From Sailors and Traders: A Maritime History of the Pacific Peoples, by Alastair Couper (U. Hawai‘i Press, 2009), pp. 140-141:
The managers of the major merchant companies based at the main entrepôts in the [Pacific] islands were often ex-sailors. Several acted as consuls for their governments and supported the companies in many ways, including evoking gunboat diplomacy. A prime example is John Bates Thurston. He served at sea in the island trades, was wrecked at Rotuma in 1865, became British consul in Fiji in 1867, was highly influential in the negotiations for the ceding of Fiji to Britain in 1874, and became governor of Fiji in 1887. The companies, the new settlers, and their sympathetic consuls pressed for annexations. The French were the first to act [but Waitangi was 1840—J.] and took Tahiti, the Marquesas, and the Tuamotus as French protectorates in 1842 and New Caledonia in 1853. These were declared colonies in 1880, and the Australs and Wallis and Futuna in 1887.
The British annexed Fiji in 1874 and established protectorates over southeast New Guinea in 1884, Gilbert and Ellice in 1892, most of the Solomons soon after, and Ocean Island in 1900. They agreed that New Zealand would exercise authority over the Kermadecs in 1887, the Tokelaus in 1889, and the Cooks and Niue in 1901. The Dutch took western New Guinea in 1848. Germany annexed northeast New Guinea in 1885, along with the Bismarck Archipelago and the northwest Solomons; took possession of most of the Carolines in 1885; and ultimately purchased Yap and other islands in the Carolines and Marianas from Spain in 1899. The Germans also acquired the Marshall Islands in 1884 and took over Nauru in 1888. Chile obtained Easter Island in 1888.
America, after its disastrous Civil War, had not recovered a significant merchant fleet and showed little inclination for acquiring Pacific territory. American guano companies had already secured legislation in 1856–1860 that allowed claims over some small Pacific islands, and the US government went on to secure others, including Baker, Jarvis, Johnson, Midway, Palmyra, and Wake. In 1893 the influential American maritime geostrategist Alfred Mahan wrote that it was “imperative to take possession, when it can be righteously done, of such maritime positions as can contribute to secure command.” In 1898, Hawai‘i was annexed (US citizenships were granted in 1900), as was eastern Samoa with Pago Pago as a main naval coaling station, while Guam was captured from Spain by the US Navy in 1898.
The Pacific was now effectively divided between several colonial powers mainly by agreements. In the final carve-up, it was confirmed that Western Samoa was a German colony separated from American Samoa in the east. In turn Germany agreed to relinquish claims for Tonga. As a result, in the closing days Tonga appeared to survive as the only independent Polynesian kingdom, although not quite. It was declared a British protectorate in 1900, and in 1905 it was decreed mandatory for the king of Tonga to take advice from the British consul on all matters of importance. Finally, in 1906 New Hebrides was divided as a condominium between Britain and France.
I’m not sure why Couper omits the 1840 Treaty of Waitangi, which made British subjects of the Maori. Maybe he considered both New Zealand and Australia to be colonial powers by the 1840s, even though both were earlier annexed by another colonial power. (Like the Americas, of course.)