Farm-raised Scottish salmon is the UK's biggest food export, supporting 12,000 jobs - many in rural and isolated areas of the country.
But despite growing worldwide demand for the high-protein fish, the labour pool has shrunk in recent years with many key workers returning to eastern Europe post-Brexit.
And there are ongoing concerns that changes to the Northern Ireland protocol could lead to retaliatory action by the EU, causing increased friction at the border, delays and queues for hauliers crossing to France, or extra costs for exporters.
Tavish Scott, chief executive of Salmon Scotland, said: "Our businesses are vital to the economic performance of the UK - not only in economically fragile coastal and rural areas, but across the length and breadth of the country in processing, engineering, science and technology industries."
Salmon Scotland is calling on the next Prime Minister to embrace a "more enlightened approach to the movement of labour into the UK", including a change to key worker definitions, changes to the salary cap level, and a broader public signal that the UK is open to people coming here to work.
The trade body also wants a "serious, pragmatic approach" to negotiations with the EU, avoiding a so-called 'trade war', with a "clear focus on the nation's export businesses who depend on a positive, professional relationship with France and the other countries of the EU".
Mr Scott's letters to Liz Truss and Rishi Sunak reads:
"Our businesses are vital to the economic performance of the UK - not only in economically fragile coastal and rural areas, but across the length and breadth of the country in processing, engineering, science and technology industries.
"In that spirit our sector has two specific asks...
"Labour shortages in our processing businesses are acute. We would urge you to embrace a more enlightened approach to the movement of labour into the UK so as to assist business.
"Steps could include a change to key worker definitions, changes to the salary cap level and a broader public signal that the UK is open to people and thus to business.
"No change to the current UK Government approach and the attitude in particular of the Home Office is a clear threat to business competitiveness against our main international competitors.
"We would urge a more pragmatic and business friendly approach."
He adds:
"Maintaining and enhancing our export position to the EU and wider European markets is of considerable importance to our businesses...
"Any escalation of EU-UK negotiations over the Northern Ireland protocol is high on our industry risk register.
"Continuous access to our main markets in Europe is vital for the UK's food and drink export success story.
"Our ask is that a pragmatic approach is taken to these negotiations by the UK Government.
"No UK export business needs a trade war or even any such suggestion between the UK and the EU.
"We would urge you to deploy a serious, pragmatic approach to these negotiations with a clear focus on the nation's export businesses who depend on a positive, professional relationship with France and the other countries of the EU."