More than 600 Navy jobs will be lost from Devonport when the base's nuclear submarines move to Scotland.
The grim revelation is set to fuel calls for the next generation of warships to be based in Plymouth to "backfill" the personnel gap left by the subs' departure.
The Ministry of Defence said that about 630 military personnel are due to transfer to Faslane when the three Trafalgar-class hunter-killers relocate.
It was unable to say what impact the change would have on civilian staff, but it was not expected to "lead to any significant changes" in the number at Devonport.
The decision to make Faslane the dedicated home for the UK's entire submarine fleet was taken under the last Labour government and so has been known for some years.
But it is the first time the impact on manpower has been revealed.
Plymouth has already suffered from redundancies and the scrapping of warships, as part of the biggest round of defence cuts since the end of the Cold War.
The news will lend added urgency to a campaign to bring the hi-tech Type 26 Global Combat Ship to Devonport. Due to enter service after 2020, they will replace the Type 23 frigates, seven of which continue to be based in Plymouth after ministers lifted the threat of a move to Portsmouth last year.
All three of Devonport's Trafalgar class vessels are to move to Scotland by 2017, where they will join the nuclear-armed Vanguard fleet and new Astute boats as they enter service.
That not only has implications for the dockyard's workload and the knock-on effect for jobs, but also the economic benefit generated by naval personnel and their families.
Base-porting on the Clyde has become central to the high-profile debate on Scottish independence.
The Scottish National Party (SNP) is demanding to remove the submarine-based nuclear deterrent in the event of a vote to go it alone in 2014.
The impact on jobs of moving Devonport's hunter-killer submarines to Faslane emerged in response to a parliamentary question. Responding Defence Minister Mark Francois said the number of jobs at Faslane were due to increase from the current figure of 6,700 to around 8,200 by 2022.
He said: "This change is primarily due to an increase of around 1,500 in the number of Royal Navy jobs at the site, of which around 630 will transfer from HMNB Devonport due to the move of the base-port for the Trafalgar Class submarines to HMNB Clyde."
Mr Francois added: "There are no plans to transfer any Ministry of Defence (MoD) civilian jobs from HMNB Devonport."