The possibility of using granulated blast furnace slag was investigated in the present study, because in the near future it may become more difficult to obtain marine sand on a massive scale. Granulated blast furnace slag is a by-product from the manufacturing of iron. It can act as an alternative material to marine sand for constructing artificial tidal flats and shallows. This studies were conducted at a Tidal Flat Mesocosm System (5m x 8m) which can reproduce physical conditions of a tidal flat such as tidal level, tidal current, wave and wind. The effect of five kinds of granulated blast furnace slag, including mixture by natural sand was assessed on the basis of the structure of benthic community, and larval settlement, post-settlement survival of the Japanese Littleneck Clam, Ruditapes philippinarum. The effects were compared to five different kinds of natural sand. There was no significant difference in the benthic community such as bacteria, meiobenthos and macrobenthos between the blast furnace slag group and the
natural sand group. On the other hand, there was no significant difference in the larval settlement and post-settlement survival of Ruditapes philippinarum between the granulated blast furnace slag group and the natural sand group. From the results of these two experiments, the possibility to used the granulated blast furnace slag as an alternative material to marine sand was suggested.
The Sekisei Lagoon surrounded by the Yaeyama archipelago is one of coral
reef areas in Japan. However, it has been partly damaged due to several causes. It
is important to note that the transport of coral eggs and larvae by the flow from the
source area, that is less damaged, will contribute to the recruitment and recovery
of the damaged area. Our goal is to identify the trajectory coral eggs and larvae
from the source area to the recruitment area based on the modeling of physical
circumstances including the flow and dispersion. It will help ascertain the protec
tive area and clarify the restoration process of damaged coral reefs. As the first
step, we examine a flow pattern in summer in the Sekisei Lagoon using a numerical
simulation of a multi-level hydrostatic model with a two-stepped Nested area. We
focus on the flow pattern both of the whole Sekisei Lagoon and the part around
Kuroshima, which locates in the southern part of this lagoon. The model is driven
by the averaged wind stress in summer and the M2 tidal component. The results
show that the northward current about lOcm/s, which basically follows the wind
direction, dominates along the eastern coast of Kuroshima and a weak flow exists
the southeastern side of Kuroshima.
In order to recover both data loggers and stomach contents of fishes, a new
device, automatic fish recapture system (AFR system) was developed. The system
can force to surface a free swimming fish at a preset time. We carried out two
recapturing experiments on Mekong giant catfish in the Mae peum reservoir,
Phayao, Thailand and successfully recovered one catfish and attached data loggers.
Furthermore, we obtained data showed vertical movement and stomach contents as
well as the AFR system.
Tuna aquaculture is currently dependent on the wild capture of juveniles for
production. The development of hatchery technology for the Pacific bluefin and
other tunas would be a major step forward in improving sustainability of their
aquaculture. The present study overviews the technology in the life cycle comple
tion of the Pacific bluefin tuna (PBT) Thunnus orientalis (Temminck et Schlegel)
under aquaculture conditions in Kinki University, and the problems to be solved for
the establishment of tuna hatchery technology. PBT juveniles were wild-caught in
1987 when they were several months old, and reared to maturity. Fertilized eggs
were obtained from these fish in 1995 and 1996, and were used for a mass rearing
experiment. Resulting juveniles (the artificially hatched first generation) were
reared to maturity and spontaneously spawned on 23 June 2002. Over the summer
of 2002, 1.63 million eggs from these fish were used for a mass rearing experiment,
and 17,307 juveniles were produced and transferred to an open sea net cage. Of
these artificially hatched second generation PBT, 1,000 grew to approximately 105
cm TL and 18 kg BW in 24 months. This procedure means the completion of PBT
life cycle under aquaculture conditions which firstly attained among large tuna
species. The problems awaiting solution in PBT hatchery production are their
unpredictable spawning in captivity, to improve survival during the first 10 days
posthatch, to reduce cannibalism in larval and juvenile stages, and to solve collision
problem causing high mortality during juvenile stage.
The cockles, Fulvia mutica, caught in Miyazu Bay, Kunda Bay and Maizuru
Bay, Kyoto prefecture, grow up nearly 10 cm of shell height that is about 1.5 times
as big as cockles caught in other sea area. Individual numbers of the cockles caught
in Kyoto prefecture, however, have fluctuated from 0 to 60,000 and in recent years
the number is less than 10,000.
In order to increase the yield of cockle, we have established the methods for
seed production and cultivation of cockle. Furthermore, we tried to develop the
breeding technique of cockle. In the present study, it was cleared that the shell
length and weight of whole body of Fl hybrid were significantly larger than those
of inbred parents.
Fish Psychology is a research field that deals with the behavior and ecology of
fishes through an approach of experimental psychology. ”How do fish maintain a
school?” ”How smart can fish be?” Research is often based on questions that arise
from direct observation during diving census. Rearing experiments are then related
to the function and mechanism of behavior with emphasis on their ontogeny. We
aim to apply the achievement of fish psychology to human psychology as well as
sustainable fishery management. In this review I presented the results of bi-monthly
diving census conducted for three consecutive years, as well as that conducted in
dawn, noon, dusk, and midnight. Then more experimental studies on the develop
ment of schooling behavior in Carangid fishes are introduced. Ontogenetic changes
of learning capability in fishes are also demonstrated.
The TraceFish was proposed by EU in November, 2002 through the discussion
of two years. The concept and the implementation method of TraceFish are
excellent, though there are remaining both an excess and deficiency in information.
The many exporters to EU will adopt TraceFish. In Japan, testing of traceability
adopted by some enterprises can apply to only internal circle between a producer
and a shop, not universal system at all. In short, the system applied by large
supermarket is a kind of tool for sorting out incapable suppliers.
The movement of the de facto standard plan is still under proceeding, because
there are neither a group nor an enterprise that takes the initiative at all, modeling
the compound circulation is difficult each fish species and various commercial
practices are varied in accordance to each region. The enterprises hope for the
standard of marine products traceability.