Life Span, Maturation, and Growth of Two Hemiurid Trematodes, <i>Tubulovesicula lindbergi</i> and <i>Lecithaster gibbosus</i>, in Pacific Salmon (Genus <i>Oncorhynchus</i>)

Abstract

Studies on the life span, maturation, and growth of two trematodes of the family Hemiuridae were based on periodic sampling of two captive stocks of naturally infected pink and chum salmon. The fish were caught during their 1st month at sea and maintained in filtered sea water to preclude further infection.Tubulovesicula lindbergi (Layman) was found to mature in 2–4 months and live at least 31 months, growing during that time from about 0.6 mm to more than 4.5 mm; Lecithaster gibbosus (Rudolphi) matured in 1–2 weeks and had a life span of about 2–9 months, growing from 0.5 mm to almost 1.9 mm. There was considerable variation in growth rate within each species. Among specimens of L. gibbosus faster growth apparently was associated with a shorter life span. Retardation of growth and maturation at high intensities of T. lindbergi infection is suggested.Evidence is presented in support of the view that the experimental results are applicable to the course of these infections in nature.