Contrasting patterns of growth and migration of tropical anguillid leptocephali in the western Pacific and Indonesian Seas

Abstract

In order to improve understanding of the larval migration and early life history characteristics of 4 tropical eels, Anguilla marmorata, A. bicolor pacifica, A. celebesensis and A. borneensis, the leptocephali, metamorphosing leptocephali and oceanic glass eels collected during 8 cruises in the western Pacific and Indonesian Seas from 1991 to 2002 were analyzed. The leptocephali of A. celebesensis and A. borneensis were collected only in close proximity to their relatively small species ranges in the Indonesian Archipelago and were found to have faster growth than the other 2 species with small-scale local migrations. The more widely distributed species A. marmorata and A. bicolor pacifica were collected in most sampling areas. Small leptocephali of A. marmorata were collected only to the west of the Mariana Islands, and only larger specimens, metamorphosing leptocephali, or oceanic glass eels of both species were collected in the Indonesian Seas. These distributions suggested that the 2 species have intermediate-scale migrations compared to other anguillid eels. The leptocephali of all 4 species appeared to reach a fully grown size of around 50 mm, which is considerably smaller than the maximum size of temperate anguillid leptocephali, and their growth was predominantly faster than that of temperate species. These data and recently derived molecular phylogenetic relationships among all anguillid species in the world suggest that the long spawning migrations of temperate eels evolved from much shorter migrations of tropical species, whose larval growth was faster and whose maximum larval sizes were smaller. KEY WORDS: Leptocephalus · Eel · Otolith · Growth · Metamorphosis · Migration Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 309: [233][234][235][236][237][238][239][240][241][242][243][244][245][246] 2006 rent (NEC) from west of the Mariana Islands in the western North Pacific (WNP) to its recruitment areas in East Asia (Tsukamoto 1992). A similar spawning area in the South Equatorial Current (SEC) also appears to be used by A. australis from Australia and New Zealand (Jellyman 1987, Aoyama et al. 1999. Therefore, most temperate anguillids appear to have very similar large-scale migrations and spawn in areas that enable their leptocephali to use low-latitude westward-flowing currents such as the NEC and SEC to transport them thousands of kilometers back to their juvenile growth habitats .Recently, however, it has been shown that some tropical anguillid eels have much shorter local migrations and spawn over the deep waters adjacent to their freshwater growth habitats in the Indonesian Seas (Aoyama et al. 2003). The presence of small leptocephali of Anguilla celebesensis and A. borneensis near Sulawesi Island of central Indonesia indicated that these tropical eels do not migrate very far to spawn, because they have relatively small species ranges, with A. celebesensis being found from Sulawesi Island north through the Philippines and east to western...

The ecology of oceanic dispersal and survival of anguillid leptocephali

“…The sampling surveys conducted in the northern Indonesian Seas region have indicated that anguillid leptocephali are usually present but not at high abundances. This was the case in the Danish survey (Jespersen 1942) and during recent surveys (Aoyama et al 2003;Kuroki et al 2006;Wouthuyzen et al 2009) (Fig. 6).…”

“…Japanese scientists then discovered the spawning area of A. japonica in 1991 (Tsukamoto 1992) after smaller and smaller larvae were collected farther offshore . These surveys expanded out across the Indo-Pacific (Aoyama et al 2003(Aoyama et al , 2007Kuroki et al 2006) with evidence of offshore spawning by eels in the western South Pacific being found (Kuroki et al 2008;Aoyama 2009) and local spawning by eels in the Indonesian seas being discovered (Aoyama et al 2003). These collections and genetic or morphological information about anguillid population structures (Minegishi et al 2008;Watanabe et al 2008Watanabe et al , 2011 and silver eel tagging studies (Schabetsberger et al 2015;Jellyman and Tsukamoto 2010) led to ideas about the locations of Indo-Pacific anguillid spawning areas ( Fig.…”

Effects of metamorphosis timing and the larval growth rate on the latitudinal distribution of sympatric freshwater eels, Anguilla japonica and A. marmorata, in the western North Pacific

“…Tsukamoto (1990) suggested that A. japonica begins to metamorphose when leptocephali reach 60 mm TL. On the other hand, metamorphosis of leptocephali of A. marmorata and other tropical eel species like Anguilla bicolor pacifica, Anguilla borneensis, and Anguilla celebesensis was found to commence at around 50 mm TL (Kuroki et al 2005(Kuroki et al , 2006, which is considerably smaller than the metamorphosing size of the temperate A. japonica. A. marmorata Cagayan River, the Philippines 19 May 08 1.0 ± 0.18 (13) 1.1 ± 0.14 (13) 1.84 ± 0.46 (13) Hsiukuluan River, Taiwan 20 May 08 0.9 ± 0.10 (13) 1.2 ± 0.18 (13) 2.29 ± 0.72 (13) Kurio River, Japan 6 June 96 0.9 ± 0.14 (15) 1.1 ± 0.17 (15) 2.18 ± 0.61 (15) Overall (μ 2 Cheng and Tzeng (1996).…”

Ecology of Anguilliform Leptocephali: Remarkable Transparent Fish Larvae of the Ocean Surface Layer

“…Castonguay (1987) examined the age and growth of the leptocephali of two Atlantic anguillids in the Sargasso Sea, and there have been studies on the leptocephali of the other species of northern temperate anguillid species, A. japonica Ishikawa et al 2001) and A. australis (Kuroki et al 2008a). There have also been studies on the age and growth of tropical species of anguillid leptocephali in the central Indo-Pacific (Kuroki et al 2005(Kuroki et al , 2006a(Kuroki et al ,b, 2007, and off west Sumatra . Some species for which only a few specimens have been examined for growth rates, such as A. interioris (0.46-0.54 mm/day, Kuroki et al 2006b), and A. obscura and A. megastoma (0.34-0.49 mm/day, Kuroki et al 2008a) are not shown in Table 1.…”

“…One obvious difference is that the maximum size of tropical leptocephali (50-55 mm; Jespersen 1942; Kuroki et al 2009b) is less than that of temperate species (typically about 70 mm) that can reach about 85 mm in A. anguilla, which has the longest larval migration (Tesch 1980;Boëtius and Harding 1985;Kleckner and McCleave 1985;Bast and Strehlow 1990). Kuroki et al (2006a) compared the growth rates of four different tropical anguillid leptocephali (Fig. 31) that recruit to habitats in the central Indonesian Seas.…”