‘Disentangling’ the advantages from gillnets in freshwater small-scale fisheries in the Brazilian Amazon

Hallwass, Gustavo; Keppeler, Friedrich W.; Tomazoni-Silva, Luís H.; Alves, Ivan A.; Isaac, Victória J.; Almeida, Morgana Carvalho de; Silvano, Renato Azevedo Matias

doi:10.1007/s11160-023-09771-w

Cited by 7 publications

(6 citation statements)

References 92 publications

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“…The frequency of extreme events, such as El Niño and La Niña, has also increased (Gloor et al, 2013;Gouveia et al, 2019;Wunderling et al, 2022). Overall, results of our analyses indicated that increasing intensity of climate change may negatively affect productivity of net fisheries, which are predominant in the region (Hallwass et al, 2023). This may also result in changes in the structure of the fish communities.…”

Section: Relationships Between Line Cpues and Predictor Variablessupporting

confidence: 48%

“…Our wavelet analyses revealed strong annual and semi-annual signals for CPUEs of nets and lines that corresponded to peaks in fish harvest. Semi-annual periods of net fisheries revealed harvests of long-whiskered, driftwood, gilded, and filhote catfish that were fished alternately from lakes in winter (high water) and rivers in summer (low water), which highlights efficiency of net fisheries that are highly productive throughout the year (Hallwass et al, 2023).…”

Section: Relationships Between Line Cpues and Predictor Variablesmentioning

confidence: 99%

“…in use of fishing gear, related to the hydrological cycle. During the high water period, fishers used gillnets, which were the most efficient, but least selective gear (Hallwass et al, 2023), whereas during low water months, they used lines, with baited hooks associated with increased foraging by predator species (Ruffino & Isaac, 1995).…”

Section: Relationships Between Line Cpues and Predictor Variablesmentioning

confidence: 99%

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How does climate change affect small scale fisheries? A case study of the Lower Amazon in Brazil

Furtado,

Queiroz,

Bentes

et al. 2023

Fisheries Management Eco

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Effects of global climate change on inland artisanal fisheries have received little attention from scientists. We investigated fisheries of the Lower Amazon in Brazil using a wavelet analysis of a 13‐year data series of fishery catches, environmental variables, and climatic indices, to determine how these variables affected catches of different species. The catch per unit of effort (CPUE) of gillnet and line fisheries increased over time. Relative humidity, latent heat, and sea surface temperatures influenced productivity of both fisheries. El Niño had a negative and immediate effect on gillnet CPUE, while its effect on line fishing was positive, with an eight month lag. Our findings indicate that fishery productivity was modulated by climate events, which influenced ecosystems and modified habitats and ecological niches, andthereby impacted fishery productivity.

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Section: Relationships Between Line Cpues and Predictor Variablessupporting

confidence: 48%

Section: Relationships Between Line Cpues and Predictor Variablesmentioning

confidence: 99%

Section: Relationships Between Line Cpues and Predictor Variablesmentioning

confidence: 99%

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How does climate change affect small scale fisheries? A case study of the Lower Amazon in Brazil

Furtado,

Queiroz,

Bentes

et al. 2023

Fisheries Management Eco

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“…With the introduction of nylon nets in the 1960s [42], nylon gillnets have become widespread for commercial fishing. Gillnets are relatively more efficient and durable [43,44], easier to handle, capture a greater diversity of fish, and provide more predictable catches than more traditional gear [45]. While gillnets are often a source of conflict [46], they support the commercial success of artisanal fisheries, and provide important economic benefits [4,5,45].…”

Section: Discussionmentioning

confidence: 99%

The Hydrological Cycle of the Lower Amazon in Brazil Determines the Variation in Local Fishing Patterns

Furtado

Queiroz

Bentes

et al. 2023

Fishes

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Fishery catches on the Lower Amazon River were analyzed in relation to the hydrological cycle, temporal shifts in fishing effort, and the use of nets or lines in lakes and rivers. The study was based on a temporal series of catch data collected between January 1993 and June 2011. The variables analyzed were the total catch, use of gillnets or lines, the environment targeted (lakes or rivers), and fishing effort. Temporal trends in the data series were analyzed using the Mann–Kendall test. An Analysis of Covariance (ANCOVA) was used to evaluate whether gillnet and line catches had independent effects on the catch data. Duncan’s test was applied to identify the groups (months) of means that were significantly different from each other. The majority of the catch landings were taken with gillnets (98.65%) in a lake environment (64.98%). The temporal series showed a significant decline over time in the gillnet catches from both lakes and rivers, as well as in fishing effort. The influence of the annual flood cycle was reflected in the catches and the flood pulse regulated fishing productivity patterns in the region. The fishers who adapt their activities to this flood pulse have good traditional knowledge of the environment. The results of the study also indicated that any changes in this dynamic system may impact traditional local fisheries and affect the economic wellbeing of local fisher populations.

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“…In Amazonian multispecies fisheries, the most used tackle is the gillnet, because it is easy for traditional people to make and use, and it also has low cost (Hallwass et al, 2023). Gillnets are considered "passive" fishing tackle, since they need fish to swim into them so that they can be caught (Sparre and Venema, 1997).…”

Section: Introductionmentioning

confidence: 99%

Selectivity of gillnets on the main fish species caught in the floodplains of the Madeira River (Rondônia, Brazil)

Lima,

Gonzaga Junior,

Sousa

2023

Bol. Inst. Pesca

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Small-scale fishing in the floodplains of the Amazon basin has intensified, with gillnets being one of the main types of tackle used. In this study, we evaluated the length structure of fish species in a floodplain lake of the Madeira River basin, emphasizing the selectivity of the nets in the main species caught. The fisheries were collected in periods of high water and low water, with nets of mesh sizes of 40, 60, 80, 100, 120 and 160 mm. Tests between the periods and also comparing the meshes were performed and the parameters of the selectivity curves estimated with the SELECT calculation code. Records of 17 new maximum lengths are presented. Of the 12 most abundant species, the selectivity of the nets in the modal lengths for Anchovia surinamensis were 13.3, 19.9, 26.6 and 33.2 cm in the nets with mesh sizes of 40, 60, 80 and 100 mm, respectively. In the three smallest mesh sizes, the values for Potamorhina altamazonica were 12.7, 19.0 and 25.3 cm and for Pellona flavipinnis values were 15.4, 23.2 and 30.9 cm. In the two smallest mesh sizes, the following values were presented for the species Potamorhina latior (12.9 and 19.4 cm), Potamorhina rutiloides (11.3 and 16.9 cm), Triportheus elongatus (19.7 and 29.5 cm), Triportheus flavus (14.1 and 21.1 cm) and Pimelodus blochii (15.5 and 23.0 cm). The estimates of selectivity of the nets, in addition to being basic information for fishery sciences, are also fundamental for the management of Amazonian fish stocks.

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‘Disentangling’ the advantages from gillnets in freshwater small-scale fisheries in the Brazilian Amazon

Cited by 7 publications

References 92 publications

How does climate change affect small scale fisheries? A case study of the Lower Amazon in Brazil

How does climate change affect small scale fisheries? A case study of the Lower Amazon in Brazil

The Hydrological Cycle of the Lower Amazon in Brazil Determines the Variation in Local Fishing Patterns

Selectivity of gillnets on the main fish species caught in the floodplains of the Madeira River (Rondônia, Brazil)

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