Geographic variations in growth of the starspotted dogfish Mustelus manazo from five localities off Japan and Taiwan were examined from centrum analysis using soft x-radiography. Based upon seasonal centrum edge analysis, dark rings were formed annually, during the period of June and July in all localities. It was suggested that ring formation did not vary among localities, although seasonal vari ations in water temperature differed among localities. Great variations in maximum ages among locali ties were found. The differences in maximum ages between the northernmost population, Aomori, and southernmost population, Taiwan, were almost two times for both sexes (male, 5-9; female, 9-17). Fe males grew to a larger size than males and were apparently longer-lived in all localities. The significant sexual differences in growth were found in Maizuru and Shimonoseki. For both sexes, Aomori was the largest length at each estimated age in five localities, and Taiwan was the smallest. The growth differed in all localities for males and most localities for females significantly, however, for females, no sig nificant differences between Tokyo Bay and Shimonoseki, and Tokyo Bay and Taiwan were found. The specimens tended to grow larger and have longer life span in the eastern and northern areas, however, the water temperature may not be a major factor for differences in growth.
We studied age, growth, and maturity of the oceanic whitetip shark Carcharhinus longimanus in the North Pacific, and the reproduction in the North and South Pacific, captured with tuna longline from Nov. 1967 to Oct. 1995. Vertebral rings were examined from 111 males (precaudal length: 54-172 cm) and 114 females (precaudal length: 50-195 cm). Minimum and maximum numbers of translucent rings were 0 and 11. Marginal increment analysis suggested annualus deposition occurs during spring. A growth difference between sexes was not found. A von Bertalanffy growth equation combining both sexes was as follows;Lt=244.58 •~ {1-e-0.103 •~(t+2.698)} Lt was expressed as precaudal length in cm at age t.The reproductive condition was examined from 136 males and 85 females. Maturation was deter mined to be when precaudal length was between 125 and 135 cm for both sexes (4-5 years). The parturi tion period is extended over a long duration. The birth size was 45-55 cm and litter size varied from 1 14 with a mean of approximately six in the North Pacific.
Long‐term changes in the demersal assemblage, including both fishes and invertebrates, in Tokyo Bay, Japan, were examined between 1977 and 1995. A total of 255 species were collected, of which 113 were regarded as representative in terms of occurrence. Multivariate analyses of the representative species showed that fluctuations in the catch were related to three periods that reflected changes in relative abundance and species composition. In particular, mantis shrimp, Oratosquilla oratoria (de Haan), whipfin dragonet, Repomucenus valenciennei (Temminck & Schlegel), and marbled sole, Pleuronectes yokohamae Günther, showed high dominance in the mid‐1980s. Discriminant analysis suggested that the demersal assemblage changed synchronously with environmental conditions. Causes of the temporal changes in the demersal assemblage in relation to variations in environmental factors are discussed.
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