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Kelp reproduction and harvest rebound in Kachemak Bay, Alaska

Investigator

Brenda Konar Brenda KonarCollege of Fisheries and Ocean Sciences
University of Alaska Fairbanks

Student

Synopsis

This project will supply managers and harvesters of seaweeds with vital information that is needed to ensure successful management and sustainable harvesting of two kelp species and one rockweed species in southcentral Alaska. This project was developed through discussions with managers at the Alaska Department of Fish and Game (ADF&G) and will address questions they have regarding seaweed harvesting. This research also is relevant to the Alaska Sea Grant Strategic Plan. It will support Healthy Coastal Ecosystems by increasing knowledge on Alaska’s diverse and productive coastal ecosystem addressing harvesting concerns of management (ADF&G). In addition, this research will support Sustainable Fisheries and Aquaculture by providing knowledge that will facilitate the sustainable use of harvested marine resources. Lastly, this research will address Resilient Communities and Economies by providing managers with information that is needed for the regulation and permitting of commercial seaweed harvesting.

Currently, kelp mariculture research focused on the sugar kelp, Saccharina latissima is funded by Sea Grant in southeast Alaska. This project will compliment that research by asking questions of the wild populations of S. latissima, the bull kelp, Nereocystis luetkeana, and the rockweed, Fucus distichus in southcentral Alaska as it relates to harvesting. Specifically, researchers will determine the timing of reproduction and the size that adults become reproductive. They will also determine temporal variability in in situ harvestable biomass and will compare these harvestable measurements with regrown biomass to determine biomass rebound rates of harvested areas. Finally, researchers will examine beach wrack for potential harvestable biomass and the reproductive potential of beach-cast seaweeds. The results of this research will be shared with managers, researchers, and the public through various venues, including presentations at meetings, a peer-reviewed publication, outreach events, and informational flyers/posters. Approximately 100 Homer Middle School students will participate in this project.

This project was highlighted in July 2018 by KTVA, Harvesting Alaska: New research could change seaweed rules

Overview

The issue

Currently, about 25 million tons of seaweeds are harvested annually for use as human food or a food additive, in cosmetics, dietary supplements and fertilizers, or used as an additive to animal feed (FAO 2014). Of the various species known, less than 20 species account for 90% of the biomass exploited commercially (Pereira 2015). Some of these seaweeds are harvested from the ocean and some are farmed. The harvesting of seaweeds in Alaska is managed by the Department of Fish and Game, Division of Commercial Fisheries. In southcentral Alaska, harvest was allowed until an overharvest was perceived in the Seward area about 15 years ago. This potential overharvest resulted in regulatory restrictions being implemented by the Alaska Board of Fisheries. Currently, along much of southcentral Alaska, seaweed harvesting for personal, noncommercial use is prohibited; however, remote areas that are not adjacent to the road system are open to subsistence harvest. For example, Cook Inlet is currently closed to the taking of aquatic plants; however, there are two subsistence areas that are open. These have a 10 pound wet weight daily bag limit (5 AAC 37.320): the Tyonek subsistence area in western Cook Inlet, and the Lower Kenai Peninsula between Jakolof Point and Rocky Bays. In the closed areas, harvest is prohibited both for attached and growing seaweed, as well as detached seaweed that has washed up on beaches. Illegal harvest primarily of washed up seaweed is ongoing (Hollowell pers. comm.). In addition, the Homer office typically gets 1–2 requests each year for a commissioner’s permit to conduct commercial seaweed harvests. So far, no one has followed through with these requests and no permits have been granted; however, one mariculture farmer in Kachemak Bay has applied for and received a permit to remove and sell seaweed that is fouling their gear. In addition, in recent weeks a permit was granted to a commercial operator at Anchor Point outside of Homer to harvest washed up seaweed for use as a component in marketed ready-to-use compost.

The issue/problem is that seaweed harvesting is currently prohibited in much of southcentral Alaska but people are illegally harvesting live/attached seaweed off beaches and unattached seaweed that has washed up on beaches (wrack) without any knowledge of potential impacts to the sustainability of these populations. Some of this harvesting is legal (done in legal areas within appropriate bag limits) and some is done illegally (done in closed areas or over-harvesting). The Department of Fish and Game is missing vital information needed to sustainably manage seaweed in the Gulf of Alaska. I have worked with managers at Fish and Game to develop the questions in this proposal, which are the most pressing questions around this issue.

I will focus this study on some of the most harvested seaweeds, the sugar kelp, Saccharina latissima, the bull kelp Nereocystis luetkeana, and the rockweed Fucus distichus. These seaweeds are primarily harvested in the summer by local people for food and dietary supplements and in the spring and fall for garden fertilizer. They are very common in the Gulf of Alaska and are easily accessible to people at low tides. The bull kelp is even accessible at high tides if you have a small boat. This kelp has a gas-filled structure (pneumatocyst) that floats on the water surface. A person on a boat can grasp one of these structures and pull up on the plant and cut the plant along the stipe at some point below the surface. People often harvest Nereocystis stipes for salsa or pickles and blades for chips. Currently, there are websites with incorrect information about kelp harvesting.

Why is this an Alaska Sea Grant project?

This research is relevant to the 2018–2021 Alaska Sea Grant Strategic Plan. It supports Healthy Coastal Ecosystems by increasing our knowledge on Alaska’s diverse and productive coastal ecosystem addressing harvesting concerns of management (ADF&G). In addition, this research will support Sustainable Fisheries and Aquaculture by providing knowledge that will facilitate the sustainable use of harvested marine resources. Seaweeds, and kelp in particular, are of much economic and ecological importance and as such need improved information that can be used to help maintain sustainable harvesting while keeping the ecosystem healthy. ADF&G managers will use the results of this study to better regulate the harvest of various seaweed populations in southcentral Alaska. This research will also address Resilient Communities and Economies by providing managers with information that is needed for the regulation and permitting of commercial seaweed harvesting. Currently, ADF&G are lacking the information needed to manage seaweed harvesting (personal consumption and commercial harvesting). There are limited data as to when seaweed are reproductive in Alaska and no data on the size most seaweeds become reproductive, how much biomass can be harvested while still sustaining the local populations and what the rebound rates are for these harvested areas. Even more concerning is the lack of any information on beach-cast seaweeds (in particular their harvestable biomass and reproductive status). This project will assist ADF&G to better manage the harvest of seaweeds in Alaska.