The mariculture of seaweeds is becoming increasingly popular in A laska. Currently, Alaska has 23 seaweed farm leases with 25 additional leases in the application process. With funds from the ARPA-E MARINER program, we tested different seaweed farm designs, seeding methods and harvest approaches.
Farm designs were based on catenary structures and the use of spreader bars with variable spacing of grow lines. Initial results show that line spacing can be as small as 1 meter with no adverse effects on yield. There was no statistical differenc e in the growth of Saccharina whether in the middle or the outside of the array. Sagging caused by the weight of the mature fronds resulted in lower growth at depth. Seeding lines was done using the current industry standard with meiospores settling on see d string. We experimented with several “direct seeding” methods – spraying or painting both gametophytes and embryonic sporophytes on both strings and on the growlines. Some success was demonstrated with the outplanting of directly seeded growlines.
Our cooperating farmers tested various approaches for harvesting mature kelps. One innovation that has worked well is the use of large bags for holding the freshly harvested fronds. Although the weight of the fronds on the growlines causes the lines to sink, the bags packed with the harvested fronds float, allowing for easy loading to the transfer vessel. Another advance in harvesting is a specially built harvest vessel, the Kelp Buddy, which was in operation for this last season. We also modified a large seiner that allowed for harvesting more than one line at a time. Next season we will continue to test various methods in kelp mariculture in an effort to make kelp farming as efficient and profitable as possible.