The Genius of Fishing with Tidal Weirs

Kata Karáth
Published on April 6, 2022

Kata Karáth is a freelance journalist and documentary filmmaker. Her work has actually appeared in The Guardian, Science Magazine, Quartz, and New Scientist, among others. She is based in Ecuador.


Seen from the air, the Micronesian state of Yap is a jewel-green archipelago of thick forests patched with taro fields, fringed by mazes of mangroves, and cut by reef. And, fanning out from the wreck lines into the turquoise shallows like a frill of beaded tassels is a geometric design of rock structures that are formed like arrows, beech mushrooms, or penises. The Yapese call these structures aech, and they are tidal fish dams, among the worlds most common Indigenous mariculture tools.
“Whatever fish I catch inside the aech is a sign of luck. Ganang, who is 66, fondly recalls how, when he was still a boy, his father, Laman, took him to the faluw– a conventional maless house in Yap– to teach him whatever about fishing, including how to utilize aech.
GONE FISHING: A fishing dam in the Micronesian state of Yap. The “arrow” of stone walls traps fish at high tides.
The mechanics of tidal dams are basic: They are made from walls, differing in shape and size. (In Yap, weir walls are built of stone, however in other regions of the world a traditional dam can have a stone base with short-term wood structures constructed on the top, or it can be made entirely out of wood.) High tide immerses these walls, letting fish swim within them freely, however as the tide lessens, the fish gets caught in the chambers. Then, fishermen– in Yap, generally, fishing is a mans task– can use butterfly webs called k ef to capture fish, or herd it toward dam baskets woven of split green bamboo stalks laced with coconut cord, which are immersed and attached to completion points– the arrowheads barbs– of the aech. If anglers are searching for a larger catch for a neighborhood occasion, they utilize leaf brooms made from coconut fronds twisted about a long rope to herd the fish into weir baskets or webs.
More than 800 tidal weirs, in between 65 to 650 feet in length, are spread across the 4 islands that make up Yap, according to William Jeffery, an Australian-born marine archaeologist at the University of Guam, some 500 miles north of Yap. In 2008, the group of Yap Main Island standard chiefs known as the Council of Pilung, along with the Yap Historical Preservation Office, hired Jeffery to survey all of Yaps surviving and undocumented tidal dams.
Western-trained scientists are starting to acknowledge what Indigenous specialists have understood for countless years.
Like many types of Indigenous mariculture worldwide, fishing with aech has fallen out of use for a variety of reasons that vary from colonialism, moving far from nourishment to industrial fishing, the accessibility of modern fishing equipment, city migration, globalization of food products, and just loss of interest. The Council fears that, considering that fishing with aech is no longer a typical practice that is given to more youthful generations, the ancestral understanding associated to the aech construction and usage will be lost.
In the last 2 years, from the aechs in Yap to clam gardens throughout the Pacific Coast of North America, the revitalization of Indigenous mariculture is making headway across the globe. “In an aech, you can see which fish you want to capture, and set a limitation on how much is enough to feed the family,” states Ganang. “Modern internet capture all sizes of fish, little ones can get stuck and tangled.
Tidal dams were designed to lessen or avoid overfishing, and even motivate fish breeding, Iwabuchi describes. In the weirs, the gaps in between the rocks allow young, small fish to pass through easily, while predators are kept outside. Big fish become caught in the dam, so anglers just harvest adult fish.
Native communities currently handle more than 40 percent of Earths ecologically undamaged landscapes. As industrialization and environment change continue to diminish marine resources while fish usage is on the rise, there is an urgent, around the world need for sustainable fishing and aquaculture. Given that 1961, international fish intake has actually increased at approximately 3.1 percent each year– a rate two times as high as the annual worlds human population development for the exact same duration, according to a 2020 report by the United Nations Food and Agriculture Organization. On the other hand, the portion of fish stock captured at biologically unsustainable levels has more than tripled, from 10 percent in 1974 to 34.2 percent in 2017.
The ingenuity of tidal weirs in Yap and around the world– from the kaki in Japans Okinawa island to the hadra in Kuwaits Failaka island, the wood fish weirs along the French coast of Brittany to the corrales de pesca in Chilean Patagonia– lies in their simplicity. Indigenous coastal communities, based upon their built up understanding of local environments, have adapted the weirs to specific coastal topographies and seascapes.
OCEAN RENEWAL: Members of the Heiltsuk Nation in British Columbia recently developed this fishing weir utilizing conventional methods. Picture by Bryant DeRoy.
The Yapese think that the aech represent an unified relationship in between mankind and the ocean. The very first seven aech, the Yapese say, were developed more than 1,500 years ago by spirits who assumed the type of guys, eels, or females, to show humans how to build the dams and discover how to fish in a sustainable manner. However the details of the aech origin tale have actually eroded with time. “All I understand is that this aech belonged to [my dad] Laman,” says Ganang. “Most of the stories and legends of this aech are long gone.”
The Yapese anglerss understanding of sea currents and tides and of fish population, migration, and behavior dynamics have permitted them to tweak their aech to perfection and practice sustainable fishing for generations. Fish are caught at specified times, for just a couple of days in a provided month. Beyond these particular days, Yapese fishermen informed Jeffery, they make an opening in the aech to let fish come and go so that they “feel comfortable.” The fishing schedule, says Ganang, depends upon the weather condition, season, or time.
The majority of Indigenous salmon fishing communities from California to Alaska hold some kind of what they call the First Salmon Ceremony to this day, to honor the life-giving salmon. While the particulars of the event differ from culture to culture, each community enforces a short-term moratorium on fishing following the occasion.
The Yapese think that the weir represents an unified relationship in between mankind and the ocean.
Catches from tidal dams play a considerable role in communal health. Freshly caught fish and other seafood are greater in nutrients than imported, processed food. Fishing with tidal dams is typically carried out by multiple families, so that the catch might be shared, and, traditionally, throughout difficult times such as epidemics, tropical cyclones, dry spell, or starvation neighboring villages supported each other. The COVID-19 pandemic has currently put some Indigenous mariculture methods to a contemporary test and proved them to be a source of strength. A recent research study released in Marine Policy demonstrated that most rural Pacific neighborhoods had actually handled to guarantee food security in the early months of the pandemic thanks to standard practices of regional food production and food sharing.
“One crucial objective is supplying chances for community members to connect with one another, and to tell stories on the beach,” says Melissa Poe, an applied environmental social scientist at Washington Sea Grant, which is dedicated to marine and seaside research, outreach, and education in Washington state. Harvesting standard foods and sharing stewardship knowledge through generations is fundamental to Indigenous cultural identity and helps reinforce neighborhoods connection to a location.
TIME-HONORED TRADITIONS: An angler sets a trap on a stone weir on Yap in 1908. Picture courtesy of William Jeffery.
Some neighborhoods along the northwest coast of Hainan Island still use such songs to direct them not just when utilizing tidal dams, however likewise other standard overseas fishing activities. Says Iwabuchi, there have not been any initiatives to restore neither the stone tidal dams nor the tidal tunes.
A number of elements are responsible for weirs decrease. Jeffery and other scientists believe that an extreme population decrease suggested that there was no need for large catches, and the labor-intensive use of tidal weirs was no longer warranted. Japanese colonizers, who occupied Yap primarily between the 2 World Wars, required the Yapese to speak Japanese, and altered their social structures through prohibiting them from leadership positions, prohibiting traditional spiritual practices, and damaging traditional council meeting sites, such as maless homes like the one where Ganangs daddy taught him about weir fishing.
Countries along the Pacific Coast have begun developing fish dams again. Modern technology has actually been available in convenient.
Comparable situations played out throughout the U.S. and Canada, where colonial policies severed access to sustainable salmon fisheries and other mariculture practices. Whole populations were by force removed from coastal locations. Between 1904 and 1905, the Canadian federal government forcibly eliminated fish weirs in the Babine River watershed in British Columbia, interfering with centuries of Indigenous management of Babine salmon. “At one time, it was unlawful for an Indian to own a fishing license,” says Housty, whose grandmother still utilized stone fish dams in the 1930s. The industrialization of fishing and urban migration prevent the robust recovery of conventional mariculture.
Still, over the last 2 decades, a growing number of seaside First Nations along the Pacific Northwest Coast of North America have actually started structure or bring back fish weirs, positioning them at estuaries or even higher up the rivers. Modern technology came in handy: “The very first dam that we in fact put together was from western red cedar,” states Housty. After each heavy rain, the Koeye River kept sweeping away the wood, and the Heiltsuk switched to aluminum.
Putting choices about mariculture in the hands of local management can press for more equitable fishing opportunities for both Indigenous and non-Indigenous communities. Examples consist of the Hui Mālama Loko Iʻa, a growing network of fishpond specialists and organizations in the Hawaiian island chain working on the revival of loko iʻa, which includes different types of conventional Hawaiian fishponds. The network presently includes over 40 fishponds and complexes that are handled by more than 100 loko i a workers, owners, and stakeholders.
Some tidal weirs and other Indigenous mariculture practices also help turn the tide on colonial disenfranchisement of Indigenous populations. In Japan and Yap, regional groups have actually reconstructed tidal weirs not just for fishing, however to protect the conventional environmental knowledge that comes with it, and so enhance cultural tourist and environmental education. Among various standard practices, fish weirs assist fisheries to measure, tag, release, and later recapture salmon, which offers indispensable information to examine fish stocks, strategy and change harvest levels, and figure out elements limiting salmon recreation.
In Yap, there arent many individuals left who really know how to build aech. Figuring out how to develop aech effectively was another factor why the Council of Pilung wanted Jeffery to survey websites and interview aech owners. As of today, The Yapese Historical Preservation Office has actually just handled to bring back a single aech.
Administration can also stand in the method. Housty says the Canadian Department of Fisheries and Oceans at first treated their fish weir job with a lot of uncertainty. He believes they were fretted that the direct, scientific data the weir was going to bring in would contradict some of the management decisions they had actually made over time.
This might change in the future, as there is an interest in integrating the standard ecological management that comes along with the use of stone tidal fish weirs into the management of MPAs. Conflict between recuperating traditional aquaculture methods and marine preservation is playing out in other areas, too: On the island of Molokai, for example, Hui Malama O Moomomi are pushing Hawaii state lawmakers to acknowledge their plan to maintain the conservation of the Moomomi Community-Based Subsistence Fishing Area, which would enable Native Hawaiians to collect fish in Moomomi Preserve, the last stronghold of a significant Hawaiian coastal community.
Ganang says his kid who lives in the U.S. has actually only seen images of aech on the web, however he is eager to discover how to fish with them. Up until the legalities around traditional fishing within an MPAs are lastly untangled, Ganang can only see from the shore as the fish feel at home in his aech.

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The Yapese call these structures aech, and they are tidal fish dams, one of the worlds most common Indigenous mariculture tools.
Fishermen– in Yap, traditionally, fishing is a mans job– can use butterfly nets called k ef to capture fish, or herd it towards dam baskets woven of split green bamboo stalks laced with coconut cord, which are submerged and connected to the end points– the arrowheads barbs– of the aech. Big fish ended up being trapped in the dam, so fishermen just collect adult fish. The very first seven aech, the Yapese state, were constructed more than 1,500 years back by spirits who assumed the form of guys, ladies, or eels, to reveal people how to build the weirs and learn how to fish in a sustainable manner. Amongst numerous traditional practices, fish dams assist fisheries to determine, tag, release, and later recapture salmon, which provides vital information to assess fish stocks, plan and adjust harvest levels, and identify aspects restricting salmon recreation.

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