Partial migration of juvenile temperate seabass Lateolabrax japonicus: a versatile survival strategy

Abstract

Partial migration describes intrapopulation variation in the migratory behavior i.e. some individuals from a population migrate to low salinity river areas, while others remain in coastal areas. This paper reviews the partial migration pattern of juvenile temperate seabass Lateolabrax japonicus, which is a migration pattern not commonly seen in Japan. Seabass spawn offshore, and eggs and larvae are transported to coastal areas. Some of these juveniles then ascend rivers, while others remain in coastal areas. Juveniles efficiently use physical structures in their habitat; they use tidal currents to ascend rivers in macrotidal estuaries, while they use the saltwedge in microtidal estuaries. Once juveniles ascend the river, they can feed on the abundant prey and attain more rapid growth than those remaining in coastal areas. As estuaries are highly productive areas, they play significant roles for juveniles of various fishes as nurseries. However, compared with coastal areas, the relative area of estuaries is considerably smaller and its environmental conditions are more variable. For example, nearly 40% of adult seabass in Tango Bay were estimated to use estuarine areas as a nursery, while the other 60% use coastal areas during their juvenile stage. Using both estuaries and coastal areas through partial migration during the juvenile stage is concluded to contribute to the stabilization and yield of seabass populations.

Modeling the coastal ecosystem complex: present situation and challenges

“…Kasai et al (2018) and Fuji et al (2018) focus on the migration of temperate seabass between estuaries and coastal areas. As reviewed by Kasai et al (2018), eggs and larvae are transported shoreward from offshore spawning grounds, and juveniles settle in coastal areas. Some of the juveniles migrate upstream in rivers, using either tidal flows or salt wedges , while others do not.…”

“…3, which conceptually models habitat connectivity for various species in a Japanese temperate coastal water such as Tango Bay Kasai et al 2018;Takeshige et al, unpublished data). It is noted that this graphical model does not represent the details of the Tango Bay ecosystem but highlights general processes and components of a CEC to be included in the model.…”

“…Below, we consider three issues (habitat function, ontogenetic development from planktonic larvae to benthic/nektonic juvenile, and recruitment variability) that have been identified in case studies of the special issue as being important Hasegawa et al 2018;Hayakawa et al 2018;Ichimi et al, unpublished data;Kasai et al 2018;Minami et al 2018;Ohtsuchi et al 2018;Shirafuji et al 2018;Takami and Kawamura 2018;Tanaka et al 2018;Sawada et al unpublished data).…”

Winter monsoon promotes the transport of Japanese temperate bass Lateolabrax japonicus eggs and larvae toward the innermost part of Tango Bay, the Sea of Japan

“…Japanese temperate bass Lateolabrax japonicus is a commercially important coastal fish, inhabiting the coastal waters of Japan and Korea (Hatooka, ). This species is among several coastal fishery resources whose landings have increased or remained high in Japan during the last few decades (Kasai, Fuji, Suzuki, & Yamashita, ; Shoji, Sato, & Ozaki, ). Ecological information about its early life history has been accumulated mainly in Japan (Fujita, Kinoshita, Takahashi, & Azuma, ; Kasai et al, ; Mito, ; Watanabe, ): Larvae hatch offshore in winter before being transported toward nursery habitats in coastal and estuarine waters.…”

“…This species is among several coastal fishery resources whose landings have increased or remained high in Japan during the last few decades (Kasai, Fuji, Suzuki, & Yamashita, ; Shoji, Sato, & Ozaki, ). Ecological information about its early life history has been accumulated mainly in Japan (Fujita, Kinoshita, Takahashi, & Azuma, ; Kasai et al, ; Mito, ; Watanabe, ): Larvae hatch offshore in winter before being transported toward nursery habitats in coastal and estuarine waters. Partial migration and flexible feeding habits characterize the early life history of L. japonicus (Fuji, Kasai, Suzuki, Ueno, & Yamashita, ; Fuji, Kasai, Ueno, & Yamashita, ; Hibino, Ohta, Isoda, Nakayama, & Tanaka, ; Hibino, Ueda, & Tanaka, ; Suzuki, Kasai, Isoda, Nakayama, & Tanaka, ; Suzuki, Kasai, Ohta, Nakayama, & Tanaka, ), potentially contributing to the stability of L. japonicus stocks despite degradation and fragmentation of the coastal environment.…”