These data reports the adult returns of data experimental field trials with releases of salmon smolts. The objective of the studies is to study the effect of sea lice (Lepeophtheirus salmonis Krøyer, 1837 and Caligus spp.) on the survival, growth and life history of Atlantic salmon (Salmo salar). To achieve this control groups and groups treated with an antiparasitic agent are released as smolts at different locations in the estuary and fjord outside the Vosso river, and comparisons are made between the subsequent recaptures of adults in the two groups. The Vosso smolt production was from eggs from the living gene bank in Eidfjord. The fish were reared through the smolt stage (1 year) in standard hatchery tanks at the Voss hatchery from 2001 to 2010 (except 2004). In 2010, smolts were also reared in a net-pen facility in Lake Evanger. Fish were randomly assigned to groups 10–14 days before release. The groups received either normal fish feed (untreated) or pellets containing emamectin benzoate (SLICE) (treated) at 50 mg per kg body weight day for 8 days. In 2005, Substance EX (Pharmaq, Norway) was applied (0.5 h bath at a concentration of 2 ppm) instead of SLICE. The smolts were towed to various locations along the fjord migration route in the inner and outer fjord systems before release. Because the Vosso salmon were protected against fishing during the study period, they were primarily recaptured by operating large bag nets at two to three locations in the fjord and estuary outside the river mouth.