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1.
SUMMARY: Stomach contents were examined from 936 individuals of Mustelus manazo , collected by trawl at five locations: Aomori, Tokyo Bay, Maizuru and Shimonoseki in Japan, and one location off Taiwan. The vacuity index was relatively low (0–6.1%). Based on three indices ( %W , %F , RI ), the major dietary component was crustaceans at all locations. The most important prey category was crabs in Aomori, Shimonosei and Taiwan, mantis shrimps in Tokyo Bay, and shrimps in Maizuru. Fishes were a minor food category for M. manazo in most locations, except in Maizuru where fishes were second in importance in the diet. Dietary overlap revealed a medium degree of overlap between Tokyo Bay and Aomori, and between Tokyo Bay and Shimonoseki. The other locations showed a high degree of overlap with each other. Significant ontogenetic dietary shifts were found in Tokyo Bay, Maizuru and Taiwan, and prey diversity showed a trend being relatively low in larger size classes. The feeding habit of M. manazo was unique in Tokyo Bay, where crustaceans in the muddy substrata were taken in preference to the most abundant benthic prey item available, such as a southern rough shrimp, Trachypenaeus curvirostris . Mustelus manazo appears to use two feeding strategies based upon stomach contents. One, in Tokyo Bay, involved the digging up or removing of burrowing invertebrates from muddy substrata without crushing them. The other, at the other four locations, involved the crushing of prey on the substrata surface. 相似文献
2.
ABSTRACT: Life history parameters (growth pattern, the length of the spawningseason and age at sexual maturity) of Apogon lineatus wereinvestigated from three localities in Japan. The maximum ages werefound to be 3 years in Tokyo Bay, 2 years in Osaka Bay and 5 yearsoff Niigata Prefecture. Both sexes from Tokyo Bay grew to largersizes between the ages of 1 and 2 years than both sexes from otherlocalities, food availability being suggested as the major factorfor differences in growth. Spawning seasons were during 4 months(July–October) in Tokyo Bay and Osaka Bay, but were foundto only occur during the two months of July and August off NiigataPrefecture. Factors that could limit the spawning season off NiigataPrefecture were not determined. Age at maturity for both sexes inall localities appeared to be 1 year. We could not elucidate whetherthese variations in life history parameters arose from genetic differencesor from phenotypic plasticity. In either case, the trade-off betweenthe maximum age and the length of the spawning season in the offNiigata Prefecture population and any other population may be interpretedas an adaptation to local conditions, such as with the off NiigataPrefecture population. 相似文献
3.
4.
The hard clam Mercenaria mercenaria was unintentionally introduced into Tokyo Bay during the 1990s. We analysed 528 bp of partial mitochondrial DNA of the cytochrome
c oxidase subunit 1 (COI) gene extracted from 135 specimens collected from populations at five sites in Tokyo Bay to determine
the genetic structure of this species. Mercenaria mercenaria populations in Tokyo Bay were dominated by haplotype 1, as in the native area. Haplotype 3, which is absent in the populations
north of Cape Hatteras (North Carolina, USA) was detected at all five sites. The haplotype diversity in Tokyo Bay was as high
as that in the native area, except at two canal sites, while the nucleotide diversity was lower. Thirty-five new haplotypes
were found that displayed only a few nucleotide differences. Pairwise F
ST values were not significantly different between any sites in the Tokyo Bay and the east coast of America, with values for
all sites in Tokyo Bay clustering near the Florida populations. The analysis of molecular variance (AMOVA) results also support
this result. This study revealed that M. mercenaria populations in Tokyo Bay have a high haplotype diversity and that populations around Florida may be the source region. 相似文献
5.
Mami Harada Tadashi Tokai Michiyo Kimura Fuxiang Hu Takamichi Shimizu 《Fisheries Science》2007,73(3):477-488
ABSTRACT: In Tokyo Bay, conger tube-trap fishers voluntarily deployed escape holes of at least 13 mm diameter to reduce the by-catch of young conger smaller than the marketable size of 35 cm total length. Comparative fishing experiments in Tokyo Bay were carried out using tube traps with seven hole diameters (3, 9, 13.5, 14, 15, 17, and 19 mm), to obtain the size-selectivity of the escape-hole size for inshore hagfish Eptatretus burgeri and white-spotted conger Conger myriaster . On the assumption of the geometrical similarity in the combination of body g and hole perimeter m at a given retention probability, a single master curve s ( R ) = exp(−13.52 + 11.31 R )/(1 + exp [−13.52 + 11.31 R ]) was estimated for the two species in terms of relative R = g / m using the Share Each LEngth's Catch Total (SELECT) process based on a multinomial distribution. Almost all conger and hagfish with a girth equivalent to the hole perimeter were able to pass through the hole. Thus, the two species have a high ability to escape through a narrow space by squeezing the body through the hole in the rigid PVC tube. Optimum escape-hole size is discussed from several objectives for conger tube-trap fishery management, e.g. reduction of hagfish by-catch. This study also specifies the conditions for pooling data when fishing experiments using more than two fishing gears are replicated. 相似文献
6.
ABSTRACT: The food habits of 595 houndsharks of four species, Triakis scyllium ( n = 179, 42–148 cm total in length), Hemitriakis japanica ( n = 57, 42–102 cm), Mustelus griseus ( n = 193, 39–100 cm), and Mustelus manazo ( n = 166, 43–120 cm), found in the central Seto Inland Sea, Japan, from March 1997 to October 1999 and May 2000 to July 2002, were studied. T. scyllium changed their main food items from shrimps to echiuran worms then to cephalopods with their growth. Comparing food habits by the value of similarity (maximum = 1), the small-sized T. scyllium had a low value (0.17) compared to larger sharks. T. scyllium gradually increased the diversity of food until it reached 700 mm long in total length, however, after that it decreased. H. japanica appeared mainly in summer and autumn and ate cephalopods and fishes. M. griseus preyed on various crustaceans and decreased the diversity of food with growth. M. manazo preferred crustaceans and polychaetes. There was no certain tendency in the diversity of the food habit for M. manazo . 相似文献
7.
Changes in reproductive patterns in relation to decline in stock abundance of the Japanese mantis shrimp Oratosquilla oratoria in Tokyo Bay 总被引：2，自引：0，他引：2
ABSTRACT: We investigated changes in the reproductive patterns of mantis shrimp Oratosquilla oratoria concurrent with stock-abundance decline in Tokyo Bay, Japan. Stock abundance was high in the mid to late 1980s but decreased abruptly in the early 1990s. The yearly change in annual mean larval abundance was similar to that of stock abundance. Mantis shrimp in the bay have two spawning seasons, an early season (May–June) for ≥1-year-old individuals and a late season (July–September) for 0–1-year-old individuals. This general reproductive pattern does not differ among different stock-abundance levels. However, the monthly pattern in larval abundance has changed with stock-abundance decline; larval abundance from the early spawning season was highest in the high-stock-abundance period, and it decreased significantly in the low-stock-abundance period, probably as a result of decreased spawning-stock abundance of large female mantis shrimp ≥1-year-old. Correlation analysis on the egg production index and larval abundance suggested that during this low-stock-abundance period the population is supported mostly by late-hatched larvae spawned by small, 0–1-year-old female mantis shrimp. Considering the reproductive pattern and the present status of the fishery, the stock of small female mantis shrimp should be conserved to enhance reproduction of the population for stock recovery. 相似文献
8.
ABSTRACT: Respiratory quinone compositions were analyzed by a high-performance liquid chromatography to characterize the depth-related changes and site-specific differences of microbial communities in marine sediments. Two deep-sea sediment samples and one coastal sediment sample were investigated from three sites on the coast of Japan, Sagami Bay, Suruga Bay and Tokyo Bay. Although depth-related changes in microbial community structures were observed, site-specific differences appeared to have greater influence on overall community structures. A variety of quinone homologs was commonly identified at all sampling sites and depths examined, but a few minor quinone fractions, mainly derived from Actinobacteria , were detected only at specific sampling sites. Methylmenaquinone-7 (MMK-7) was the major component throughout the examined depths in Sagami Bay and Tokyo Bay. Most abundant quinone homologs changed with each depth in Suruga Bay. Menaquinone-6 (MK-6) predominated in the 0 to 2-cm layer (19%). Below 0–2 cm, the most abundant homolog in each sampling depth was phylloquinone (K1 ; 13%, 4–6 cm), MK-8 (19%, 8–10 cm) and MK-7 (13%, 16–18 cm). The microbial respiratory quinone profiling method shown here, successfully demonstrates the usefulness of this approach to characterize microbial communities in marine sediments. 相似文献
9.
Winter flounder, Pseudopleuronectes americanus, caught in Passamaquoddy Bay, New Brunswick, Canada, and held captive under crowded conditions, developed mixed infections of Trichodina murmanica Polyanski, 1955 (Ciliophora) and Gyrodactylus pleuronecti Cone, 1981 (Monogenea). A protocol involving sequential sieving was used to separate the two species of parasites and produce viable experimental baths. Replicate groups of juvenile, hatchery-reared flounder received one of the following treatments: mixed bath of G. pleuronecti and T. murmanica , bath of G. pleuronecti, bath of T. murmanica or parasite-free (controls). The abundance of both parasites correlated negatively with condition factor of the flounder ( r =−0.354, P < 0.001 for Trichodina ; r =–0.205, P < 0.05 for Gyrodactylus ). During the periods of peak parasite abundance (1–2 weeks postinfection), the effect of the two parasite species was additive, as mean condition factor and the percentage change in weight were significantly lower (ANOVA, P < 0.05) among fish with mixed infections compared to single infections or controls. The most common signs of tissue pathology were increased density of epidermal mucous cells on the fins and macrovesicular lipidosis of the hepatocytes. After a significant decline in parasite infrapopulations (3 weeks postinfection), infected fish resumed normal growth, indicating the observed effects were somewhat reversible. 相似文献
10.
ABSTRACT: The reproductive traits and the monthly larval abundance of the mantis shrimp Oratosquilla oratoria were investigated in Tokyo Bay, Japan, in 2002. The goal of the study was to elucidate the cause of changes in the monthly pattern of larval abundance from the 1980s to the 1990s as these changes relate to variation in the stock size of the adult shrimp. Oogenesis was divided into 10 stages by histological observation. The developmental stage of oocytes in an individual's ovary was synchronous, suggesting that almost all the oocytes in an ovary are spawned at the same time. The size at first maturity was estimated to be 7 ≤ body length ( BL ) < 8 cm. Fecundity was expressed as a function of BL , ranging from 19 300 eggs for 8 cm BL to 92 100 eggs for 14 cm BL . Small female shrimps (<10 cm BL ) spawned around August. Most large female shrimps (≥10 cm BL ) spawned around May, and some large female shrimps also spawned until September. Although most large female shrimps spawned in spring, the larval abundance was low before July and high from August onwards. The results suggest that a substantial decrease in the stock size of large individuals causes the low larval abundance before July. 相似文献
11.
ABSTRACT: Porphyra yezoensis and P. tenera are the representative species of the marine crop Porphyra (nori) in Japan. Since the two species are extremely similar to each other in morphology, nori breeders have tentatively classified many strains of cultivated Porphyra into the two species without strict species identification. In order to facilitate rapid and reliable identification of the many strains of Porphyra currently cultivated in various Japanese regions, 24 conchocelis strains were examined by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis using the plastid RuBisCo spacer and the nuclear internal transcribed spacer regions. From the results, all the strains were identified as P. yezoensis f. narawaensis , and P. tenera was not detected. Hence, it was confirmed that most of the Porphyra strains currently cultivated in Japan are P. yezoensis f. narawaensis , and that intensive selective breeding has led to a reduced genetic diversity in the stock used for nori cultivation. 相似文献
12.
Takehiko Hiwatari Yumi Shinotsuka Kunio Kohata Masataka Watanabe 《Fisheries Science》2006,72(3):578-584
ABSTRACT: An exotic hard clam has been observed in Tokyo Bay since the mid-1990s, which has been morphologically identified as Mercenaria mercenaria . The authors have determined 444-bp partial nucleotide sequences of mitochondrial DNA (mtDNA) 16S rRNA gene of 31 hard clam individuals collected in three locations of Tokyo Bay. Phylogenetic analysis indicated all individuals to be M. mercenaria . Two shell interior colorations (white or purple) were observed, but no relationships between the colorations and mtDNA haplotypes were detected. Frequency of clam individuals having white or purple shell significantly differed among locations, which was accompanied by heterogeneous amounts of acid-volatile sulfides and organic matter and mud ratio. 相似文献
13.
Jeong-Hoon Lee Keita Kodama Masaaki Oyama Gen Kume Yuji Takao Hiroaki Shiraishi Toshihiro Horiguchi 《Fisheries Science》2009,75(4):929-935
We examined the age and growth of the marbled sole Pseudopleuronectes yokohamae collected from Tokyo Bay, Japan, during two study periods between 2002 and 2008, when the stock size was consistently low.
The von Bertalanffy growth equations were found to differ significantly between sexes, and females attained a larger standard
length than males of the same age. These results were then compared with those reported for 1974–1983 and 1986–1988, two study
periods when the stock size was high. The growth of both sexes of marbled sole in Tokyo Bay during the 2000s was found to
be significantly higher than that in the 1970s and 1980s. To explore possible factors causing these changes in the growth,
we examined bottom water temperature and population density. We found that the population density decreased and the bottom
water temperature increased between the late 1970s and the late 2000s. However, despite evidence of changes in population
densities and water temperatures, further study is needed to determine the main factors causing the observed changes in growth. 相似文献
14.
H. T. WENG 《Journal of fish diseases》1987,10(3):221-227
Abstract. The parasitic barnacle, Sacculina granifera , changed the abdominal morphology of the host crab, Portunus pelagicus (L.). Three different shapes were recognizable with increase of the host size. Crabs carrying externae could be found throughout the year with higher percentages in the dry season (May-October) in the Gulf of Carpentaria and in warm months (October-March) in Moreton Bay. The parasite infested more males than females in the Gulf but both sexes of crabs equally in the Bay. Generally, the parasite matured when the host (always immature) reached the size of mature crabs. The smallest crab carrying an externa was 70 mm carapace width from the Gulf and 90 mm CW from the Bay. Overall, 6.6% of P, pelagicus were found with externae in the Bay, a subtropical area where crabs are heavily exploited by amateur and commercial fishermen. In comparison, only 1.2% of crabs were found with externae in the Gulf, a tropical area where no commercial fishery is targeted at this species. 相似文献
15.
Yasuhiro Yube Tomoaki Iseki Manabu Hibino Kouki Mizuno Kouji Nakayama Masaru Tanaka 《Fisheries Science》2006,72(6):1236-1249
ABSTRACT: Daily age and food habits of Lateolabrax latus larvae and juveniles were investigated at two different habitats in Uwajima Bay, western Shikoku, Japan. In the shallow zone at Miura, which contained eelgrass beds, larvae occurred from January and were collected abundantly in March. The size, age, and hatch-date distributions suggested that late-hatched specimens stay longer than early-hatched specimens at this station. On the contrary, in the intertidal flats of the Kunomura River mouth larvae were rarely collected, but juveniles were collected in relative abundance from April. The distributions in the intertidal flats station suggested that specimens had migrated from another location and then resided in the intertidal flats. Spatial and temporal trophic variations increased remarkably with metamorphosis, and thus, the spatial differences in growth rate were considered in relation to the trophic diversity of prey items. Our results suggest that the nursery environment, nursery utilization pattern, and food habits of early life stages of L. latus show remarkable flexibility. From the similarity of these ecological aspects with L. japonicus , which is a closely related species, we suggest the important role of the interspecific competition to the realized niche difference between Lateolabrax congeners. 相似文献
16.
Keita Kodama Gen Kume Hiroaki Shiraishi Masatoshi Morita Toshihiro Horiguchi 《Fisheries Science》2006,72(4):804-810
ABSTRACT: There is concern regarding a possible decrease in the minimum exploitable size of the mantis shrimp Oratosquilla oratoria in Tokyo Bay, coincident with a decline in stock size. To assess this problem, the condition factor, the relationship between body length and processed-meat length, and the estimated body length for each market size category were investigated and compared monthly. The condition factor was lowest in spring and peaked in winter. The difference between body length and meat length was higher in summer and winter than in spring and autumn, suggesting that a high condition factor does not result in an increased net yield of processed meat. The annual mean minimum exploitable size in the present low-stock-size condition did not differ from the minimum exploitable size measured during a high-stock-size period (11-cm body length). However, the minimum exploitable size changed seasonally, which coincided with seasonal change in the net processed-meat yield. Exploitation during the season when net meat yield is high would result in increase of the large-sized meat products of high price. 相似文献
17.
Seiji Akimoto Shiro Itoi Keijiro Sezaki Philippe Borsa Shugo Watabe 《Fisheries Science》2006,72(1):202-207
ABSTRACT: The sequences spanning 307 bp of the mitochondrial cytochrome b gene were determined for 45 sepcimens of Beryx splendens and seven specimens of B. mollis collected in Japan, resulting in identification of 11 and three haplotypes in the two species, respectively. The parsimony tree was constructed from the determined sequences and those registered into the GenBank database as species A and W of B. splendens collected in New Caledonia, featuring with two clades. The first clade comprised species W from New Caledonia and B. mollis in the present study, whereas the second one contained species A from New Caledonia and B. splendens in the present study. These results demonstrate a large geographic distribution for both B. splendens and B. mollis. Some of the haplotypes found in Japan were identical to those of New Caledonia for both B. mollis and B. splendens , suggesting levels of gene flow at the trans -oceanic scale. 相似文献
18.
ABSTRACT: To clarify the feeding habits of tidal mudflat fishes, the gut contents of 29 fish species, collected from unvegetated tidal mudflats in Tokyo Bay, central Honshu, Japan, were examined. Ontogenetic changes in food preference were recognized in 21 species, including several of commercial importance (e.g. Acanthogobius flavimanus , Konosirus punctatus , Mugil cephalus cephalus , Plecoglossus altivelis altivelis , and Sardinella zunasi ). In general, larvae and/or juveniles of these species fed mainly on small zooplankton or benthic harpacticoid copepods, later switching to other prey items with growth (e.g. gammaridean amphipods, mysids, polychaetes, detritus, bivalves, and juvenile fishes). A cluster analysis based on dietary overlaps showed that the tidal mudflat fish assemblage comprised six feeding guilds (small benthic and epiphytic crustacean, zooplankton, detritus, mollusc, polychaete, and fish feeders). Of these, small benthic and epiphytic crustacean feeders were the most abundantly represented in the number of species. 相似文献
19.
Masatomi HOSOI Shoko HOSOI-TANABE Hideki SAWADA Masahiro UENO Haruhiko TOYOHARA Isao HAYASHI 《Fisheries Science》2004,70(4):629-637
ABSTRACT: One of the biggest and long-standing difficulties in investigation of larval ecology in the field is species-level identification. In the present study, we developed polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) analysis based on the large subunit (LSU) rRNA gene (rDNA) D1/D2/D3 region for identification of multiple species of bivalve larvae using 14 species of bivalve collected from Maizuru Bay. The LSU rDNA D1/D2/D3 region of all analyzed species could be amplified by PCR using bvD1f/bvD3r primers, and RFLP analysis by Hae III digestion on the PCR products showed species-specific fragment patterns. Furthermore, this analysis applied to single bivalve larvae in Maizuru Bay revealed efficient amplification of the target region and the species-specific pattern from 80% of the larvae, 75% of which showed a pattern that matched a certain pattern of the adult bivalves. In addition, the analysis of inter- and intraspecies variation of the LSU rDNA D1/D2/D3 region using the sequence data of the genus Crassostrea from the DDBJ database showed high applicability of this RFLP analysis on closely related species. Because of the wide applicability and technical simplicity, this method can become the standard for the identification of bivalve larvae species once the sequence data of the LSU rDNA D1/D2/D3 region of many bivalve species have been accumulated. 相似文献
20.
A recent epidemic of the invasive monogenean Neoheterobothrium hirame is suspected to have caused the significant decline of the commercial catch of olive flounder, Paralichthys olivaceus, in Japan. To clarify the causal link between parasite invasion and host depletion, we monitored the infections of N. hirame on juvenile flounder for 2 years at two widely separate bays, Obama Bay, experiencing a devastating reduction in flounder catches, and Miyako Bay with a stable catch. Prevalence, mean intensity and abundance of developmental stages of N. hirame were compared between the bays and between fish year classes. Fishes captured at Obama Bay harboured three times more worms than those at Miyako Bay and had a significantly higher overall prevalence of infection. In addition, there was a negative correlation between parasite intensity and host condition factor at Obama Bay, suggesting a causal link between the N. hirame epidemic and the reduction of local flounder populations. 相似文献