scholarly journals Estimation of Ingestion Rate as Nitrogen and Factors Creating its Seasonal Changes in Ruditapes philippinarum Population in Banzu Tidal Flat, Tokyo Bay.

1998 ◽  
Vol 21 (11) ◽  
pp. 751-756 ◽  
Author(s):  
Ryosuke S. ISONO
Keyword(s):  
Tidal Flat ◽  
Seasonal Changes ◽  
Ingestion Rate ◽  
Ruditapes Philippinarum ◽  
Tokyo Bay

Small-scale variation in feeding environments for the Manila clam Ruditapes philippinarum in a tidal flat in Tokyo Bay

2009 ◽  
Vol 75 (4) ◽  
pp. 937-945 ◽  
Author(s):  
Satoshi Watanabe ◽  
Satoshi Katayama ◽  
Masashi Kodama ◽  
Naritoshi Cho ◽  
Kaoru Nakata ◽  
...  
Keyword(s):  
Tidal Flat ◽  
Ruditapes Philippinarum ◽  
Manila Clam ◽  
Tokyo Bay ◽  
Small Scale ◽  
Feeding Environments ◽  
Scale Variation

Production of asari (Manila) clams, Ruditapes philippinarum, during the period of harvest decrease in the 2000s in the Banzu tidal area, Tokyo Bay

2020 ◽  
Vol 33 ◽  
pp. 14
Author(s):  
Mitsuharu Toba ◽  
Jun Kakino ◽  
Kazuo Tada ◽  
Yutaka Kobayashi ◽  
Hideharu Tsuchie
Keyword(s):  
Field Investigation ◽  
Ruditapes Philippinarum ◽  
Management Style ◽  
Seed Stock ◽  
Tokyo Bay ◽  
Yearly Variation ◽  
Culture Area ◽  
Stock Biomass ◽  
Tidal Area ◽  
High Level

In Tokyo Bay, the harvestable quantity of asari (Manila) clams Ruditapes philippinarum has been decreasing since the late 1990s. We conducted a field investigation on clam density in the Banzu culture area from April 1988 to December 2014 and collected records spanning January 1986 to September 2017 from relevant fisheries cooperative associations to clarify the relationship between the temporal variation in stock abundance and the production activities of fishermen. The yearly variation in clam abundance over the study period was marked by larger decreases in the numbers of larger clams. A large quantity of juvenile clams, beyond the biological productivity of the culture area, may have been introduced as seed stock in the late 1980s despite the high level of harvestable stock. The declines in harvested quantity began in the late 1990s and may have been caused by decreases in harvestable stock despite the continuous addition of seed stock clams. The harvested quantity is likely to be significantly dependent upon the wild clam population, even within the culture area, as the harvestable quantity was not correlated with the quantity of seed stock introduced during the study period. These declines in harvested quantity may have resulted from a decreasing number of operating harvesters due to the low level of harvestable stock and consequently reduced profitability. Two findings were emphasized. A certain management style, based on predictions of the contributions of wild and introduced clams to future stock biomass, is essential for economically-feasible culturing. In areas with less harvestable stock, actions should be taken to maintain the incomes of harvesters while avoiding overexploitation, even if the total harvest quantity decreases.

scholarly journals Seasonal changes in short-neck clam (Ruditapes philippinarum) population and its controlling factors on Sashiki Tidal Flats

2018 ◽  
Vol 73 (1) ◽  
pp. 1-10
Author(s):  
Hiroaki TSUTSUMI ◽  
Tasuku NISHIOKA ◽  
Noboru KITAGAWA ◽  
Yoshihiro FUJIYOSHI ◽  
Moriyuki KOZAKI ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Ruditapes Philippinarum ◽  
Tidal Flats ◽  
Controlling Factors ◽  
Short Neck

scholarly journals Fish assemblages in a tidal flat

2003 ◽  
Vol 46 (2) ◽  
pp. 233-242 ◽  
Author(s):  
Ana Lúcia Vendel ◽  
Sabine Granado Lopes ◽  
César Santos ◽  
Henry Louis Spach
Keyword(s):  
Cluster Analysis ◽  
Community Structure ◽  
Tidal Flat ◽  
Seasonal Changes ◽  
Dominant Species ◽  
Fish Assemblages ◽  
Seasonal Pattern ◽  
Abundant Species ◽  
Structure Index ◽  
Total Capture

Studies were carried out on fish assemblages in a tidal flat. Samples were obtained monthly at low tide of the half moon in the tidal flat of Paranaguá Bay, Brazil, with two seine nets, one with a 1 mm mesh, 30 m in length and 3 m in height and another with a 10 mm mesh, 65 m in length and 2 m in height. A total of 8,890 fish were captured, comprising 24 families and 53 species. The most abundant species were Harengula clupeola and Atherinella brasiliensis, which represented 63.4% of the total, capture. A seasonal tendency was observed in the abundance of fishes, with less fishes being captured during winter and part of spring. The number of species showed a seasonal pattern, with the gradual decrease through winter and a marked increase in summer. The community structure index indicated seasonal changes in the assemblage. The faunistic similarities between months separated the 12 months into four major groups. The seasonal pattern was apparent in the numerically dominant species and the Cluster Analysis revealed five main groups.

scholarly journals Field Observation to evaluate Function of Yatsu Tidal Flat in Nutrients Budget of Tokyo Bay in Autumn

2008 ◽  
Vol 55 ◽  
pp. 1126-1130
Author(s):  
Asami WADA ◽  
Ryota OSHIRO ◽  
Yukio KOIBUCHI ◽  
Shinji SATO ◽  
Masahiko ISOBE
Keyword(s):  
Tidal Flat ◽  
Field Observation ◽  
Tokyo Bay

Utilization of Adaptive Management Technique for Restoration of Large-Scale Tidal Flat in Tokyo Bay

2010 ◽  
Author(s):  
Tetsuo Ohmura ◽  
Yoichi Arai ◽  
Takeo Kondo ◽  
Yasushi Hosokawa
Keyword(s):  
Adaptive Management ◽  
Tidal Flat ◽  
Large Scale ◽  
Tokyo Bay ◽  
Management Technique ◽  
Shallow Sea ◽  
Systematic Observation ◽  
Technical Approach ◽  
Technical Problems

This paper proposes that the pilot field be created to apply the Adaptive Management Technique in order to promote the policy of large-scale restoration of the tidal flat/shallow sea. It will be a case study in Tokyo Bay, a major enclosed urban sea in Japan. The motif and background of the study are stated in the beginning. Creation of the symbiotic structure with marine life, of which the artificial tidal flat is a representative example, is more and more in need as a new direction of port environmental policymaking. This paper discusses that the creation of large-scale tidal flat will be especially effective in Tokyo Bay, a highly reclaimed and enclosed sea and that an innovative technical approach is necessary in view of the long-term efforts. First, an artificial tidal flat built in the past, Itsukaichi Area Artificial Tidal Flat in Hiroshima Prefecture, was analyzed to identify its technical problems. Based on what occurred in this case, the need for a new technical approach to practice the Adaptive Management Technique is discussed. Secondly, Tokyo Bay is taken up as a case study. With the ultimate goal of restoring the tidal flat/shallow sea on a large-scale, it is proposed that small pilot fields be created in the Bay and that the Adaptive Management Technique be applied. Technical and social problems will be addressed step by step in the pilot field, which will be gradually expanded. They are open experimental fields, where systematic observation will be conducted. Technically appropriate structure of the tidal flat will be assessed. The pilot field will also be a forum where consent and support of those concerned including citizens and non-specialists is sought. Furthermore, “Shiosai no Nagisa,” an artificial tidal flat with a reinforced seawall in Port of Yokohama is examined from the viewpoint of the Adaptive Management Technique. It was built by Kanto Regional Bureau of Ministry of Land, Infrastructure, Transport & Tourism in 2008.

Molecular detection of protists associated with the Manila clam Ruditapes philippinarum inhabiting the Wajiro tidal flat in Hakata Bay, Fukuoka Prefecture

2020 ◽  
Vol 86 (4) ◽  
pp. 633-643
Author(s):  
Kiyotaka Takishita ◽  
Rihoko Kawai ◽  
Ayaka Tsutsumi ◽  
Goro Tanifuji ◽  
Mayuko Otsubo
Keyword(s):  
Tidal Flat ◽  
Molecular Detection ◽  
Ruditapes Philippinarum ◽  
Manila Clam ◽  
Fukuoka Prefecture
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