The Marin Agricultural Land Trust will purchase a conservation easement from Hog Island Oyster Company, the first time the nonprofit has bought development rights from an oyster farm. The easement covers the 250-acre Leali Ranch, a property across the highway from Hog Island’s main buildings that the company purchased in 2017. The pandemic dealt a blow to Hog Island’s restaurants, pushing the company—the second largest aquaculture company in California—to put the ranch on the market.…