Search

In this study, we determined the genomic DNA sequences of the mucosal galectin-encoding genes from all 19 species and subspecies of the genus Anguilla. The nucleotide sequences of the galectin genes were c. 2.3-2.5 kb long and the organisation of their four exons and three introns was conserved in all species. An unusual sequence was found in the fourth exon of Anguilla reinhardtii, resulting in a unique deduced amino-acid sequence at the C-terminus. All six amino-acid residues important for β-galactoside binding were conserved in three species, while one residue (R73 ) was substituted to K73 in the other 16 species-subspecies, including Anguilla marmorata. However, this substitution did not appear to affect the sugar-binding ability of galectins because the galectin of A. marmorata was previously shown to bind to lactose. We also discuss the molecular evolution of galectins among Anguilla spp. and the homologues previously identified in Conger myriaster.

Three species of Pseudodactylogyrus Gusev, 1965 (Monogenea: Pseudodactylogyridae) were collected from the gills of Anguilla reinhardtii Steindachner and A. australis Richardson from several localities in Australia and eels imported to Japan from Australia. Pseudodactylogyrus gusevi sp. n. from A. reinhardtii (type host) and A. australis in Queensland, Australia is most similar to P. bini (Kikuchi, 1929), but can be differentiated by the shorter male copulatory tube, heavy sclerotisation of the vaginal tube and the presence of a small projection of the supplementary piece of the hamulus. Pseudodactylogyrus rohdei sp. n. from A. australis (type host) in Queensland, Australia is most similar to P. anguillae (Yin et Sproston, 1948), but differs in the possession of a longer cement gland and the presence of a small projection on the supplementary piece of the hamulus. Pseudodactylogyrus bini sensu Gusev, 1965 and P. anguillae sensu Gusev, 1965 are synonymised with P. gusevi sp. n. and P. rohdei sp. n., respectively. Pseudodactylogyrus mundayi sp. n. from A. australis, originating in Tasmania, Australia and sent alive to Japan, is most similar to P. kamegaii Iwashita, Hirata et Ogawa, 2002, from which it can be discriminated by the shorter male copulatory tube and the shorter vaginal tube. Dactylogyrus bialatus Wu, Wang et Jian, 1988 from Synechogobius ommaturus (Richardson) (Gobiidae) is transferred to Pseudodactylogyrus as P. bialatus comb. n. A phylogenetic tree based on the ITS2 region of six species of Pseudodactylogyrus including P. gusevi and P. mundayi shows that P. haze from a goby diverged first, and that species from eels are monophyletic, forming three lineages differing by their zoogeographical distribution. With the three new species and one new combination proposed in this paper, Pseudodactylogyrus is now comprised of eight species infecting anguillid and gobiid fish, and a key to species is presented.

Longfinned eels Anguilla reinhardtii were captured by both fishery-dependent and independent sampling methods from three rivers in New South Wales, south-eastern Australia. Growth rates were examined in two zones (fresh water and tidal) in the Hacking, Hawkesbury and Clarence Rivers. Mean annual growth increments of sampled longfinned eels ranged from 30 to 60 mm year-1 using age-length analyses and up to 167 mm year-1 based on tag-recapture model estimates (GROTAG), with both methods showing high intra- and inter-population variability. Growth was significantly faster in younger (5-15 years) fish than older (>15 years) fish, with females growing an average 10 mm year-1 faster than males of similar age and capture location. Longfinned eels found in tidal areas grew significantly faster than those in non-tidal freshwater areas as a result of longer growing seasons in the highly productive estuarine habitats. Other possible factors influencing variability in growth rates for this species include habitat preference, density and fishing pressure. © 2006 The Fisheries Society of the British Isles.

The sanguinicolids Paracardicoloides yamagutii Martin, 1974 and Plethorchis acanthus Martin, 1975 were obtained from their definitive hosts, Anguilla reinhardtii Steindachner and Mugil cephalus Linnaeus (respectively) in the tributaries of the Brisbane River, Queensland, Australia. Two putative sanguinicolid cercariae were collected from a hydrobiid gastropod, Posticobia brazieri Smith, in the same waters. The two cercariae differ markedly in size and the form of their sporocysts. Both putative cercariae develop in the digestive gland of Po. brazieri. The ITS2 rDNA region from these sanguinicolids and a Clinostomum species (utilised as an outgroup due to the close morphological similarities between the cercarial stages of the Clinostomidae and the Sanguinicolidae) were sequenced and aligned. Comparison of the ITS2 sequences showed one cercaria to be that of P. yamagutii. This is the first sanguinicolid life history determined by a molecular method. P. yamagutii is the fourth sanguinicolid known to utilise a freshwater hydrobiid gastropod as its intermediate host. ITS2 rDNA is effective in distinguishing sanguinicolids at the species level.

The sex and stage of gonadal development of longfinned river eels Anguilla reinhardtii, captured from nine river catchments in New South Wales, Australia, between 1999 and 2001, were determined macroscopically. Sex was verified by histology. Histology was also necessary, however, to accurately define stages of gonadal development, particularly in individuals

To handle large river eels during procedures such as measuring and tagging for field and aquaculture studies, they must be anaesthetized. During our initial biological studies of Anguilla reinhardtii (Steindachner) it was found that the anaesthetic benzocaine was relatively expensive and elicited a variable response, even when used at relatively high concentrations. Human health risks are also a concern when using benzocaine, as some of the eels may later be sold for human consumption. Therefore, experiments were done to evaluate the use of clove oil (a safe, naturally occurring product) for anaesthesia of this species at a range of temperatures (17 and 25 degrees C) and salinities (0-32 g L(-1)). It was found that clove oil provided a suitable anaesthetic response through this wide range of temperatures and salinities. Response times were found to be relatively variable for both benzocaine and clove oil. This variability may be related to stress, environmental factors, or the condition of the fish. Clove oil is recommended for anaesthesia of anguillid eels because it is effective, relatively inexpensive, and poses little risk to human health.

A species of Gyrodactylus collected from 2 species of anguillid eels (Anguilla australis Richardson, 1841 and Anguilla reinhardtii Steindachner, 1867) from Australia is identified as Gyrodactylus anguillae Ergens, 1960. The morphology of sclerites of G. anguillae specimens from Australia is in accordance with previous descriptions of specimens collected from A. anguilla (Linnaeus, 1758) from Europe and A. anguilla imported into Japan. Gyrodactylus anguillae was previously thought to be a parasite specific to A. anguilla, an eel that is native to freshwater catchments throughout Europe. Information on eel translocations and host and parasite biology is reviewed and it is hypothesized that G. anguillae is a naturally occurring parasite in Australia and not an introduction.

SUMMARYThe prediction that richness and diversity of helminth communities would be greater in tropical fish was tested by analysing total and intestinal helminth communities in samples of Anguilla reinhardtii taken from 10 localities in tropical and semi-tropical freshwaters in Queensland, Australia. Comparison of findings with those from A. anguilla in the UK revealed that regional species richness was higher in Queensland and that helminth communities harboured a suite of common species, virtually all eel specialists, that were responsible for the observed higher levels of similarity between component communities. All measures of community richness and diversity adopted indicated that the poorest helminth communities in A. reinhardtii were comparable with the richest ones reported from the northern temperate A. anguilla. The richest communities in A. reinhardtii were more diverse than those reported from any other species of fish, whether marine or freshwater, to date, and were comparable with the communities found in some species of aquatic birds. Both tropical conditions and age and endemism of the host, i.e. the time hypothesis, were considered as explanations for this richness but neither could be favoured. A cautious approach to generalizations based on data from temperate regions only is advocated, and the need for more studies on tropical parasite communities is strongly emphasized.

Adult trematodes of the genus Stegodexamene Macfarlane, 1951 were recorded from the intestines of two species of freshwater eels, the Pacific short-finned eel Anguilla obscura Günther and the speckled longfin eel Anguilla reinhardtii Steindachner from the Pouembout and La Foa Rivers, New Caledonia, South Pacific. They were identified as Stegodexamene anguillae Macfarlane, 1951, a species previously reported only from eels in New Zealand. The morphology of adult S. anguillae seems to be practically identical with that of the later described Stegodexamene callista Watson 1984 from eels in Australia. The finding of S. anguillae in A. obscura and A. reinhardtii in New Caledonia represents new geographical and host records. In addition to this trematode, two larval specimens of a cestode of the order Proteocephalidea were found in the intestine of one A. obscura from the Pouembout River. No monogenean was found in eels of New Caledonia.

A new species of parasitic nematode, Procamallanus(Procamallanus) pacificusn. sp., is described from the stomach of the Pacific shortfinned eel,Anguilla obscura (type host), and from the speckled longfin eel,Anguilla reinhardtii, from northern New Caledonia (Melanesia, South Pacific); fromAnguilla sp. (cf. obscura) from the Fiji Islands (Melanesia, South Pacific); and from the giant mottled eel Anguilla marmorata from Futuna Island (Wallis and Futuna Islands, Polynesia). Although a total of 450 nematodes were collected, all specimens were females; this suggests either an extremely rare occurrence of males or par- thenogenetic reproduction in this species. Procamallanus pacificusdiffers markedly from all congeners from fish hosts in pos- sessing a greater number (4-9) of caudal mucrons in the female and by other morphological features. This parasite might become a serious pathogen of cultured eels in the region of the South Pacific. BatrachocamallanusJackson and Tinsley, 1995 is considered a junior synonym of Procamallanus Baylis, 1923, to which 2 species are transferred as Procamallanus occidentalis(Jackson and Tinsley, 1995) n. comb. and Procamallanus siluranae(Jackson and Tinsley, 1995) n. comb. One third-stage larva of Procamal- lanus (Spirocamallanus) sp. was also recorded from Anguilla sp. (cf. obscura) from the Fiji Islands. Parasitological examinations of some freshwater fishes in New Caledonia carried out in 2003 and 2004 revealed, among other helminths, numerous nematodes of the Camallanidae par- asitic in the stomachs of 2 species of native eels (Anguilla). These proved to be members of an undescribed species of Pro- camallanus (Procamallanus) Baylis, 1923. Conspecific nema- todes were previously (in 1995) obtained from an unidentified eel from the Fiji Islands (F. Moravec, unpubl. obs.), in which also 1 third-stage larva of Procamallanus(Spirocamallanus) sp. was found, and recently (in 2004) also from a giant mottled eel from Futuna Island (Wallis and Futuna Islands). Both the new camallanid species and the larva are described herein.

Longfinned eels Anguilla reinhardtii were captured by both fishery-dependent and independent sampling methods from three rivers in New South Wales, south-eastern Australia. Sex ratios, catch per unit effort and population age and total length structure were examined in three zones (fresh water and upper and lower tidal) in the Hacking, Hawkesbury and Clarence Rivers. Females were found in relatively high proportions in all zones, ranging from 97% in a freshwater (non-tidal) site down to 59% in a tidal site. Males were found primarily in tidal zones (only two of the 677 longfinned eels caught in non-tidal fresh water were males), with the greatest proportions being found in the brackish upper tidal areas. The mean number of fish captured per trap was higher in the fresh water and upper tidal zones than in the lower tidal zones. The mean±S.E. age, 17.9±0.3 years, and age range, 5-52 years for females were significantly higher than those of males 12.2±0.4 years; range 5-22 years, which is typical of other anguillid species. Longfinned eels captured in fresh water were found be significantly larger and older than those in tidal zones due to the almost exclusive predominance of females. © 2004 The Fisheries Society of the British Isles.

International audience; Freshwater eels are important fisheries species in parts of the western South Pacific, but little is known about their oceanic early life history or spawning areas. The age, growth, morphology and geographic distribution of five species of genetically identified anguillid leptocephali collected in 1995, 2000 and 2005 were compared. The sizes and ages of the leptocephali collected, Anguilla australis (n = 18), Anguilla marmorata (n = 15), Anguilla reinhardtii (n = 12), Anguilla megastoma (n = 2) and Anguilla obscura (n = 1), ranged from 19.0 to 50.9 mm and from 25 to 155 days, respectively. Leptocephali were mostly collected in the South Equatorial Current region. The total myomere ranges overlapped among species, but anodorsal myomere numbers clearly divided shortfinned and longfinned eels. The myomere ranges of the leptocephali were similar to the reported ranges of the numbers of vertebrae in adults. Larval growth rates suggested that the temperate species A. australis had slightly slower growth than the tropical species A. reinhardtii. The present study suggests that both temperate and tropical anguillid eels use the South Equatorial Current region for spawning and larval development, although some species might have different early life parameters and migration routes to their recruitment areas

The primary objective of the present study was to validate the annual nature of growth rings in otoliths of 'yellow eel stage' (fully pigmented, premigratory) Australian longfinned eels (Anguilla reinhardtii) in New South Wales, Australia, using a combination of laboratory and field experiments. Eels were injected with oxytetracycline (OTC) and tagged with external 'T-bar' tags. Microscopic examination of thin transverse sections of the sagittal otoliths from recaptured eels showed that one opaque annulus was typically formed in the otolith during each year subsequent to OTC marking. The seasonal timing of opaque annulus formation was highly variable, but generally occurred between May and November. Supernumerary (false or incomplete) rings were observed in many of the otoliths. Examination of otolith sections from a sample of very small, untagged yellow eels verifed the age at first annual increment formation. Marked and tagged longfinned eels did not have a significantly higher mortality rate than controls in the laboratory experiment, but tag loss rates may be high. The field study also indicates that Australian longfinned eels generally have a very restricted home range of 300 m or less. This study is believed to provide the first otolith age validation of a tropical anguillid.

The differences in geographical distribution between Anguilla reinhardtii and A. australis on the eastern coast of Australia can be understood by comparing otolith growth increments and microchemistry, the ages between species of the eels at metamorphosis from leptocephalus to glass eels and the ages of glass eels at estuarine arrival. The ages at metamorphosis were determined from where the increment width dramatically increased and the Sr/Ca ratio dropped. The mean age (± s.d.) of A. reinhardtii (n = 176) at metamorphosis was 144.5 ± 12.2 days and at estuarine arrival was182.7 ± 16.3 days. For A. australis (n = 150) it was 173.7 ± 20.5 days and 229.2 ± 29.4 days, respectively. The differences in age between species were significantly larger than the annual and seasonal variations within species. Australian eels are believed to spawn in the tropical oceans and larval eels drift in the South Equatorial Current to eastern Australia. The younger ages at estuarine arrival of A. reinhardtii suggest that the spawning grounds of this species lie closer to Australia than those of A. australis. In addition, the mean total length at recruitment of A. reinhardtii (49.9 ± 2.0 mm) was significantly smaller than for A. australis (54.6 ± 5.4 mm) (t = 3.8, P < 0.01). However, the growth rates of A. reinhardtii (0.25 ± 0.02 mm/d) were significantly faster than for A. australis (0.23 ± 0.022 mm/d)(t = 7.6, P < 0.01). The smaller sizes of A. reinhardtii at recruitment were likely due to the shorter marine larval period and faster growth rate compared with A. australis. The duration of the marine larval period and growth rate may be the principal factors in determining the geographical distribution of both A. reinhardtii, which tend to occur in tropical-subtropical waters, and A. australis, which predominate in more temperate waters. Extra keywords: otolith, early life history. M la t ar nt Jao et W A nd Y.

Anguilla reinhardtii has been identified by vertebral counts and DNA markers, from a sample of 27 individuals (364-790 mm), within eight consecutive year classes caught by commercial eel fishers in the Waikato River, North Island, New Zealand. There is anecdotal evidence that A. reinhardtii has been present in small numbers in New Zealand for at least 25 years, although its incidence in commercial catches is thought to be increasing. The present known distribution covers approximately 500 km of latitude along the top half of the west coast of the North Island.

Austrohalipegus anguillicola gen. et sp. nov. is described from the stomach of Anguilla reinhardtii Steindachner. Austrohalipegus is distinguished from other derogenid genera by the absence of filaments on its eggs, by the presence of blindly ending caeca, by having the ventral sucker in the middle of the body, by having the sinus-sac enclose only the hermaphroditic duct, and by the uterus which does not extend posterior to the vitellarium. Austrohalipegus anguillicola is distinctive in having a large temporary sinus-organ formed by a completely eversible hermaphroditic duct. Isoparorchis hypselobagri (Billet) is recorded as juveniles of 1–3 mm in length from the coelom and as larger juveniles and adults from the swim bladder of Tandanus tandanus Mitchell. The miracidium is typically hemiuroid and has a crown of apical spines and cilia in lateral bunches. Experimental infections in which the prosobranch snails Posticobia brazieri and Melanoides tuberculatus were fed embryonated eggs produced infections of...

Phyllodistomum magnificum sp. nov., is described from the urinary bladder of Australian and New Zealand freshwater fish. Australian hosts were Anguilla reinhardtii, Tandanus tandanus, Hephaestus fuliginosus and Scortum hilli. New Zealand hosts were Anguilla australis and A. dieffenbachii. A presumed part of the life-cycle is described. Typical cystocercous cercariae are produced by sporocysts in the gills of a Pisidium species and are eaten by aquatic arthropods in which they encyst. The taxonomy of the genus Phyllodistomum is discussed and it is suggested that those species with cystocercous cercariae form a phylogenetic unit with Gorgodera, Gorgoderina, Progorgodera and Gorgotrema species.

SUMMARY Histological sections of primary segmental arteries and associated interarterial anastomoses and secondary vessels from the long-finned eel Anguilla reinhardtii were examined by light and transmission electron microscopy. Interarterial anastomoses were found to originate from the primary vasculature as depressions through the tunica intima and media, from where they ran perpendicularly to the adventitial layer, before coiling extensively. From here the anastomoses travelled a relatively linear path in the outer margin of the adventitia to anastomose with a secondary vessel running in parallel with the primary counterpart. In contrast to findings from other species, secondary vessels had a structure quite similar to that of primary vessels; they were lined by endothelial cells on a continuous basement membrane, with a single layer of smooth muscle cells surrounding the vessel. Smooth muscle cells were also found in the vicinity of interarterial anastomoses in the adventitia, but these appeared more longitudinally orientated. The presence of smooth muscle cells on all aspects of the secondary circulation suggests that this vascular system is regulated in a similar manner as the primary vascular system. Because interarterial anastomoses are structurally integrated with the primary vessel from which they originate, it is anticipated that flow through secondary vessels to some extent is affected by the vascular tone of the primary vessel. Immunohistochemical studies showed that primary segmental arteries displayed moderate immunoreactivity to antibodies against 5-hydroxytryptamine and substance P, while interarterial anastomoses and secondary vessels showed dense immunoreactivity. No immunoreactivity was observed on primary or secondary arteries against neuropeptide Y or calcitonin gene-related peptide.

Two new lepocreadiid digeneans, Tetracerasta blepta, gen. sp. nov., and Stegodexamene callista, sp. nov., are described from the intestine of the long-finned freshwater eel, Anguilla reinhardtii, in the Brisbane River, Queensland, and from the Australian bass, Macquaria novemaculeata, in the Richmond River in New South Wales. Their life cycles have been elucidated and completed in the laboratory, by means of uninfected hosts. Both lepocreadiid species use the prosobranch gastropod, Posticobia brazieri, as their first intermediate host. Cercariae of T. blepta penetrate and encyst in the pharyngeal muscle, external muscle, and viscera of fishes in the genera Gobiomorphus and Hypseleotris, and in several species of tree frog tadpoles. The cercariae of S. callista are often eaten or accidentally inhaled by several small fishes, including Retropinna, Craterocephalus, Pseudomugiland Ambasszs, and encyst in the pharyngeal muscle and viscera. All developmental stages are described and illustrated.