The aim of this paper is to elucidate the fluctuation mechanism in the catch of pink salmon Oncorhynchus gorbuscha harvested in the Maritime Province of Siberia. We used catch data on pink salmon born in odd- and even-numbered years. Monthly indices of the Arctic Oscillation and the Pacific Decadal Oscillation were used as the environmental factors. We assumed that the catch in year t, C_t, and that in year t 2, C_t₂, could be used to represent the spawning stock biomass and recruitment, respectively, and C_t₂/C_t could then be used to represent the recruitment per spawning stock biomass. Under these assumptions, we adopted the equation C_t₂/C_t = g (environmental factors) as the model that forecasted the trajectories of the catch. The results were as follows: 1) the trajectories of the catches of pink salmon born in odd- and even-numbered years can be well reproduced by the model mentioned above. No density-dependent effect was detected in the relationship between C_t₂ and C_t, which corresponds to the stock-recruitment relationship (SRR), for catches in both odd- and even-numbered years. The relationship between C_t₂ and C_t for odd-numbered years showed a clockwise loop; however, that for even-numbered years showed an anticlockwise loop. It is believed that this difference occurs in response to the negative relationship between the catches born in odd- and even-numbered years. Pink salmon is one of the typical fish species to which a density-dependent SRR can be applied; however, this study indicates that the assumption of a density-dependent SRR is not valid.