Graduate Thesis Or Dissertation
 

Host-parasite relationships of the staghorn sculpin Leptocottus armatus Girard in Oregon

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  • The staghorn sculpin Leptocottus armatus is abundant in the Yaquina Bay estuary on the central Oregon coast and also occurs offshore in shallow water. A total of 560 L. armatus were collected at three locations in Yaquina Bay and between 7 and 11 kilometers offshore in depths of 40 to 80 meters. Staghorn sculpins were present in all areas where collections were made throughout the year except during the summer when most offshore sculpins moved into Yaquina Bay. Leptocottus armatus spawned primarily in the bay during the fall and early winter. The young fish remained in Yaquina Bay for about one year at which time they were about 12.0 cm in length. Subsequently, some of them moved offshore. Seventeen different species of parasites were collected from the 526 L. armatus examined. Genolinea laticauda was collected from the stomachs of 25.1% of the fish and had greater incidence and intensity in larger fish. Recruitment of immature forms began in April and the average life span was about seven months. The life cycle was most efficient in the lower estuary. Tubulovesicula lindbergi occurred in the stomachs of 50.8% of the fish and had greater incidence and intensity in small fish. Recruitment of immature individuals occurred all year, but was greatest in June. The life cycle was most efficient in the upper estuary. Podocotyle atomon was found in 42.6% of the fish and was most abundant in the larger fish. Bucephalopsis ozakii was collected in 38.8% of the L. armatus and was more abundant in large fish, as were larval tetraphyllidean cestodes which were present in 40.7% of the fish. These two parasites were found to be positively associated because they were both more likely to parasitize larger fish. Nematodes believed to be Contracaecum cornutum were found in ulcers in the stomach of 28.0% of the fish. This was the only parasite that was obviously pathogenic. Echinorhynchus gadi occurred in 47.4% of the fish. Immature worms were obtained all year, but only from fish in the upper estuary. Other parasites encountered were the protozoans Scyphidia sp., Trichodina sp. and Ceratomyxa sp.; the trematodes Gyrodactylus sp., Neopodocotyloides sinusaccus and Derogenes sp.; the nematode Contracaecum aduncum; a piscicolid leech; the copepod Acanthochondria rectangularis and the isopod Lironeca vulgaris. It was concluded that all the parasites of L. armatus could be acquired in Yaquina Bay, although it was more likely that the larval cestode was acquired offshore. The parasite data could not be used to determine movements of L. armatus in and out of Yaquina Bay, but the data were utilized to show that movements between the upper and lower estuary were not extensive.
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