The tagging experiments on Japanese alfonsin, Beryx splendens LOWE have been operated from 1957 to 1967 by Kanagawa Prefectural Fisheries Experimental Station at the Sagami Bay and its adjacent waters. The fish used for the experiments are of 16 to 37cm, mainly 17 to 31cm, in fork length. Using the data of time intervals from release to recapture and the fork length at the times of release and recapture, it is tried to estimate the parameters k and l_∞ in von BBRTALANFFY's growth equation,
l_t=l∞(1-e^-k(t-t₀)).
Where, t denotes a time and l_t fork length at the time.
To estimate the parameters following three methods are used, viz. (A) WALFORD's graphic method⁶⁾, (B) GULLAND and HOLT's method¹¹⁾, and (C) FABENS' method⁵⁾. For using of the WAFLORD's method, the growth of the fish based on the present data is transformed to one year growth by means of proportional allotment. In using the FABENS' method an electronic computer is employed because of extreme complexity of the calculations.
The results of estimation by the methods given above are as follows:
(A) l_t=33.65(1-e^{-0.5051(t-t₀)})
(B) l_t=42.9O(1-e^{-0.2254(t-t₀)})
(C) l_t=34.78(1-e^{-0.4572(t-t₀)})
The estimations of k and l∞ by method (C) are also made for the data classified by the time interval between release and recapture, fork length at the time of release, and fishing grounds. As the result it is shown that the estimated instantaneous growth rates of the tagged fish of about 24cm in fork length are the same in those classified groups. The fact is also found that the over-estimation of l∞ is associated with the under-estimation of k, and vice versa, and the relationship between k and l∞ can be expressed as k(ll∞-24)=3.657.

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1. Influence of different acclimation temperature was observed with the cruising performance in flowing water in a V-shaped conduit one m long under the test temperature 10 to 40°C with two species, Tilapia mossambica and T. sparmanni acclimated at 20° and 30°C and kept at 24°C (Av. temperature) before test (Fig. 4), and the influence was found more significant in the former species.
2. The comparison of cruising performance among seven species of Tilapia acclimated at 25°C for 20 days was carried out by a same apparatus under the test temperatures of 10° to 40°C at intervals of 3°C, and these seven species showed their maximum of performance at four test temperatures (Fig. 5), which may be presumed to categorized eventually into two groups; 28°-32°C: T. galilaea, T. mossambica, T. nilotica, T. macrochir and T. zillii, and 24°-28°C: T. macrocephala, T. sparmanni.
3. The preliminary test for temperature tolerance was made finding a correlation between body length and chill tolerance (Fig. 5). Secondly, T. mossambica about eight cm long in S. L. kept at 24°C (Av. temperature) revealed “apparent death” in 2.5 minutes at 1°C, and more than ten minutes following lead the fish to true death. Thus, “apparent death” was defined and adopted.
4. The influences of acclimation to temperature tolerance were tested at 1°, 5°, 10°, 35°, 40°C, with two species of Tilapia as in crusing performance, and significant influence was observed (Fig. 6), and the influence was more regular in T. mossambica than T. sparmanni, a similar result observed in cruising performance experiment.
5. The difference of tolerance among three species of Tilapia was tested with fishes acclimated at 25°C for 20 days, an order of tolerance was, T. sparmanni>T. mossambica>T. nilotica at low test temperatures (1°, 5°, 10°C), but the order became opposite direction at high temperatures (35°, 40°, 45°C) (Fig. 7).

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Former studies on “green oyster” were all done on the samples which had abnormally accumulated copper and zinc in aquatic environment. We have no information on the accumulating process of cpper and zinc in normal oysters which were transplanted to the water area producing green oyster. In the previous paper, the author reported the evident difference between the contents of copper in oysters collected at southern coast of Nobeoka Bay (S-group) and the adjacent waters to north of Nobeoka Bay (N-group). The oysters collected at the former were all regraded as green oyster. Therefore, normal oysters at Urashiro Bay (one of N-group) were transplanted to Akamizu Inlet (one of S-group), where we examined the variation of copper and zinc accumulation in the meat of oysters. The variation of accumulated quantity of copper and zinc in oysters during 125 days from July to November in 1965 is reported in this paper.
The technical terms concerned with the accumulation used in this paper is defined as follows: 1) Normal accumulation indicated the phenomenon of the increase and decrease of heavy metals in organisms which the metabolism of heavy metals at normal physiological condition bring on. 2) Abnormal accumulation indicates the phenomenon of the increase of heavy metals in organisms brought by the influence of abnormal environmental factors. 3) Moreover, abnormal accumulation shows continual increase of heavy metals in organisms by abnormal accumulating phenomenon, therefore, the quatity of Absolute abnormal accumulation is calculated by subtracting the quantity of normal accumulation from the quantity of abnormal accumulation.
In this paper, the normal accumulation refers to the copper and zinc accumulation in oysters at Urashiro Bay, the control field, and the abnormal accumulation refers to the copper and zinc accumulation in oysters at Akamizu Inlet, the test field. The quantity of absolute abnormal accumulation is calculated by subtracting the normal accumulation of copper and zinc at Urashiro Bay from the abnormal accumulation of copper and zinc at Akamizu Inlet.
The normal oysters were transplanted to the water area of green oyster, and the variation of accumulative quantity of copper and zinc in the meat of oysters, and the influence of normal accumulation upon the abnormal accumulation, were discussed, and we obtained following results:
1) The quantity of copper in abnormal accumulation increases in the exponential function type, log Y=1.4399+0.0069X, and that of zinc indicates sigmoid type (Fig. 1, 2, 3).
2) The critical points (Fig. 4) are remarked on the variation of quantity of absolute abnormal accumulation of copper and zinc. The regression lines are straight over and under of the points. It appears that the normal accumulation has influence upon the variation of quantity of absolute abnormal accumulation of copper and zinc.
3) It is clear that the absorption and accumulation of copper and zinc are not done in same mechanism in oysters, that each of these metals has its peculiarity in the metabolism of oysters, and that the ratio of zinc to copper in oysters becomes smaller in the process of abnormal accumulation of copper and zinc.

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In the previous paper, the author reported the variation of accumulated quantity of copper and zinc in the whole body of oysters which abnormally accumulated these metals after transplanted to Akamizu Inlet in Nobeoka Bay. In this paper, the author reports the variation of accumulated quantity of copper and zinc in five parts of oysters: mantles, gills, labialpalps, adductor muscle and the rest organs. The curve of abnormal accumulation of copper in the meat of oysters indicated the exponential function type and that of zinc indicated sigmoid type. Normal, abnormal, absolute abnormal and relative accumulation in the parts of oysters transplanted to Akamizu Inlet and normal oysters at Urashiro Bay are discussed here.
In the previous paper, the normal, abnormal, absolute abnormal accumulation were defined. The relative accumulation used in this paper is defined as follows: Relative accumulation refers to the relation between accumulated quantity of heavy metal in a whole body or in a part or an organ of organism, and quantity in a part or an organ of organism. Relative accumulation has three cases: 1) Tachy-accumulation that is superior to the accumulated quantity of the standard, 2) Brady-accumulation that is inferior to the standard, 3) Iso-accumulation that is equal to the standard.
Oysters which were transplanted to the water area of green oyster, are separatd into the five parts, and we have discussed on the normal, abnormal, absolute abnormal and relative accumulation of copper and zinc in each part of oysters. Obtained results are as follows:
1) Proceeding of abnormal accumulation of copper and zinc are recognized in each part of oysters. In mantles, gills and labial palps of the five parts the accumulated copper increases evidently on the contrary, in adductor muscle and the rest organs increases hardly. In labial palps increases the accumulated copper extremly.
2) It seems that the abnormal accumulation that increase continuously the quantity of copper and zinc by abnormal accumulative phenomenon, can not occur without the abilitv of normal accumulation of each part of oysters.
3) The absolute abnormal accumulation of copper is recognized in each part of oysters, but that of zinc is not recognized. Even negative values were remarked in labial palps and gills.
4) In both relative normal and abnormal accumulation, the accumulated quantities of mantles, gills and labial palps indicate the tachy-accumulation comparing with that of whole body, and that of adductor muscle and the rest organs indicate the brady-accmulation.

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Every cold season the fish and other organisms are stranded upon some beaches along the Tsushima Current. Of these, the egg and larva of Pacific saury, Cololabis saira (Brevoort), are ones of the most numerous forms. To make clear the destruction of this fish by stranding, the authors observed the phenomenon every morning in the seasons of 1964-1967 at the beach (1.5km length) of Shingu, northern Kyushu (Fig. 1).
The results obtained are as follows:
(1) The eggs of Pacific saury were found from the end of November to the end of January (Fig. 2), and the larvae, from the beginning of December to the end of March (Fig. 7). These eggs and larvae were supposed to have been originated from the southward migrating fish in our waters.
(2) Besides on the some floating Sargassum, the main spawning bed of the fish (Fig. 3 and 4), the eggs were found being attached on the materials from the land (Table 1). They were considered to have been spawned in the inshore waters, which was also supported by the evidence in the developmental stages of the collected eggs (Fig. 5).
(3) In the highest peak the number of stranded eggs was estimated to amount to 15 millions a day, and that of larvae to over 1, 000 individuals. These were recorded distinctively just after the prevailing northwester and cold (Fig. 6 and 10).
(4) The stranded fish range from 6 to 87mm in total length, accounting the larvae less than 20mm for over 90% of all fish (Fig. 8 and 9). The natural mortality of the fish caused by this phenomenon occur in both the egg and the larva stages mainly less than 20mm.
(5) This phenomenon was recognized on the beaches along the Tsushima Current in the spawning season of the southward migrating population (Fig. 1). It may be, hence, considered that the offsprings of the southward migrating population are sometimes destroyed in enormous quantities by this phenomenon in our waters.

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The noxious dinoflagellate species which was thought to be a causative organism for the shellfish poisoning in Lake Hamana was identified as Exuviaella mariae-lebouriae.
These Exuviaella cells were collected from the “red-tide” waters which contain high concentrations of Exuviaella mariae-lebouriae by filtration through the BUCHNER's funnel followed by centrifugation.

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It is well known that so-called “pear-shaped cell” or “rodlet cell” is found to occur in the epithelium of the digestive tract of fishes. In the black rockfish, Sebastes inermis CUVIER, pear-shaped cells are frequently found among the columnar epithelial cells and goblet cells forming the lining epithelium of pyloric caeca (Figs. 1 and 2). Electron microscopy revealed that the cell is enclosed by a thick fibrous capsular wall (Fig. 3). Mitochondria are clustered in the apical cytoplasm. The nucleus is located at the basal end. A moderate amount of endoplasmic reticulum is scattered in the remainder of the cytoplasm as well as vesicles, vacuoles, and ribosomes. The rodlets lying parallel to the long axis of the cell are composed of three principal layers; dense central axis, moderately dense medullary part, and thin cortical layer (Fig. 3). Judging from the evidence of fine structure, it is conceivable that the pear-shaped cell is protozoan parasite, not a tissue cell. However, the taxonomic status of this peculiar parasite is uncertain.

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This paper deals with the number of times of molting estimated from the frequency distribution of carapace width of the commerically important tanner crab, Chionoecetes opilio, caught in the Japan Sea.
During the course of our fisheries biological survey on the tanner crab, 17, 097 individuals of males and 12, 155 females were examined. Except them, 68 individuals were too small for the present writers to discriminate the sexes. The whole materials used in this study were caught by a motor trawl net which was operated in Wakasa Bay of the Japan Sea at the depths of 175-375m during the winter seasons of 1964-1965 and 1965-1966.
Frequency of the carapace width of the female and male crabs not exceeding 18mm shows five modes, namely the average width of 3.1±0.2, 4.6±0.4, 6.5±0.4, 9.7±0.6 and 13.5± 1.5 (mm), respectively, and that of the males ranging from 10 to 155mm shows five modes, 19.6±1.8, 27.3±2.2, 36.8±3.3, 49.2±4.7 and 65.2±5.4 (mm). However, as for the larger individuals, the clear modes could not be recognized. On the other hand, the carapace width frequency of the females ranging from 10 to 98mm indicates six modes; these are 19.0±1.8, 27.9±2.3, 37.2±3.0, 49.6±4.6, 66.2±5.9 and 77.4±5.4 (mm), respectively.
Applying these average carapace widths to Hiatt's growth diagram in which the postexuvial lengths (L_n+1) were plotted against the initial lengths (L_n), the following formulas are calculated: immature male, L_n+1=1.32L_n+0.78; immature female, L_n+1=1.32L_n+0.85; and mature female, L_n+l=0.67L_n+32.7. Each point of these carapace widths exists almost on each formula, and is arranged as geometric progression without excess or deficiency. On the other hand, judging from the size of the megalopa of the tanner crab, the rate of development of the individuals with 3.1±0.2mm in average carapace width is thought to be the first molting stage of adult type or first post-larva. Therefore, it is estimated that these modes mentioned above show 10th molting stage of male and 11th molting one of female, respectively.

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In the previous paper¹⁾, it has been pointed out that the low molecular weight fraction obtained from dark muscle of jack mackerel plays an important role in rusting of the dark muscle caused by lipids oxidation.
As appreciable amounts of hexose and pentose occur in the dark muscle, the participation of reducing sugar in the rusting reaction was studied. In an attempt to elucidate the mechanism of rusting, the authors devised model dehydrated systems in which lysine, ribose, phosphate buffer (pH 6.85) and jack mackerel lipids were added and Celite was used as a support medium of the reactants. Discoloration rates of the systems during storage at 30°C and reflectance spectra of the systems and rusted dark muscle were studied (Figs. 2, 3). The data presented in this investigation suggested the probability that sugar might participate in the rusting reaction.

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Although the numbers of pearl oyster, Pinctada fucata, used in the production of cultured pearl are increasing year after year in Japan, during pearl collection the shell meat is mostly forsaken. Whether or not the meat is food for food, or for feed, the large amount of production as well as its rich content of protein suggests much imaginative worth. Therefore, some tentative attempts were made on evaluating the taste and the nutrition of the shell meat.
In this paper, most of the nitrogenous compounds in the extracts of adductor muscle of pearl oyster were quantitatively measured and some comparative aspects were discussed. Results obtained are summarized as follows.
Taurine, glycine, arginine, glutamic acid, proline and alanine were conspicuously abundant in the extracts, and the other amino acids were of traces. Betaine was also abundant in the extracts. Such an amino acid pattern of this extracts was similar to that of soft part of shortnecked clam, Tapes japonica.

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The nutritive quality of the adductor protein of Japanese pearl-oyster, Pinctada fucata, was examined in terms of amino acid composition and digestibility. Results obtained are summarized as follows.
(1) The amino acid composition of the adductor protein was similar to that of fish muscle and short necked clam muscle.
(2) Chemical score and essential amino acid index were derived from the amino acid composition. In reference with whole egg protein, the two values were found 61 and 80 respectively. In reference with HALVER's formula for rainbow trout feed, the two values were 80 and 98 alternatively.
(3) The adductor protein was further examined with respect to digestibility by both in vitro and in vivo tests. There was some 80% of trypsin-susceptible linkage in the protein seen to be cleaved within a 4-5 hour interval at 37°C, whereas only 20 minutes were sufficient for casein to reach the same level. On the other hand, in vivo digestibility estimated on feeding carps was 87%.
(4) Thus, the high digestibility on carp as well as the high essential amono acid index in reference with HALVER's formula for rainbow trout suggests the due consideration of a profitable applicabilitv of the adductor protein to fish feed.

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Carotenoids of short-neck clam, Veneus japonica, were studied on the muscles and viscera of three samples. Unsaponifiable matters of the crude oils of the samples were chromato-graphed on almina column and twelve fractions, A₁-A₁₂, were separated. Yields of the crude oils and carotenoids are shown in Table 1. As the absorption spectra of the unsaponifiable matters did not differ from those of the crude oils (Fig. 1), carotenoids of the samples seem to remain unaltered by saponification. Absorption spectra and absorption maxima of the separated carotenoids are shown in Figs. 2-5 and Table 2.
Short-neck clam always contain β-carotene in relatively high amount but lack lutein, showing distinguishing traits from the other bivalves as will be reported in the following papers.

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Carotenoid components were studied on the muscle and viscera of hard clam, Meretrix lusoria, in the same way as the authors adopted for short-neck clam. As shown in the Table 4, carotenoid component of hard clam consists of far simpler members than that of shortneck clam, and the tendency is especially emphasized in the muscle.
Hard clam contains relatively more lutein than other carotenoids and lacks β-carotene in its muscle, which seem to be distinguishing traits if compared to short-neck clam.

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The variation of acidic and basic components during the ripening process of Ika-Shiokara were investigated. The results obtained are as follows:
1. Acetic acid, propionic acid, iso-butyric acid, ammonia and iso-butylamine were observed to be present in newly-made Ika-Shiokara. Other components such as formic acid, n-butyric acid, n-valeric acid, n-caproic acid, trimethylamine and dimethylamine were produced during the later ripening period (Tables 3, 4, Figs. 2, 3).
2. The variation of the components belonging to the acidic fraction were more marked than those of the basic one.
3. It may be assumed that the ripening of Ika-Shiokara begins at about the 20-th day after the commencement of processing and is finished within about 40 days.

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