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Examines the effect of increased seawater temperature on Ecklonia cava population in Tosa Bay, southern Japan. Ecophysiology; Seasonal average surface water temperature; Photosynthetic rate of bladelets of Ecklonia cava.

The present study examined whether the elemental compositions of whole otoliths and chronological transect profiles of otoliths covering the complete life history are useful for evaluating the population structure of Pacific herring. Eight elemental ratios, Li:Ca, Na:Ca, Mg:Ca, K:Ca, Mn:Ca, Cu:Ca, Sr:Ca, and Ba:Ca, were measured in whole otoliths and in a series of ablations across the life-history transects by laser ablation inductively coupled plasma mass spectrometry. We studied fish from three sample groups collected from Lake Obuchinuma, Miyako Bay, and Akkeshi Bay of northern Japan from March to May 2008. Significant differences were found in the Na:Ca, Mg:Ca, P:Ca, K:Ca, Mn:Ca, and Ba:Ca ratios of the whole otoliths and in the Li:Ca, Na:Ca, K:Ca, Mn:Ca, Sr:Ca, and Ba:Ca ratios of the otolith core among the three sample groups. Therefore, the present study showed clear differences in elemental composition among the three sample groups from different locations, suggesting that otolith elemental compositions reflect the habitats experienced by individual fish. [ABSTRACT FROM AUTHOR]

Elongate ilisha Ilisha elongata is a commercially important fishery resource in both Japan and China. Age and growth of the species were investigated by scale analysis from June 1996 to July 1997 in Ariake Sound, Japan. Scale annuli were formed once a year mainly between June and July. The age was 1–6 years for both male and female individuals. There was no significant difference in the regression of fork length (FL) on scale radius ( R) between sexes by a covariance analysis. The combined sex von Bertalanffy growth equations were expressed as L t = 495.4 × (1 − e−0.3176( t + 0.4108)), where L t is FL in mm at age t. Comparison of the age and growth among different populations from coastal waters in the western North Pacific Ocean suggested that the FL of the Ariake population is the smallest at each age. The spatio–temporal variations in growth are possibly relevant to environmental conditions of the growth grounds of subadults; however, there was no gradient change in the growth of I. elongata with latitude. Water temperature may not be the main factor affecting the growth of this species . The growth of the tropical population from Sarawak differs greatly from those of temperate and subtemperate populations, which implies genetic variation or phenotypic plasticity in different climate zones. [ABSTRACT FROM AUTHOR]

Stock structure of Japanese flounder Paralichthys olivaceus has been inferred mainly from either morphological or genetic analyses. However, because the results of both analyses did not always agree with each other, an inclusive conclusion has never been obtained. In this study, the stock structure has been inferred from both morphological and genetic analyses using 722 wild Japanese flounder collected from nine locations along the Japanese coast. The dorsal and anal fin ray counts were larger in the southern than in the northern populations. In total, 1041 bp of mitochondrial NADH dehydrogenase subunit-2 ( ND2) and 1830 bp of ND5 sequences were aligned. There are 578 variable sites in the concatenated sequence from the two genes, which defined a total of 490 haplotypes. Both results of morphological and genetic analyses indicated that the western Kyushu group, which included the Nagasaki and Kagoshima populations, was divided from the other seven populations. This is the first report to reveal the heterogeneity of the western Kyushu group based on statistical analysis. [ABSTRACT FROM AUTHOR]

Whistles of Indo-Pacific bottlenose dolphins from three populations in Japan were collected and analyzed quantitatively. Geographic variations in the whistles among populations were found. Significant differences in the whistles among years within each population were also found, but those differences could not explain whole differences among populations because some parameters of the whistles had more differences among populations than among years within each population. As changes with time in the whistles within each population might cause the geographic variations among populations, researchers should take the yearly change within populations into consideration when they study the geographic variation in the whistle of dolphins. [ABSTRACT FROM AUTHOR]

Age-based population assessment is widely used, but there are cases where information on age or even body length of landed fish is difficult to collect. In the present study, the biomass and fishing mortality of the southern Hokkaido stock of Pacific codGadus macrocephaluswas estimated directly from body weight composition, using weight-based virtual population analysis, from 1994 to 2000. The estimated biomass over 1 kg body weight was 5607 t in 1994 and increased to 7908 t in 2000. The increase was explained by an increase in recruitment. [ABSTRACT FROM AUTHOR]

The article provides information on the study why interpopulation variation of egg size in white-spotted charr is poorly examined. It focuses on the egg size variations for fluvial white-spotted charr populations found in Lake Biwa water system and its adjacent basins in Japan. Genetic structure studies of white-spotted charr show that they form a well-defined populations even if they are geographically close to one another. Furthermore, a field research conducted in seven other isolated reaches where white-spotted charr exists allopatrically along with the procedures of the research is presented. It shows that the findings of the latter research indicate a support to the findings of the former study and these findings are as well explained.

Examines the clarification of the population origin of landlocked ayu Plecoglossus altivelis in the Kasumigaura Lake system in Japan. Commercial importance of ayu for freshwater fisheries; Observation of all stages of life history of ayu; Genetic relationships among ayu populations.

Examines the characteristics of the comb-like teeth in amphidromous and landlocked ayu Plecoglossus altivelis populations having a similar size range in Japan. Correlation between teeth development and changes in feeding habits; Coefficient variance for the total number of teeth groups; Standard length of the fish jaw.