Fish Weirs Research Articles

Middelalderfiske, fellefangst og fraflytting: En dendrokronologisk undersøkelse av et 1300-talls stasjonært fiskeanlegg i Nord-Mesna, Sørøst-Norge

Fishing in rivers and lakes has traditionally been a longstanding and dependable means of sustenance for the people of inland Scandinavia. However, our understanding of pre-modern fishing traditions has been hampered by a lack of written sources, as well as a scarcity of archaeological data. However, a recent excavation and comprehensive dendrochronological analysis of a fish trapping enclosure system in Lake Nord-Mesna (520 masl.), in the boreal forests of inland Norway, has provided unique insight into freshwater fishing traditions, techniques and organization. The excavated structure, believed to be a fish weir with lath screen traps set into shallow water, was established in the late 1200s. In the following years it was regularly maintained in the spring/early summer. The last documented repair was in 1343. Its abandonment is interpreted as resulting from a recession likely induced by factors such as plague and climatic deterioration, that affected inland areas of Scandinavia in the 1300s. These results provide archaeological evidence of medieval utilization of effective enclosure traps in the region. This contradicts the prevailing notion that this form of fishing was later introduced by Forest Finns who migrated to the area in the 17th century. In addition, the findings give new and significant information about the organization and practice of medieval fishing in inland Scandinavia.

Evolution of stone fish weirs in Jibei area, Penghu Archipelago (eighteenth to twenty-first century)

ABSTRACT Jibei Island, in Taiwan's Penghu area, is famous for its abundance of stone fish weirs (SFWs). This research used historical charts, archives, and high-resolution orthophoto images for the SFWs mapping and spatial pattern analysis exercise. We found that the birthplace of SFWs was in the southern part of Jibei Port and Mudou Isle. In the early stage of the Japanese governing period (1895–1945), SFWs were mainly constructed in the North and North-West parts of the Jibel Isle and gradually migrated toward the east and north. In the middle to late Japanese governing period, the SFWs’ construction hot zone was in the South-West and South-East sides of the Jibei Isle. Understanding the SFW's evolution in the Jibel area is critical for local and regional cultural history, offering insights into land use and fish culture in Penghu and shedding light on ancient fishing culture in the broader pan-Pacific region.

Garnys: An underwater riverine site with delayed Neolithisation in the southeastern Baltic

This paper presents the first results of both dryland and underwater investigations at the multi-period Garnys riverine site situated on the Žeimena River in eastern Lithuania. There, during 2017–2020 a professional diver and amateur archaeologist collected hundreds of Mesolithic-Neolithic archaeological finds made of wood, bone, antler, stone, and ceramic from the riverbed and on its bank. Moreover, in eroded places of the riverbed, the wooden remains of several fish weirs were observed. In 2021 professional archaeologists continued the research, including field investigations followed by various laboratory analyses. These included AMS 14C dating of 16 various ecofacts, artefacts and wooden constructions, wood and animal taxa determinations, and the results of traceological analysis of the flint and osseous artefacts. Our research demonstrates that the site was intensively used for hunting, gathering and fishing during the Mesolithic and subsequent Subneolithic and Neolithic. Intriguingly, there was no evidence for agriculture, while the numerous Neolithic ceramics largely follow the Subneolithic traditions. The Garnys site is therefore unique and a clear example for delayed Neolithisation in a forested and lacustrine area in the eastern Baltic region. During the Metal Ages, the site had been used exclusively for stationary fishing.

Indigenous fish traps and fish weirs on the Darling (Baaka) River, south‐eastern Australia, and their influence on the ecology and morphology of the river and floodplains

ABSTRACTFish traps and fish weirs built by Indigenous people in the Barwon‐Darling River system of the Murray Darling Basin (MDB), south‐eastern Australia, are an important component of their traditional social, spiritual and economic systems. The celebrated Brewarrina stone fish traps (Ngunnhu) on the Barwon River are the largest and best documented stone fish traps in the Basin. However, there has been minimal research on the many other stone fish traps in this system. This paper focusses on the in‐stream stone fish traps downstream of Brewarrina along the Darling (Baaka) River, some still partly extant, remembered, or documented in historical material. Wooden and earthen bank fish traps and weirs, while not as enduring and archaeologically visible as stone fish traps, were frequently used on the Darling (Baaka) floodplain lakes, swamps and billabongs. Archaeological evidence, traditional cultural knowledge and historical materials are utilised to document the complex social processes and modification of landscapes associated with fish traps and weirs. By demonstrating that Barkandji were active and successful managers of the river and its ecology prior to colonisation, and that much of this cultural knowledge is retained by current generations, the authors make a case for them to renew their custodianship and a decision‐making role in water management.

왕손 사대부 집안의 충남 당진 어살터 지배와 분쟁 배경에 대한 연구 －서울대 규장각 소장 17~20세기 충남 당진 어전 문서를 중심으로－

이 논문은 서울대 규장각에 소장된 충청도 당진에 위치했던 漁箭과 관련된 소지 20점을 분석한다. 문서를 사건의 흐름에 따라 분류해 작성 연대와 주체를 확정한 후, 어구의 형태와 구체적인 설치 위치를 파악한다. <당진문서>는 17세기 말부터 20세기 초까지 해미 여미리에서 세거해 온 정종의 방계 후손이자 권세가 집안에서 작성했다. 이 집안은 1681년 『선원록』에 수록된 것을 계기로 당진 맹곶면 일대의 어살터를 입안 받기 시작했다. 이렇게 입안 받은 어살터는 당진 맹곶면 일대를 아우르는 매우 광범위한 지역이었고, 어살터에 설치된 어구도 어살 외 다양한 어구를 포괄했다. 이로 인해 어살터의 경계가 애매하고 권리가 포괄적이라는 점에서 출발부터 분쟁의 소지가 있었다. 어살터에 대한 권리는 권리자가 어구 설치에 필요한 자본을 어민에게 제공한다는 점에서 경제내적 관계에도 기초했지만, 본질적으로 어살터와 어민에 대한 입안․면세․면역이라는 경제외적 관계에 근거했다. 이로 인해 집안의 가세가 기울어 관리가 소홀해지면, 어살터에 대한 권리도 유지하기 어려웠다. 무엇보다 어살터에 대한 입안이 출발부터 국가의 공식적인 신분 질서에 기초해 일정한 구역에 대한 지배권을 위임받는 것이었기에 중앙의 정책에 따라 항상 거부될 수 있는 것이었다.

The social history of a medieval fish weir, c. 600–2020

ABSTRACT This article presents the longue durée social history of a medieval fish weir. It reveals the significant role of fishing and fish weirs in the construction and reconstruction of social structures and cultural identities. It focuses on an enigmatic annual ceremony – the construction of the Horngarth or Penny Hedge at Whitby, North Yorkshire. The article begins by arguing that the ceremony descends from the construction of a medieval intertidal fish weir, before exploring the possible social and cultural contexts in which the fish weir originated and the social and cultural circumstances that perpetuated its construction to the sixteenth century. It proceeds to consider the social and cultural changes that undermined its original function and transformed its significance in the sixteenth, seventeenth and eighteenth centuries, and how a tradition invented about it became important to the local identity and national reputation of the town.

Evaluation of Juvenile salmon passage and survival through a fish weir and other routes at Foster Dam, Oregon, USA

AbstractDownstream passage for juvenile Chinook salmon Oncorhynchus tshawytscha (Walbaum) and steelhead Oncorhynchus mykiss (Walbaum) through the fish weir at Foster Dam, Oregon, was evaluated to assess the weir's efficacy as a long‐term passage solution. Radio telemetry was used to estimate survival, passage and effectiveness for the fish weir, spillway and turbines. Survival of Chinook salmon through the fish weir varied by season and reservoir elevation (66%–87%), and passage proportions were low (8%–20%). Fish weir effectiveness was low to moderate (0.39–2.09). Steelhead survival was lower (57%–77%) but passed the fish weir in higher proportions (77%), and weir effectiveness was consistently high (2.96–5.49). The results indicate the existing fish weir will not be a suitable long‐term passage solution for all species. However, because of the high passage proportions and effectiveness observed for steelhead, further development of the surface‐flow concept appears to be promising for safely passing downstream‐migrating fishes.

THE NEKSELØ FISH WEIR AND MARINE RESERVOIR EFFECT IN NEOLITHIZATION PERIOD DENMARK

ABSTRACTThe Nekselø Wickerwork provides an unusually solid estimate on the marine reservoir age in the Holocene. The basis for this result is a 5200-year-old fish weir, built of hazel wood with a brief biological age of its own. Oysters settled on this construction. They had lived only for a short number of years when the fence capsized and was covered in mud and the mollusks suffocated. Based on the difference in radiocarbon (14C) age between accelerator mass spectrometry (AMS) samples of oyster shells and wood, respectively, the marine reservoir age for this site is estimated to 273 ± 18 14C years. Re-evaluations of previously produced data from geological and archaeological sites of Holocene date in the Danish archipelago indicate marine reservoir ages in the same order as that of the Wickerwork. Consequently, we recommend the use of the new value, rather than the ca. 400 14C years hitherto favored, when correcting for the dietary induced reservoir effect in radiocarbon dates of humans and animals from the Late Mesolithic and Early Neolithic periods of this region.

A review of the fishes and fisheries of Minas Basin and Minas Passage, Nova Scotia, and their potential risk from tidal power development

A total of 85 species of fish are known or suspected from Minas Basin and Minas Passage, Nova Scotia, Canada. This systematic review details their seasonal occurrence, habitat, abundance, migratory behavior, fisheries and potential impact from tidal power development. The fish assemblage is a mixture of species common to the Bay of Fundy and the Atlantic coast of Nova Scotia as well as numerous warm- and cold-water visitors seldom found elsewhere in Canada. Minas Basin fisheries exploit some species especially those that migrate through the Basin during summer. Fishes were captured or observed using angling, seines, benthic long lines, drift and fixed gill nets, intertidal fish weirs, bottom trawls and sightings while on vessels. Fishes are categorized with respect to their taxonomic diversity, seasonal occurrence, status, fisheries and the potential impact from tidal lagoons and propeller turbines resulting from development of tidal power in Minas Basin and Minas Passage. Keywords: Bay of Fundy, habitat, species status, propeller turbines, taxonomic relationship, tidal lagoons.

Fish Ladder Weir Modifications to Minimize Escapement

A fish ladder, weir, and raceway at Whitlock Spawning Station are used to capture and retain feral fall Chinook salmon (Oncorhynchus tshawytscha) for spawning from Lake Oahe, South Dakota. Nearly 40% of the salmon ascending the fish ladder have been documented to escape from the holding raceway by descending the ladder. This manuscript describes modifications to the weir that eliminated nearly all escapements, except for an inconsequential number of small non-spawning fish. The modified design using the existing structure incorporated free-swinging, spaced steel bars with a back-stop to create a one-way gate. The modified gate does not require springs, hydraulics, or electrical power. It is relatively simple to construct and requires minimal maintenance.

Diversity, abundance and size structure of fishes and invertebrates captured by an intertidal fishing weir at Bramber, Minas Basin, Nova Scotia

Capturing fish using a weir or trap on the intertidal flats of the Bay of Fundy was developed by native Mi’kamaq who later taught the method to the European settlers. Between 1800-1910 fish weirs were a significant part of the important American shad fishery in the inner Bay of Fundy before the collapse of the northwest Atlantic population from pollution and damming of major spawning rivers in the United States. Weirs remain an important segment of the Minas Basin fisheries but now the largest commercial catches consist of Atlantic herring, gaspereau and flounders. Studies on the fishes captured in Minas Basin weirs were published in 1852, 1924, 1984 and 2014, but all lacked a sampling intensity which would fully describe the diversity, abundance and size structure of the catch. An intertidal weir at Bramber, Minas Basin was surveyed during April-July, 2017 where catches were examined at each low tide. The weir was constructed on the intertidal flat during early April after Minas Basin cleared of drift ice. During the study period mean daily tide range was 10.46 m with a maximum spring tide range of 13.72 m. A total of eight neap and eight spring tide cycles were observed. Daily water temperature of Minas Basin was 8.0 C° during late May and increased to a maximum of 21.4 C° in late July. Fish and invertebrate collections began on April 10 and continued daily until July 22 when water temperatures in the trap became too warm for by-catch species to survive (+25 C°). During the study period an estimated total of 674,402 fishes consisting of 45 species were captured and of these 57,950 were measured. The most abundant fishes observed were gaspereau (alewife and blueback herring 51.9%), rainbow smelt (13.9%), Atlantic herring (13.0%) and tomcod (10.1%). Other commonly captured fishes were American shad, skate (little and winter), winter flounder, windowpane flounder, striped bass, mackerel and Atlantic sturgeon. A total of 18,511 invertebrates were captured and counted. The most abundant were long-fin squid (13.8%) and crustaceans (rock crab, lady crab; 84.0%). Keywords: Bay of Fundy; Canada; Clupeidae; commercial fishing; temperatures; tides

Effects of a fish weir on the structure of the macrobenthic community of a tropical sandy beach on the Amazon coast

AbstractThe present study investigated the effects of a fish weir, a fixed trap used by artisanal fisheries, on the intertidal macrobenthic infauna of a macrotidal sandy beach on the Amazon coast. Biological and sediment samples were collected from within the weir and at five points of increasing distance (10 cm, 50 cm, 1 m, 2 m, 5 m and 50 m) from the external portion of the trap. The sediments from the weir and at 10 cm were dominated by mud, with a gradual decline in fine grains, water content and organic matter with increasing distance from the weir to 50 m (control). Taxon abundance and richness were significantly higher in the weir and at 10 cm than at the other sampling points. There was a trend of decreasing density and richness of the infauna from the weir to 1 m (which was a point of transition between the muddy and sandy sediments), after which the biological descriptors tended to increase once again. A shift was also observed in the dominant trophic groups, with a decrease in the abundance of the deposit feeders with increasing distance from the weir. By contrast, predators were more abundant at the points further from the weir. Our results indicate that fish weirs alter the associated sedimentary habitats, due to the increased protection from the action of waves and currents, with a micro-scale (from a few centimetres to 1–2 m) influence on the local macrofauna.

In situ Monitoring of Longfin Inshore Squid Egg Deposition and Embryonic Development

Knowledge of squid early life history is relatively poor despite its importance for fisheries management. The longfin inshore squid Doryteuthis pealeii (Lesueur, 1821) is a commercially important species harvested extensively along the northeastern United States continental shelf. To understand the effects of fishing and environmental variability on D. pealeii in an inshore spawning ground (Nantucket Sound, MA), egg deposition and embryonic development were monitored in situ at commercial fish weirs in spring and summer 2008 to 2016. Logbooks were maintained in which catch (including the presence of egg masses) and effort data for each weir were recorded daily. Seawater temperature was recorded using data loggers affixed to the weirs. Newly deposited egg masses were transferred to a mesh enclosure on an opportunistic basis and placed immediately adjacent to the weir to permit semiweekly retrieval and sampling. Samples (five randomly chosen “fingers” excised from a mass) were chilled and transported to a nearby wet lab for microscopic examination to determine embryonic development stage. Hatch timing was determined via direct observation of paralarvae emerging from egg masses and development time was calculated as the number of days between egg mass deposition and hatching. The timing and duration of egg mass deposition varied between years. Embryonic development time of 15 egg masses ranged from 12 to 34 days and generally decreased at warmer temperatures. In situ observations were consistent with the findings of laboratory studies of D. pealeii and other loliginid squids.

The Stone Tidal Fish Weirs of the Molène Archipelago, Iroise Sea, Brittany, Western France: a long‐term tradition with early megalithic origins

This reports on a project that combined evidence gleaned from aerial photographs, place-names, interviews, topography, LIDAR data, and sonar bathymetry to locate stone tidal fish weirs in the Mol`ene Archipelago. The results were verified by diver and pedestrian visual surveys. Models of Holocene sea-level change allowed a group of possibly Late Mesolithic–Early Neolithic weirs to be recognized, with a second group broadly dated to the later Neolithic–Early Bronze Age. The construction of these long megalithic structures is compared to the funerary monuments for which the Mol`ene Archipelago is well known, in terms of technique, cost, and societal organization.

A large‐scale medieval dam‐lake cascade in central Europe: Water level dynamics of the Havel River, Berlin–Brandenburg region, Germany

AbstractAn interdisciplinary study was carried out to trace the hydrological changes of the Havel River in northeastern central Europe over the last ca. 2000 years. This research was driven by the hypothesis that the present‐day riverscape is to a large degree a result of medieval and modern human transformation of the drainage system. The river system forms a series of dammed lakes and river sections that were greatly altered through hydraulic engineering in the past. Along the middle course of the Havel, 16 sedimentary sequences available for geoarchaeological and paleoecological research were analyzed in order to reconstruct regional water level dynamics. Chronological control was ensured through a multitude of palynological, dendrochronological, archaeological, and radiocarbon data. The sections upriver from the Brandenburg/H. and Spandau weirs, representing sites with historic watermills, reveal substantial water level changes during the late Holocene. Generally, lower water levels before and higher levels during the medieval German colonization of that area (ca. A.D. 1180/1250) can be inferred. This water level increase, which is primarily attributed to dams constructed for watermills and secondarily due to a multitude of fish weirs, took place rapidly and amounted to a relative height of ca. 1.5 m. It enlarged the river's cross‐sections and increased the size of existing lakes or initiated secondary lakes that previously aggraded, and thus caused flooding of large parts of land. The rising water level even influenced the settlement topography to a large degree. Several medieval rural settlements were abandoned due to flooding. In total, a ca. 150‐km long dammed lake cascade was formed.

First record of epizootic ulcerative syndrome from the Upper Congo catchment: An outbreak in the Bangweulu swamps, Zambia.

We report on the first outbreak of epizootic ulcerative syndrome (EUS) amongst wild fish populations in the Bangweulu swamps, an inland delta, in the north of Zambia during 2014. The area supports a large and diverse fish fauna related to, but distinct from, that of the Zambezi River system where EUS outbreaks have occurred since 2006. A sizeable artisanal fishery, based on extensive fish weirs, is sustained by the annual flooding of the swamps, and observations of the disease outbreak by fishermen were recorded. Signs typical of infection with Aphanomyces invadans were observed in a number of species. Clinical observations, histology and molecular diagnostic methods were used to confirm infection with A.invadans in two of the most commonly and severely affected species. Several features of the wetland may have contributed to the outbreak and the annual recurrence of the disease. Modes by which the disease may have been introduced into the swamps are discussed. The outbreak is of great significance as the Bangweulu swamps drain into the Congo River in neighbouring Democratic Republic of Congo, Africa's largest drainage system with an extensive and diverse fish fauna previously unaffected by EUS.

Ancient fish weir technology for modern stewardship: lessons from community-based salmon monitoring

ABSTRACTIntroduction: The UN Declaration on the Rights of Indigenous Peoples states that indigenous people have a fundamental right to contribute to the management of the resources that support their livelihoods. Salmon are vital to the economy and culture of First Nations in coastal British Columbia, Canada. In this region, traditional systems of management including weirs – fences built across rivers to selectively harvest salmon – supported sustainable fisheries for millennia. In the late-19th century traditional fishing practices were banned as colonial governments consolidated control over salmon.Outcomes: In collaboration with the Heiltsuk First Nation we revived the practice of weir building in the Koeye River. Over the first four years of the project we tagged 1,226 sockeye, and counted 8,036 fish during fall stream walks. We used a mark-recapture model which accounted for both pre-spawn mortality due to variation in temperature, and tag loss, to produce the first mark-resight estimates of sockeye abundance in the watershed (4,600 – 15,000 escapement).Discussion: High river temperatures are associated with increased en route morality in migrating adult sockeye. We estimated pre-spawn mortality ranged from 8 – 72% across the four years of study, highlighting the degree to which climate conditions may dictate future viability in sockeye salmon populations. These results demonstrate the power of fusing traditional knowledge and management systems with contemporary scientific approaches in developing local monitoring.

A Saxon Fish Weir and Undated Fish Trap Frames Near Ashlett Creek, Hampshire, UK: Static Structures on a Dynamic Foreshore

The remains of a wooden V-shaped fish weir and associated structures have been discovered near Ashlett Creek on the tidal mudflats of Southampton Water in Hampshire, southern Britain. Radiocarbon dating of oak roundwood stakes taken from the main weir structure date it to the middle Saxon period. Clusters of as-yet undated roundwood posts within the catchment area of the weir are interpreted as the frames for fish traps that are assumed to pre- or post-date the operational period of the weir itself. The weir is contemporary with wooden V-shaped fish weirs found elsewhere in southern and central Britain, and also Ireland, but its circular catchment ‘pound’ remains restricted, in these islands, to the Solent and Severn estuaries: it has a close parallel with another Saxon-era weir on the nearby Isle of Wight. It also shows striking structural similarities with examples in use today in Basse Normandy, on the southern shore of the English Channel. The paper discusses the function and operation of the weir, and places it in its social and historical context. Regressive cartography demonstrates that the structures have become exposed as a result of saltmarsh retreat in this area of Southampton Water since the nineteenth century. The radiocarbon dates returned for the posts demonstrate that this transgression of the marsh must have been preceded by a prolonged period of progradation, which covered and preserved the site; its subsequent re-exposure has negative implications for its survival.

Present-day African analogue of a pre-European Amazonian floodplain fishery shows convergence in cultural niche construction

Erickson [Erickson CL (2000) Nature 408 (6809):190-193] interpreted features in seasonal floodplains in Bolivia's Beni savannas as vestiges of pre-European earthen fish weirs, postulating that they supported a productive, sustainable fishery that warranted cooperation in the construction and maintenance of perennial structures. His inferences were bold, because no close ethnographic analogues were known. A similar present-day Zambian fishery, documented here, appears strikingly convergent. The Zambian fishery supports Erickson's key inferences about the pre-European fishery: It allows sustained high harvest levels; weir construction and operation require cooperation; and weirs are inherited across generations. However, our comparison suggests that the pre-European system may not have entailed intensive management, as Erickson postulated. The Zambian fishery's sustainability is based on exploiting an assemblage dominated by species with life histories combining high fecundity, multiple reproductive cycles, and seasonal use of floodplains. As water rises, adults migrate from permanent watercourses into floodplains, through gaps in weirs, to feed and spawn. Juveniles grow and then migrate back to dry-season refuges as water falls. At that moment fishermen set traps in the gaps, harvesting large numbers of fish, mostly juveniles. In nature, most juveniles die during the first dry season, so that their harvest just before migration has limited impact on future populations, facilitating sustainability and the adoption of a fishery based on inherited perennial structures. South American floodplain fishes with similar life histories were the likely targets of the pre-European fishery. Convergence in floodplain fish strategies in these two regions in turn drove convergence in cultural niche construction.

Statistical arrival models to estimate missed passage counts at fish weirs

Missed counts are commonplace when enumerating fish passing a weir. Typically “connect-the-dots” linear interpolation is used to impute missed passage; however, this method fails to characterize uncertainty about estimates and cannot be implemented when the tails of a run are missed. Here, we present a statistical approach to imputing missing passage at weirs that addresses these shortcomings, consisting of a parametric run curve model to describe the smoothed arrival dynamics of a fish population and a process variation model to describe the likelihood of observed data. Statistical arrival models are fit in a Bayesian framework and tested with a suite of missing data simulation trials and against a selection of Pacific salmon (Oncorhynchus spp.) case studies from the Yukon River drainage, Alaska, USA. When compared against linear interpolation, statistical arrival models produced equivalent or better expected accuracy and a narrower range of bias outcomes. Statistical arrival models also successfully imputed missing passage counts for scenarios where the tails of a run were missed.