The age, body growth and scale characteristics of the Ito in northeastern Hokkaido were studied. The Ito might be long lived; over ten years at least. Generally the body growth is represented by a graded curve. But, in the scale, the nuclear area marked by narrow circuli is followed by widely spaced circuli in the second or third year of growth. This fact suggests the occurrence of smolt transformation and a vigorous growth of body in the second or third spring.

View full abstract

To investigate some fatigue properties of netting twines as shown in Table 1, the present experiments were carried out by giving netting twines with various static loads (W) for about a week.
Various values measured are shown in Table 1.
As it is unsuitable to use initial diametre of twines (D₀) in static loads being equal to zero, they are decided reasonably (Fig. 1).
In order to examine shrinkage and elongation of twines, D/D₀, (1-D/D₀)/W/D² and ε/30/W/D² are calculated by making use of the diameter above mentioned when values of W/D² are ?? large and small (Fig. 1 and Table 3. ε is elongation by static loads).
From Table 3, order of easily deformation is as following, cremona, polyethylene, polypro-pylene. amilan and tetoron.
When values of W/T(_W-0) are equal to or below 0.4, values of T/T(_W=0) are equal to one and if values of W/T(_W=0) go over 0.4, values of T/T(_W=0) decrease rapidly (Fig. 3). (T shows breaking strength).
Elongation of polyethylene, polypropylene and cremona netting twines are uneasy to reco-ver compared with amilan and tetoron (Fig. 4 and Table 5).

View full abstract

It is the purpose of this paper to discuss the fishing efficiency of purse seiner of one-boat and two-boat operation types against jack mackerel, Trachurus japonicus (TEMMINCK et SCHLEGEL), based on the daily records of catch during the eight-year period (1956-1963) in the East China Sea, by the purse seiner.
Results obtained are as follows:
1) In Table 2, the power factor of the purse seiner is given, by type of fisheries and class of vessel sizes in ton.
2) The power factor of the larger-sized vessel is higher than that of the smaller-sized one. In the case of the same size, the factor of the two-boat operation type is higher than that of the one-boat operation type.
3) In the jack mackerel fishing in the East China Sea in recent years, the purse seiner of one-boat operation type of 50-100 ton outnumber all other classes. The number of actual fishing units of the purse seiner has been decreasing year by year since 1957 as the peak, and in 1963 the number decreased to about two thirds of that in 1957. On the other hand, the power factor has shown a rising tendency since 1956, and in recent years has reached a level about twice that in 1956. Judging from the above facts, it is clear that the fishing pressure on the jack mackerel resources in the East China Sea has not decreased as generally thought.

View full abstract

The present work deals with the pollution of sea bottom by wastes from oil factories, as indicated by ether-extractable substances, ignition loss, COD and sulfide in the bottom mud.
The distributions of ignition loss and ether-extractable substances are shown in Figs. 1 and 2, and the relation between their values presented in Fig. 3. The marked correlations between them were observed it the regions of Osaka and Shimotsu, both of which have semiclosed geographical features. The appearance of visible spots or odour of oily waste was observed on the mud which contained ether-extractable substances more than 4mg/g, and located within the limits of l km from the out-fall of oily waste.
The distributions of sulfide and COD are shown in Figs. 4 and 5. The relations between ether-extractable substances and sulfide or COD in the mud are given in Figs. 6 and 7, res-pectively. Both sulfide amounts and COD values increased with increment of ether-extractable substances. This tendency observed in the Shimotsu area, where oily wastes are mainly discharaged, may indicate that the oil pollution brings about the increases of sulfide amounts and COD values in the mud.

View full abstract

When this fish grows to about 13.5mm. in total length, the first scute appears on the shoulder region of lateral line. Scute formation of this fish begins a little earlier than that of Gasterosteus aculeatus aculeatus, Pungitius pungitius and P. sinensis (IGARASHI, 1962, '63, '64). This first appeared scute is, in fact, situated the fifth numbered from anterior most one when the scute formation is completed. Starting from this fifth scute, the order of appearance is 5th-6th-4th-3rd-2nd-lst.
This fish having six scutes of anterior series only, the formation of posterior series, which is degenerate, differs from that of Gasterosteus aculeatus aculeatus. The scute forma-tion stops when the fish reaches about 20 mm. in total length, completed in scute arrangement of Gymnura type. In this size the fish matures. In this respect the author supposes it shows an instance of “neoteny” in comparison with those of Gasterosteus aculeatus aculeatus. Fundamentally the scute developmental process of this fish resembles that of Gasterosteus aculeatus aculeatus. It shows this fish has phylogenetical similarity to that fish, though it differs markedly from him in fish size in scute appearance, order of scute appearance, ar-rangement of scute as well as in degeneration of posterior series scute formation, etc.. And as a whole, structure of the scute of this fish showing more or less tendency of degeneration. From these facts the author supposes that this fish should be an independent species in Genus Gasterosteus, not a subspecies of Gasterosteus aculeatus aculeatus.

View full abstract

Gas chromatographic analysis of the volatiles of “Katsuobushi”, one of the most common seasonings in Japan, revealed thirty five peaks (Fig. 1), and six kinds of volatile fatty acids (acetic, propionic, isobutyric, n-butyric, isovaleric, and n-valeric), two kinds of amines, (trimethylamine and ammonia) and six kinds of phenols (phenol, o-cresol, m- or p-cresol, guaiacol, 2, 4-dimethylphenol and 4-methylguaiacol) were identified gas chromatographically and infra red spectroscopically. The phenolic fraction was found to be important in making up the flavor of “Katsuobushi” and possibly they may be derived from lignin or coniferyl alcohol in woods and remove into “Katsuobushi” during the smoking process.

View full abstract

Six kinds of volatile fatty acids (acetic, propionic, isobutyric, n-butyric, isovaleric, n-valeric) and six kinds of phenols (phenol, o-cresol, m-or p-cresol, guaiacol, 2, 4-dimethyl-phenol, 4-methylguaiacol) have been found gas chromatographically in the volatiles of tarry matter accumulated on the wall of “Katsuobushi” -smoking room. The presence of these compounds in “Katsuobushi” has been shown in the previous paper. These results clearly show the flavor of “Smoke” and “Katsuobushi” are closely related with each other and phenols in “Katsuobushi” are derived from the “Smoke” of woods (an oak etc.).

View full abstract

When the diet of chickens contains more than 10% of commercial fish-solubles sometimes toxic effects are seen. The toxicity results from an excess or imbalance of the minerals which are present. However, the nutritive value of commercial fish solubles has great variability apparently depending on the raw material or the processing methods. It may be that this variability depends upon the presence of substances resulting from putrefaction.
The present experiments were conducted to determine the effect of 4 lots of commercial fish-solubles as the sole source of protein in the diets of growing rats. Paired-feeding was used for the comparison. Three lots showed high nutritive value but one produced a slight loss in weight (Table 3, Exp. 1). The volatile basic nitrogen content of this lot was very high (Table 1). Removal of volatile components from the fish-solubles by steam distillation improved the nutritive value slightly (Table 3, Exp. 2). The toxicity of this preparation of fish-solubles was further examined with rats and mice. The alcohol-soluble fraction was toxic for mice by intraperitoneal injection (Table 8). Histamine and tyramine were shown to be present by paper chromatography (Table 11). These substances are probably produced by putrefaction of the raw material.

View full abstract

The action of the pyloric caeca of Alaska pollock was examined in connection with temperature and pH relation, effect of heating, and betaine and choline if they might be the precursor of FA and DMA.
Betaine and choline proved not to be the precursor of the two compounds.
And, a limited range of both temperature and pH value for good yield of FA and DMA from TMO by pyloric caeca suspension, as well as a complete inactivation of the action by heating at 100C for 5 minutes, revealed that a most probable agent involved in this reaction is a specific enzyme.

View full abstract

In the aquarium with a circulating system, nitrification (ammonium and nitrite oxidation) is one of the most important reactions which are found in the filter-sand bed. This paper deals with the nitrifying activity of the filter-sand used in the aquarium in which fish has been cultivated for a long period and then the breeding water has reached to an equilibrium in its quality.
The results obtained are as follows.
1. A number of nitrifying bacteria, as well as different biochemical types of heterotrophs, is found in the upper layer of the filter-sand bed, and the lower the layer, the more decrea-sed in the bacterial counts. By which, the nitrifying activity is the largest in the upper layer of the bed.
2. The nitrifying activity of the sand decreases gradually when the sand is washed with sea water, however, a somewhat large activity still lies in the sand even after washed.
3. The nitrifying activity of the sand is the largest at 30°-35°C and at pH ca. 9.0, though somewhat different with sea water or fresh water aquarium.
4. The filter-sand of sea water aquarium shows the largest nitrifying activity in the solution of natural sea water or saline with the same salt concentration. Contrary to this, the higher the concentration of sea water or sodium chloride, the lower the activity in the case of the sand of fresh water aquarium. Nitrification of the former sand is completely inhibited in fresh water, and also that of the latter in sea water or in saline of the same salt concentration.
5. The nitrifying activity of the sand decreases under low oxygen tension. However, the nitrification occurs in a fair degree even under extremely low oxygen tension. Effect of aeration on the nitrification of sand of a sea water aquarium is different from that of fresh water one, namely, the activity of the former sand decreases by aeration but it is not so in the case of the latter.

View full abstract

In order to demonstrate the variation with season and growth in nitrogenous extractives of dark-fleshed fishes, free amino acids, trimethylamine oxide, creatine, creatinine and nucleotides in the dorsal muscle of mackerel were determined.
The following are evident in the present analyses (Table 2-4).
1) The mackerel caught in spawning spring contained smaller amounts of extractive nitrogen, free histidine and creatine than the fish in winter.
2) In the small-sized mackrel, lower contents of extractive nitrogen and free histidine were found than in the large-sized one.
These variations in the extractive constituents are schematically shown in Fig. 1.

View full abstract

1) Considerable loosening at the tin-seal of the casing of commercial fish sausage was observed after pasteurization by measurement of electrical resistance of the opening at the seal before and after heating.
2) The seal of the specially prepared stuffingless casing seemed to enlarge to some degree while it was hot, but the opening narrowed again after cooling.
3) Majority of the tin-sealed casings tested had free bacterial permeability at the seal, and the mechanically tightest seal gave no reproducible resistance against bacterial passage. Industrial cleanliness of cooling water and dry storage were also discussed from standpoint of food sanitation.

View full abstract