Of the common adult lanternfishes found off Oregon, two species have fat-invested swimbladders (Stenobrachius leucopsarus Eigenmann and Eigenmann 1890 and Stenobrachius nannochir Gilbert 1891), two species have reduced swimbladders (Lampanyctus ritteri Gilbert 1915 and Lampanyctus galis Gilbert 1891), two species have gas-filled swimbladders ((Protomyctophum thomp soni (Chapman 1944)) and (Protomyctophum crockeri (Bolin 1939)). Adult Diaphus theta Eigenrnann and Eigenmann 1891 and adult Tarletonbeania crenularis Jordan and Gilbert 1880 however, have either gas-filled or reduced swimbladders. Small individuals of all the above species have gas-filled swimbladders. The primary buoyancy mechanism is lipids for large S. leucopsarus, S. nannochir, L. ritteri andD. theta, is reduction of dense material for large L. regalis, and is gas for all juveniles and for P. thompsoni, P. crockeri and some adult T. crenularis and D. theta. / Graduation date: 1971