Morphological and histological changes in the swim bladder during maturation of the Japanese eel

Yamada, Yoshiaki; Zhang, H.; Okamura, Atsushi; Tanaka, Satoru; Horie, Noriyuki; Mikawa, Naomi; Utoh, Tomoko; Oka, Hideo

doi:10.1111/j.1095-8649.2001.tb00532.x

Cited by 37 publications

(12 citation statements)

References 22 publications

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“…Gonads do not develop any further since the gonadotropic function is blocked until eels reach the ocean (Dufour & Fontaine, 1985). Ovaries in A. anguilla are much less developed than in other species of eels ( A. rostrata , Anguilla dieffenbachii Gray, Anguilla australis Richardson and Anguilla japonica Temminck & Schlegel) where they can reach 4%(Jessop, 1987; Lokman & Young, 1998; Yamada et al ., 2000).…”

Section: Discussionmentioning

confidence: 96%

The silvering process of Anguilla anguilla: a new classification from the yellow resident to the silver migrating stage

Durif

Dufour

Élie

2005

Journal of Fish Biology

320

364

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The identification of five stages for female and two stages for male eels Anguilla anguilla using multivariate analysis was carried out on a large sample of individuals collected at six different locations in France. Stages corresponded to a growth phase (stages I and II), a pre-migrant phase (III) and two migrating phases (IV and V). It is likely that an important period of growth triggered silvering through the production of growth hormone (GH) in stage III eels. In migrating eels gonad development, gonadotropin hormone (GTH-II) production and increase of eye surface were similar at all sites. Differences among locations were found in gut regression and pectoral fin length. As variability for these increased with the size of the watershed and values were highest for the most downstream locations, fin length and gut regression may indicate the time since an eel started its migration. # 2005 The Fisheries Society of the British Isles

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Section: Discussionmentioning

confidence: 96%

The silvering process of Anguilla anguilla: a new classification from the yellow resident to the silver migrating stage

Durif

Dufour

Élie

2005

Journal of Fish Biology

320

364

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“…More works would be welcome to precisely assess the factors that may interact with the swimbladder measures. For instance, the silvering process induces morphological, physiological and histological changes in the swimbladder (Durif, Van Ginneken, Dufour, Müller & Elie 2009; see also Kleckner 1980 for A. rostrata and Yamada, Zhang, Okamura, Tanara, Horie, Mikawa, Utoh & Oka 2001 for A. japonica ), but what is the effect on the SDI and LRI measurements? In our sample, silver eels had swimbladders significantly more degraded than the rest of the sample, and the difference was particularly marked in the SDI scores, but more work is clearly needed (especially taking into account the eel size effect).…”

Section: Discussionmentioning

confidence: 99%

An evaluation of indices of gross pathology associated with the nematode Anguillicoloides crassus in eels

Lefebvre

Fazio

Palstra

et al. 2010

Journal of Fish Diseases

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This study compares two alternative indices for quantifying the gross pathology of the swimbladder of eels, Anguilla anguilla (L.), infected with the nematode Anguillicoloides crassus. Two observers recorded twice the scores obtained by the two indices on the same set of 71 wild caught eels (from elver to silver eels, French Mediterranean lagoons). The Length Ratio Index (LRI), performed better than the Swimbladder Degenerative Index (SDI), in three of four predefined criteria of decision. First, the LRI better correlated with an estimate of the swimbladder volume reduction, a functional consequence of the infection (representativeness). Also, the LRI was less prone to subjectivity (inter-observer variability) and more precise (intra-observer variability), although less easy to generate (time needed for measurement/assessment). Using a sub-sample of 32 unaffected eels (showing minor if any swimbladder damage and no living worms at autopsy), we ascertained a linear relationship between the swimbladder length and the total body length, a prerequisite of isometric growth, to definitively accept the new ratio index as a valid alternative to the SDI. Also, because the LRI can be recorded on live specimens with radio-imagery (non-invasive method), we recommend its use, and provide a graph of correspondence between the SDI scores, the LRI scores and the estimated proportion of gas loss in the swimbladder.

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“…A variety of morphological and physiological changes in relation to downstream migrations have been reported in temperate anguillid species such as Anguilla japonica Temminck & Schlegel 1846, Anguilla anguilla (L. 1758), Anguilla rostrata (LeSueur 1817), Anguilla australis Richardson 1841 and Anguilla dieffenbachii Gray 1842. These include changes in the structure and colour of skin (Sinha & Jones, 1975; Pankhurst, 1982 a ; Pankhurst & Lythgoe, 1982), enlargement of the eyes and pectoral fins (Tesch, 1977; Boëtius & Boëtius, 1980; Todd, 1981; Pankhurst, 1982 b ; Lokman et al , 1998), degeneration of the gut (Pankhurst & Sorensen, 1984; Lionetto et al , 1996), a shift in retinal sensitivity (Pankhurst, 1982 b ; Pankhurst & Lythgoe, 1983; Wood & Partridge, 1993; Andjus et al , 1998; Hope et al , 1998), changes in fat content (Larsson et al , 1990; Svedäng & Wickström, 1997) and in musculature (Pankhurst, 1982 c ; Eggington, 1986), swimbladder modifications (Kleckner, 1980; Yamada et al , 2001), and enlargement and increase of chloride cells in the gills (Fontaine et al , 1995; Sasai et al , 1998). These changes may be adaptations to the environments of the open ocean that are drastically different from their typical freshwater or coastal habitats.…”

Section: Introductionmentioning

confidence: 99%

Morphological and physiological changes of female tropical eels, Anguilla celebesensis and Anguilla marmorata, in relation to downstream migration

Hagihara

Aoyama

Limbong

et al. 2012

Journal of Fish Biology

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The morphological and physiological characteristics of migrating and non-migrating female tropical eels, Anguilla celebesensis and Anguilla marmorata were examined in relation to their downstream migration on central Sulawesi Island, Indonesia. Migrating eels (64 A. celebesensis and 37 A. marmorata) were obtained from weirs set near the outlet area of Poso Lake and non-migrating eels (21 A. celebesensis and 21 A. marmorata) were sampled by set-lines and eel pots in Poso Lake, its inlet rivers, and in the La River system during February 2009 to October 2010. In both species, values of eye index, pectoral-fin length index, gonado-somatic index (I(G)), hepato-somatic index, swimbladder-somatic index and cardio-somatic index of migrating eels were significantly higher than those of non-migrating eels and the gut-somatic index values of the migrating eels were significantly lower than that of non-migrating eels. When silvering stages of eels were classified by the silvering index for Anguilla japonica, in A. celebesensis, all non-migrating eels were Y1 stage and the migrating eels consisted of Y2, S1 and S2 stages eels. In A. marmorata, the non-migrating eels consisted of Y1 and Y2 eels, and the migrating eels consisted of Y2 and S1 eels, but there were no S2 eels. Results of principal component analysis (PCA) of morphological and physiological variables suggested that these characteristics changed drastically between the Y1 and Y2 stages in A. celebesensis, while A. marmorata showed a gradual change with silvering, which differs from the temperate species A. japonica. The mean ±S.D. I(G) value of migrating A. celebesensis (6.9 ± 1.8, 3.3-11.4) was very high and that of A. marmorata (3.1 ± 0.8, 1.8-5.7) was comparatively low. The very different rates of maturation that were found between these two species provide support for the hypothesis that the reproductive characteristics of silver eels can reflect their migration scale.

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Morphological and histological changes in the swim bladder during maturation of the Japanese eel

Cited by 37 publications

References 22 publications

The silvering process of Anguilla anguilla: a new classification from the yellow resident to the silver migrating stage

The silvering process of Anguilla anguilla: a new classification from the yellow resident to the silver migrating stage

An evaluation of indices of gross pathology associated with the nematode Anguillicoloides crassus in eels

Morphological and physiological changes of female tropical eels, Anguilla celebesensis and Anguilla marmorata, in relation to downstream migration

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