Diversifying the New England Sea Vegetable Aquaculture Industry: Modification of kelp nursery and grow-out technology for nori production

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Christopher Neefus UNH - Department of Biological Sciences Principal Investigator
Michael Chambers N.H. Sea Grant Collaborator
Sarah Redmond Maine Sea Grant Collaborator
Paul Dobbins Ocean Approved, LLC Industry Partner
Matt Moretti Wild Ocean Aquaculture Industry Partner

Sea vegetable aquaculture in New England is based solely on production of sugar kelp (Saccharina latissima) using long-line kelp production methodology developed in our previous N.H./CT Sea Grant project. The proposed project would diversify the industry by developing techniques and procedures for growing nori on long-lines using the same equipment, and methods that are very similar to kelp aquaculture. Nori production will be based on Wildemania amplissima, a native nori species that can grow to 2 meters in length. Kelp is grown during the winter, while nori grows from spring to early summer. Growing both sea vegetables can extend the production season without requiring additional laboratory, nursery or grow-out facilities. Nori is an attractive, nutritious sea vegetable that can be marketed through the same channels as sugar kelp.

The first objective of the project will be to establish stock cultures of W. amplissima and determine optimal laboratory conditions for maintain the culture and inducing the release of spores to seed lines for grow-out. Field trials will be conducted during the second year at lease sites in Maine (Ocean Approved, LLC and Wild Oceans, LLC) and New Hampshire (UNH Research Pier Aquaculture Farm). A Nori Long-Line Grower’s Manual and accompanying video will be produce. Workshops for potential nori growers will be held during the second year.


In the broad sense, the objectives of the proposed project will be to utilize the established methods from our previous project (Development of seaweed culture system technologies to support integrated multi-trophic aquaculture and sea vegetable aquaculture in New England coastal waters) to initiate cultures of Wildemania amplissima (a North Atlantic species of nori), to optimize the production of nori seed strings using the same equipment used for kelp, to provide seeded lines to existing kelp growers for initial long-line nori field trials, and to provide training and nursery technology to commercial growers. Specific objectives include:

1. To collect nori (W. amplissima) from several sites and establish laboratory cultures.

2. To determine optimal conditions for nursery production.

3. To develop simple string seeding procedures similar to kelp seeding methods.

4. To determine optimal light, temperature and daylength parameters for blade growth on seed strings.

5. To conduct field grow-out trials at two sites in Maine and one in New Hampshire.

6. To work directly with our industrial partners to get them started with nori nursery production for long-line aquaculture.

7. To develop a manual and video for nori nursery and long-line grow-out methods.

8. To work with Maine and New Hampshire Sea Grant Extension personnel to present workshops for nori long-line production.


Laboratory methods developed in our previous Sea Grant project will be used to establish cultures of Wildemania amplissima and to determine the optimum laboratory conditions to promote spore release for seeding spools of synthetic line. Grow-out methods will be essentially the same as those currently used by New England growers for sugar kelp.


The fledgling New England sea vegetable industry is based on long-line production of sugar kelp. Sugar kelp is grown during the winter, harvested in early spring. Harvested kelp is cut into "noodles," frozen, and marketed through national retail markets such as Whole Foods. There is an established market in the U.S. for the red sea vegetable nori. In New England, nori is harvested from the wild, dried and sold through multiple retail channels. Demand has exceeded the supply. Wildemania amplissima is a species of nori that occurs only in the North Atlantic during the spring and early summer. Unlike other nori species, it is large enough to grow on long-lines. Long-line nori production will allow New England kelp producers to diversify their operation with a crop that will extend their growing season while utilizing their existing equipment.



N.H. Sea Grant researchers establish cultures and improve techniques for nori culture in New England

N.H. Sea Grant-funded researchers established stock cultures and determined optimum lab conditions for a native species of the edible seaweed nori in 2015, which will help to extend the sea vegetable production season in New England for aquaculturists.
Relevance: Sea vegetable aquaculture in New England is based solely on the production of sugar kelp. Scientists and aquaculturists want to diversify the industry and extend the growing season by developing techniques similar to kelp long-line production for Wildemania amplissima, a native species of the edible seaweed nori.
Response: In 2015, N.H. Sea Grant-funded researchers established and maintained 24 cultures of W. amplissima. They also improved the culture system used for nori grow-out in the lab and installed a monitoring system that will report deviations from optimum conditions.
Results: Establishing stock cultures and determining optimum lab conditions for W. amplissima is the first step in helping to seed long-lines to be able to grow nori in aquaculture. These techniques will help aquaculturists to grow nori in spring and early summer. Since kelp is grown in the winter, this extends the sea vegetable production season without requiring additional laboratory, nursery or grow-out facilities.


N.H. Sea Grant researchers develop protocol to establish young life phase of nori seaweed in a laboratory setting
Sea vegetable aquaculture in New England is currently limited to sugar kelp production in the winter using long-lines. Nori, a type of red seaweed used for sushi, is a very popular species on the worldwide market and grows in spring and early summer, but techniques to grow the species in New England have not previously been optimized. In 2014, NHSG-funded researchers developed a protocol to establish cultures of the conchocelis life phase of nori seaweed. This protocol will help aquaculturists to seed spools of line for growing nori at aquaculture sites in N.H. and Maine. The ability to grow both sea vegetable species will extend the production season without requiring additional laboratory, nursery or grow-out facilities, thus helping to diversify the sea vegetable industry in Northern New England.

NHSG researchers construct seeding and nursery equipment for kelp and nori production
Nori is a species of red seaweed that is very popular on the worldwide market, most notably for its use in sushi. Although sea vegetable production in New England is currently limited to kelp, nori might serve as a nutritious and profitable addition to the aquaculture efforts taking place in Maine and N.H. With funding provided by N.H. Sea Grant, researchers constructed seeding and nursery equipment in 2014 to produce kelp lines for grow-out and nori nursery production. This equipment, housed at UNH’s Durham campus and at the UNH Coastal Marine Lab in New Castle, N.H., will help aquaculturists to optimize the process of growing two different species, thus helping to diversify the sea vegetable industry in Northern New England.


Available from the National Sea Grant Library (use NHU number to search) or NH Sea Grant

Journal Article

  • Green, L. and C. Neefus (2014). The effects of short- and long-term freezing on "Porphyra umbilicalis" Kützing (Bangiales, Rhodophyta) blade viability. Journal of Experimental Marine Biology and Ecology 461:499-503, 2014.
  • Green, L. and C. Neefus (2015). Effects of temperature, light level, photoperiod, and ammonium concentration on Pyropia leucosticta (Bangiales, Rhodophyta) from the Northwest Atlantic. Journal of Applied Phycology 27(3):1253-1261, June 2015.
  • Green, L. and C. Neefus (2015). Effects of temperature, light level, and photoperiod on the physiology of Porphyra umbilicalis Kutzing from the Northwest Atlantic, a candidate for aquaculture. Journal of Applied Phycology, published online 12 September 2015.