STRATEGY FOR BREEDING STUDY OF FISHERIES ORGANISMS BY FRA
Okamoto, H
Fisheries Research Agency, Japan (2013). Strategy for breeding study of fisheries organisms–A plan of proceedings of fisheries breeding in Japan. 1-20. (in Japanese)
A sea area of around Japan is one of the fertile areas to produce marine natural
resources in the world, the product amount of Japanese fisheries and aquaculture is only
covered 60 % of the domestic demand itself. Japanese Fisheries Agency made a plan to raise
the food self-sufficiency ratio up to 70% for fin-fish, and 73% for seaweeds in 2022. The
domestic aquaculture production is mostly consumed in the domestic consumption, andtherefore needs to develop itself to achieve the goal of marine food self-sufficient ratio.
However, the business condition of Japanese aquaculture is rather serious, because of
hardness to keep fish-meal for feeding from overseas, to save the cost for preventing disease,and to compete against cheaper import marine products. To overcome these serious problemsof aquaculture farmer in Japan, Fisheries Research Agency (FRA) made strategy for breeding
study of fisheries organisms to achieve genetically improvement, for example, about theadaptation in aquaculture environment, or more suitable products for consumer demand. The
establishment of breeding in aquaculture is expected to maintain the amount of domestic
production, to enhance international competitiveness and to activate related industries, byreduction of production cost and enhancement of domestic consumption. The strategy iscomprised of two parts, one is “Present situation of research and development of aquatic
breeding study”, the other is “Direction and policy for promotion of aquatic breeding study”.
K. T. Wada (2012). Evaluation of Parental Breeding Values in Aquaculture-Revies. Fish
Genetics and Breeding Science, 41, Issue 2, 87-96. (in Japanese)
The strategies in evaluation of parents and in mating design are important inaquaculture breeding programs. This review deals with topics of evaluating the breedingvalues of parents in fish and shellfish species of aquaculture. (1) In order to evaluate offspring
reared at a communal environment, various chemical or physical tags and molecular markers
have been developed for assigning the parentage in mating experiments or in selection
programs. (2) Accuracy of selection is a main target in genetic evaluation of parental animals
and the breeding value has been estimated in many traits of many species. Methodology like
BLUP developed in breeding sciences of livestock can be applied to aquatic animals withsome modification. (3) Increased cost and inbreeding rate and decreased genetic diversity areconcerns in selective breeding since the number of offspring is much larger in aquaculture
breeding program than in those of livestock.
A. Ozaki, W. Kai, J. Aoki, K. Nomura, K. Araki, K. Yoshida, T. Tsuzaki, T. Sugaya, M. Sano,
K. Kobayashi-Fuji, T. Sakamoto and N. Okamoto (2012). Application to the genetic breeding
using by genomics information in Aquaculture. Fish Genetics and Breeding Science, 41, Issue2, 173-178. (in Japanese)
Ten years ago, genetic breeding study of fisheries organisms was mainly about
salmonids because it was the main production of world aquaculture. But now, the aquacultureof marine fish is getting important, the center of breeding study is moving in marine fish. As
developing technique of fish seedling, not only the main aquaculture fish species, for example,
flounder, puffer fish and yellowtail, but also the hard seedling species like eel and tuna are
expected to be applied with breeding study based on genomic information after establishmentof complete raising technique in aquaculture farm. We are introducing about studies of
Quantitative Trait Loci (QTL) and Marker-Assisted Selection (MAS) in aquaculture fish, anddiscussing about necessity and possibility of breeding study in aquaculture.

IDENTIFICATION OF QUANTITATIVE TRAIT LOCI (QTL) AND
MARKER-ASSISTED SELECTION (MAS) USING BY GENOMICS INFORMATIONIN YELLOWTAIL (SERIOLA QUINQUERADIATA)
Ozaki, A
Akiyuki Ozaki, Kazunori Yoshida, Kanako Fuji, Satoshi Kubota, Wataru Kai, Jun-ya Aoki,
Yumi Kawabata, Junpei Suzuki, Kazuki Akita, Takashi Koyama, Masahiro Nakagawa,Takurou Hotta, Tatsuo Tsuzaki, Nobuaki Okamoto, Kazuo Araki, Takashi Sakamoto. 2013.
Quantitative Trait Loci (QTL) Associated with Resistance to a Monogenean Parasite(Benedenia seriolae) in Yellowtail (Seriola quinqueradiata) through Genome Wide Analysis.
PLoS ONE 8(6): e64987. doi:10.1371/journal.pone.0064987
Benedenia infections caused by the monogenean fluke ectoparasite Benedenia
seriolae seriously impact marine finfish aquaculture. Genetic variation in host has beeninferred to play a significant role in determining the susceptibility to this parasitic disease. To
evaluate the genetic basis of Benedenia disease resistance in yellowtail (Seriola
quinqueradiata), a genome-wide and chromosome-wide linkage analyses were initiated using
F1 yellowtail families (n = 90 per family) based on a high density linkage map with 860

microsatellite and 142 single nucleotide polymorphism (SNP) markers. Two major
quantitative trait loci (QTL) regions on linkage groups Squ2 (BDR-1) and Squ20 (BDR-2)
were identified. These QTL regions explained 32.9–35.5% of the phenotypic variance. On theother hand, the relationship between QTL for susceptibility to B. seriolae and QTL for fish
body size were investigated. The QTL related to growth was found on another linkage group(Squ7). As a result, the authors present first genetic evidence that contributes to detailingphenotypic resistance to Benedenia disease, and the results will help resolve the mechanismof resistance to this important parasitic infection of yellowtail.
Kanako Fuji, Takashi Koyama, Wataru Kai, Satoshi Kubota, Kazunori Yoshida, Akiyuki
Ozaki, Jun-ya Aoki,Yumi Kawabata, Kazuo Araki, Tatsuo Tsuzaki, Nobuaki Okamoto,Takashi Sakamoto. 2014. Construction of a high-coverage bacterial artificial chromosome
library and comprehensive genetic linkage map of yellowtail Seriola quinqueradiata. BMC
Research Notes 7:200. http://www.biomedcentral.com/1756-0500/7/200
Japanese amberjack/yellowtail (Seriola quinqueradiata) is a commonly cultured
marine fish in Japan. For cost effective fish production, a breeding program that increases
commercially important traits is one of the major solutions. In selective breeding, informationof genetic markers is useful and sufficient to identify individuals carrying advantageous traits
but if the aim is to determine the genetic basis of the trait, large insert genomic DNA libraries
are essential. In this study, toward prospective understanding of genetic basis of several
economically important traits, the authors constructed a high-coverage bacterial artificial
chromosome (BAC) library, obtained sequences from the BAC-end, and first comprehensive
female and male linkage maps of yellowtail using Simple Sequence Repeat (SSR) markers
developed from the BAC-end sequences and a yellowtail genomic library. The total insert
length of the BAC library the authors constructed here was estimated to be approximately 11
Gb and hence 16-times larger than the yellowtail genome. Sequencing of the BAC-ends
showed a low fraction of repetitive sequences comparable to that in Tetraodon and fugu. A
total of 837 SSR markers developed here were distributed among 24 linkage groups spanning
1,026.70 and 1,057.83 cM with an average interval of 4.96 and 4.32 cM in female and male
map respectively without any segregation distortion. Oxford grids suggested conserved
synteny between yellowtail and stickleback. In addition to characteristics of yellowtail
genome such as low repetitive sequences and conserved synteny with stickleback, thegenomic and genetic resources constructed and revealed here will be powerful tools for theyellowtail breeding program and also for studies regarding the genetic basis of traits.

Jun-ya Aoki, Wataru Kai, Yumi Kawabata, Akiyuki Ozaki, Kazunori Yoshida, Tatsuo
Tsuzaki, Kanako Fuji, Takashi Koyama, Takashi Sakamoto, Kazuo Araki. 2014. Constructionof a radiation hybrid panel and the first yellowtail (Seriola quinqueradiata) radiation hybrid
map using a nanofluidic dynamic array. BMC Genomics 15:165.
http://www.biomedcentral.com/1471-2164/15/165
Yellowtail (Seriola quinqueradiata) are an economically important species in Japan.
However, there are currently no methods for captive breeding and early rearing for yellowtail.
Thus, the commercial cultivation of this species is reliant upon the capture of wild immaturefish. Given this, there is a need to develop captive breeding techniques to reduce pressure on
wild stocks and facilitate the sustainable development of yellowtail aquaculture. the authors
constructed a whole genome radiation hybrid (RH) panel for yellowtail gene mapping anddeveloped a framework physical map using a nanofluidic dynamic array to use SNPs (single
nucleotide polymorphisms) in ESTs (expressed sequence tags) for the DNA-assisted breedingof yellowtail. Clonal RH cell lines were obtained after ionizing radiation; specifically, 78, 64,
129, 55, 42, and 53 clones were isolated after treatment with 3,000, 4,000, 5,000, 6,000, 8,000,
or 10,000 rads, respectively. A total of 421 hybrid cell lines were obtained by fusion withmouse B78 cells. Ninety-four microsatellite markers used in the genetic linkage map were
genotyped using the 421 hybrid cell lines. Based upon marker retention and genome coverage,
the authors selected 93 hybrid cell lines to form an RH panel. Importantly, the authors
performed the first genotyping of yellowtail markers in an RH panel using a nanofluidic
dynamic array (Fluidigm, CA, USA). Using this, 580 markers containing ESTs and SNPs
were mapped in the yellowtail RH map. The authors successfully developed the firstyellowtail RH panel to facilitate the localization of markers.. This high-density physical map
will serve as a useful tool for the identification of genes related to important breeding traits
using genetic structural information, such as conserved synteny. Moreover, in a comparisonof 30 sequences in the RH group 1 (SQ1), yellowtail appeared to be evolutionarily closer to
medaka and the green-spotted pufferfish than to zebrafish. The authors suggest that synteny
analysis may be potentially useful as a tool to investigate chromosomal evolution bycomparison with model fish.

ASSESSMENT OF FERTILIZATION ABILITY OF CRYOPRESERVED SPERM IN
FISH USING INTERSPECIFIC HYBRIDIZATION
Shimada, Y
M. Suquet, C. Dreanno, C. Fauvel, J. Cosson, and R. Billard (2000). Cryopreservation of

Sperm in Marine Fish. Aquaculture Reserch 31:231-243.
Since 1953, cryopreservation of sperm in fish has been performed on about 30
marine species. The paper reviews the techniques used and the results published in these
species. The quality of frozen-thawed semen was evaluated using previously standardized
biotests (i.e. fertilization capacity). Of the investigated cryoprotectants, dimethyl sulphoxide(DMSO) generally leads to the best results. Cooling rates range from 8 °C to 99 °C min-1; thethawing rate is generally high. Compared with freshwater species, a high percentage of sperm
survives in cryopreservation. Therefore, the cryopreservation of marine fish sperm is suited
for application in aquaculture.
T. Morita, N. Kumakura, K. Morishima, T. Mitsuboshi, M. Ishida, T. Hara, S. Kudo, M. Miwa,
S. Ihara, K. Higuchi, Y. Takeuchi, and G. Yoshizaki (2012). Production of Donor-Derived
Offspring by Allogeneic Transplantation of Spermatogonia in the Yellowtail (Seriola
quinqueradiata). Biology of Reproduction 86(6):176,1-11.
Authors established a method for the allogeneic transplantation of yellowtail
spermatogonia and the production of donor-derived offspring. Donor cells (i.e. type A
spermatogonia) were collected from immature (10-month-old) yellowtail males, labeled with
PKH26 fluorescent dye, and transferred into the peritoneal cavities of 8-day-old larvae.
Fluorescence observation at 28 days post-transplantation revealed that PKH26-labeled cells
were incorporated into recipients’ gonads. To assess whether donor-derived spermatogonia
could differentiate into functional gametes in the allogeneic recipient gonads, gametes
collected from nine male and four female adult recipients were fertilized with wild-type eggs
and sperm. Analysis of microsatellite DNA markers confirmed that some of the first filial (F)offspring were derived from donor fish, with the average contribution of donor-derived F1
offspring being 66% and the maximum reaching 99%. These findings confirmed that authors’
method was effective for transplanting yellowtail spermatogonia into allogeneic larvae toproduce donor-derived offspring.
S. Lee, Y. Iwasaki, S. Shikina, and G. Yoshizaki (2013). Generation of Functional Eggs andSperm from Cryopreserved whole testes. PNAS 110(5):1640-1645.
The conservation of endangered fish is of critical importance. Cryobanking could
provide an effective backup measure for use in conjunction with the conservation of natural
populations; however, methodology for cryopreservation of fish eggs and embryos has not yet
been developed. Authors established a methodology capable of deriving functional eggs andsperm from frozen type A spermatogonia (ASGs). Whole testes taken from rainbow trout

were slowly frozen in a cryomedium, and the viability of ASGs within these testes did notdecrease over a 728-d freezing period. Frozen-thawed ASGs that were intraperitoneallytransplanted into sterile triploid hatchlings migrated toward, and were incorporated into
recipient genital ridges. Transplantability of ASGs did not decrease after as much as 939-d ofcryopreservation. Approximately half of triploid recipients produced functional eggs or sperm
derived from the frozen ASGs and displayed high fecundity. Fertilization of resultant gametes
resulted in the successful production of normal, frozen ASG-derived offspring. Feasibility andsimplicity of this methodology will call for an immediate application for real conservation ofendangered wild salmonids.

DEMANDS FOR INFERTILITY OF CULTURED MARINE FISHES AND STUDY OF
UV IRRADIATION AT DEVELOPMENTAL STAGES IN JAPANESE FLOUNDER
Yamaguchi, T
Toshiya Yamaguchi and Takeshi Kitano 2012. High temperature induces cyp26b1 mRNA
expression and delays meiotic initiation of germ cells by increasing cortisol levels during
gonadal sex differentiation in Japanese flounder. Biochemical and Biophysical ResearchCommunications, 419(2), 287-292
The Japanese flounder (Paralichthys olivaceus) is a teleost fish that has an XX/XY sex
determination system. However, the XX flounder can be sex-reversed to phenotypic males byrearing the larvae at high or low water temperatures. Thus, sex in the flounder is determinedby genotype plus temperature effects. Therefore, the flounder provides an excellent model tostudy the molecular mechanisms underlying temperature-dependent sex determination. We
previously showed that cortisol, the major glucocorticoid produced by the interrenal cells in
teleosts, causes female-to-male sex reversal by directly suppressing mRNA expression ofovary-type aromatase (cyp19a1), a steroidogenic enzyme responsible for the conversion ofandrogens to estrogens in the gonads. In the present study, we found that exposure to hightemperature during gonadal sex differentiation upregulates the mRNA expression ofretinoid-degrading enzyme (cyp26b1) concomitantly with masculinization of XX gonads anddelays meiotic initiation of germ cells. We also found that cortisol induces cyp26b1 mRNA
expression and suppresses specific meiotic marker synaptonemal complex protein 3 (sycp3)
mRNA expression in gonads during the sexual differentiation. In conclusion, cyp26b1
expression in gonads is in male-specific manner during gonadal sex differentiation and delays
meiosis onset not only in mouse, chick and amphibian, but also in a teleost with TSD.

Therefore, CYP26B1 appears to regulate germ cell fate by controlling retinoic acid signaling
in a manner common among vertebrates.
Yamaguchi T., N. Yoshinaga, T. Yazawa, K. Gen, and T. Kitano. 2010. Cortisol is involved intemperature-dependent sex determination in the Japanese flounder. Endocrinology,
Endocrinology, 151(8), 3900–3908
The Japanese flounder (Paralichthys olivaceus) is a teleost fish with an XX/XY sex
determination system. However, XX flounder can be induced to develop into either
phenotypic females or males, by rearing at 18 or 27 ℃, respectively, during the sex
differentiation period. Cytochrome P450 aromatase, the product of the gene cyp19, isexpressed in various tissues and plays an important physiological role in the regulation of
estrogen biosynthesis. Recently, it has been reported that, in nonmammalian vertebrates, theexpression of cyp19 mRNA in the ovary is very much higher than in the testis during theperiod of gonadal sex differentiation. In this sutudy, we demonstrated that cortisol causes
female-to-male sex reversal by directly suppressing cyp19a1 mRNA expression via
interference with cAMP-mediated activation and that metyrapone (an inhibitor of cortisol
synthesis) inhibits 27℃-induced masculinization of XX flounder. Moreover, cortisol
concentrations in 27℃-reared juveniles were significantly higher than in 18℃-reared fishes
during sexual differentiation. In conclusion, this study has presented the evidence of
involvement of cortisol in TSD. Cortisol induced the masculinization of XX fish by directly
suppressing cyp19a1 mRNA expression via interference with the cAMP-mediated activation.
These findings provide new insights into to the elucidation of molecular mechanisms
underlying environmental sex determination, including TSD.

DEVELOPMENT OF INTEGRATED MULTI-TROPHIC AQUACULTURE USINGSEA CUUCMBER
Watanabe, S
S. Watanabe, J. G. Sumbing and Ma. J. H. Lebata-Ramos (2014) Growth pattern of tropicalsea cucumber, Holothuria scabra, under captivity, Japan Agricultural Research Quarterly, 48,
457-464
The growth of the juvenile sea cucumber, Holothuria scabra, was studied undercaptivity to elucidate the growth variation pattern and determine the best-fit growth model toestimate age- and size-specific growth rates. Individual growth was extremely variable, with

some individuals below the mean initial weight and some expanding their original bodylength (L) and weight (W) by up to 6.4 and 156 times, respectively; during 84 days of culture
starting at 127 days of age. Some of the smallest individuals showed a higher condition factor
than larger individuals in the presence of ample food, indicating that lack of food may not be
the only impediment to growth. Among the three growth models compared (von Bertalanffy,
Gompertz and logistic), the Gompertz model was considered optimal to express H. scabra
growth; both in L and W. The age- and size-specific daily growth rate for L and W up to 365
days of age, as estimated by the Gompertz model, had a range of two and nine orders ofmagnitude in L (0.035 – 0.96 mm/day) and W (3.4 × 10-7 – 3.5 g/day), respectively. Use of
the Gompertz model over the linear model, which tends to overestimate growth rates, isencouraged to estimate the growth of H. scabra more accurately.
Z. G. A. Orozco, J. G. Sumbing, Ma. J. H. Lebata-Ramos and S. Watanabe (2014) Apparent
digestibility coefficient of nutrients from shrimp, mussel, diatom and seaweed by juvenile
Holothuria scabra Jaeger, Aquaculture Research, 45, 1153–1163
The ability of Holothuria scabra to digest nutrients, such as organic matter (OM),
protein and carbohydrate from animal and plant feed ingredients was investigated. Four test
feeds prepared by mixing sand with single ingredients from animal sources (shrimp andmussel) and plant sources (diatom and seaweed) were fed to H. scabra to estimate apparent
digestibility coefficient (ADC). The total assimilated nutrient (TAN) increased with ADC,
whereas ingestion rate (IR) varied slightly among the feeds suggesting that ADC might be agood indicator of nutrient availability to H. scabra. The ADCOM of shrimp and mussel was
significantly higher than that diatom and seaweed: 86.2%, 77.1%, 55.1% and 32.3%
respectively. ADCprotein was similar for shrimp (88.7%), mussel (84.8%) and diatom (75.2%),
but significantly lower in sea- weed (34.4%). ADCcarbohydrate was similar in mussel (58.5%)
and diatom (58.3%) as well as in seaweed (31.6) and shrimp (28.0%). ADCprotein was
relatively higher than ADCcarbohydrate suggesting that H. scabra generally digests more protein
than carbohydrate. Furthermore, results indicated that nutrients from animal-based feeds are
more efficiently digested by H. scabra; thus, animal ingredients rich in easily digestible
protein could potentially provide an efficiently balanced diet for H. scabra fed with diatom
containing high easily digestible carbohydrate.
S. Watanabe, M. Kodama, J. G. Sumbing and Ma. J. H. Lebata-Ramos (2013) Diet-tissue
stable isotopic fractionation of tropical sea cucumber, Holothuria scabra, Japan Agricultural
Research Quarterly, 47, 127-134

To provide a basis for a stable carbon and nitrogen isotope ratio (δ13C / δ15N)
analysis to determine the assimilated organic matter in sea cucumber, Holothuria scabra,
diet-tissue fractionations were experimentally determined by mono-feeding rearing with
diatom. While δ15N fractionation of the whole body wall (2.4‰) was similar to the commonly
accepted value (2.6 – 4‰), δ13C fractionation of the body wall (4.2‰) showed considerable
discrepancy with the commonly accepted value (0 – 1‰) due to the high content (35% dry
wt/wt) of calcareous spicules (CaCO3) in the body wall, which had significantly higher δ13C(-8.6‰) than the organic fractions. Computational elimination of spicules based upon spicule
content and spicule δ13C reduced the δ13C fractionation of the body wall to 1.5‰, close to thecommon value. δ13C fractionation after spicule removal by acid decarbonation and subsequentrinsing (3.2‰) did not agree with the common value, and δ15N fractionation was significantly
elevated by decarbonation. δ15N and δ13C fractionations of the intestine (1.5 and 2.2‰,
respectively) did not agree with the common values. Since δ13C and δ15N of the feces did not
differ significantly from those of the diet, feces may be used to determine ingested organic
matter in the wild.
S. Watanabe, J. M. Zarate, J. G. Sumbing, Ma. J. H. Lebata-Ramos and M. F. Nievales (2012)
Size measurement and nutritional condition evaluation methods in sandfish (Holothuria
scabra Jaeger), Aquaculture Research, 43, 940-948
The aims of this study were to establish an accurate size measurement method and anutritional condition evaluation method of Holothuria scabra (Jaeger). Although 0.5% KCl
and 0.05% MgSO4 did not induce anaesthesia, 2% menthol-ethanol for 20 min was found tobe effective and harmless. The anaesthetization significantly reduced the coefficient ofvariation of the mean body length and weight by 68% and 43% respectively. During
starvation, body size and weight decreased concomitantly, resulting in an unchanged
condition factor (body weight/volume), suggesting that the condition factor cannot be used as
an index of nutritional condition. Protein, cholesterol and carbohydrate concentrations in the
body fluid were analysed to study the relationship with starvation. As the protein andcholesterol concentrations initially increased and then decreased during the starvation period,
it is difficult to use them as an index of nutritional condition. The carbohydrate concentration
showed a gradual one-fold increase during 10 days of starvation, and it may be used as aproxy for nutritional condition; however, further physiological studies are needed. Body fluid
density and volume relative to body size gradually increased and decreased, respectively,
during starvation. These methods may be used to correctly monitor the conditions of H.
scabra in studies for aquaculture and stock enhancement techniques.

S. Watanabe, M. Kodama, J. M. Zarate, Ma. J. H. Lebata-Ramos and M. F. J. Nievales (2012)
Ability of sandfish (Holothuria scabra) to utilise organic matter in black tiger shrimp ponds.
ACIAR Proceedings, 136, 113-120
Due to frequent viral disease outbreaks, a large proportion of shrimp aquaculture in
South-East Asian countries has switched from black tiger shrimp (Penaeus monodon) to P.
vannamei, an exotic species originally imported from Latin America. One of the causes of
disease outbreaks is thought to be poor water and sediment conditions in the shrimp ponds,
which may aggravate disease symptoms. To obtain basic information for co-culture methodsof black tiger shrimp and sandfish (Holothuria scabra) for possible mitigation of shrimp-pondeutrophication and prevention of disease outbreaks, basic laboratory experiments wereconducted at the Southeast Asian Fisheries Development Center - Aquaculture Department in
Iloilo, the Philippines. A feeding trial of juvenile sandfish showed that they do not grow wellwith fresh shrimp feed on hard substrate. Another trial indicated that sand substrate enhances
the growth of juvenile sandfish fed with shrimp feed. A feeding trial using shrimp tankdetritus, shrimp faeces and Navicula ramosissima (a benthic diatom) as food sources showedthat sandfish grew fastest with the faeces, followed by detritus and N. ramosissima. Dissolved
oxygen consumption and acid-volatile sulfur levels in the shrimp tank detritus were reducedby sandfish feeding. This suggests that sandfish are capable of growing with organic matter inshrimp ponds, and can bioremediate shrimp-pond sediment.

SUSPENDED CULTURE OF ASARI CLAM, RUDITAPES PHILIPPINARUM, AND
THEIR ROLES IN THE ECOSYSTEM
Higano, J
Fujiwara M., S. Tsuji, M. Tanaka, Y. Imanishi and M. Nakanishi. 2008. Growth of Manila
Clam Ruditapes philippinarum On Hanging Culture Using Containers. Bull. Kyoto. Inst.
Ocean. Fish. Sci., 30, 49-53 (in Japanese)
In order to examine the growth of the manila clam Ruditapes philippinarum, ahanging cultivation experiment using containers was conducted in Kunda and Maizuru Bay.
We covered the upper part of the culture containers with a fine mesh net, and put anthracite
soil (particle size : 2 - 3 mm) into the containers for bed material. The wild juvenile clams
used in this experiment were collected from hanging cockle culture containers in Kunda Bay.
We could recognize from the time of discovering juvenile clams whether they were autumn orsummer broods. Autumn broods grew well from spring to summer, but hardly grew inautumn. Summer broods grew well from the first autumn to the summer of the following year,
but hardly grew in autumn of the next year. The mean shell length of 1-year-olds was 32 - 42
mm in autumn broods, and 45 mm in summer broods. These results revealed markedly highgrowth rates not reported to date.
Mizuno T., T. Maruyama and J. Higano. 2009. Transition and Prospect of Asari clam
(Ruditapes philippinarum) Fisheries in Ise Bay, Mie Prefecture. Bull. Mie Pref. Fish. Res.
Inst., 17, 1－21 (in Japanese)
The authors took an overview on the history of the clam fishery in the western-side
region of Ise Bay, a large bay (2,342km2 with 660 km coastline) in the central part of Japan(as shown in the left figure below). Major commercial clams produced in the bay are Asariclam Ruditapes philippinarum living in shallow coastal areas, freshwater clam Corbicula
japonica and hard clam Meretrix lusoria in brackish-water.
The annual yield of these 3 species decreased in response to fishing efforts andenvironmental changes. Until early 1960s, tidal flats at river mouths covered in excess of
6,000 ha, and eelgrass beds grew there as well as in other parts along the coastline. After theannual catch of Asari clam peaked at ca. 15,000 tons in the late 1960s, it decreased rapidly
when coastal developments destroyed tidal flats and eelgrass beds during 1970s (right figure).
In this period, the structure of coastal fisheries changed then laver culture and fisheries on
clams and pelagic fish were continued.

The second peak of Asari yield was seen in 1980s

when clams in the subtidal zone were also exploited.

Aged fishermen recruited into clam

fisheries during 1990s avoiding intensive labors in the laver culture. In 2000s, the 70% offishermen are working in clam fisheries, and the yield of Asari clam became stagnant in 1,000
to 3,000 tons due to the strong fishing pressure.
In the early 2000s, very few Asari clam larvae, less than 200 individuals/m3 in the main
reproductive period (spring and autumn in this region), were observed at the river mouth in
the southern part of the bay. This abundance of larvae was contrastingly smaller than that in
Mikawa Bay adjacent to Ise Bay where stable annual yields and high abundances of larvae,
thousands of individuals in 1 m3, were reported.

In the survey point in Ise Bay, it wasobserved that juveniles immediately after settlement rarely survived after the flood in June
through August, while juveniles occurred in autumn survived once in a few years.

These

survivors were exploited soon after their shell length reached at 25mm, the minimum size
allowed to catch, in 2 years.
Catch per unit effort (CPUE) of hard clam and freshwater clam recovered when thesociety of local fishermen became aware of the importance of regulating their catch andprotecting fishing grounds in the light of field surveys.

As contrasted with cases of these 2

species living in or around rivers, the spatial scale necessary for the fishing management of
Asari clam should be much larger.

In 2009, fishing cooperatives along the bay wereorganized to conduct resource surveys and activities to protect fishing grounds fromundesirable predators. It has been also planned to enhance the quality of some fishinggrounds in the bay by creating artificial tidal flats and adjusting the ground height to the
known suitable level for the habitat of Asari clam.

Goulletquer, P., J.M. Deslous-Paoli, M. Héral. 1989. Ecophysiologie et Bilan Energétique dela palourde japonaise d'élevage Ruditapes philippinarum. Jour. Exp. Mar. Biol. Ecol., 132,
85-108.
Rates of filtration and respiration both follow a nonlinear model based on
temperature of the form:

with maximal values at 15 and

20°C, respectively. Quantities of seston varying from 0 to 30 mg · 1−1 have no effect inreducing the filtration rate. > 8 mg · 1−1, ingestion is regulated by the production ofpseudofaeces. Maximal assimilation efficiency is ≈ 78%, but this is considerably reduced
when the mineral content of the water increases. Assimilation efficiency for the Manila clamis reduced at both high (> 10 mm3· h−1) or low (< 2 mm3· h−1) values of ingested ration. The
estimated value of growth efficiency (75%) and values of growth efficiency derived from themodel k1 = 33%, K2 = 51% are optimized when ingested volumes are between 1 and 2 mm3.
Standard metabolism is estimated as 0.11 ml O2 · h−1. Zero growth efficiency occurs at aration level of 2 J · h−1 for an adult. The individual energy budget shows that production isdependent more on temperature than on the energy value of the food. Comparison of
calculated and measured production reveals differences resulting from the higher levels of
seston found in the field. In particular, during the winter when the mineral content of the
seston is high (90 mg · 1−1), there is a continuous loss of weight. This results from a lower
assimilation efficiency together with production of pseudofaeces. Excretion of organic
nitrogen varies throughout the year, ammonia representing no more than a mean of 29.8% of
the total nitrogen excretion.

Magni P., S. Montani, C. Takada and Tsutsumi H. 2000 Temporal scaling and relevance ofbivalve nutrient excretion on a tidal flat of the Seto Inland Sea, Japan. Mar. Ecol. Prog. Ser.,

198, 139-155
Using an indirect and integrated approach, we quantified the magnitude and temporalvariability of the contribution of macrozoobenthos to the upward flux of inorganic nitrogenand phosphorus on a sandy tidal flat of the Seto Inland Sea, Japan. From April 1994 to April
1996, we conducted monthly field surveys on the abundance and faunal composition of themacrozoobenthic communities inhabiting the lower part of the intertidal zone. Subsequently,
we carried out 24 h day/night laboratory experiments on the nutrient excretion rate by various
size-classes of the dominant species. We then obtained the animal nutrient excretion over a 2
yr period, multiplying the species-specific excretion rates by the actual animal biomass foundon the tidal flat. Additionally, for all different seasons, we calculated the upward diffusive flux
from the sediments from the vertical profiles of nutrient concentrations in the porewater. On
the flat, the bivalves Ruditapes philippinarum (Veneridae) and Musculista senhousia(Mytilidae) were dominant, making up 86 ± 5.6% when the total biomass exceeded 100 g DW
(dry weight) m-2. From our laboratory experiments, the mean (day and night) nutrient
excretion rates at 20 to 22ºC by the 2 bivalve species were 18.9 µmol NH4+-N g-1 DW h-1, 4.8µmol (NO3- + NO2-)-N g-1 DW h-1 and 3.3 µmol PO43--P g-1 DW h-1. In addition, NH4+-N
excretion by R. philippinarum, but not that by M. senhousia, was significantly higher during
the day than during the night. This occurred while the food (Thalassiosira sp.) offered in
spikes was rapidly taken up irrespective of the concentration (within a field relevant
spring-summer range of 10 to 60 µg l-1 chl a) and in day/night treatments. The release of
nitrogen (N) and the release of phosphorus (P) were highly correlated with each other, forboth R. philippinarum and M. senhousia, with a N/P ratio of 7.8 ± 3.0 and 9.9 ± 3.5,
respectively. In the field, the bivalve excretion rates of nutrients were calculated to be up to
35.2 mmol NH4+-N m-2 d-1, 8.8 mmol (NO3- + NO2-)-N m-2 d-1 and 5.8 mmol PO43--P m-2 d-1.
These values rank in the upper range of nutrient excretion by intertidal macrozoobenthos andare comparable to those found on dense assemblages (800 to 2000 g ash free DW m-2) of themost investigated mussel, Mytilus edulis. In addition, nutrient fluxes through bivalve
excretion varied strongly within a few months, up to 10-fold (R. philippinarum) and 100-fold(M. senhousia) between April 1994 and August 1994, as related to the temporal change ofbivalve standing stock. The extent of nutrient regeneration through diffusive flux wascomparable to that reported for other intertidal zones of Japan and in the eutrophic Seto
Inland Sea, within a range of 0.2 to 1.5 mmol NH4+-N m-2 d-1 and 0.01 to 0.05 mmol PO43--P
m-2 d-1, thus more than 1 order of magnitude lower than that due to the excretory activity by R.
philippinarum and M. senhousia. Our results indicate that the dominant bivalves, R.
philippinarum and M. senhousia, play a major role in the processes of benthic nutrientregeneration within the intertidal zone, rapidly and efficiently recycling the inorganic forms of
N and P available to primary producers. This study highlighted the importance of considering
the temporal scaling of intertidal macrozoobenthos distribution in the quantification of theprocesses of benthic nutrient regeneration in these highly variable systems.