Over 120 years of landing trends in Japan, for the commercially exploited shark species, Squalus suckleyi

Yano, Toshikazu; Hattori, Tsutomu; Shibata, Yasutoki; Tanaka, Shô

doi:10.1016/j.fishres.2022.106257

Cited by 3 publications

(9 citation statements)

References 24 publications

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“…However, we have not simultaneously caught both spiny dogfish and other elasmobranchs at the same sites during bottom trawl surveys in SJ for stock assessments (personal observation). Moreover, Yano et al (2022) showed evidence that data for elasmobranchs in SJ and NP mostly reflect the catch weight of spiny dogfish.…”

Section: Occurrence Data For Spiny Dogfishmentioning

confidence: 99%

Spatio-temporal model and machine learning method reveal process of phenological shift under climate change of North Pacific spiny dogfish

Kanamori

Yano

Okamura

et al. 2022

Preprint

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Climate change has disrupted natural phenological patterns, including migration. Despite extensive studies of phenological shifts in migration by climate change and driving factors of migration, a few issues remain unresolved. In particular, little is known about the complex effects of driving factors on migration with interactions and nonlinearity, and partitioning of the effects of factors into spatial, temporal, and spatio-temporal effects. The Pacific spiny dogfish Squalus suckleyi (hereafter ''spiny dogfish'') is a coastal elasmobranchii that migrates southward for parturition and northward for feeding in the western North Pacific. Here, to elucidate the migration patterns as well as the driving factors under climate change, we first examined long-term changes in the timing and geographic location of migration by applying a spatio-temporal model to ca. 5-decade time series data for the presence/absence of spiny dogfish in the western North Pacific. We then evaluated the spatial, temporal, and spatio-temporal effects of driving factors (sea surface temperature [SST], depth, productivity, and magnetic fields) on seasonal occurrence patterns using a machine learning model. We found that the migration area did not change over ca. 5 decades, whereas the migration timing advanced by a month after 2000. The spatial effects of magnetic fields and depth were consistently large and the spatial and spatio-temporal effects of SST increased in the migration season, even though temporal effect of SST was always weak. These results suggest that the migration area of spiny dogfish was stable over time because their spatial distribution was determined by geographic features, whereas the migration timing advanced by tracking a suitable SST location which increased steeply after 2000. Therefore, temperature as well as other factors influence migration simultaneously under climate change and underline the importance of paying attention biotic/abiotic factors including temperature and process-based understanding to predict future impacts of climate change on phenological shifts.

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Section: Occurrence Data For Spiny Dogfishmentioning

confidence: 99%

Spatio-temporal model and machine learning method reveal process of phenological shift under climate change of North Pacific spiny dogfish

Kanamori

Yano

Okamura

et al. 2022

Preprint

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Section: Introductionmentioning

confidence: 99%

“…Japan has historically exploited a great amount of Pacific spiny dogfish in the western North Pacific (Yano et al ., 2022). Its landings in Japan reached 60,023 tons in 1949, around the time when it became the country's most‐landed shark species (Yano et al ., 2022). Thereafter, Pacific spiny dogfish landings began to drastically decrease, reaching <10,000 tons by 1965 (Taniuchi, 1990; Yano et al ., 2022).…”

Section: Introductionmentioning

confidence: 99%

“…Its landings in Japan reached 60,023 tons in 1949, around the time when it became the country's most‐landed shark species (Yano et al ., 2022). Thereafter, Pacific spiny dogfish landings began to drastically decrease, reaching <10,000 tons by 1965 (Taniuchi, 1990; Yano et al ., 2022). Although the drastic drop suggests reduction of the stock (Taniuchi, 1990), recent research showed that the drop in landings was probably caused by the rapidly declining social demand for this species, rather than stock depletion (Yano et al ., 2022).…”

Section: Introductionmentioning

confidence: 99%

“…Thereafter, Pacific spiny dogfish landings began to drastically decrease, reaching <10,000 tons by 1965 (Taniuchi, 1990; Yano et al ., 2022). Although the drastic drop suggests reduction of the stock (Taniuchi, 1990), recent research showed that the drop in landings was probably caused by the rapidly declining social demand for this species, rather than stock depletion (Yano et al ., 2022). Nevertheless, since 1990, to satisfy local demand for this species as a food resource, the landings have remained relatively stable at 2800–4500 tons.…”

Section: Introductionmentioning

confidence: 99%

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High reproductive potential of the commercially exploited shark Squalus suckleyi in the major fishing grounds of the western North Pacific

Yano

Hattori

Narimatsu

et al. 2023

Journal of Fish Biology

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The present study examined body length (precaudal length, PCL) and age at sexual maturity, as well as fecundity and maternal investment in the Pacific spiny dogfish Squalus suckleyi, a long‐term commercially exploited shark in the western North Pacific, using samples caught in several fisheries and across seasons. The PCL and age at 50% sexual maturity of males were 60.6 cm and 9.4 years, respectively, and those of females were 73.1 cm and 17.8 years, respectively. The PCL and age at 50% maternity were 77.4 cm and 19.7 years, respectively. General or generalized linear models revealed that capture by different fishing method did not significantly correlate with sexual maturity and maternity rates or litter size. Other general linear models revealed an increase in offspring size with maternal size, but litter size was not affected by embryonic development. These findings indicate that the reproductive potential of Pacific spiny dogfish is relatively high throughout the whole North Pacific region because of a smaller size and earlier age at sexual maturation in both sexes. In addition, pregnant females displayed no resting phase and produced 0.45 more embryos per centimetre of PCL in their lifetime after the onset of maturity, which is higher than in the eastern North Pacific. We suggest that these qualities are not a consequence of stock decline associated with the long‐term exploitation of the species, but that its high reproductive potential has likely contributed to the long‐term stability of the landings in Japan. Significance statement While reproductive potential has been determined for many fish species, such information is scarce for Pacific spiny dogfish. We evaluated the reproductive characteristics of this species in the major fishing grounds of the western North Pacific. The productivity and rebound potential of sharks is extremely low compared with those of bony fishes. However, our results indicate that even if the reproductive potential has a small effect on the population dynamics, it should not be ignored for sustainable stock utilisation.

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Uninvited guests and permanent residents: long-term changes in the distribution and abundance of the five most common sharks in the northwestern Pacific

Orlov,

Volvenko

2024

Rev Fish Biol Fisheries

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Over 120 years of landing trends in Japan, for the commercially exploited shark species, Squalus suckleyi

Cited by 3 publications

References 24 publications

Spatio-temporal model and machine learning method reveal process of phenological shift under climate change of North Pacific spiny dogfish

Spatio-temporal model and machine learning method reveal process of phenological shift under climate change of North Pacific spiny dogfish

High reproductive potential of the commercially exploited shark Squalus suckleyi in the major fishing grounds of the western North Pacific

Uninvited guests and permanent residents: long-term changes in the distribution and abundance of the five most common sharks in the northwestern Pacific

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