Naturally occurring lesions and micro‐organisms in two species of free‐living sharks: the spiny dogfish, Squalus acanthias L., and the smooth dogfish, Mustelus canis (Mitchill), from the north‐western Atlantic

Abstract

Twenty‐three smooth dogfish, Mustelus canis L., and 20 spiny dogfish, Squalus acanthias (Mitchill), were examined for the presence of diseases. Sharks were collected from the north‐western Atlantic between April and September 2000. Major organs were sampled for histopathology and bacterial cultures were taken from kidneys. Macroscopic lesions were infrequent and included intestinal cestodiasis and gastric and dermal erosions. Microscopic lesions were common in both shark species. Mustelus canis had numerous degenerative lesions involving the pancreatic ducts, seminiferous tubules and coronary vessels. The most frequent lesions in S. acanthias were parasitic and included pancreatic nematodiasis and biliary myxosporeosis. Additionally, both species had focal meningitis, encephalitis, dermatitis, gastritis, enteritis and glomerulomesangial thickening. Microscopic parasites included intestinal coccidiosis, unclassified gastric and testicular protozoa, skeletal muscle and renal tubular myxosporeans, a branchial trichodinid ciliate, olfactory and branchial trematodes, gastrointestinal cestodes and larval nematodes. Shewanella putrefaciens, Photobacterium sp., Vibrio sp., Pseudomonas sp. and Alteromonas sp. were isolated from kidneys of nine sharks. The role of the above lesions in the natural mortality and morbidity of the two shark species is unknown. The finding that apparently healthy sharks can harbour potentially debilitating lesions warrants the inclusion of histopathological studies in the management and conservation of sharks.

Parasitic metritis and oophoritis associated with nematode larvae in an Atlantic sharpnose shark, Rhizoprionodon terraenovae (Richardson), collected in the western Atlantic off Florida

“…Although histozoic larval nematodes have been reported frequently from the subcutis (Williams ) and internal organs from numerous sharks (Mudry & Dailey 1969; Rosa‐Molinar et al . ; Credille, Johnson & Reimschuessel ; Borucinska & Heger ; Borucinska & Frasca ), only two reports describe them in the reproductive tract. Accordingly, these are from the ovary (Rosa‐Molinar et al .…”

“…; Credille et al . ; Borucinska & Heger ; Borucinska & Frasca ). This is the first report that notes marked changes in the ovary and uterus in association with larvae.…”

Candidatus Renichlamydia lutjani, a Gram-negative bacterium in internal organs of blue-striped snapper Lutjanus kasmira from Hawaii

“…Nearly full sequences revealed 2 novel Chlamydiae affecting salmonids, Candidatus Piscichlamydia salmonis and Candidatus Clavochlamydia (= Clavichlamydia) salmonicola (Draghi et al 2004, Karlsen et al 2008, whereas partial sequences revealed the involvement of Neochlamydia sp. (Parachlamydiaceae) and other phylotypes (Meijer et al 2006, Draghi et al 2007, Polkinghorne et al 2010) falling within Rhabdochlamydiaceae and the E6 lineage (Corsaro & Venditti 2009 Epitheliocystis is an infectious disease affecting the gills of several marine and freshwater teleost fishes (Corsaro & Venditti 2004, Nowak & LaPatra 2006, although infections have been occasionally reported in chondrichthyan fishes (Borucinska & Frasca 2002, Polkinghorne et al 2010. Infection with epitheliocystis is limited to the gills and less commonly the skin and oral cavity.…”

Epitheliocystis hyperinfection in captive spotted eagle rays Aetobatus narinari associated with a novel Chlamydiales 16S rDNA signature sequence

“…Re ports in elasmobranchs are limited. Presumptive le sions have been observed in gills of wild spiny and smooth dogfish Squalus acanthias and Mustelus canis, respectively (Borucinska & Frasca 2002). An unreferenced mention of compatible lesions (Nowak & La Patra 2006) and epitheliocystis associated with a novel Chlamydiales (Polkinghorne et al 2010) have also been reported in the leopard shark Triakis semifasciata.…”