Hiroomi Miyamoto's research while affiliated with Tohoku National Fisheries Research Institute and other places

... The cold Oyashio Current flows southward from the Kamchatka Peninsula along the Kuril Islands in subarctic region (Sakurai, 2007;Qiu, 2019) and its nutrient-rich water nourishes large diatoms (micro-autotrophs) and subsequently large zooplankton such as Neocalanus spp., which provides food resources for various marine organisms through the grazing food chain (Miyamoto et al., 2022). This area is an important feeding ground for sardine, mackerel, and squid in summer (Sakurai, 2007;Yatsu, 2019). ...

... In the epipelagic Transition Province, the abundant malacostracan, hydrozoan, and thaliacean reads were primarily identified as euphausiids, siphonophores, and salps, respectively. This aligns with previous reports of increased euphausiid abundance in this region (Brodeur et al., 1999) and the association of thaliaceans with productive regions of ocean mixing (Ishak et al., 2022). Within the mesopelagic zone, the change from a community dominated by Metridinidae in the Subtropical Province to one dominated by Calanidae in the Subarctic Province agrees with previously described distributions. ...

... Marine plastic pollution is a pressing environmental issue (Wilcox et al., 2015(Wilcox et al., , 2020 with large plastic debris and small plastic particles spreading throughout oceans including deep-sea sediments and Arctic sea ice (Cózar et al., 2017;Collard et al., 2021;Bergmann et al., 2022). While plastic input into the ocean is increasing, particles fragment with age and environmental exposure leading to an increase in the relative number of small particles, which eventually sink (Shaw and Day, 1994;Morét-Ferguson et al., 2010;Law et al., 2014;Eriksen et al., 2014;Cózar et al., 2017;Wang et al., 2020;Wilcox et al., 2020;Pabortsava and Lampitt, 2020;Miyazono et al., 2021). ...

... Miyamoto et al. (2020) found that the feeding habits were different between the western and eastern parts of the North Pacific; more specifically, the important prey species were Neocalanus plumchrus and Neocalanus flemingeri in the area west of 175 E, whereas Neocalanus cristatus was important in the east. Fuji, Nakagami, et al. (2021) also suggested that higher nitrate concentration in the western part of the North Pacific resulted in higher ocean productivity and better prey environment than in the eastern part, accelerating the growth and maturation of Pacific saury in the western region. However, it should be noted that the decreasing pattern of mean ROA from west to east during June-July could vary substantially among years, and thus, it would be highly uncertain to classify the origin of age 1 fish solely based on an ROA threshold (i.e., 550 μm). ...

... Its members are known to infect teleost fishes and cetaceans (Boxshall & Halsey, 2004;Nagasawa & Uyeno, 2014;Hogans, 2017). Pennellid infections can cause damage to host animals (Nagasawa & Maruyama, 1987;Khan & Lee, 1989;Khan et al., 1990;Khan et al., 1997;Pascual et al., 1997;Suyama et al., 2021a). For instance, Suyama et al. (2021a) indicated that Pennella sp. ...

... In terms of broad oceanographic conditions, the 2021 HABs appeared primarily at the sea surface in Pacific coastal shelf waters near the confluence of the Oyashio and Coastal Oyashio currents ( Fig. 1B; Kuroda et al., 2022). The Oyashio, which is the western boundary current of the North Pacific western subarctic gyre (Kuroda et al., 2021b), transports subarctic, nutrient-rich water along a slope region associated with high productivity (e.g., Sakurai, 2007). The Coastal Oyashio, which is located inshore of the Oyashio, flows westward along the Pacific shelf as a coastal boundary current throughout the year and transports mixed waters known as Modified Soya Warm Current Water during summer-autumn. ...

... In the subtropical areas of the northwestern Pacific, larvae of Pacific saury feed on copepod nauplii and several tiny copepod species (Odate 1977;Fuji et al. 2019). They migrate northward to a transitional zone on the Oyashio and Kuroshio current, where the saury shows outstanding growth and massive energy storage for the following spawning migration to subtropical areas, relying on abundant zooplankton such as Neocalanus copepods and the North Pacific krill Euphausia pacifica (Sugisaki and Kurita 2004;Miyamoto et al. 2020). Due to the substantial amounts of bioactive n-3 LC-PUFAs in the aforementioned important prey items (Saito and Kotani 2000;Kusumoto et al. 2004;Yamada et al. 2016Yamada et al. , 2017, Pacific saury would not experience depletion of preformed EPA and DHA throughout their entire life as a zooplankton feeder, although the capability of endogenous production is available. ...

... However, SST showed a significant negative effect on monthly CPUE 1 in the GAM (Fig. 8), indicating that the Pacific saury is likely aggregate in cool waters at least in 2014-2017. The migration of Pacific saury is thought to be driven by the requirement for suitable water temperatures for spawning and the need for optimal access to food resources 18,19,25 . SSC, a proxy of the phytoplankton biomass, provides valuable information about the trophic interactions in marine ecosystems, and is considered an important factor in the formation of fishing grounds 13,27 . ...

... Various fishes, such as chub mackerel and Japanese jack mackerel, use this current as a migration route and spawning ground (Sassa and Tsukamoto, 2010;Takahashi et al., 2019). These differences in nutrient dynamics and dominant organisms at lower trophic level in Oyashio and Kuroshio currents result in distinct differences in stable carbon and nitrogen isotopes values (d 13 C and d 15 N) for zooplankton and small fishes in each region (Ohshimo et al., 2019;Matsubayashi et al., 2020). In addition, water masses such as warm and cold anticyclonic eddies derived from the Kuroshio Extension and Oyashio form fronts between different water masses (Itoh and Yasuda, 2010) and produce dense schools of fish. ...

... Various studies have indicated that the spatial and temporal distribution of Pacific saury could be affected by changes in sea surface temperatures (SST; Chang et al., 2019;Hsu et al., 2021). Specifically, a fishery-independent survey for Pacific saury showed that it prefers a habitat with SST between 7 and 15 • C (Hashimoto et al., 2020). Therefore, we used SST at fishing and its squared value (SST 2 ) as continuous variables in the GLMM standardization models, which allowed for the assumption that observed CPUE had a peak at an intermediate level of SST (Thorson and Barnett, 2017;Hashimoto et al., 2019). ...