BJ's deal: EU tariffs will be applied to 'selected' as yet unknown goods crossing from GB into Northern Ireland. Goods deemed “at risk” of moving into the EU after entering Northern Ireland will be subject to the EU tariff, and potential rebate if they don't.
Outside of a small quota of 450 tonnes, smoked salmon from Norway has a 13% tariff on it into the EU. It could potentially be imported into Scotland on a UK zero tariff, and then transited across into Northern Ireland among a consignment of Scottish smoked salmon.
Checks would be required either way ... to check.
trade-tariff.service.gov.uk/commodities/03…