Age and growth of migrating tropical eels, Anguilla celebesensis and Anguilla marmorata

Abstract

The age and growth of migrating tropical eels, Anguilla celebesensis and Anguilla marmorata from central Sulawesi, Indonesia, were examined. Migrating eels (63 A. celebesensis and 38 A. marmorata) were obtained from weirs near the Poso Lake outlet and non-migrating eels (35 A. celebesensis and 119 A. marmorata) were captured by baited hooks, eel pots, scoop net and electro-fishing in the Poso River system, Laa River system, Baluga River, Tongku River and Padapu River from February 2009 to October 2010. In both species, the proportion of eels with opaque otolith edges showed a single peak in July, suggesting that one annulus (a pair of translucent and opaque zones) was formed each year in their otoliths. Mean ± s.d. and range of total length (L ) and age was 785·2 ± 114·9 (585-1083) mm and 7·5 ± 1·6 (5-11) years in migrating female A. celebesensis and 1132·2 ± 173·7 (800-1630) mm and 11·6 ± 3·3 (7-23) years in A. marmorata. The age of migrating female eels was negatively correlated with annual growth rate, 100·7 ± 17·2 (68·1-145·0) mm year in A. celebesensis and 97·9 ± 19·3 (66·6-131·6) mm year in A. marmorata, but there was no significant correlation between the L and annual growth rate in either species. The annual growth rates of these female tropical eels were typically higher than those of temperate anguillid species, suggesting a latitudinal cline in growth rate in the genus Anguilla reflecting the environmental conditions of their growth habitat.

Reproductive physiological characteristics of tropical Celebes eels Anguilla celebesensis in relation to downstream migration and ovarian development

“…During February 2009-October 2010, A. celebesensis eels were collected from the Poso Lake-River system on Sulawesi Island, Indonesia ( Figure 1). Eels were captured using large commercial weirs (Hagihara et al, 2018b) that were set near the outlet area of Poso Lake (120 38 0 30 00 E, 1 45 0 30 00 S). These eels were regarded as migrating eels that had just started their downstream migration from Poso Lake to HAGIHARA ET AL.…”

“…Thus, accumulation of knowledge about the ecology and physiology of these short‐migration species is important to deepen our understanding of the freshwater eels, in general, and the evolutionary processes of migration ecology, in particular. Although the ecology of most tropical eel species is still poorly understood, research on A. celebesensis has been conducted in recent years, and consequently, the ecological knowledge about each life‐history stage of this species, for example its spawning area (Aoyama et al ., ; Wouthuyzen et al ., ), the growth of leptocephali (Kuroki et al ., ), recruitment of glass eels (Arai et al ., ; Sugeha et al ., ), riverine distribution (Hagihara et al ., ), migratory history (Chino & Arai, ; Hagihara et al ., ), age and growth (Hagihara et al ., ), morphological and physiological changes in relation to downstream migration (Hagihara et al ., ), seasonality of downstream migration (Hagihara et al ., ; Sugeha et al ., ), swimming behaviour of migrating eels in a freshwater lake (Watanabe et al ., ) and in coastal waters (Manabe et al ., in prep), has increased rapidly.…”

Habitat preference, movements and growth of giant mottled eels, Anguilla marmorata, in a small subtropical Amami-Oshima Island river

“…The growth rate (GR) of anguillid eels is another key aspect of their ecology that reflects many characteristics of the environments where they live. It has been intensively studied for temperate eels (e.g., Vøllestad, 1992;Morrison & Secor, 2003;Daverat & Tomás, 2006;Yokouchi et al, 2008), and GR was recently studied for tropical eels as well (Hagihara et al, 2018b;Kumai, Tsukamoto & Kuroki, 2020). There is considerable intra-interspecific variation in the annual GR of eels that is related to their latitudinally expanded distributional regions (Hagihara et al, 2018b) and the different environments of the wide-range of continental habitats where eels are present (Morrison & Secor, 2003;Yokouchi et al, 2008).…”

Interspecific and sexual differences in riverine distribution of tropical eels Anguilla spp.

“…Ecological knowledge on the yellow‐eel growth phase of tropical anguillids is especially limited despite the fact that anguillid eels spend most of their life as yellow eels that inhabit the benthic environments of continental waters (Hagihara et al ., ). In temperate eels such as the European eel Anguilla anguilla (L. 1758), Japanese eel Anguilla japonica Temminck & Schlegel 1846 and New Zealand longfin eel Anguilla dieffenbachii Gray 1842, a variety of ecological studies have been conducted on yellow eels (see Moriarty, ).…”

“…Important information about habitat use of the yellow-phase temperate eels, such as the occurrence of sea eels (mean otolith Sr:Ca ratio ≥ 6Á0) that spend their entire life in the marine environment (Tsukamoto et al, 1998;Tsukamoto & Arai, 2001) and the sexual differences in riverine distribution (Helfman et al, 1987;Oliveira & McCleave, 2000;Tesch, 2003) has also been obtained. In contrast, although several studies of tropical anguillids related to their age and growth (Hagihara et al, 2018) and migratory history (Chino & Arai, 2010) have been conducted, even riverine distribution, which is fundamental to our understanding of habitat use, is poorly understood.…”