Glenn A. Bristow

A report on some metazoan parasites of wild marine salmon (Salmo salar L.) from the west coast of Norway with comments on their interactions with farmed salmon

Abstract A survey of metazoan parasites of wild salmon returning to western Norway revealed copepod, nematode, cestode and trematode species to be present. Two species, the copepod Lepeophtheirus salmonis and the cestode Eubothrium sp., are currently known to cause serious economic losses in Norwegian salmon farming. Larvae of the nematode species Anisakis simplex , while not currently a problem in farmed salmon, are a well known problem in wild fisheries. The prevalence and distribution of each species are presented for both wild and farmed salmon, where known, and discussed in light of present day knowledge of the life cycles of the individual species.

The effect of long term, low level Eubothrium sp. (Cestoda: Pseudophyllidea) infection on growth in farmed salmon ( Salmo salar L.)

Abstract Loss of potential growth in farmed salmon with persistent low-grade infection of Eubothrium sp. is shown to be approximately 450 g per fish for females and 800 g per fish for males. The systematics of Eubothrium sp. are discussed with regard to Eubothrium crassum and its sibling species in relation to salmon farming. The epidemiological implications of the infections are discussed with regard to aquaculture.

Prevalence of Zoonotic Metacercariae in Two Species of Grouper, Epinephelus coioides and Epinephelus bleekeri, and Flathead Mullet, Mugil cephalus, in Vietnam

Fishborne zoonotic metacercariae have not been reported from brackish water and marine fish from Vietnam waters although these parasites are common in the countrys freshwater fish. Both wild-caught and cultured grouper (Epinephelus coioides and Epinephelus bleekeri), and mullet (Mugil cephalus) from brackish and marine waters located in Khanh Hoa province in central coastal Vietnam were examined, and found positive for zoonotic trematode metacercariae. From grouper, Heterophyopsis continua and Procerovum varium were recovered. The prevalence of H. continua ranged from 2.0 to 6.0% and that for P. varium ranged from 11.6 to 15.8%. Mullet were infected with Pygidiopsis summa and H. continua both of these species are new records for Vietnam. The prevalence of P. summa in mullet was generally high, ranging from 17.6 to 75.5%, and was significantly higher than the prevalence of H. continua (2.5 to 32.4%). There were no significant differences in the prevalence of metacercariae between grouper from natural or cultured habitats, indicating that the highest risk of infection occurs in the wild-caught state prior to their placement in culture. Further, there was no difference in metacercarial prevalence between the 2 species of grouper. Infected wild-caught seed were only observed from January to October. Monthly variation in prevalence suggests seasonal variation in mullet infections occurs in this region with the highest transmission taking place from October to December. Basic investigations on the ecology and epidemiology of these intestinal flukes need to be carried out to determine their significance as a public health problem and the aspects of their biology that may be vulnerable to control interventions.

Some Haliotrema (Monogenea: Dactylogyridae) from Cultured Grouper (Epinephelus spp.) with Emphasis on the Phylogenetic Position of Haliotrema cromileptis

Abstract Three Haliotrema spp. are reported from the Vietnamese grouper. Morphological and morphometric characters show minor deviations from original descriptions of H. cromileptis Young, 1968 and H. epinepheli Young, 1968. The third encountered species (Haliotrema sp.) appears to be new to science. Genetically, H. cromileptis clusters with Bravohollisia, Pseudohaliotrema, and Haliotrema. The group is well supported by partial large subunit rDNA (LSU), complete small subunit rDNA (SSU), and partial SSU + ITS1 rDNA analyses. Ingroup phylogenetic relationships are not well resolved. Haliotrema cromileptis, H. fleti Young, 1968, and Pseudohaliotrema sphincteroporus Yamaguti, 1953 are closely related to a monophyletic group of 5 Haliotrema spp. characterized by bell- or horn-shaped bases of the male copulatory organ (MCO), which contains an accessory piece. Based on SSU rDNA, H. cromileptis is a sister species to P. sphincteroporus and, together, they form a clade to 3 other Haliotrema spp. characterized by a bell-shape based MCO with an accessory piece. Data analysis conducted on partial SSU + ITS1 rDNA confirms the close phylogenetic relationship of H. cromileptis, H. fleti, H. chenhsintaoi Zhang, 2001 (possessing a horn-shaped base of the MCO), and Bravohollisia rosetta Lin, 1995. However, because major differences in diagnostic characters exist, this genetic relationship needs further elucidation.

Goezia bangladeshi n. sp. (Nematoda: Anisakidae) from an anadromous fish Tenualosa ilisha (Clupeidae)

A total of 1432 hilsa shad, Tenualosa ilisha (=Hilsa ilisha) from 11 fresh water, brackish water and marine localities in Bangladesh yielded 13 adult Goezia bangladeshi n. sp., all specimens being found in the intestine of a single fish host caught in the lower Ganges. A total of 2372 Goezia juveniles were recovered from 490 infected fish (prevalence 34.2%). This is the first Goezia species recorded from Bangladesh, and it differs from other valid species by the number of caudal papillae (pre 7-9, para 3, post 6); encircled by tiny spines, the position of double papillae, the arrangement of body spines, and the length ratio of the intestinal caecum and the ventricular appendix (1: 3.33-4.72). Juveniles were free in the gut, embedded in the gut wall and encapsulated in mesenteries. Tenualosa ilisha serves as the definitive host, but the predominance of juveniles may indicate that piscivorous hosts may also serve as such. A list of the nominal Goezia species with important characters is provided.

A New Endosymbiotic Bivalve (Heterodonta: Galeommatoidea), From Pacific Holothurians

Abstract A fourth known species of Entovalva (Mollusca: Galeommatoidea), found in the esophagus of Holothuria spinifera and Holothuria leucospilota from Nha Trang Bay, Viet Nam, is described. Morphologic comparisons with the 3 previously described species are presented and the first DNA sequences for Entovalva are provided. Entovalva nhatrangensis, n. sp., differs from Entovalva mirabilis Voeltzkow, 1890 in its body shape, folded outer body epithelium, and lack of ovary in the foot. It differs from Entovalva (Cycladoconcha) amboinensis (Spärk, 1931) in its body shape and folded outer body epithelium. It differs from Entovalva lessonothuriae Kato, 1998, in shape of its foot. Two partial cytochrome oxidase I sequences for species diagnostic use have been submitted to GenBank.

Parasites of Norwegian freshwater salmonids and interactions with farmed salmon—a review

Abstract Of the 40 known species of parasites of wild freshwater Norwegian Salmonidae, nine are currently recognised as pathogens in Norwegian freshwater aquaculture of salmonids and/or salvelinids. A further five are known as pathogens of wild Norwegian Salmonidae, while at least eight of the remaining species are known as pathogens in wild or farmed Salmonidae outside of Norway. Some of the Norwegian pathogens have only been recognised as such in the last 5 years. Wild Salmonidae are, in most cases, the only reservoirs for these parasites in Norwegian freshwaters and the number of parasite species and instances of their known pathogenicity are likely to rise at current levels of production.

A preliminary electrophoretic investigation of the gyrocotylid parasites of Chimaera monstrosa L.

Abstract An electrophoretic survey covering 15 enzyme systems of Gyrocotyle urna, G. confusa, and Gyrocotyloides nybelini the cestodarian parasites of Chimaera monstrosa, revealed consistently scorable results in five of the 15. The re~ults clearly show differences at the species level between Gyrocotyle urna and G. confusa and between G. confusa and Gyrocotyloides nybelini. The relationship between G. nybelini and Gyrocotyle urna is less clear but the data support the retention of the species designator while bringing into question the validity of the genus Gyrocotyloides.

On the distribution, ecology and evolution of Gryocotyle urna, G. confusa and G. nybelini (Cercomeromorpha: Gyrocotylidea) and their host Chimaera monstrosa (holocephalida: chimaeridae) in Norwegian waters, with a review of the species question

Abstract Three hundred and eighty Chimaera monstrosa from Norwegian waters from Lofoten to the Skagerrak were examined for Gyrocotyle spp. G. urna was found, evenly dispersed, throughout the area. G. nybelini and G. confusa appeared to have more restricted distributions and to be slightly overdispersed. These rare species overlapped only in the area of Bergen, Norway. Mixed species infections were common. Prevalence of G. urna was from 48 to 100 %. All host size classes were found only in 6 of the 11 areas examined. A new geographic record for G. urna is included for the Faroes. Gyrocotylid speciation and evolution are discussed.

Parasitism of Two Species of Caligus (Copepoda: Caligidae) on Wild and Cultured Grouper in Viet Nam

Grouper culture is an important source of income in Viet Nam. However, during the last decade, the industry has suffered numerous serious disease outbreaks, including some due to pathogenic parasites. This study examined the prevalence and intensity of Caligus species on two commonly cultured Vietnamese groupers, Epinephelus coioides and E. bleekeri. A total of 469 fish (241 Epinephelus coioides, 228 E. bleekeri) from both brackish and marine waters, including wild, pond cultured and cage cultured fish, were examined. Two caligid species, Caligus epidemicus and C. multispinosus, were found. In addition, caligid larvae were found on skin and/or gills. Differences in parasite burden were found between host species and within host species by environment.