Commercial gill‐nets of three mesh sizes (3.5”, 4.5”, 5.5” diagonal measure) were joined into a single net 300 m long and 5 m high, and set at three localities (New Plymouth, Palliser Bay, Bay of Plenty) in the lower North Island, New Zealand. The nets were bottom‐set in shallow (9–26 m depth) and deep (35–100 m depth) water, mostly for 16 h, to test the effects of mesh size on the species composition and sizes of fish caught. In 17 sets, 3284 fish of 55 species were caught. Across all species, larger fish were caught in deep water and at the two largest mesh sizes. The species caught and proportional composition of the catches varied both between locations and mesh sizes. Overall, there were important differences between mesh sizes, depths, and locations in the species composition and size distribution of gill‐net catches, as well as a wide range of species and sizes caught within single sets. Indications are that effective targeting of individual species at the nearshore‐pelagic interface may be confounded by bycatch.