Original Paper
Title Modified analytical method for Organotin Compounds in high-volume water samples, and concentrations in sea water and suspended solids in Hiroshima Bay
Authers Toshimitsu ONDUKA* and Hiroyuki TANAKA*
Keywords Organotin compounds(OTs), Hiroshima bay, suspended solid(SS), environmental dynamics
Citation Bull. Fish. Res. Agen. No.13, 1-10, 2004
To analyze low concentrations of Organotin compounds(OTs)in sea water, we modified a standard analytical method for high-volume water samples. ΣOT concentrations of Hiroshima bay and Kure port measured by this method were 3.2-11ng/L in surface seawater and 1.4-4.7ng/L in suspended solids. Higher concentrations of ΣOTs occurred more as the dissolved form than as the particulate form. The ratios of dissolved forms to particulate ones ranged form 0.51: 0.49 to 0.81: 0.19. Results showed a positive correlation between ΣOT concentration and suspended solids weight.

Received on August 20, 2004
* National Research Institute of Fisheries and Environment of Inland Sea, 2-17-5, Maruishi, ohno, saeki, 739-0452, Japan

Short Paper
Title Where’s the cadmium in biogenic particulate matter?
Authers Kazuo ABE *
Keywords cadmium, biogenic particulate matter, chemical leaching treatment, subtropical sea
Citation Bull. Fish. Res. Agen. No.13, 11-14, 2004
A preliminary study on the cadmium (Cd) distribution in biogenic particulate matter was carried out in the subtropical sea near Ishigaki Island. Almost all of the biogenic Cd was determined to be associated with the organic materials, and the possibility of the estimation of the Cd adsorbed onto the surface of organic materials and associated with metalloproteins was suggested; however further methodological examination such as checking the dissolution of the calcium carbonate (CaCO3) phases (hard protective shell) during the chemical leaching treatment of acid hydrogen peroxide (H2O2) might be necessary.

Received on July 16, 2004
* Ishigaki Tropical Station, Seikai National Fisheries Research Institute, 148-446 Fukai-Ota, Ishigaki 907-0451, Japan

Technical Report
Title Search for the Japanese tuna fishing data before and just after World War II
Authers Hiroaki OKAMOTO*
Keywords pre-war, Japanese tuna fisheries, statistics, research vessel, fishing data
Citation Bull. Fish. Res. Agen. No.13, 15-34, 2004

Existing Japanese tuna fishery data before and just after the World War II was investigated and summarized in this paper. As the reliable statistics and fishing data before the war, “Annual statistics of Ministry of agriculture and forestry” and the data of longline and pole and line operations made by prefectural research vessels were recognized to be available.

In the former Japanese official statistics, fishing vessel statistics categorized by fishing gear and annual catch statistics for tunas and relevant fish groups had been compiled since 1905 and 1894 (1922 for billfishes), respectively. The annual catch of skipjack tuna was 30,000 - 50,000 MT before 1914 when coastal fisheries were main, increased to 60,000 - 80,000 in 1915 - 1935, and up to more than 100,000 MT in 1936 - 1940 because of the development of offshore pole and line fishery. Total catch of tunas, which was less than 20,000 MT before 1918, had increased steeply according as the development of the offshore longline and driftnet fisheries derived from the motorization of the fishing vessel and it exceeded 60,000 MT in 1929.

The fishing data of the prefectural research vessels was recorded for 10 years from 1933 to 1942, and total number of available longline and pole and line operations were 5,302 and 3,315, respectively. Main fishing ground of their longline operation from 1934 to 1937 was distributed at north-western Pacific Ocean north of 20°N targeting albacore. After 1938, their fishing ground had extended and shifted toward tropical region of western Pacific from 20°N to the equator targeting mainly yellowfin tuna. The fishing operation data recorded indicates that the night-setting longline operation, which is used to catch swordfish or sharks effectively, was already common before the war. Usefulness of these fishery data for the stock assessment is not clear and would be different for each species. It ought to be cleared through the analyses comparing pre- and post-war data.

Just after the finish of the war, the fishing data of commercial longline and pole and line fisheries were started to be collected by transcribing logbooks at the major landing port. However, the data from 1946 to 1951 has been remained as the hand writing data sheet to be compiled.

Received on August 20, 2004
* National Research Institute of Far Seas Fisheries, 5-7-1, Shimizu-Orido, Shizuoka, Shizuoka 424-8633, Japan

Doctoral Thesis
Title Studies on molecular mechanisms underlying high pressure adaptation of α-actin from deep-sea fish
Authers Takami MORITA
Keywords deep-sea fish, high pressure adaptation, actin, Coryphaenoide, molecular phylogenetic tree
Citation Bull. Fish. Res. Agen. No.13, 35-77, 2004

Deep-sea fish distribute to depths of several thousand meters and at these abyssal depths encounter pressures that shallower-living fish cannot tolerate. Tolerance to abyssal pressures by deep-sea fish is likely to depend at least in part on adaptive modifications of proteins. However, structural modifications that allow proteins to function at high pressures have not been well elucidated. The objective of this study is to disclose the mechanisms underlying adaptation of deep-sea fish to high pressures. First, in order to select sample fish for this study, the author constructed the molecular phylogenetic trees for the deep-sea fish Coryphaenoides using the nucleotide sequences of the mitochondrial 12S rRNA and COI genes. The trees showed new arrangements of seven Coryphaenoides species with distinct groups, abyssal and non-abyssal species, that differed from previous taxonomic studies. Using the mutation rate of mitochondrial genes, the divergence time between abyssal and nonabyssal Coryphaenoides was calculated to be 3.2-7.6 million years ago. The present study suggests that hydraulic pressures play an important role in the speciation process in the marine environment. Second, the author cloned cDNAs encoding a-actin, which was used as a model protein to elucidate the mechanisms involved in protein adaptation to high pressures, from two abyssal Coryphaenoides species, C. armatus and C. yaquinae. Consequently, the author identified three amino acid substitutions, V54A or L67P, Q137K and A155S, that distinguished these abyssal a-actins from orthologs from non-abyssal Coryphaenoides. Finally, the author examined by several biochemical analyses which of the three substitutions makes possible for a-actin of the deep-sea fish adapt to high hydrostatic pressures. It was found that the substitutions of Q137K and A155S prevent the dissociation reaction of ATP and Ca2+ from being influenced by high pressures. In particular, the substitution of Q137K results in a much smaller change in the apparent volume for Ca2+ dissociation reaction. The substitution of V54A or L67P reduced the volume change associated with actin polymerization and has a role in maintaining the DNaseI activity of actin at high pressures. Taken together, these results indicate that a few amino acid substitutions in key functional positions can adaptively alter the pressure sensitivity of abyssal proteins.

Received on August 6, 2004
* Marine Productivity Division National Research Institute of Fisheries Science, Fukuura, Kanazawa, Yokohama 236-8648, Japan