Exports of farmed salmon from Scotland rose 17% by value last year, but there was another steep drop in the volume of fish sold overseas.
The year also saw a big recovery in exports into the European Union, up by more than a third on 2015.
But there was a warning about the impact on jobs if tariffs are introduced, and on the wider industry if migrant workers are cut back.
Sector leaders are in Brussels for the world's biggest fish industry expo.
The effort is seen as an important one for promoting Scotland's biggest food export, which was, in 2014, the biggest UK food export, above confectionery.
Much higher prices, due to a shortfall in supply, meant a sharp increase in profits for producers during the last year.
The new figures are from HM Revenue and Customs. They show that the tonnage of exported salmon fell by more than a quarter, from 100,000 tonnes in 2014 to 83,400 tonnes in 2015. And last year, it fell by 10%, to 74,600 tonnes.
The export value fell from £494m in 2014, to £386m. It then rose to £451m in 2016.
The decline is largely due to a fall in the supply of fish, and a reduced average size.
Much of this is explained by sea lice - what the industry calls "biological challenges".
The biggest producer, Marine Harvest, published figures recently showing that 69% of its farms last year breached levels when an outbreak of the parasite has to be notified. That was far higher than any other producing nation.
One response is to harvest fish quickly from an infected cage, long before they reach their optimum size. Over 7kg, the Atlantic salmon has a premium price in the US and Far East markets.
The industry has been strongly criticised by those who oppose intensive salmon farming, saying the sea lice problem has damaged eco-systems in sea lochs.
The industry body, the Scottish Salmon Producers Organisation (SSPO), claims that recent evidence suggests that the problem may now be reducing.
It expects an increase of 15,000 to 20,000 tonnes in production this year. If that happens, it could make 2017 a record export year.
Exports tend to soak up extra supply contracts after longer-term UK contracts have been fulfilled. Around 52% of salmon farmed in Scotland is consumed in the UK.
Exports of Scottish farmed salmon into the European Union was up 37% to £204m-worth last year. France is the biggest single EU market.
'No shortage of demand'
It fell the previous year because of the collapse in 2015 of the Norwegian krone, which made imports from Norway cheaper. Last year, the weakening of sterling helped with exports from Scotland.
Scott Landsburgh, chief executive of the Scottish Salmon Producers Association, said: "We sell every fish we produce. There's never a shortage of demand. The price may not be as strong in 2016, but it will still be very strong this year. We hope we can get back to 90,000 tonnes of export.
"New production sites are being added, and fish health performance looks like it's turning the corner."
However, the industry warned of the impact of losing migrant workers who do much of the processing of salmon and other food.
If Scotland has to trade with the rest of the European Union on the same basis as Norway, that would mean a 2% tariff on exports of fresh fish and 13% on processed fish, including smoked salmon.
The industry chief said there would be even more of a concern about future delays due to paperwork at European borders, following Britain's exit from the EU.