WA agribusiness and Pemberton avocado orchard developer, Alterra Ltd’s shareholder register has been fortified following the sale of a block of shares by its former chairman. Existing major Alterra shareholder, Sandon Capital and fellow major shareholders, Emanuel Exports and the Daws family, who came on board six months ago, have stepped up to the plate to boost their holdings to 22.2 per cent and 19.95 per cent, respectively.