The biological pump that transports carbon from the surface ocean to the ocean interior is an important determinant of ocean carbon absorption from the atmosphere, and of biological activity beneath the euphotic zone. Various factors influence the magnitude and efficiency of this biological pump, such as primary production, particle size, and the composition of consumers of particulate organic carbon (POC). The complex factors...

We analyzed distribution and differences in body length, age, and maturation rate of Pacific saury Cololabis saira in the western North Pacific Ocean, during the main spawning season (winter), to locate its spawning ground. Sampling was conducted in the coastal area north of the Kuroshio axis (CA), the offshore area of the southern Japanese archipelago (SA), and the area east of the Honshu Island (EA) from 1996 to 2017. Higher...

In the summer of 2013, we measured the radiocesium ( 134 Cs and 137 Cs) concentrations in aquatic organisms inhabiting the estuary of the Abukuma River, which flows through the Fukushima and Miyagi Prefectures. Radiocesium concentrations in four muscle‐tissue samples of blackhead seabream ( Acanthopagrus schlegeli ) [1240, 914, 202 and 106 Bq kg −1 wet weight (w.w.)] and two whole‐body samples deriving from multiple individual...

Strontium‐90 ( 90 Sr) was released together with radioactive cesium (Cs) from the Fukushima Dai‐ichi Nuclear Power Plant ( FNPP ) accident. Although the total amount of 90 Sr released into the marine environment from the FNPP was estimated to be a factor of 100 lower than that of 137 Cs, the public have been concerned about the safety of commercial species because of the tendency of accumulation in bones of organisms, its long...

A two‐dimensional individual‐based fish movement model coupled with fish bioenergetics was developed to simulate the observed migration and growth of Japanese sardine ( Sardinops melanostictus ) in the western North Pacific. In the model, derived from the observed ocean–environmental data as the driving force, fish movement was adapted as a kinesis behavior. The model successfully simulated the observed transport patterns duri...