Some indices of antioxidant protection (AOS) (level of glutathione (GSH), the activity of glutathione-S-transferase (GST), catalase (CAT) in the three-spined stickleback, Gasterosteus aculeatus, from the three points of the White sea (Bay Seldjanaja, Lagoon Kolushkovaja and Channel Sukhaja Salma) at the beginning (May) and end (July) of the spawning season wereexamined. At the beginning of the spawning period (may), the GSH content in the Bay Seldjanajaand the LagoonKolushkovajain both muscles and liver was higher than in the Channel Sukhaja Salma. In July (the end of the spawning and transition to the feeding period) in the studied tissues the level of GSH was higher than in May. GST activity in the muscles of the three-spinedstikleback was on average 8 times lower than in the liver, and catalase 37 times. In July, the activity of GST in the muscles of fish of both sexes of all three biotopes was 1.7 – 2.4 times higher than in May, liver – 1.6 – 3.3 times. The activity of CAT also increased from May to July in the muscles in 1.5-2 times, in liver – in 1.2-1.7 times. The most pronounced changes in the indicators of AOS occurred in individuals from the Channel Sukhaja Salma. Changes in indicators of AOS correlates with the time factor: May (beginning of spawning) – July (completion of spawning). Activation of the components of AOS in the body of the stickleback at the final stage of spawning is aimed at compensating for metabolic changes caused by an increase in the level of oxidative stress, stimulators of which are the increase in ambient temperature and active nutrition.