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Volume 48, Issue 1
Displaying 1-22 of 22 articles from this issue
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Masaki HONDA, Kenji HORIYA, Seifu HIRAI, Sayuko NINOMIYA, Ryuichi KAMI ...2000 Volume 48 Issue 1 Pages 1-7
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSThe estimated light-saturated photosynthesis of Ulva sp. and Ahnfeltiopsis paradoxa at 20°C were 5.42 mgO2/g wet mass⋅ h and 0.86 mgO2/g wet mass⋅ h, respectively. The value of the standard enthalpy and the standard entropy of Ulva sp. photosynthesis were estimated to be 260 kJ/mol and 884 J/mol⋅ K, respectively. The value of A. payadoxa were estimated to be 118 kJ/mol and 399 J/mol⋅ K, respectively. Production calculated by the model agreed with observed data at field observation sites (2 m depth) on the blocks of breakwater of Futaba, Fukushima Prefecture. Predicted results of dynamic nature of the production and biomass of the Ulva bed and the Ahnfeltiopsis bed by the model are: the annual productions from April 1995 by the Ulva bed and the Ahnfeltiopsis bed were 5.8 and 1.2 kg/m2⋅ y, respectivery. The result of the computing showed that predicted annual production and average biomass of Ulva bed were influenced by average insolation and average water temperature. On the other hand, average insolation is a significant single factor affecting predicted annual net production and predicted average biomass of Ahnfeltiopsis bed.View full abstractDownload PDF (874K) -
Kiyoshi YOSHIHARA, Shoji KITAMURA, Kazumasa IKUTA, Kimiyuki KAMIYAMA2000 Volume 48 Issue 1 Pages 9-15
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSBy examing the body length of migrated spawning kokanee, Oncorhynchus nerka, in relation to environmental factors in the lake Chuzenji from 1983 through 1991, we found that the bigger fish appeared in every five or six years.
Multiple regression analysis was calculated with predictor variables and criterion variables. The predictor variables are the following; total amount of influent in year, mean level of pondage in year, mean water temperature, number of stocking juvenile kokanee, body weight of stocking juvenile and biomass of crustacean. The criterion variables are length of mode of adult kokanee migrated after 2 years. The result showed that the appearance of bigger fish which formed the mode of body length composition was influenced by the biomass of the bait crustacean at the year juvenile kokanee were stocked, and not by the size of stocked kokanee. The decrease of amount of influent cause the rise of water temperature, and increase of the amount of crustacean. When total amount of influent at the stocked year increased, the stocked kokanee showed a higher survival rate. Consequently, many adult kokanee return to the mother river after two years. The result suggested that the increased number of migrated adult kokanee and the growth of body size in the Lake Chuzenji were density-dependent effects.View full abstractDownload PDF (905K) -
Masaki ITO, Osame TABETA2000 Volume 48 Issue 1 Pages 17-24
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSWe carried out a questionnaire survey at fishery co-operative associations which exist all around Japan to obtain information on the distribution of ocellate puffer, Takifugu ruburipes. The result showed that ocellate puffer were caught in the Yellow and East China Seas, and in all waters off Japan other than the Nemuro straits, waters off the Izu Ogasawara Islands and the Nansei Okinawa Islands. It was estimated from the amount of catch and state of the puffer fishery that the main distribution area of puffer was in the Japan Sea south of Aomori Prefecture and in the Pacific Ocean south of Miayagi Prefecture, around the Seto Inland Sea, and in the Yellow and East China Seas. Comparing the fishing grounds and seasons in which the puffer were caught, the puffer distributed in its major distribution areas from autumn to early spring, and then migrate from thier feeding areas to the spawning ground from spring to early summer (around the spawning season) which occur in areas except Hokkaido. Some areas that have both spawning grounds and high catch rate occur in a discontinuous pattern around Japan. This suggesed the possibility that the ocellate puffer distributed around the seas off Japan was composed of several sub-populations.View full abstractDownload PDF (1203K) -
Ratu Siti ALIAH, Shoh SATO, Nobuhiko TANIGUCHI2000 Volume 48 Issue 1 Pages 25-31
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSGenetic variability in the most popular varieties of nishikigoi such as Kouhaku, Taisho and Showa were surveyed using four microsatellite DNA loci, Cca-8*, Cca-17*, Cca-21*, and Cca-30*. The Cca-17* was monomorphic in all the varieties surveyed. The average number of alleles was low with a small range, from 3.25 in Showa to 4.5 in Kouhaku and Taisho. The average heterozygosity (Ho) was also low, ranging from 0.325 in Showa to 0.456 in Kouhaku. The Nei's genetic distance values between any pair of Kouhaku, Taisho, and Showa were smaller than those in other domesticated strains. Their low genetic variability may be due to the small size of brood stock as well as the small size of ancestral population.View full abstractDownload PDF (877K) -
Kaoru YAMANAKA, Ren KUWABARA2000 Volume 48 Issue 1 Pages 33-38
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSStomach contents were examined in 63 individuals of Japanese smelt, Hypomesus nipponensis, caught by dragnet off the coastal Abashiri, northeastern Hokkaido. The research was conducted monthly from May to November 1995. From May to August, the body lengths of the samples were consistently greater than 80 mm, but from September to November the sample lengths were less than 50 mm.
Thirty species of prey organisms representing five different phyla were found in the stomach contents. Crustacean was the most abundant and accounted for 80% of total number of prey organisms. Pranktonic copepods, particularly Paracalanus parvus, Eurytemora herdmani, Tortanus forcipatus, were much abundant. P. parvus was the dominant species in September and October, E. herdmani was dominant from May to August and many benthic crustaceans such as, amphipods and Cumacean were also found in the stomach contents. Thus the studied Japanese smelt chose crustacean as the major prey organism.
The stomach contents were grouped by feeding types. The samples in May-June included many detritus feeders and carnivores of macrobenthic animals. However, after July, the numbers of plankton feeders increased considerably. This followed the changes of zooplankton biomass in the Sea of Okhotsk.
Although, the small size smelt caught only small sized prey, it became able to catch larger sized prey with the growth. However, the size of the dominant species in the stomach contents were consistently 1-5 mm, regardless of the body length of the fish. Thus, large sized fish preferentially caught the smaller and more abundant prey organisms in the environment than the larger and less abundant ones.View full abstractDownload PDF (1000K) -
Katsutoshi KAWABE2000 Volume 48 Issue 1 Pages 39-46
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSMorphological observations were made on larval and juvenile blacktip grouper, Epinephelus fasciatus, reared in the laboratory, with reference to fin development and squamation.The developmental stage transformation from larvae to juveniles occurred between 12.0 mm and 17.5 mm in total length (TL). Elongated spines of the dorsal and pelvic fins were observed from 3 mm up to 40 mm in TL. The segmentation of soft ray in each fin began in specimens between 7.5 mm and 9.9 mm in TL and was completed when the juvenile attained between 19.6 mm and 38.7 mm in TL. Whereas the branching of soft rays began between 17.4 mm and 20.4 mm in TL and was completed between 35.3 mm and 42.9 mm. The first appearance of scales was observed when the juvenile attained at the range of about 21.6 mm to 27.1 mm in TL. Squamation completely covered the body about 35.1 to 38.8 mm in TL.
Fin differentiation, elongation and involution on dorsal and pelvic spiny fm rays and squamation are associated with larval behavior and feeding, and can be used as important indicators for seed production such as transfer of survivors from indoor tank to floating cage facilities or a change of feedstuffs.View full abstractDownload PDF (1221K) -
Ken-ichi YAMAMOTO2000 Volume 48 Issue 1 Pages 47-52
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSIn the pearl oyster, Pinctada fucata martensii, amount of oxygen uptake (Vo2), ventilation volume (Vg), oxygen utilization (U) and gill cilia movement (SP) increased with water temperature rising at a rate of 1°C/30 min. Vo2 showed a maximum at 27, 31 and 33°C, and U a maximum at 30, 34 and 35°C, when rising from 12 (February), 20 (May) and 27°C (September), respectively. Vg showed a maximum at a temperature 5°C higher than each of the initial one. SP showed a maximum at 30, 34 and 35°C which showed no agreement with the maximum of Vg. Vg increased when the shell valves and the mantle lobes were open in the high water temperature. The decrease of Vg was observed when the shell valves and the mantle lobes was kept on compulsorily. The results showed that the pearl oyster corresponded mainly by increasing U to the increase of metabolism as water temperature rising, and that ventilation was done by moving water through the gill cilia movement, but Vg was controlled synthetically by the size of the opening of the shell valves and the mantle lobes, and by changing the watercouse resistance in the gills.View full abstractDownload PDF (904K) -
Hideo AOKI, Yasuhiro SANADA, Masayuki FURUICHI, Rie KIMOTO, Masashi MA ...2000 Volume 48 Issue 1 Pages 53-63
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSFeeding trials were conducted with yellowtail and red sea bream to examine effects of partial or complete replacement of fish meal in their diets. Experimental diets were formulated to replace fish meal with various combination of plant and animal protein meals (dietary fish meal: 40, 30, 20, 10, and 0%). Commercial dry pellets containing 65% fish meal was used as a control diet. These experimental diets were fed to yellowtail, Seriola quinqueradiata, weighing 140 or 105 g on average for 101 or 97 days in net cages, respectively, and to red sea bream, Pagrus major, of 30 g for 70 days in aquaria.
In both species, palatability of diets was not affected by inclusion of alternate proteins. Growth rate and feed gain ratio of yellowtail were proportional to the fish meal content in diets and were especially low in fish fed diets containing fish meal below 20%. However, performance parameters of fish on diets containing 40 and 30% fish meal were nearly comparable to those of the control. A similar tendency was also observed in hemochemical constituents. The poor feed performances due to high inclusion levels of alternate proteins might result from the deficiency of essential amino acids such as lysine and methionine in diets. In red sea bream, there was no marked difference in growth and feed performance, and health status among dietary treatments.
Thus the alternate protein ingredients can be effectively included to reduce fish meal content to 30% (replacing around 50% of fish meal) in yellowtail diets. On the other hand, fish meal could be completely replaced by a suitable combination of substitutive proteins in red sea bream diets without ill effects.View full abstractDownload PDF (1583K) -
Hideo AOKI, Masayuki FURUICHI, Kanako WATANABE, Shuichi SATOH, Yoichi ...2000 Volume 48 Issue 1 Pages 65-72
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSFeeding experiments were conducted to examine the possibility to utilize low or non fish meal diets for red sea bream, Pagrus major. In Expt. I, three low-fish meal (10% fish meal) and one non-fish meal diets were prepared to contain soy protein concentrate (SPC, a main ingredient), defatted soybean meal (SBM), corn gluten meal (CGM), meat meal (MM), and poultry feather meal (PFM) in different combinations, and fed to juvenile red sea bream weighing 27 g on average for 56 days. In Expt. II, adult fish with an initial body weight of around 550 g were fed the four experimental non-fish meal diets for 183 days.
Palatability of the experimental diets was not affected by dietary fish meal levels in both sizes of fish. In both the experiments, growth and feed gain ratio were the highest in fish fed the control fish meal diet and tended to decrease with reduction of the SPC content in the test diets. However, in Expt. II, these performances in fish on the non fish meal diet containing 40% SPC were comparable to those of the control. Supplemental effects of crystalline amino acids to low-fish meal diets on growth and feed performances were not observed in Expt. I. Moreover, hemochemical examination at the end of feeding revealed that both juvenile and adult fish kept in good health status.
Therefore, it was suggested that a combination of SPC, SBM, CGM, MM, and PFM can be effectively employed as alternate protein sources to develop low or non-fish meal diets if these ingredients were adequately incorporated.View full abstractDownload PDF (1064K) -
Hideo AOKI, Kanako WATANABE, Shuichi SATOH, Yoichi YAMAGATA, Takeshi W ...2000 Volume 48 Issue 1 Pages 73-79
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSFeeding experiments with young and juvenile yellowtail, Seriola quinqueradiata, were performed to examine the use of non-fish meal diets formulated with soy protein concentrate, defatted soybean meal, corn gluten meal, meat meal, and poultry feather meal in combination. The fish weighing about 210g (Expt.I) or 8g (Expt.II) on average were fed the experimental diets for 113 or 41 days, respectively.
The experimental non-fish meal diets showed good palatability to the young fish, but poor to the juvenile fish. In Expt.I, the normal growth and feed performances were obtained in young fish fed the non-fish meal diets for the first about 8 weeks of feeding, but thereafter growth was gradually retarded and high mortality was observed without regard to the dietary treatments at the end of feeding. A similar pattern was also obtained in Expt.II, although supplemental effect of amino acids was observed to some extent in juvenile fish. Moreover, the anatomical examination at the end of feeding revealed that both young and juvenile fish on the non-fish meal diets had green liver status, which was not found in the fish fed the control fish meal diet. This observation together with hemochemical assessments demonstrated that feeding non-fish meal diets resulted in physiological conditions inferior to the control for both sizes of fish.
Thus, these results confirmed that the non-fish meal diets could not sustain normal growth and health conditions of yellowtail due to induction of green liver.View full abstractDownload PDF (1008K) -
Hideo AOKI, Takeshi WATANABE, Yasuhiro SANADA, Yoichi YAMAGATA, Kazumi ...2000 Volume 48 Issue 1 Pages 81-90
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSTwo feeding experiments were conducted in net cages to evaluate the availability of extruded dry pellets (EP) with both alternate protein and lipid sources to yellowtail, Seriola quinqueradiata. The experimental EP were formulated to contain 8% defatted soybean meal (SBM), 10-15% corn gluten meal (CGM), 10% meat meal (MM), and 0-5% blood meal in combination reducing dietary fish meal content to 30-40% (replacing 38-54% of fish meal), and contain palm oil and beef tallow (0-10%) replacing 50% of fish oil. A commercial yellowtail EP containing 65% fish meal and 15% fish oil was used as a control diet. These EP were fed to yellowtail of 172 or 144 g on average for 97 or 93 days, respectively.
Palatability and acceptability were not influenced by dietary inclusion of both alternate proteins and lipids in both the experiments. Growth and feed performances were not markedly different between fish fed the control fish meal diet and those on diets with 40% fish meal, irrespective of lipid sources, but slightly reduced in fish on the diets with 30 or 35% fish meal. Blood biochemical parameters showed that fish of all the experimental groups were in good physiological condition, not affected by feeding of alternate protein and lipids. Dilution of fish oil with palm oil or beef tallow reduced dietary levels of unsaturation, resulting in reduced peroxidizability or unsaturation index of lipids in muscle and liver, and elevated accumulation of vitamin E in these tissues. These results suggested that replacement of fish oil lowered in vivo peroxidation in yellowtail.
Thus, results of the present study have shown that both fish meal and fish oil can be substituted up to 50% with alternate proteins in combination of SBM, CGM, and MM, and lipids such as palm oil and beef tallow, respectively, in EP for yellowtail.View full abstractDownload PDF (1282K) -
Kenji TAKII, Manabu SEOKA, Tomoko NAGAOKA, Tomohiko USUI, Motoji NAKAM ...2000 Volume 48 Issue 1 Pages 91-97
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSThe inhibition of soybean trypsin inhibitor (SBTI) in brown fish meal diets for digestive and absorptive functions was investigated using juvenile red sea bream, Pagrus major, (mean body weight 62.1 g). Apparent protein and fat digestibilities indicated no significant differences among dietary supplements of SBTI at the levels of 0, 0.6, and 6.0 trypsin inhibitory units (TIU)/mg diet during a 22-day rearing period. Gastral digesta indicated an increasing tendency with an increase in dietary TIU at 6 h after feeding (AF), despite no differences among the dietary treatments at 3 h AF. Intestinal digesta of the 6.0 TIU diet group showed a lower tendency than the O and 0.6 TIU diet groups at 3 h AF; all groups at 6 h AF gave a similar low level. Basic protease and SBTI-insensitive basic protease activities of intestinal digesta in the 6.0 TIU diet group were significantly higher than the other diet groups at 3 h AF; all diet groups at 6 h AF reached a similar high activities. These suggest that red sea bream compensate dietary SBTI to promote the secretion of basic protease and SBTI-insensitive basic protease from the hepatopancreas in a relatively early time after feeding. Equivalent protein digestibilities among the dietary treatment might be due to the compensation as well as the prolongation of digesta transit time in the SBTI diet group.View full abstractDownload PDF (991K) -
Sadao SHIMENO, Masaya MATSUMOTO, Hidetsuyo HOSOKAWA, Toshiro MASUMOTO, ...2000 Volume 48 Issue 1 Pages 99-104
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSFingerling yellowtail, Seriora quinqueradiata, were fed for 50 days in a 0.8t aquarium on moist pellet diets containing 0-15% commercial poultry feather meal (PFM) as a partial substitute for fish meal. The results showed that dietary inclusion of PFM tended to decrease the growth and feed conversion as its level increased. The inclusion of 15% PFM markedly lowered these values as well as the hematological characteristics and protein retention rate, mainly due to its poor digestibility. However, dietary inclusion of less than 10% resulted in a comparable growth rate, feed efficiency, nutrient digestibility and hematological characteristics to a PFM-free control diet. These results indicated that PFM is a potential alternative protein source with low carbohydrate contents, and that commercial PFM can substitute for fish meal up to 10% of the diet for fingerling yellowtail without any adverse effects.View full abstractDownload PDF (885K) -
Kumiko MIYAJIMA, Nobuhiro MANO, Kiyoshi YOSHIHARA, Hitomi HIROSE2000 Volume 48 Issue 1 Pages 105-108
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSHematological and Histopathological studies were undertaken to determine the effect of Acanthocephala, Arhythumacanthus fusiformis, infection on eosinophils in the blood of seacatfish, Plototusus lineatus. In the blood of the fish infected with A. fusiformis, the eosinophils increased in the blood, but the neutrophils did not change in number. Histopathologically invastion of the eosinophilic granular cells (EGCs) in submucosal connective tissue was observed in the intestine of the infected fish. These results suggest that eosinophils have defense function to acanthocephala infection.View full abstractDownload PDF (5831K) -
Keiichi MUSHIAKE2000 Volume 48 Issue 1 Pages 109-115
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSThe present study was aimed to investigate the effects of multiple spawnings and rearing conditions for spawning (hormone injection and rearing density) on multiplication of the causative virus (SJNNV) of viral nervous necrosis (VNN) in Broodstocks of striped jack, Pseudocaranx dentex. Plasma cortisol was measured as an indicator of primary stress response caused by the rearing conditions. The level of plasma cortisol in spawners was gradually elevated with the increase in the number of spawnings of Broodstocks. Both SJNNV and plasma antibodies against SJNNV became detectable when the number of spawnings reached more than 10 times in each season. Plasma cortisol levels also increased by hormone (human chorionic gonadotropin: HCG) injection and with a higher rearing density of Broodstocks (1.76 kg/m3). In the higher rearing density, plasma glucose, which is an indicator of secondary stress response, also increased. These results suggested that rearing conditions such as more-than-l0-time multiple spawnings, HCG injection and higher rearing density would allow SJNNV to multiply in the spawners by reducing their resistance, which leads to the vertical transmission of SJNNV from spawners to their offsprings.View full abstractDownload PDF (1084K) -
Munenori MIYAKAWA2000 Volume 48 Issue 1 Pages 117-122
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSSimple and practical method is needed for detecting drug residues in eel cultured in semi-closing system. In this study, a simplified bioassay (direct bioassay) was developed, by using Bacillus subtilis ATCC6633 as a test strain and small pieces of eel liver and muscle instead of common paper discs. Orally administration of oxytetracycline (OTC), oxolinic acid (OA) or miloxacin on eels showed that the clear inhibition zone appeared around the pieces of liver and muscle just after dosing, and then the zone narrowed with time and finally disappeared. The detection limit of the present bioassay was estimated to be ca. 0.4 ppm for both OTC and OA.View full abstractDownload PDF (747K) -
Kozo IWAMOTO, Takeshi YOSHIKAWA, Taizo SAKATA2000 Volume 48 Issue 1 Pages 123-130
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSAlgicidal filamentous bacteria were isolated from shrimp aquaculture ponds and coastal seawaters in Kagoshima Bay, Japan by use of double layer agar plates containing Chaetoceros ceratosporum cells. The isolated strains were tentatively identified as the genus Saprospira and composed of 3 subgroups according to their cell morphology, pigmentation and GC%. On the other hand, RFLP analysis of 16S rDNA and DNA-DNA hybridization of total DNA were performed in order to clarify the taxonomic relationships among the isolates, and it became clear that the isolates were distributed into 4 subgroups. The reference strains of Saprospira grandis showed no DNA-DNA hybridization reaction with total DNAs of all isolates. These molecular biological techniques were found to be useful for rapid identification and classification of algicidal filamentous bacteria.View full abstractDownload PDF (5346K) -
Effects of Antibacterial Substances on the Nitrifying Activity of Filter Materials in a Model SystemHaruo SUGITA, Yuko MAKUTA, Hiroyuki MIZUNO, Kiyoshi YOSHIHARA2000 Volume 48 Issue 1 Pages 131-134
Published: March 20, 2000
Released on J-STAGE: January 31, 2011
JOURNAL FREE ACCESSThe effect of antibacterial substances on nitrifying activities of filter materials was examined in a batch system. The nitrifying activity of 10 g of the conditioned pebbles as filter materials ranged from 1.19 to 2.09μM/h in the absence of any antibacterial substances. Inverse relationships were observed between the nitrifying activity of filter materials and the log concentrations of five different drugs over given levels (31 mg/l for sulfamonomethoxine and 10 mg/l for the other four drugs). The activities decreased to half degrees at 106 to 156 mg/l for ampicillin, oxytetracycline and sulfamonomethoxine, and 305 and 910 mg/l for colistin and kanamycin. This result strongly suggests that the activity of nitrifying bacteria is remarkably influenced by the antibacterial substance used for the treatment of infected fish.View full abstractDownload PDF (574K) -
Kioshi YOSHIHARA, Torakichi KADOMATSU, Eri TSUTSUI2000 Volume 48 Issue 1 Pages 135-136
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSIn the present paper, authors tried to estimate the period of annulus formation of nibbler, Girella punctata Gray, with otolith and scale at the eastern coastal waters of Izu Peninsula. The 120 fishes used were collected by angling and trammel net during the period from January to December 1999. The obtained results showed that the resting zone of the scale were formed from May to July and the hyaline zone were formatted from October to March on the otolithView full abstractDownload PDF (256K) -
Izumi SAKURAI, Masabumi SETO, Norihito MAKIGUCHI, Takashi OGATA2000 Volume 48 Issue 1 Pages 137-138
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSThis study examined the tolerance of the Japanese scallop, Patinopecten yessoensis, to low concentrations of dissolved oxygen and salinity at 13.5°C. Scallops survived for 16 hr in anoxic conditions and at least 2 days in hypoxic conditions with oxygen saturation of 20%. Scallops died within 24 hr if the salinity decreased to 18 PSU or less; they died within a few hours if the salinity dropped to 10 PSU or less.View full abstractDownload PDF (322K) -
Maidie ASFIE, Hideki YANAGI, Ryuji OKANO, Nobuhiko AKIYAMA, Haruo SUGI ...2000 Volume 48 Issue 1 Pages 139-140
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSA total of 780 vibrios were isolated from Japanese flounder, Paralichthys olivaceus, at different stages of development and examined for the proteaseproducing ability of each isolate. The highest and lowest values in mean enzyme activities of isolates were observed on days 109 and 67 after hatching, respectively. High abilities (≥1.00U/μg) were detected in the isolates from fish on days 3, 23 and 45 after hatching, while as many as 62% of all vibrios showed low potential of production (<0.10U/μg). Inhibitory effects of PMSF and OPA were found in 61 and 50% of all Vibrio isolates, respectively. These results showed that larvae and juveniles of Japanese flounder harbor the vibrios capable of producing various types of proteases at different activities, in their intestines.View full abstractDownload PDF (352K) -
Kiyoshi YOSHIHARA, Reika FUJII2000 Volume 48 Issue 1 Pages 141-147
Published: March 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSWe performed a questionnaire investigation at the Lake Chuzenji to collect information of leisure angling which is one of the background elements for stock assessment, and which cannot be collected through co-operative association, in 1997 and 1998. Answers were given by total of 208 leisure anglers in 2 years. Although there were more boat fishing anglers among the answers, there were more of those who do shore fishing when checked with the sales of fishing ticket in the co-operative. More than half of boat fishing anglers targeted kokanees, Oncorhynchus nerka, and they catch them actually. In the case of shore fishing, the target species varied so that they enjoy fighting spirit with fishes. But the majority fish caught were rainbow trout, O. mykiss. It is interesting that the average age of the anglers shore fishing was approximately 10 years younger than that of boat fishing ones. It is thought that this reflects the diversification of fishing types such as bait, lure or fly fishing whose popularity has been rising among the young anglers recently. In April at the time of removal of the ban on both boat and shore fishing, quite a good number of fishes can be caught in both ways. But in August when the prohibited season closed most of anglers were even not able to catch a single fish.
From the results of this investigation, we can propose some policies for continual development of leisure fishing business of the co-operative association.View full abstractDownload PDF (928K)
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