Progress report for FW23-415
Project Information
Kelp farming is a relatively new method of food production in Alaska, with the first commercial harvest in 2017. Kelp farming in the U.S. began with the deployment of a submerged horizontal line (rope) seeded with spores that grow to harvestable size in six months. The conventional single-line approach takes up a lot of ocean space and tends to sag deeper than desired. Without wide spacing between these lines, tangling can occur, causing loss of crop or damage to the lines.
In Prince William Sound, Noble Ocean Farm is one of three commercial farms growing kelp (seaweeds) for food. During the first season, these farms struggled to keep the underwater array system (anchors, lines, buoys, connection points) tensioned during large tidal fluxes. We experienced equipment failures and lower crop density compared to kelp farms in other areas. This is a common issue for kelp farmers in Alaska, most of whom are struggling to achieve profitability.
As the seaweed farming industry expands, it is important to optimize kelp growth per foot of seeded line and per acre of farmed lease. Therefore, our research questions are: 1) How do we grow the most amount of kelp in the smallest footprint? And 2) What is the minimum amount of spacing allowable between lines?
Recently, our Technical Advisor, Clifford Goudey, developed novel 5-line and catenary arrays. These allow close line spacing, powerful tensioning to prevent tangling, and numerous other advantages over present practices.
We will conduct a side-by-side comparison of a conventional single-line array, a 5-line array, and a 25-line catenary. Metrics will include: kelp growth per foot, ocean space used, costs, and array performance. This research will identify the most efficient configuration to inform current and future kelp farmers' design decisions. Results will be shared via a workshop, farm tour, and fact sheets.
Research Objectives:
- Determine the efficiency of various kelp farm systems in producing kelp biomass.
- Characterize the pros and cons of kelp farming system options with respect to equipment, installation, monitoring, and labor costs vs. crop harvested.
- Compare monthly growth, quality, and end-of-season biomass harvests per foot and per acre among the farm systems tested.
Education Objectives:
- Inform present and aspiring seaweed farmers about opportunities in kelp farming.
- Explain farm system options and their pros and cons using a hand-on educational workshop.
- Show three different array systems to current and aspiring farmers, including early career mariculturists from the local and nearby communities.
- Create fact sheets to disseminate our research findings to kelp farmers throughout the entire Western United States via email and social media networks.
| Dates | Activities | Task | Team Members |
| August 1, 2024 | Team meeting | Project starts - ACCOMPLISHED | Melissa Skye Steritz (PI), Clifford Goudey (TA), Sean Den Adel |
| August-October 2024 | Build & install farm systems (arrays) before planting sugar kelp seed in October | Research Task 1 - ACCOMPLISHED | Sean Den Adel, Clifford Goudey (TA) |
| January-May 2025 | Monitor kelp growth on different array types & quantify efficiency of array types by comparing crop growth data & costs |
Research Tasks 2 and 3 - IN PROGRESS |
Melissa Skye Steritz (PI), Clifford Goudey (TA) |
| April-June 2025 | Determine pros & cons of array types | Research Task 4 - IN PROGRESS | Sean Den Adel, Clifford Goudey (TA) |
| February-March 2025 | Plan workshop in Cordova | Education Task 1 - IN PROGRESS | Melissa Skye Steritz (PI), Clifford Goudey (TA), Sean Den Adel |
| February-March 2025 | Invite stakeholders to workshop | Education Task 2 - IN PROGRESS | Melissa Skye Steritz (PI) |
| March 2025 | Host workshop in Cordova with online option | Education Task 3 - IN PROGRESS | Melissa Skye Steritz (PI), Clifford Goudey (TA), Sean Den Adel |
| March 2025 | Perform targeted outreach for farm tour | Education Task 4 - IN PROGRESS | Melissa Skye Steritz (PI) |
| April 2025 | Facilitate farm tour | Education Task 5 - PLANNING | Sean Den Adel, Melissa Skye Steritz (PI) |
| May-June 2025 | Develop factsheet | Education Task 6 - PLANNING | Melissa Skye Steritz (PI), Clifford Goudey (TA) |
| June-August 2025 | Distribute factsheets | Education Task 7 - PLANNING | Melissa Skye Steritz (PI) |
| August 2025 | Project reporting & submission | Project conclusion - PLANNING | Melissa Skye Steritz (PI) |
Cooperators
- - Producer
- - Technical Advisor
- - Technical Advisor
- - Producer
Research
Research Objectives:
- Determine the efficiency of various kelp farm systems in producing kelp biomass.
- Characterize the pros and cons of kelp farming system options with respect to equipment, installation, monitoring, and costs vs. crop harvested.
- Compare monthly growth, quality, and end-of-season biomass harvests per foot and per acre among the farm systems tested.
We will meet these research objectives using the following steps:
Research Task 1: Installation and seeding of test arrays
In the Noble Ocean Farms’ 22-acre aquatic farm lease, we have installed three different types of kelp farm array systems side by side for comparison: one conventional single-line array, one novel 5-line array, and one novel 25-line catenary array.
Noble Ocean Farms has a 10-year lease through the Alaska Department of Natural Resources. This site is in the western arm of Simpson Bay in Eastern Prince William Sound.
Throughout this proposal the term array means a farming system that supports neutrally buoyant grow lines at a specific depth below the surface, supported by surface floats and held in position by other lines and anchors.
1,200 feet total of native sugar kelp was seeded on horizontal suspended grow lines in the fall of 2024. This total amount accounts for all three array types.
During our planting in October of 2024, the grow lines on the arrays were carefully and tightly wrapped with kelp seed string containing thousands of tiny kelp sporophytes. The holdfasts (roots) of the kelp now seems to have transferred from the seed string and attached directly to the grow lines.
We are seeing more productivity (longer kelp blades) during the month of February than we have seen before.
The three different array types are all rigged with 200’ and 400’ grow lines, and aligned with the dominant tidal currents in Simpson Bay. Cross-sectional and design views of each array type are shown in the attachment "Maps and Figures" within the Other Documents section, along with site maps.
The single-line array has been spaced according to normal practice, which is 40’ from any neighboring arrays and aligned with the dominant tides. This is the most common, straightforward design for growing kelp in the United States, yet farmers have struggled with tensioning, efficiency, and productivity using this conventional single-line design. The single-line array is performing amazingly well for this time in the season (February) with denser growth than the two other array types.
The 5-line arrays are fitted with two 10’ aluminum end spreader bars and one mid-line spreader bar, with the grow lines spaced 2.5’ apart. The design of the 5-line array expands on the basic single-line approach, incorporating aluminum spreader bars that allow precisely measured grow lines to be used in close proximity without tangling or overlapping. Spreader bars theoretically can enhance the productivity of the farm by allowing farmers to seed kelp on more grow lines using the same or even less ocean space. Additionally they allow us farmers to save money on anchors because you can deploy multiple grow lines using two anchors, rather than deploying a single-line array, also using two anchors. The hope is to boost the growing capacity without increasing the site footprint. Currently, our 5-line array is also performing quite well for this point in the season, only slightly behind the single-line array.
The catenary array is by far the largest of the three array designs, with a width of 75’ and including a total of 50 grow lines, spaced 3’ apart. Each of these grow lines are approximately 200' long. This array type allows farmers to use more grow lines than other arrays and create optimal underwater tensioning.
A curved horizontal line is used as the catenary framing line. This secures grow lines to the anchor system. The grow lines are pretensioned with equal force and precisely measured before installation. The catenary array is designed to benefit farmers by increasing productivity per area, profitability and efficiency.
Interestingly, this catenary array system, which we had the most hope for, is showing less consistent kelp growth so far (as of February 2024). Some of the lines have succeeded while others have completely failed (probably related to variable seed quality). The most biofouling has also occurred on the catenary arrays (unwanted growth of undesirable, wild macroalgae and animals).
The farm systems was installed by Noble Ocean Farms’ partner team: Melissa Skye Steritz and Sean Den Adel. Seeding of all grow lines utilized seed spools from the Alutiiq Pride Marine Institute in Seward, Alaska. Once seeded, the systems were tightened to provide the level of pre-tension needed to control vertical sag, keeping all grow lines to the optimal 6’ of submergence.
This task was led by Sean Den Adel at Noble Ocean Farms with the technical advice from Clifford Goudey and using key farm supplies provided by TendOcean™.
Research Task 2: Determination of the installation and operational efficiency of various kelp farm array systems
We are currently working on compiling our data, including costs of equipment, supplies, and labor associated with each array system. This includes the entire course of the kelp season, from installation, through harvest, and including seasonal gear removal. Hours of labor required to build, install and maintain each individual farm system will be recorded, so future farmers know how labor efficiency varies based on design.
This data collection and complication task is being led by Melissa Skye Steritz at Noble Ocean Farms with the technical advice from Clifford Goudey.
Research Task 3: Measurement of the monthly growth, quality, and end-of-season biomass harvests
All systems and grow lines are now being checked on an every two-week, regular basis to maintain pretension, measure growth, and evaluate the performance of each system with respect to grow line interactions and the presence of any inter-line tangles. We record data during each farm monitoring visit.
As the crop grows, parameters including stipe (stalk/stem) counts per foot of grow line, average stipe lengths, average blade (leaf) lengths and the presence of any competing organisms are being entered and recorded in an Excel spreadsheet.
At harvest time, the harvested crop from each grow line will be collected and weighed to determine the average harvest per foot of line. The quality of each line's harvest will be assessed based on subsamples of stipe and blade length.
This task will be led by Melissa Skye Steritz at Noble Ocean Farms with the technical advice from Clifford Goudey.
Research Task 4: Characterization of the pros and cons of kelp farming array system options tested.
The results of Tasks 2 & 3 will be used to determine the efficiency of each type of farm system based on harvested pounds vs. the associated costs. We will convert the growth per foot of line into growth per acre of ocean space used.
This task will be led by Sean Den Adel at Noble Ocean Farms with the technical advice from Clifford Goudey.
Research Outcomes
Since there were significant logistical challenges that prevented farming, Noble Ocean Farms and Cliff Goudey needed to delay the project for one year. Currently, the project team has installed the new gear and is in the process of collecting data, while testing the three kelp farming array types side-by-side over the course of the growing season.
In March, we are looking forward to sharing our preliminary data with interested mariculture industry stakeholders, including prospective kelp farmers in our area. Then, following our final harvest in May, we will make our final recommendations and share our results.
Education and Outreach
Facilitated hands-on experience building kelp arrays
Participation Summary:
Education Objectives:
1. Inform present and aspiring seaweed farmers about opportunities in kelp farming.
We have been informing present and aspiring seaweed farmers about the three array types we are using this growing season, including reporting to the GreenWave Farmer Cohort our challenges and successes associated with gear work/array preparation, deployment, and maintenance. For example, we had challenges installing the aluminum spreader bars of the novel 5-line system, so we shared that with the group.
2. Explain farm system options and their pros and cons using a hand-on educational workshop.
This educational kelp farming workshop is set to take place on March 25th, 2025. Currently we are in the planning process, creating slides for this workshop and developing a flyer to raise awareness and hopefully increase attendance and participation.
3. Show three different array systems to current and aspiring farmers, including early career mariculturists from the local and nearby communities.
We are currently planning for our farm tour(s) to take place in April. It will probably be two different dates, with 4-6 people on each farm tour in order to allow for more a safe and in-depth experience. In March, we will perform targeted outreach for our April farm tours. We will invite both current and future Cordova-based farmers as well as those in neighboring communities within Prince William Sound.
4. Create fact sheets to disseminate our research findings to kelp farmers throughout the entire Western United States via email and social media networks.
This will be our final educational task -- synthesizing and analyzing all of the data from the three array types, creating an accessible/digestible factsheet, and performing dedicated outreach to disseminate the factsheet that summarizes our finding and recommendations. This will be completed by June/July 2025.
We began educational and outreach activities in the summer of 2024, beginning to engage other producers and underserved community members about sea vegetables, like kelp, and mariculture in general. We hosted a community potluck called "Taste of Cordova" in order to celebrate local foods and help people understand the different ways that sea vegetables can be consumed in delicious and nutritious dishes. There was quite a bit of engagement, with at least 12 people bringing homemade dishes and more than 100 people participating in the tasting.
Additionally, we engaged with local current and prospective farmers as we built our three array systems this fall. We invited six people and provided them with a hands-on experience connecting grow lines together and attaching them to the perimeter array structure, so they will know how to do this on their own farms in the future.
The rest of the educational objectives will be completed in the coming spring and summer season.