Evaluation of the pigmentation stages and body proportions from the glass eel to yellow eel in Anguilla japonica

Fukuda, Naoko; Miller, Michael J.; Aoyama, Jun; Shinoda, Akira; Tsukamoto, Katsumi

doi:10.1007/s12562-013-0621-x

Cited by 43 publications

(16 citation statements)

References 46 publications

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“…All stations were sampled once. In this study, we targeted eels with total length (TL; mm) below 200 mm, which corresponds to elver and early yellow eel stages (Fukuda, Miller, Aoyama, Shinoda, & Tsukamoto, 2013). In the field, we determined the size class of eels (<200 mm TL or not) through visual observation.…”

Section: Materials S and Me Thodsmentioning

confidence: 99%

Longitudinal distribution and microhabitat use of young Japanese eelAnguilla japonicain a small river flowing through paddy areas

et al. 2019

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Although the Japanese eel Anguilla japonica is a commercially important species, its habitat use is not well understood during its life stages in the river. In this study, we investigated the longitudinal distribution and microhabitat use of young Japanese eels (<200 mm in total length [TL], which correspond to elver and early yellow stages) using 180 quadrates (1 m × 1 m) in six stations in a small river (approximately 11.5 km long, 3.0–25.0 m wide) that flows through paddy areas in Fukushima Prefecture, Japan. No differences were observed in the TL of eels among the sampling stations. The analysis using generalized linear models showed that eel density increased as number of weirs decreased. The analysis using generalized additive models showed that water depth, current velocity, and substrate complexity were important factors determining microhabitat use. Eels used shallow habitats (<35 cm) with slow currents (5–40 cm/s) and high complex riverbeds (>0.35 in index of substrate complexity). These findings provide useful information to conserve and manage wild eels inhabiting small rivers flowing through paddy areas.

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Section: Materials S and Me Thodsmentioning

confidence: 99%

Longitudinal distribution and microhabitat use of young Japanese eelAnguilla japonicain a small river flowing through paddy areas

et al. 2019

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“…S1), the L T of the Taiwan samples were corrected by this value. The pigmentation stages of the glass eels were classified according to Fukuda et al (2013). To allow the L T of V A stage glass eels to be used to back-calculate the size at the onset of metamorphosis, they were estimated using the size reduction from V A to each glass-eel stage that was evaluated by Fukuda et al (2013).…”

Section: E P T O C E P H a L U S S U Rv E Y Smentioning

confidence: 99%

Location, size and age at onset of metamorphosis in the Japanese eel Anguilla japonica

Fukuda

Kurogi

Ambe

et al. 2018

Journal of Fish Biology

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This study clarifies the location, size and age at the onset of metamorphosis in Japanese eels Anguilla japonica through oceanic surveys, rearing experiments and analyses of the morphology and otoliths of leptocephali and glass eels. Twenty-eight metamorphosing leptocephali were collected in the mesoscale eddy region to the east of Taiwan during research expeditions in 2004. Rearing experiments showed that the total length (L ) of leptocephali decreased by an average of 12·5% during metamorphosis and 13·9% during the 2-12 h after death. Thus, the mean back-calculated L at the onset of metamorphosis for 630 glass eels from Taiwan and Japan was estimated at 67·8 ± 2·7 mm (mean ± S.D.). The estimated mean ante-mortem size of the fully grown pre-metamorphic leptocephali collected in 2004 was 64·6 ± 3·4 mm, which was consistent with the L estimate for glass eels. Otolith analysis showed that the mean age at the onset of metamorphosis was 137 ± 15 days and indicated that Japanese eels may have a recruitment route through the mesoscale eddies to the east of Taiwan in addition to the direct transfer route from the North Equatorial Current to the Kuroshio Current.

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“…The elver eel stage (Stage VI B of pigmentation according to Bertin, ) is preceded by the glass eel stage (Stage V A –VI A of pigmentation) (Bertin, ; Fukuda, Miller, Aoyama, Shinoda, & Tsukamoto, ) (Figure ). These eels metamorphose from the leptocephalus larvae on arrival at the European shelf.…”

Section: Introductionmentioning

confidence: 99%

Built to bite? Differences in cranial morphology and bite performance between narrow‐ and broad‐headed European glass eels

Meyer

Wassenbergh²,

Bouilliart

et al. 2017

Journal of Morphology

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The presence of two phenotypes in a single species is a widespread phenomenon, also observed in European eel (Anguilla anguilla). This dimorphism has been related to dietary differences in the subadult elver and yellow eel stages, with broad-heads generally feeding on harder and/or larger-bodied prey items than narrow-heads. Nevertheless, both broad- and narrow-headed phenotypes can already be found among glass eels, the stage preceding the elver eel stage. As these glass eels are considered nonfeeding, we investigate here to what degree the observed variation in head width is reflected in variation in the musculoskeletal feeding system, as well as whether this reflects the same variation observed in the older, dimorphic yellow eels. Additionally, we investigate whether musculoskeletal differences between broad- and narrow-headed glass eels have implications on their feeding performance and could thus impact prey preference when eels start feeding. Therefore, we compared the cranial musculoskeletal system of five broad- and narrow-headed glass eels using 3D-reconstructions and simulated the glass eel's bite force using the data of the muscle reconstructions. We found that the variation in the musculoskeletal system of glass eels indeed reflects that of the yellow eels. Broader heads were related to larger jaw muscles, responsible for mouth closure. Accordingly, broad-heads could generate higher bite forces than narrow-headed glass eels. In addition, broader heads were associated with higher coronoid processes and shorter hyomandibulae, beneficial for dealing with higher mechanical loadings and consequently, harder prey. We, thus, show that head width variation in glass eels is related to musculoskeletal differences which, in turn, can affect feeding performance. As such, differences in prey preference can already take place the moment the eels start feeding, potentially leading to the dimorphism observed in the elver and yellow eel stage.

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Evaluation of the pigmentation stages and body proportions from the glass eel to yellow eel in Anguilla japonica

Cited by 43 publications

References 46 publications

Longitudinal distribution and microhabitat use of young Japanese eelAnguilla japonicain a small river flowing through paddy areas

Longitudinal distribution and microhabitat use of young Japanese eelAnguilla japonicain a small river flowing through paddy areas

Location, size and age at onset of metamorphosis in the Japanese eel Anguilla japonica

Built to bite? Differences in cranial morphology and bite performance between narrow‐ and broad‐headed European glass eels

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