throughout the year. The occurrence of mature blue marlin at Yonaguni Island suggests
that spawning occurs here. The mean condition factors (fatness of the fish) of both sexes decreased from March to June or
July, presumably as they expended energy to reproduce. We discuss our results in the context of migration theory for blue
marlin in the western North Pacific Ocean. 相似文献
2.
We monitored feeding behavior and survival of starved juvenile olive flounder experimentally infected with the gill monogenean
Neoheterobothrium hirame. Infected flounder increased amount of the time spent in the water column by 117% when trying to capture live mysids, Neomysis sp. They also showed different feeding patterns from those of uninfected fish and made fewer attacks towards prey during
one feeding attempt. Although the average numbers of mysids captured by individuals were similar between infected and uninfected
fish, heavily infected fish tended to catch less prey. These results indicate that N. hirame reduces the feeding efficiency of the host for capturing live prey and possibly makes them more vulnerable to predation during
feeding. We could not detect any obvious difference in survival rates between uninfected, lightly and heavily infected fish
during 3 months of starvation. There was no evidence that starvation makes fish more susceptible to N. hirame. The present study provides first experimental evidence that N. hirame affects feeding behavior of juvenile olive flounder and supports the idea that this parasite indirectly reducing the host’s
survival and may be responsible for the recent reduction of the flounder population in Japan. 相似文献
3.
Julia Ramos-Miranda Rodolfo del Río-Rodríguez Domingo Flores-Hernández Ramón Isaac Rojas-González Mónica Gómez-Solano Ana Delia Cu-Escamilla Francisco Gómez-Criollo Atahualpa Sosa-López Yassir Eden Torres-Rojas Paloma Juárez-Camargo 《Fisheries Science》2017,83(5):699-714
The reproduction of Holothuria floridana in Campeche bay, southern Gulf of Mexico, was investigated over a period of 12 months by macroscopic and histological examination of the gonad and gametogenesis. A total of 1938 specimens were collected. Their body gutted weight and body gutted length ranged from 15 to 225 g and 5 to 21 cm, respectively. Percentage of the gonad weight to the gutted body weight (gonad index, GI) increased steadily from December to April, rapidly declined in May, and remained low during the following months. GI displayed a negative correlation with temperature of the habitat and no correlation with salinity. The gonad maturity scale with five stages was developed from macroscopic and microscopic observations; I, recovery; II, growing; III, early mature; IV, mature and V, spent. Stages III to V were observed all around the year, suggesting that this species displays continuous reproduction with two peaks of spawning events; from March to April and in September. The presence of viscera regurgitated individuals caused high variability in GI. The sex-ratio varied from 1:1 (December 2013 to June 2014), to 1.37:1 (November 2013); we suggest that this may be the consequence of unintentional selective fishing. The body length and body weight at the first maturity were calculated to be 13.4 cm and 87.0 g, respectively. For resource management it will be necessary to address some reference points like harvest season and avoidance of catches shorter than length at first maturity. 相似文献
4.
5.
6.
Melatonin production by the fish pineal is under the control of photoperiod. In addition, in some fish species pineal melatonin production is self-sustained by an intrapineal circadian pacemaker, not in salmonids, though. The aim of this research was to test melatonin release in vitro by the pineal of sea bass held under LD 12:12 and DD conditions to determine the endogenous nature of melatonin rhythm. Circadian rhythmicity ( = 28.3 h) was found since rhythmic melatonin release persisted on DD. 相似文献
7.
Pseudotuberculosis is a bacterial septicaemia caused by Photobacterium damselae subsp. piscicida in several marine fish species. Yellowtail Seriola quinqueradiata is the most sensitive fish species to this disease. The internal organs of naturally infected yellowtail exhibit whitish
spots, tubercle-like tissue structures, consisting of bacterial accumulations. There have been many trials for experimental
infection, however adequate method of infection that reproduces moderate mortality and primary clinical signs has not yet
established. Present investigation evaluated an immersion infection method by using logarithmic culture-phase bacteria resulting
in higher mortality than that using stationary culture-phase bacteria. Typical white spots on the spleen and kidney were also
observed constantly in dead fish. Transmission electron microscopy and fluorescent antibody microscopy showed bacterial clusters
not only in the spleen and kidney but also in the blood channels in the secondary gill filaments. These results were confirmed
repeatedly by plural experiments. The use of logarithmic-phase bacteria in immersion infection is an appropriate technique
to reproduce moderate mortality and primary clinical signs, which will be a reliable infection method also for the challenge
test of pseudotuberculosis vaccine. 相似文献
8.
To find out whether or not the locomotor activity of the Japanese sea catfish, Plotosus lineatus, shows a circadian rhythmicity, the locomotor activity of this catfish was recorded in a laboratory. All of the catfish recorded
(n = 20) showed a nocturnal locomotor activity rhythm under a light–dark (LD) cycle (LD 12:12). The locomotor activity started
after the light was turned off, and declined during the period of darkness. In five of the six catfish we examined, locomotor
activity shifted gradually over the course of 3–4 days in order to synchronize to the LD cycle after it was advanced by 6 h.
Locomotor activity persisted within a constant darkness (DD) in all eight of the catfish. The average free-running period
of locomotor activity under DD lasted for 24.2 ± 0.4 h (mean ± SD). Thus, the present results demonstrate that the Japanese
sea catfish has an endogenous circadian oscillator entrained by an LD cycle. 相似文献
9.
We evaluated the mass production of competent larvae of the sea urchin Lytechinus variegatus cultured at three initial densities (0.25, 0.5, and 1 larvae per ml) and fed Chaetoceros muelleri. Survival, length, dry weight of larvae, and larval stage index (LSI) were estimated in each treatment as a function of the density. Density decreased during the experiment due to mortality, but the percentage was similar in all three treatments (68.5, 66.7, and 76.0%). The experiment was stopped at 13 days after fertilization, when most of the larvae were competent and had settled. There were no significant differences in survival (exceeded 65% in all treatments), length and larval stage index among treatments. However, larvae weight in the two low density treatments (1.1 ± 0.11 mg and 1.2 ± 0.05 mg, respectively) was greater than the high density treatment (0.59±0.376 mg). This study demonstrates that competent larvae of Lytechinus variegatus can be produced with less than 25% mortality in 13 days when cultures are started at densities of 0.25–1 larvae/ml. Culturing at higher densities (0.5–1 larvae/ml) had no apparent disadvantages and would reduce the cost of production. 相似文献
10.
Jian-He Xu Feng You Wei Sun Bin-Lun Yan Pei-Jun Zhang Bi-Xiang Jing 《Aquaculture International》2008,16(6):623-634
Turbot Scophthalmus maximus exhibits sexually dimorphic growth, with females growing faster and reaching larger adult sizes than males. Thus, development
of techniques for preferentially producing females is necessary to optimize production of these species. In this paper, gynogenetic
diploids of turbot were induced by activating egg development with ultraviolet (UV)-irradiated left-eyed flounder Paralichthys olivaceus sperm combined with cold shock to prevent extrusion of the second polar body. The results of UV irradiation experiments showed
that survival, motility, and duration of activity of P. olivaceus sperm generally decreased with increase in UV dose. The typical Hertwig’s effect was observed after fertilized turbot eggs
with UV-irradiated P. olivaceus sperm and the optimal UV dose for gynogenetic haploid production was 36,000 erg mm−2. At 15°C, appropriate timing of cold shock for retention of the second polar body in turbot eggs was at 6 min after fertilization.
Results of different combinations of two shock temperatures (1 or 3°C) and four shock durations (15, 25, 35 or 45 min) at
6 min after fertilization demonstrated that shock of 25 min at 1°C gave the highest production of diploid gynogens (39.58%
relative to its diploid control). The results of this study reveal that the use of UV-irradiated P. olivaceus sperm for activation of turbot eggs and cold shock for polar body retention is an effective method to produce gynogenetic
offspring. 相似文献
11.
The effects of soy sauce koji and the lactic acid bacterium, Tetragenococcus halophilus, were studied on the fermentation of fish sauce prepared from Chinese silver carp. The fish sauce prepared without koji and the lactic acid bacterium contained low levels of organic materials, total nitrogen, and organic acids. The use of koji was effective in increasing these qualitative parameters and further improved the amino acid score of the fish sauce. Addition
of T. halophilus had an effect on lowering the pH value during the initial period of fermentation when the soy sauce koji was also supplemented. In contrast, T. halophilus-like bacteria were found to be predominant for all tanks fermented under the different starting conditions. Although it was
not examined whether the T. halophilus-like bacteria observed after fermentation were the same as the starter-bacterium or not, it was suggested that T. halophilus plays an important role in the successful fermentation of silver carp fish sauce. Sensory evaluation conducted with Japanese
and Chinese panelists also suggested the superiority of the use of koji for fermentation of silver carp fish sauce. 相似文献
12.
To examine the distribution pattern of adult Apostichopus japonicus, approximately monthly surveys were conducted during a 2-year period in the subtidal zone of a harbor area in Yoshimi Bay,
western Yamaguchi Prefecture. Results showed a clear seasonal change in distribution pattern: many animals were distributed
on the seabed and the lower part of a jetty during winter to spring, whereas most animals occurred on the upper part of a
jetty during summer to autumn, namely, the aestivation season. Such change is considered to be due to the migration of animals
within the present study site.
Y. Yamana is a Research Fellow of the Japan Society for the Promotion of Science. 相似文献
13.
Hirotoshi Endo Eun-Jeong Park Youichi Sato Hiroyuki Mizuta Naotsune Saga 《Fisheries Science》2009,75(2):393-400
As a trial to develop a method of authenticating the place of origin of circulated Undaria pinnatifida products, we investigated their intraspecific genetic diversity using the mitochondrial cytochrome c oxidase subunit 1 gene
(cox1) and the internal transcribed spacer 2 (ITS2) region of the nuclear ribosomal DNA (rDNA) sequence. Four dried U. pinnatifida products labeled with their origins (one from Japan, one from China and two from Korea), natural plants collected from three
locations (two from Japan and one from China), and cultivated plants collected from two locations (one from Japan and one
from China) were used in the present study. The amplified fragments of cox1 were 664 bp in length, and the aligned sequences were highly homologous. Among the nine sequences, no insertions or deletions
were found and six substitution positions were detected, and they were classified into five haplotypes. In contrast, multiple
highly variable regions were found in ITS2, and some of them carried a restriction site for Mbo II. Polymerase chain reaction-restriction fragment length polymorphism analysis showed different restricted profiles among
the tested samples. The availability of molecular markers for authenticating food products of U. pinnatifida is discussed. 相似文献
14.
15.
Tetsuro Shiraishi Suvarna D. Ketkar Yoshiki Katoh Mitsuo Nyuji Akihiko Yamaguchi Michiya Matsuyama 《Fisheries Science》2009,75(3):649-655
Female Japanese chub mackerel Scomber japonicus of the Tsushima Current subpopulation were collected during the spawning season from March to May 2001. A total of 137 adult
females were caught between midnight and daybreak. A considerable number of fish displayed new postovulatory follicles (POF),
whereas there was no evidence of germinal vesicle breakdown or hydrated oocytes in any of the fish collected. This suggests
a daily spawning synchronicity toward midnight. To estimate the spawning frequency (S), the female reproductive state was classified into four criteria based on the degenerative stage of the POFs and the developmental
stage of the oocytes. To stage the POFs according to age and determine the stage duration, ovaries from S. japonicus were induced to spawn in the laboratory and were sampled 0–72 h after ovulation at appropriate intervals. The average S, which is evaluated from four different indices, was 16.9%, corresponding to the average female chub mackerel spawned every
5.9 days (8.5 times) during the 50 days. 相似文献
16.
Bacillus circulans PB7, isolated from the intestine of Catla catla, was evaluated for use as a probiotic supplement in the feeds for the fingerlings of Catla catla. The effect of supplement on the growth performance, feed utilization efficiency, and immune response was evaluated. Catla
fingerlings (ave. wt. 6.48 ± 0.43 g) were fed diets supplemented with 2 × 104 (feed C1), 2 × 105 (feed C2), and 2 × 106 (feed C3) B. circulans PB 7 cells per 100 g feed for 60 days at 5% of the body weight per day in two equal instalments in triplicate treatments.
The control feed (CC) was not supplemented with the B. circulans. All the feeds were isocaloric and isonitrogenous. Fish fed with feed C2 displayed better growth, significantly (P ≤ 0.05) highest RNA/DNA ratio, a lower feed conversion ratio (FCR), and a higher protein efficiency ratio (PER) than the
other experimental diets. Highest carcass protein and lipid was also observed in the fish fed C2 feed compared to the others.
Significantly (P ≤ 0.05), highest protease was recorded in fish fed feed C2 (47.9 ± 0.016) and lowest in fish fed feed C3 (32.10 ± 0.009),
where α-amylase activity did not differ significantly (P ≤ 0.05) beyond the lowest inclusion level. ALP, ACP, GOT, and GPT in the liver of Catla catla were the highest (P ≤ 0.05) in fish fed C2 feed. The highest TSP, albumin, and globulin was observed in fish treated with C2 feed after 60 days
feeding trial, but the lowest glucose level was observed in the same treatment. After the feeding trial, the non-specific
immunity levels and disease resistance of fish were also studied. Phagocytic ratio, phagocytic index, and leucocrit value
were the highest in fish fed feed C2. After the feeding trial, the fish were challenged for 10 days by bath exposure to Aeromonas hydrophila (AH1) (105c.f.u. ml−1 for 1 h, and, after 7 days, 107c.f.u. ml−1 for 1 h). Highest survival percentage was observed in fish fed with feed C2 compared with only 6.66% in the controls, which
indicated the effectiveness of B. circulans PB 7 in reducing disease caused by A. hydrophila. 相似文献
17.
18.
The age and growth of two Nematalosa species around Okinawa Island were examined using sectioned otoliths collected from September 2003 to April 2006. Monthly
changes in the frequency of the appearance of a translucent band on the outer margin of the otoliths indicated that ring formation
occurred once a year from January to July for Nematalosa come and from January to March for Nematalosa japonica. The von Bertalanffy growth equations for both species were as follows: N. come: L
t
= 365.5{1 − exp[−0.111 × (t + 0.288)]} for females and L
t
= 214.7{1 − exp[−0.700 × (t – 1.110)]} for males; N. japonica: L
t
= 205.1{1 − exp[−1.068 × (t − 1.180)]} for females and L
t
= 195.5 {1 − exp[−1.293 × (t − 1.269)]} for males. The maximum ages observed for N. come and N. japonica were 11 and 6 years old, respectively. The growth of these species was characterized by the slow growth of N. come over many years, resulting in a larger size than N. japonica. 相似文献
19.
ABSTRACT: A total of 414 fish (female, 59.3–275.0 mm and male, 61.0–220.0 mm standard length) were collected from December 2000 to March 2002 around Okinawa Island, Japan, for the determination of sex, spawning season, maturity and fecundity. Monthly changes in the gonadosomatic index (GSI) exhibited similar trends for both sexes and the mean GSI maintained a high level between February and May. Furthermore, the percentage frequency of hydrated oocytes and the spermatozoic activity suggested that main spawning occurred between February and May. Some hydrated oocytes were found throughout the year, with a GSI value greater than 1.0, suggesting that sporadic spawning occurred. Length at first maturity was determined for females and males as 120 and 113 mm standard length, respectively. Almost 50% and 100% males were matured at the end of their 0 and 1 year of age group, respectively. In contrast, no females were found to be mature at 0+ age group, and almost 60% of females were mature at 1+ age group. At ages over 2 years, all males and females were found to be mature. Batch fecundity (BF) of 33 females was related to standard length, and the relationship between standard length and BF was expressed by the exponential equation: BF = 269.5e0.020954SL . 相似文献
20.
Compensatory growth following stress is a strategy aquatic animals use to adjust themselves to a variable environment. Studies
on the recovery growth of aquatic animals are not only of theoretical value in ecophysiology and evolution, but also important
to applications in aquaculture and fisheries resource management. In this experiment, juvenile Fenneropenaeus chinensis with an initial average body weight of about 3.72 g were exposed to hypoxic water (about 2.08 and 3.11 mg/l of dissolved
oxygen (DO) content) for 10 days and then switched to normoxic water (about 5.63 and 5.59 mg/l DO). Compared with juveniles
in normoxia, juveniles in the hypoxia period allocated a greater proportion of energy to metabolism and exuviations but allocated
less energy to daily metabolism per gram shrimp weight (J/g/day). This reduced feed conversion efficiency and feeding rate.
Finally, F. chinensis suffered growth depression. The juveniles completely compensated for hypoxia-induced growth depression in 30 days after being
switched into normoxic water and the compensation was achieved mainly by hyperphagia and slightly by improvement of feed conversion
efficiency. During the recovery period the hypoxic-stressed shrimp showed higher daily metabolic energy (J/g/day) than controls
(P < 0.05). Which means the stressed shrimp had more energy for feeding-related activities. So hyperphagia was observed. Energy
analysis indicated that F. chinensis improved feed-conversion efficiency mainly by reducing the percentage of energy lost in feces and exuviations. The results
showed that short-term non-lethal hypoxia would not affect the growth of juvenile F. chinensis if there were enough time for the stressed shrimp to recover. This suggested F. chinensis was capable of adapting to DO fluctuation to some extent and short-term non-lethal hypoxia would not have an obvious effect
on natural, released, and cultured shrimp stock. 相似文献