Boston’s marine industrial park is about to become a little less marine industrial.

The caretakers of this roughly 190-acre corner of the city, now known as the Raymond L. Flynn Marine Park, hope to attract more tenants beyond its core of fish processing and ship repair. One way they’ll try: by spurring higher-rent uses on upper floors, such as labs and design studios, that could help subsidize lower rents on the ground floors for a broader mix of manufacturing and warehouse work.

The Jamestown investment and management company already takes a mixed-use approach at its Innovation and Design Building, a redeveloped former military warehouse at the southern edge of the park.

The Boston Planning & Development Agency, which oversees the park, hopes to replicate that success, according to a long-awaited master plan released on Monday. Waterfront planner Richard McGuinness said the park is about half developed under current floor-area ratio limits. The proposed changes, he said, include raising those thresholds to essentially double the park’s remaining development capacity.

Perhaps the most important recommendation: adjusting the requirement that two-thirds of the park be devoted to marine industrial uses.

“That’s a lot of acreage,” McGuinness said. “We don’t think there’s enough demand.”

Some suggestions from the development agency: broadening the definition of “marine industrial” to include airport-related shipping, scaling back the marine industrial requirement to cover half the park, or allowing only ground-floor uses to count toward that threshold.

“We’re not giving up on port uses,” McGuinness said. “I think we can be a little more deliberate based on what we know are growing industries and what they need for space and infrastructure.”

Other recommendations include improving public transit access to the park, such as by changing the Silver Line route in the park and exploring opportunities for water transportation services. The agency would also like to see a new connector road to send trucks to the Haul Road from the Summer Street entrance to the park.

The agency will now discuss its ideas with tenants and with state environmental officials, who have the final say over changes to the park’s makeup.

The ultimate goal: harnessing the intense interest among developers in the South Boston waterfront while protecting the park as an important haven for blue-collar jobs for decades to come.