Habitat use and movement patterns of small (age‐0) juvenile Pacific bluefin tuna (Thunnus orientalis) relative to the Kuroshio

Abstract

The habitat use of Pacific bluefin tuna (Thunnus orientalis; PBF) in nursery waters off the southern coast of Japan was investigated using archival tags over a 3 year study period (2012–2015), and the data were used to examine the free‐ranging habitat preferences of PBF and the relationship between their horizontal movements and the path of the Kuroshio off the Pacific coast of Japan. The path of the Kuroshio fluctuated seasonally, leading to changes in water temperature that strongly influenced the habitat use of small PBF (2–3 months after hatching). Most PBF were present in coastal waters inshore of the path of the current, and their habitat use changed in response to the distance of the current from the coast. The Kuroshio typically flowed along the coast from summer to autumn, and PBF remained in the coastal waters off Kochi Prefecture during this period. In contrast, PBF quickly moved eastward in winter when the current moved away from the coast. Throughout the winter and spring, the area of habitat use extended widely from the eastern end of the southern coast of Japan (the Boso Peninsula) to the offshore Kuroshio‐Oyashio transition region. These findings suggest that the seasonal habitat use and movement behavior of juvenile PBF are influenced by the distance of the Kuroshio axis from the coast, and the ultimate drivers are likely variations in oceanographic conditions and prey availability along the southern coast of Japan.

Interannual variation of the diet shifts and their effects on the fatness and growth of age‐0 Pacific bluefin tuna (Thunnus orientalis) off the southwestern Pacific coast of Japan

“…Fujioka et al. () showed that most age‐0 PBF tagged and released in the coastal waters off Kochi Prefecture during the summer were present inshore of the path of the Kuroshio Current. In other words, age‐0 PBF remained in the same coastal waters as the anchovy.…”

“…When the non-Kuroshio meander occurs, anchovy remain within the coastal region, where there is high food availability (Nakata et al, 2000). Fujioka et al (2018) showed that most age-0 PBF tagged and released in the coastal waters off Kochi Prefecture during the summer were present inshore of the path of the Kuroshio Current. In other words, age-0 PBF remained in the same coastal waters as the anchovy.…”

“…Recent studies using archival tags have revealed the fine‐scale horizontal and vertical distributions of age‐0 PBF in the waters off Kochi Prefecture (Fujioka et al., ; Furukawa et al., ). Fujioka et al.…”

“…Recent studies using archival tags have revealed the fine-scale horizontal and vertical distributions of age-0 PBF in the waters off Kochi Prefecture (Fujioka et al, 2018;Furukawa et al, 2017). Fujioka et al (2018) reported that most age-0 PBF were distributed inshore in the area of the path of the Kuroshio Current from summer to autumn, and they stayed in coastal waters where the productivity is higher than that offshore of the Kuroshio Current. In terms of vertical distribution, age-0 PBF were mainly located above the thermocline in August, potentially maximizing the probability of encountering prey that aggregate in this layer (Furukawa et al, 2017).…”

Assessing the Hydrodynamic Response of the Mar Menor Lagoon to Dredging Inlets Interventions through Numerical Modelling

“…Finally, it must be taken into account that WRT and the intensity of currents are two variables that contribute to connectivity but probably act through different mechanisms. Many species, both in their larval stages, as juveniles, and as adults, move or select their habitats depending on the intensity or proximity to coastal currents [65][66][67] Furthermore, fish optimise their swimming performance and swimming costs by taking advantage of the water currents [68]. In this way, currents contribute to determine habitat suitability and connectivity [68].…”