The main harvests were of mussels (43.5 per cent of the total aquaculture harvest), Atlantic salmon (42.5 per cent) and rainbow trout (7.4 per cent).
The total fish harvest was 278,400 tonnes, and the contribution of fish harvests to the cumulative total of national harvests was 54.5 per cent.
In the case of Atlantic salmon a total of 217,000 tonnes was harvested, representing a decline of 5.7 per cent from the accumulated in the first five months of 2016.
There were 38,000 tonnes of rainbow trout harvested, a fall of 0.3 per cent year-on-year.
By contrast, Pacific salmon harvests grew 70 per cent from last year to 24,000 tonnes, something Subpesca said reflected decisions of the private sector in the face of regulatory, environmental and market changes.
Salmonid egg production was estimated at 240 million to May, 15 per cent below the level of 2016. The proportion per species is 84 per cent of Atlantic salmon, 10 per cent of Pacific salmon and 6 per cent of rainbow trout. Imports of eggs up to May 2017 reached 6.6 million of Atlantic salmon from Iceland.
Shellfish harvests up to May reached 224,000 tonnes, a 44 per cent increase compared to last year. Mussels represented 98.9 per cent of the total, with 222,000 tonnes and a year-on-year growth of 45 per cent.
There were 994 tonnes of Northern scallop harvested, a decrease of 32 per cent compared to the year 2016. The drop is attributed to unusual environmental conditions that affected the availability of food for scallops.