The effect of environmental salinity on the gill proteome was isolated in controlled mesocosm experiments. Salinity-dependent changes in the gill proteome were analyzed by LCMSMS data-independent acquisition (DIA) and Skyline. For this purpose, relative abundances of 1691 proteins representing the molecular phenotype of stickleback gills were quantified using previously developed MSMS spectral and assay libraries in combination with data-independent acquisition (DIA) quantitative proteomics (Li et al. 2018). Osmoregulatory responses were distinguished from general stress responses based on the direction of protein abundance changes. If the abundance of a protein was consistently regulated in opposite directions by hyper- versus hypo-osmotic salinity stress in all six mesocosm experiments then it was considered an osmoregulatory protein. If protein abundance was always increased in all six mesocosm experiments independent of whether salinity was increased or decreased then it was considered a stress response protein. KEGG pathway analysis revealed that the inositol phosphate metabolism, salivary secretion, several endocrine and extracellular signaling, valine, leucine and isoleucine degradation, citrate cycle, and oxidative phosphorylation pathways contain most osmoregulatory gill proteins whose abundance is directly proportional to environmental salinity. Most proteins that were inversely correlated with salinity map to pathways that represent proteostasis, immunity and intracellular signaling processes. General stress response proteins represent fatty and amino acid degradation, purine metabolism, focal adhesion, mRNA surveillance, phagosome, endocytosis, and several intracellular signaling pathways. Some proteins in these general stress response pathways are consistently down-regulated instead of being up-regulated during any type of salinity stress indicating that these KEGG pathways are not uniformly induced or repressed but that their function is being altered more intricately.