This report presents data collected from the observational studies on Hawaiian monk seals and green turtles at Pearl and Hermes Reef in the Northwestern Hawaiian Islands. The data presented was taken on 9-8 of June 1990 and 1 August to 13 September 1991. The data collected was limited to objectives conducting atoll-wide seal censuses, resighting tagged seals, tagging weaned pups, and surveying and destroying debris capable of entangling wildlife. Additionally, efforts in 1991 included retagging seals, tagging unknown-age seals, weighing and measuring immature seals, and bleach-marking seals for ID purposes. Also, interatoll movement, survival, injuries, and entanglement of seals were monitored, seal scats and spews were collected, turtles were tagged, and previously tagged turtles were resighted.