Lake Falconer Ayson was the 13th of the 14 children of Peter Ayson, a carpenter, and his wife, Douglas Lamont (Lamond). They had emigrated from the Scottish Highlands to Otago, New Zealand, in 1853, and were amongst the earliest settlers in the lower Clutha valley. Lake was born at Warepa on 7 June 1855. He grew up on the family farm and, after leaving school, worked there for a time before moving to other farms: fencing, ploughing, harvesting and shearing in Otago and (later) Cheviot in North Canterbury. Subsequently he became a rabbit inspector in the Waitaki valley, based in Duntroon, but working up the big river valley and into the foothills of the Southern Alps. On 11 June 1880 at Knox Church, Dunedin, he married Alice Dabinett, whose parents farmed a property next to the Aysons' at Warepa.
Lake Ayson became a keen angler for the brown trout that were introduced into New Zealand during the late 1860s. He met Francis Scott Pillans, another pioneering farmer in the lower Clutha valley, who had experience in fish culture in England. His interest in fishing and his acquaintance with Pillans combined to determine his future career.
Ayson was appointed in 1886 as curator of the Masterton trout hatchery of the Wellington Acclimatisation Society, which also provided trout to other acclimatisation societies in New Zealand. In 1898 the government sent him overseas to investigate fisheries in Italy, Switzerland, Great Britain, the United States and Canada. He was to determine the methods used in research and management of fisheries, and to identify fish species suitable for acclimatisation in New Zealand, primarily freshwater salmonids (such as trout, salmon and whitefish). He also made enquiries in Britain about the reasons Atlantic salmon had failed to become established in New Zealand.
On his return Ayson was appointed an inspector of sea-fishing in the Marine Department. He expressed a desire to see fisheries managed on scientific principles, and was soon promoted to chief inspector of fisheries. Aware that New Zealand had very large areas of coastal seas that should have prolific stocks of fish, he initiated an extensive experimental trawling programme. He had made enquiries overseas about useful marine species such as herring, cod and turbot, and provided details of facilities needed for handling importations. Establishment of the Marine Fish-hatchery and Biological Station at Portobello, in Otago Harbour, in 1904 was an outcome of Ayson's recommendations. A variety of exotic marine fishes and crustaceans were reared there and released into the sea, although none of them became established.
Ayson had also sought suitable game for introduction to New Zealand. He brought 400 Virginian quail and a few Canada geese back with him in 1899 and suggested that wapiti and white-tail deer be imported, recommended against Rocky Mountain sheep, and provided a list of seven game fowl that he thought should be considered.
Ayson pursued a vigorous programme of Atlantic salmon ova importations, until the species eventually became established. However, these fish were landlocked, and not the sea-migratory stocks that anglers desired. He had been offered chinook salmon and whitefish ova in the United States and sockeye salmon in Canada, and had returned with a large number of whitefish ova in 1899. He persuaded the government to establish a substantial hatchery on the Hakataramea River, a major tributary of the Waitaki, as a base for chinook salmon importations, and between 1900 and 1906 five consignments of chinook ova and one of sockeye ova were imported. Some were sent under the supervision of American fish culturists, although Ayson himself went to California to take delivery of others. He had watched earlier efforts to establish Atlantic salmon, and attributed their failure to the liberation of small numbers in many rivers. Hence he adopted a strategy of making large chinook releases over several years into just one river, the Waitaki. He reasoned, correctly, that once established, the fish would spread north up the Canterbury coast and colonise other rivers. Within a decade chinook salmon were widespread in the eastern South Island. Ayson hoped for a commercial salmon fishery, like that along the Pacific coast of North America, and he continued to press for it while he was chief inspector, but this hope was not fulfilled.
Ayson was ambitious, and suggested that there should be a separate Department of Fisheries, evidently seeing himself as 'Secretary and Chief Inspector'. He also recommended that the role of the acclimatisation societies be taken over by the government, clearly expecting that responsibility for managing trout fisheries would become his. He never achieved these goals.
Ayson remained chief inspector until his retirement in 1926, and died in Wellington on 17 June 1927, survived by six sons (Alice Ayson had died in 1910). The highly valued stocks of chinook salmon in the rivers of Canterbury are undoubtedly his lasting memorial.