In 1953, specification of vessels fishing in the Convention was requested. In 1954, statistical Divisions were created to accommodate stock partitioning of various species. The ICNAF collection and reporting system was considered one of the worlds best fisheries data-bases of the time.
Early efforts focused on determining a mesh size of trawls that would allow sufficient escapement of young haddock and for this reason ICNAF was informally referred as the “haddock Commission”. From the start, the principle information needed to assess status of the stocks, to estimate natural mortality, examine age frequencies, estimate recruitment and adult population size, comparing the latter with total catch was collected.
The 2nd Annual Report brought together for the first time, data on landings of groundfish in the Convention Area, listing 17 groundfish species and 2.3 million metric tonnes of landed fish. This showed that a wide array of fish species was already being heavily exploited in the Convention area.
Various countries were also undertaking exploratory fishing to expand the scope of the fisheries. At great depths they found dense concentrations of grenadier mixed with Greenland halibut. The 1968 Annual Report noted that “the doubling of the catch of other groundfish species from 11,000 tons to 22,000 tons was due to a new fishery for roundnose grenadier by the USSR”.
A research plan was formulated by STACRES in 1953. Studies dealt with stock structure, life history and size composition of haddock, redfish and Atlantic halibut. Later, cod became the focus of research with emphasis on tagging (for stock definition), on aging of fish and age based catch rates in the fisheries. Plankton surveys were also undertaken to study recruitment.
The study of hydrographic conditions in the northwest Atlantic was also an ICNAF mandate under the Hydrography Committee. Symposia were undertaken decadally, often in coordination with ICES, enhancing knowledge of the hydrography and its influences on the resources.
By 1960, scientific focus was shifting from fish size based management advice (mesh size) to assessment of stock status, that work coordinated by the Subcommittee on Fishery Assessment in Relation to Regulation Problems. Also the Convention was changed to include seals, pelagic fish and molluscs. Salmon and large pelagic species (sharks and tunas) were briefly considered to become part of the Commissions management mandate but that was put aside.
In 1964, the Commission requested: "that the Chairman of Research and Statistics and of the Assessment Subcommittee review in general terms the various kinds of action which might be taken by the Commission for the purpose of maintaining the stocks of fish at a level at which they can provide maximum sustained yields”. Gulland and Templeman (1965) produced a report indicating that “Any conservation or management measure consists of restricting present catching operations in some way in order to ensure better catches in the future”. The realization that limitations on catch were required to try to reduce declines in fish populations.
To this end, ICNAF developed scientific techniques necessary to determine stock status and recommend catch levels intended to attain sustainability. However, many stocks were already in decline, effort, already excessive, continued to build as existing fleets expanded, new fleets joined the fishery and fishing by non-member countries increased. Management actions based on the scientific advice was slow to follow. Although STACREC noted in 1966 that effort was “approaching or may even be beyond the level giving the maximum sustained yield per recruit”, catch limitations based on the scientific advice was still years away.
The first analytical assessments were carried out in 1969 on cod and haddock by the Assessment Committee. In that year, there was a recommendation for no fishing for haddock on Georges Bank/Gulf of Maine, leading to the first closure of a fishery under ICNAF. By the early 1970s, scientifically based management was being implemented across the board, a first in the world in international waters.
Despite restriction placed on catches, heavy exploitation over many years had far too long exceeded the point of sustained yield. The 1971 report concluded that “the rate of increase of fishing intensity has far exceeded the rate of scientific studies to determine the effects of it”.
The ICNAF system, some argued, gave scientists a greater degree of understanding of management needs and processes. One explanation of ICNAF's success on the scientific advisory front rested precisely in its marriage of science and management. distant-water fishing nations had strong interests in sending their best scientists to the meetings.