Age and Growth of the Dusky Shark, Carcharhinus obscurus, in the Western North Pacific Ocean

Joung, Shoou‐Jeng; Chen, Jun-Hsu; Chin, Chien-Pang; Liu, Kwang‐Ming

doi:10.3319/tao.2014.10.15.01(oc)

Cited by 13 publications

(10 citation statements)

References 12 publications

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“…We found a similar relationship and an r-value of 0.82, suggesting that our estimate of the TL-VR relationship for Blue Sharks was reasonable. Simple linear models for the TL-VR relationship were also reported for Dusky Sharks Carcharhinus obscurus (Joung et al 2015) and Whale Sharks Rhincodon typus (Hsu et al 2014).…”

Section: Distribution Of Blue Sharksmentioning

confidence: 91%

Distribution Pattern, Age, and Growth of Blue Sharks in the South Atlantic Ocean

Joung

Lyu

et al. 2017

Mar Coast Fish

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The distribution pattern and the age and growth of Blue Sharks Prionace glauca were described based on 44,092 and 785 specimens, respectively, that were collected by scientific observers onboard Taiwanese longline fleets in the South Atlantic Ocean between December 2004 and December 2013. Size segregation was found, and the mean length of Blue Sharks was significantly larger in the equatorial–tropical area (0–15°S) than in the subtropical–temperate area (south of 15°S) during all seasons. Males predominated in both areas and during all seasons; the exceptions were seasons 2 (April–June) and 3 (July–September) in the equatorial–tropical area and season 2 in the subtropical–temperate area. The sex ratio increased with shark size in the equatorial–tropical area but decreased with size in the subtropical–temperate area. Growth band pairs (including translucent and opaque bands) were counted on images photographed from X‐ray films of vertebrae from the caudal peduncle region. The centrum edge analysis indicated that a growth band pair was formed on the vertebral centrum once per year. Corrected Akaike's information criterion values indicated that the von Bertalanffy growth function (VBGF) provided the best fit to the observed TL‐at‐age data. The likelihood ratio test indicated that the VBGF equations were not significantly different between the sexes. For both sexes combined, VBGF parameters were estimated as follows: asymptotic length was 352.1 cm TL, the Brody growth coefficient was 0.13/year, and the theoretical age at zero length was –1.31 years. Age at first maturity was estimated as 6.5 years for males and 6.7 years for females; theoretical longevity was estimated to be at least 21.4 years.

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Section: Distribution Of Blue Sharksmentioning

confidence: 91%

Distribution Pattern, Age, and Growth of Blue Sharks in the South Atlantic Ocean

Joung

Lyu

et al. 2017

Mar Coast Fish

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“…As a result, many sharks are overfished globally (Davidson et al, 2016), and their populations have rapidly decreased regionally (Musick et al, 2000;Baum et al, 2003;Ferretti et al, 2010). Although chondrichthyan faunas are rich in the waters around Taiwan (Ebert et al, 2013), stock status of sharks is still unevaluated, and stock assessments are focused on age and growth studies (e.g., Joung et al, 2008;Hsu et al, 2014;Joung et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Dusky sharks in the U.S. waters have been overfished since 1990 (Sulikowski et al, 2020). The medium sized fins make dusky shark a major target species in Taiwan waters (Joung et al, 2015). The mean annual landing of the dusky shark is 210 metric tons which accounts for 11.5% of the total shark landings from1990 to 2008 in northeastern Taiwan (Joung et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Stock Status Estimating of 5 Shark Species in the Waters Around Taiwan Using a Length-Based Bayesian Biomass Estimation (LBB) Method

Chen

Tian

et al. 2020

Front. Mar. Sci.

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Five shark stocks in the waters around Taiwan were assessed using the LBB method, addressing the present gap. Among them, only one filter-feeding shark, megamouth shark Megachasma pelagios, qualified as having a healthy status. Of the remaining filter-feeding shark, whale shark Rhincodon typus, was seriously overexploited, possibly even collapsed, spadenose shark Scoliodon macrorhynchos, and other two large sharks (dusky shark Carcharhinus obscurus and silky shark Carcharhinus falciformis) were also overexploited. These stock status estimates for the five shark species using the LBB method were consistent with international agreements such as IUCN, CITES and CMS.

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“…In addition, vertebrae in this region have been successfully used to estimate the age of several pelagic shark species (Joung et al. , , , ). Vertebrae from Shortfin Makos were stored frozen onboard and transported back to Taiwan and stored frozen in the laboratory until processed.…”

Section: Methodsmentioning

confidence: 99%

Age and Growth of the Shortfin Mako Shark in the Southern Indian Ocean

et al. 2018

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The Shortfin Mako Isurus oxyrinchus is one of the major shark bycatch species in the longline fishery for tuna Thunnus spp. in the Indian Ocean; however, its biological information is still little known. This study estimated the age and growth of Shortfin Makos in the southern Indian Ocean. In total, 178 specimens (72 females and 106 males) were opportunistically collected by the scientific observers onboard Taiwanese large‐scale longline fishing vessels from February 2013 to September 2016 in the southern Indian Ocean. The relationship of gutted weight (GW; in kg) to curved fork length (CFL; in cm) for both sexes combined was estimated as GW = 0.00001 × CFL2.517 (n = 170, r2 = 0.85). Growth band pairs (including translucent and opaque bands) were counted based on sectioned vertebral centra from the caudal peduncle region. The periodicity of band‐pair deposition on vertebral centra was estimated to be 1 year, with opaque bands deposited around August based on edge analysis. On this basis, the maximum observed ages of females and males were 18 and 14 years, respectively. The von Bertalanffy growth function best fitted the observed sexes‐combined length‐at‐age data, with growth parameter estimates as L∞ = 267.6 cm CFL, k = 0.123/year, and t0 = −2.487 years (n = 159). The growth model could be improved for future stock assessments by increasing the sample size, particularly on very small (neonates and small subadults) and very large female Shortfin Makos.

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Age and Growth of the Dusky Shark, Carcharhinus obscurus, in the Western North Pacific Ocean

Cited by 13 publications

References 12 publications

Distribution Pattern, Age, and Growth of Blue Sharks in the South Atlantic Ocean

Distribution Pattern, Age, and Growth of Blue Sharks in the South Atlantic Ocean

Stock Status Estimating of 5 Shark Species in the Waters Around Taiwan Using a Length-Based Bayesian Biomass Estimation (LBB) Method

Age and Growth of the Shortfin Mako Shark in the Southern Indian Ocean

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