The occurrence of the marine ectoparasitic copepod Lepeophtheirus salmonis and the prevalence of lesions caused by its feeding activities were monitored on sockeye salmon (Oncorhynchus nerka) adults returning to the Sproat and Stamp rivers through Alberni Inlet, British Columbia, in 1990. All sockeye examined were infected with L. salmonis and had higher intensities of infection than previously reported. The presence of high numbers of early developmental stages of L. salmonis suggests a high rate of infection for sockeye in coastal waters. Lesions attributable to L. salmonis ranged from minor skin discoloration to large open lesions that exposed the musculature. In 1990, when escapement into these river systems was delayed, sockeye holding in the inlet developed severe lesions and suffered high mortalities. High percentages of fish with open lesions entered both river systems in 1990, but few fish with open lesions were observed on the spawning grounds, suggesting additional prespawning mortality. In 1992 and 1993, when escapement patterns were more normal than in 1990, the severity of lesions owing to L. salmonis was reduced and no mortalities were observed. Throughout the study, fish in the Sproat River escapement had more severe lesions than those in the Stamp River escapement.Résumé : Nous avons surveillé l'occurrence du copépode marin ectoparasite Lepeophtheirus salmonis et la prévalence des lésions causées par son activité alimentaire chez des adultes de saumon rouge (Oncorhynchus nerka) retournant aux rivières Sproat et Stamp en passant par l'inlet Alberni (Colombie-Britannique) en 1990 et en 1992-1993. Tous les saumons rouges examinés étaient infestés par L. salmonis, et présentaient des infestations plus intenses que ce qui avait été observé jusque-là. La présence d'un nombre important de parasites aux premiers stades du développement indique probablement un fort taux d'infestation des saumons dans les eaux côtières. Les lésions attribuables à L. salmonis allaient de simples altérations de la couleur de la peau à de grandes lésions ouvertes qui exposaient la musculature. En 1990, alors que la remonte vers ces cours d'eau a été retardée, les saumons rouges qui demeuraient dans l'inlet ont subi de graves lésions et une forte mortalité. Des pourcentages importants de poissons portant des lésions ouvertes ont pénétré dans les deux réseaux en 1990, mais rares étaient les individus atteints de lésions observés sur les frayères, ce qui permet de penser qu'il se produit une mortalité additionnelle avant la fraye. En 1992 et 1993, alors que les patrons des échappées étaient plus normaux qu'en 1990, la gravité des lésions dues à L. salmonis a baissé, et on n'a observé aucune mortalité. Tout au long de l'étude, les poissons de l'échappée de la rivière Sproat présentaient des lésions plus graves que ceux de l'échappée de la rivière Stamp. [Traduit par la Rédaction]

Kudoa hypoepicardialis n. sp. infects the space between the epicardium and the compact myocardium and, in intense infections, the pericardial chamber of man-of-war fish (Nomeus gronovii) (Nomeidae) (the type host), blue runner (Caranx crysos) (Carangidae), Warsaw grouper (Epinephelus nigritus) (Serranidae), Atlantic tripletail (Lobotes surinamensis) (Lobotidae), northern red snapper (Lutjanus campechanus) (Lutjanidae), black drum (Pogonias cromis) (Sciaenidae), and bluefish (Pomatomus saltatrix) (Pomatomidae) in the northern Gulf of Mexico. This is the first report of a Kudoa sp. from the heart of a fish in the Gulf of Mexico, and of these hosts, only the bluefish was previously identified as a host for a species of Kudoa. Spores of the new species varied slightly in size among these hosts but were regarded as conspecific based on their nearly identical (99.9%) small-subunit (SSU) ribosomal DNA (rDNA) sequence. The new species differs both from the 4 nominal species of Kudoa reported from fishes in the Gulf of Mexico and from K. pericardialis, an allopatric species that infects the pericardial cavity, by the combination of having a large spore, a small polar capsule, and a polar filament with a single coil. The new species is morphologically and genetically most similar to K. shiomitsui, an allopatric species that infects the heart and pericardial cavity, but is distinguished from it based on a 4.2% difference in the SSU rDNA sequence. Heart lesions primarily were restricted to the vicinity of plasmodia and included a layer of fibrinous inflammation characterized by lymphocytes, macrophages, and granulomas as well as epithelioid encapsulations around plasmodia. Heavily infected hosts had melanin-like deposits and adipose cells beneath the epicardium. and the epicardium was discontinuous and apparently breached by plasmodia in some regions. Cardiac muscle, gill, liver, spleen, intestine, and kidney were normal.

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The parasite fauna of 336 adult Pacific halibut (Hippoglossus stenolepis) from 15 geographic localities along the North American coast, ranging from northern California to the northern Bering Sea, was examined to assess zoogeographic and latitudinal zonation of Pacific halibut parasites in the eastern North Pacific. Results show the existence of three zoogeographic zones in the northeast Pacific with boundaries near the southern Queen Charlotte Islands and in the vicinity of Kodiak Island. "Fuzziness" around these boundaries probably reflects small-scale fish movement and the complexity of parasite life cycles. These boundaries roughly correspond to those previously established using the fish and invertebrate faunas. Parasite species richness appears to be more directly correlated with halibut abundance than with latitude; parasite abundance appears to be correlated with temperature and therefore negatively correlated with latitude.

Aquaculture is the fastest-growing segment of food production and is expected to supply a growing portion of animal protein for consumption by humans. Because industrial aquaculture developed only recently compared to industrial agriculture, its development occurred within the context of a growing environmental awareness and acknowledgment of environmental issues associated with industrial farming. As such, parasites and diseases have become central criticisms of commercial aquaculture. This focus on parasites and diseases, however, has created a nexus of opportunities for research that has facilitated considerable scientific advances in the fields of parasitology and aquaculture. This paper reviews Myxobolus cerebralis , Lepeophtheirus salmonis , white spot syndrome virus, and assorted flatworms as select marquee aquaculture pathogens, summarizes the status of the diseases caused by each and their impacts on aquaculture, and highlights some of the significant contributions these pathogens have made to the science of parasitology and aquaculture.

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