Relationships between maturational status and migration behavior of homing chum salmon Oncorhynchus keta in inner bays of the Sanriku coast

Nobata, Shigenori; Kitagawa, Takashi; Houki, Shouji; Ito, Motohiro; Aoki, Yosuke; Sato, Katsufumi; Hyodo, Susumu

doi:10.1016/j.ygcen.2021.113896

Cited by 1 publication

(6 citation statements)

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“…In addition, males caught in the river have been used successfully for artificial propagation just after fishing. Moreover, in this study, plasma DHP level negatively correlated with time duration until river entry (Figure 2a,b and Supporting Information Table S1), which corresponds to the authors’ previous observation (Nobata et al ., 2021). These facts suggest that the preparations for spermiation are completed in males caught in the river.…”

Section: Discussionmentioning

confidence: 99%

“…A total of 250 homing chum salmon caught in Otsuchi Bay were tagged with an ultrasonic transmitter and were released in the inner bay from 2014 to 2016 (Nobata et al ., 2021). Of the 250 fish, the tracking data of 10 males, which were recaptured by weirs situated at less than 1 km upstream from the mouths of the Otsuchi and the Unosumai Rivers (Figure 1b), were analysed afresh in this study.…”

Section: Methodsmentioning

confidence: 99%

“…Plasma concentration was calculated using a standard curve for each steroid. Cross‐reactivities of the antibodies with other steroids were negligible as shown in technical sheets provided by the company, and the procedures were validated as shown in the technical sheets and the previous papers (Kusakabe et al ., 2019; Nobata et al ., 2021).…”

Section: Methodsmentioning

confidence: 99%

“…In the population homing to the Sanriku region (see Figure 1a), on the contrary, gonad maturation completes by the time of arrival at the bay (Onuma, Higashi, et al ., 2003). The authors’ recent study further showed that, in the Sanriku chum salmon, full maturational status occurs during migratory holding in an inner bay (Nobata et al ., 2021). The difference in maturational status at river entry between Hokkaido and the Sanriku populations may be partially attributable to the distance of upriver migration (Aoyama, 2017; Makigushi et al ., 2008; Miyakoshi et al ., 2012; Onuma, Higashi, et al ., 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Fish approach the rivers by following river water spreading in the bay (Nobata et al ., 2019). Although homing adults arrive on the coast with widely varied maturational status (Kusakabe et al ., 2019), completion of full maturation occurs near the time of river entry (Nobata et al ., 2021). In addition, the gills are transformed to freshwater‐residence type (hyperosmoregulation) just before river entry even while in the bay (Uchida et al ., 1997).…”

Section: Introductionmentioning

confidence: 99%

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Straightforward upriver migration to spawning sites by chum salmon Oncorhynchus keta homing to coastal short rivers in the Sanriku region

Nobata

Sato

Houki

et al. 2022

Journal of Fish Biology

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In chum salmon (Oncorhynchus keta) homed to the Sanriku region, Japan, most of the fish are matured in bays and spawn near river mouths in coastal short rivers; therefore, their upriver migration is extremely short, but their behavioural characteristics have remained unknown. Upriver migration in the Otsuchi River, a typical coastal river, was evaluated from behavioural and physiological aspects. Homing salmon tracked in Otsuchi Bay held in the inner bay for less than 1 day to more than 10 days before river entry. The varied holding duration was negatively correlated with plasma 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) concentration, an indicator of maturation. After river entry, however, most fish were captured in weirs near the river mouths within 2 days regardless of the DHP concentration. Of the 34 fish released in the river, on the contrary, eighteen and five fish were seen next day in the main spawning sites located at c. 1.5 km upstream and in the branch creek, respectively, and 85% of the fish held position there until their death. The mean survival time of released fish was 5.8 days. Plasma DHP level suggested that preparations for spawning were already completed at the timing of the release. Taken together, homing salmon completed spawning preparation in the bay, and then they moved to their spawning sites immediately after river entry and spawned there during their short remaining life. This upriver migration contrasts with those of other populations, such as early migrants and long river migrants, whose maturation is completed during upriver migration.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%