Fishers' ecological knowledge points to fishing-induced changes in the Peruvian Amazon.

Scientists increasingly draw on fishers' ecological knowledge (FEK) to gain a better understanding of fish biology and ecology, and inform options for fisheries management. We report on a study of FEK among fishers along the Lower Ucayali River in Peru, a region of exceptional productivity and diversity, which is also a major supplier of fish to the largest city in the Peruvian Amazon. Given a lack of available scientific information on stock status, we sought to identify temporal changes in the composition and size of exploited species by interviewing fishers from 18 communities who vary in years of fishing experience since the mid-1950s. We develop four FEK-based indicators to assess changes in the fish assemblage and compare findings with landings data. We find an intensification of fishing gear deployed over time and spatiotemporal shifts in the fish assemblage and reported declines in species weight, which point to a fishing-down process with declines across multiple species. This finding is reflected in a shifting baseline among our participants, whereby younger generations of fishers have different expectations regarding the distribution and size of species. Our study points to the importance of spillover effects from the nearby Pacaya-Samira National Reserve and community initiatives to support the regional fishery. Reference to fishers' knowledge also suggests that species decline is likely underreported in aggregated landings data. Despite the dynamism and diversity of Amazonian floodplain fisheries, simple FEK-based indicators can provide useful information for understanding fishing-induced changes in the fish assemblage. Fishers hold valuable knowledge for fishery management and conservation initiatives in the region.

-I fish, therefore I monitor: Participatory monitoring to assess inland small-scale fisheries.

Analysis of small-scale inland fisheries (SSIFs) is often highly dispersed and tends not reflect the true magnitude of their contribution to society. This is partly due to the insufficient attention given to this sector by the relevant authorities, in addition to its highly diverse characteristics, with complex patterns of operation in a wide range of systems, often in remote areas. Here, by integrating fishers as participatory fishery monitors, we provide fishery-dependent estimates of yields, the biological attributes of the fish species, and the spatiotemporal dynamics of the fisheries of lakes on the floodplain of the São Francisco basin in northeastern Brazil. As the fishers were willing participates in the monitoring, the results revealed well-structured artisanal fishing activities, with the lake system providing high-profile fish harvests from both monthly and annual perspectives. The spatial distribution of fishing effort reflected the adaptation of the fishers to the flood cycle of the river, in order to maintain high fishery productivity throughout the year. The results also indicate that participatory monitoring can help to overcome knowledge gaps and provide a database that is readily applicable to management needs at both local and regional scales. As Brazil is one few world's nations that no longer have national fishing monitoring program, participatory monitoring represents a low-cost solution for the credible and useful data on small-scale fisheries. It would thus appear to be extremely worthwhile to invest in the empowerment of communities in order to overcome the historic vulnerability of productive sector and the food security of the populations that depend on these fisheries.

Length-weight relationship of the six most abundant fish species in prawn fishery semi-fixed trap bycatches in the lower amazon region (Pará, Brazil) / Relação peso-comprimento das seis espécies de peixes mais abundantes na pesca de camarão em armadilhas semifixas na região do baixo amazonas (Pará)

In this study, the length-weight relationships (LWR) were estimated for six fish species captured during prawn fishing in the Lower Amazon region (Pará, Brazil). Prawn fishing boosts the socioeconomic development of riverine communities and is a relevant activity as a source of income and subsistence in this region. In addition, we registered new LWRs for the species Ossancora punctata and Hypoptopoma elongatum. The samplings were performed in prawn catches monthly from February 2018 to January 2019, using a “matapi”, which consists of a semi-fixed trap that has a galvanized iron structure (2.5 m height by 2.0 m in length) and nylon mesh (1.40 x 1.60 mm mesh), and has two tapered openings to facilitate the entry and trapping of the prawn. The results show that 75% of the fish caught as prawn bycatches had not yet reached sexual maturity. Thus, it is clear that fisheries need to develop fishing gear that allow small fish to escape from the traps during the prawn fishery.(AU)

Neste estudo, as relações de peso-comprimento (RPC) foram estimadas para seis espécies de peixes capturadas durante a pesca do camarão de água doce na região da Baixa Amazônia (Pará, Brasil). A pesca do camarão promove o desenvolvimento socioeconômico das comunidades ribeirinhas, sendo uma atividade de fonte de renda e subsistência nesta região. Além disso, registramos novas RPCs para as espécies Ossancora punctata e Hypoptopoma elongatum. As amostragens foram realizadas mensalmente em capturas de camarão, entre fevereiro de 2018 e janeiro de 2019, com o uso de “matapi”, que consiste em uma armadilha semifixa, com estrutura de ferro galvanizado (com altura de 2,5 m por 2,0 m de comprimento) e tela de náilon (malha de 1,40 mm x 1,60 mm), com duas aberturas afuniladas para facilitar a entrada e aprisionamento do camarão. Os resultados mostraram que 75% dos peixes capturados como fauna acompanhante de camarão ainda não tinha atingido a maturidade sexual. Assim, é evidente que as pescarias precisam desenvolver equipamentos de pesca que permitam que os peixes menores escapem da captura durante a pesca do camarão.(AU)

Length-weight relationship of the six most abundant fish species in prawn fishery semi-fixed trap bycatches in the lower amazon region (Pará, Brazil) / Relação peso-comprimento das seis espécies de peixes mais abundantes na pesca de camarão em armadilhas semifixas na região do baixo amazonas (Pará)

In this study, the length-weight relationships (LWR) were estimated for six fish species captured during prawn fishing in the Lower Amazon region (Pará, Brazil). Prawn fishing boosts the socioeconomic development of riverine communities and is a relevant activity as a source of income and subsistence in this region. In addition, we registered new LWRs for the species Ossancora punctata and Hypoptopoma elongatum. The samplings were performed in prawn catches monthly from February 2018 to January 2019, using a “matapi”, which consists of a semi-fixed trap that has a galvanized iron structure (2.5 m height by 2.0 m in length) and nylon mesh (1.40 x 1.60 mm mesh), and has two tapered openings to facilitate the entry and trapping of the prawn. The results show that 75% of the fish caught as prawn bycatches had not yet reached sexual maturity. Thus, it is clear that fisheries need to develop fishing gear that allow small fish to escape from the traps during the prawn fishery.

Neste estudo, as relações de peso-comprimento (RPC) foram estimadas para seis espécies de peixes capturadas durante a pesca do camarão de água doce na região da Baixa Amazônia (Pará, Brasil). A pesca do camarão promove o desenvolvimento socioeconômico das comunidades ribeirinhas, sendo uma atividade de fonte de renda e subsistência nesta região. Além disso, registramos novas RPCs para as espécies Ossancora punctata e Hypoptopoma elongatum. As amostragens foram realizadas mensalmente em capturas de camarão, entre fevereiro de 2018 e janeiro de 2019, com o uso de “matapi”, que consiste em uma armadilha semifixa, com estrutura de ferro galvanizado (com altura de 2,5 m por 2,0 m de comprimento) e tela de náilon (malha de 1,40 mm x 1,60 mm), com duas aberturas afuniladas para facilitar a entrada e aprisionamento do camarão. Os resultados mostraram que 75% dos peixes capturados como fauna acompanhante de camarão ainda não tinha atingido a maturidade sexual. Assim, é evidente que as pescarias precisam desenvolver equipamentos de pesca que permitam que os peixes menores escapem da captura durante a pesca do camarão.

Commercial fisheries in a mega unregulated floodplain river: Assessment of the most favourable hydrological conditions for its preservation.

This paper deals with the hydrological variability effects on the primary commercial fish species inhabiting the main channel and the floodplain of the large Paraná River in its middle reaches in Argentina. Analysing more than eight decades (1935-2016) of information on the most frequent and abundant commercial species in conjunction with hydrological levels and temperature, our results show that spring-summer floods of a certain magnitude (c. 6 m) and durations (> 80 days) are crucial for sustaining commercial fisheries. Moreover, the frequency of these floods was modulated by the decadal climatic fluctuations that have occurred over the past 100 years in the Paraná Basin. An insight into the probable incidence of some anthropogenic influences is also provided.

Terrestrial-aquatic trophic linkages support fish production in a tropical oligotrophic river.

Despite low in situ primary productivity, tropical oligotrophic rivers support highly diverse fish assemblages and productive fisheries. This raises the question, what energy sources support fish production in these ecosystems? We sampled fish and food resources in the floodplain of a nearly pristine, large, oligotrophic river in western Amazonia. We combined data from stomach contents and stable isotopes to test the hypothesis that floodplain forests sustain fisheries in tropical oligotrophic rivers. Analysis of stomach contents from > 800 specimens of 12 omnivorous fish species demonstrated that during the annual flood, forest plant matter dominated diets. Yet, our isotope mixing models estimated that arthropods from the forest canopy made a greater proportional contribution to fish biomass. Most of these arthropods are entirely terrestrial and, therefore, serve as trophic links between forests and fishes. Our results suggest that forest vegetation, particularly fruits, may provide much of the energy supporting metabolism and arthropods contribute significant amounts of protein for somatic growth. Moreover, the importance of terrestrial arthropods in support of fish biomass in oligotrophic rivers depends on interactions between riparian vegetation, terrestrial arthropods and flood pulse dynamics affecting accessibility of arthropods to fishes. The apparent paradox of high fish diversity in an oligotrophic river with low primary productivity may be explained, at least partially, by dynamic terrestrial-aquatic trophic linkages. This study further emphasizes the importance of seasonally flooded forests for sustaining fisheries in the Amazon.

Fisheries artisanal diagnosis in the Machadinho reservoir in the upper Uruguay River, Brazil / Diagnóstico da pesca artesanal na usina hidrelétrica de Machadinho, alto Rio Uruguai - Brasil

Machadinho reservoir, formed in 2001, is located in the upper Uruguay River. Aiming to diagnose fish production in this reservoir, as well as fisheries composition along the years after its formation, surveys of catches were taken from fishermen that represent the fishing activity in this reservoir between 2003 and 2009. A total of 81 fishermen took part in these surveys, totalizing 1,907 fishing days during the study period. The analysis of fisheries showed an annual average CPUE, based on the biomass of capture of each morphospecies registered per each fisherman per day (kg fisherman1 day-1), of 9.60 (± 3.27) kg fisherman-1 day-1, in 2003, and 18.28 (± 8.57) kg fisherman-1 day-1 in 2006, with a subsequent fall over time, reaching 8.65 (± 2.92) kg fisherman-1 day-1 in 2009. Twenty-six morphospecies were recorded during the studied period, with emphasis on biomass for the catfish, lambari, mandi, suruvi, carpa, cascudo and traira, being the last three the most captured fishes between 2003 and 2009. Among migratory species, stood out curimba (Prochilodus lineatus) and dourado (Salminus brasiliensis), species which were targeted by experimental storage actions. CPUE values estimated to Machadinho reservoir were relatively low when compared to those of other reservoirs. The observed decline of fisheries in Machadinho reservoir over the years may be related to sedimentation process, increase in fishing effort and to the reductionof nutrientsin the reservoir, which are released through spillways.

O reservatório de Machadinho, formado no ano de 2001, está localizado na região do alto rio Uruguai. Procurando diagnosticar a pesca neste reservatório, assim como a composição ictiofaunística ao longo dos anos após o represamento foram aplicados questionários aos pescadores da região entre os anos de 2003 e 2009. Participaram destes levantamentos 81 pescadores que representam a atividade da pesca neste reservatório, totalizando 1.907 viagens de pesca declaradas ao longo do período de amostragem. A análise das pescarias mostrou uma Captura por Unidade de Esforço (CPUE), calculada com base na biomassa de cada morfoespécie registrada por pescador por dia de pesca (kg pescador-1 dia-1), com média anual de 9,60 (± 3,27) kg pescador-1 dia-1, em 2003, e 18,28 (± 8,57) kg pescador-1 dia-1, em 2006, com posterior queda ao longo do tempo, chegando a 8,65 (± 2,92) kg pescador-1 dia-1 em 2009. Vinte e seis morfoespécies foram amostradas durante o período de estudo, com destaque em biomassa para jundiá, lambari, mandi, suruvi, carpa, cascudo e traíra, sendo que as três últimas se alternaram como as mais capturadas entre 2003 e 2009. Dentre as espécies migradoras destacaram-se o curimba (Prochilodus lineatus) e o dourado (Salminus brasiliensis), espécies que foram alvo de ações de estocagens experimentais. Os valores de CPUE estimados para o reservatório de Machadinho foram baixos quando comparados a outros reservatórios. Esta tendência de depleção pode ser atribuída a processos de sedimentação, remoção pelapesca ou exportação de nutrientes pelo vertedouro.

A composição dos custos de armação e a renda das expedições de pesca da frota pesqueira artesanal da região do Médio rio Madeira, Amazonas, Brasil

Studies emphasizing the physical, operational and economics characteristics of the fishing fleet were realized, focusing the fleet based in Central Amazon but with gaps about the characteristics in peripheral regions. In this sense the work aimed to analyze the necessary costs to entry of new vessel on activity and to provide information in relation to the costs of fishing expeditions and economic revenue of fishing activity. The study was realized in the Medium Madeira River region and collected information about maintenance, cost and income of fishing expeditions, from June 2003 until May 2004, using questionnaires applied to skippers and fishers of boats and motorized canoes. The gear it was most expensive item on acquisition and the fishers the financer. The fishing expeditions of vessels were financed by six agents, fishers and ice plant owner were the principal financers. Fuel was the main items of cost on fishing expeditions of boats, fuel and ice to motorized canoes. The skippers and owners of fishing boats had a clear gain of 0.6 and 0.5 living wages by fishing expeditions and the fishers 0.3 while fishers of motorized canoes had a clear gain of 0.5 living wages.

Estudos buscando identificar as características físicas, operacionais e econômicas da frota pesqueira sediada na Amazônia Central foram efetuados, deixando lacunas sobre as características da frota nas regiões periféricas. Este trabalho teve como objetivo analisar os custos necessários para a entrada de novas embarcações na atividade pesqueira e fornecer informações relativas ao custo das expedições e da renda econômica da atividade. O estudo foi realizado na região do Médio rio Madeira e foram coletadas por intermédio de questionários, informações sobre os custos de manutenção, armação e a renda das viagens de pesca, no período de junho de 2003 a maio de 2004, junto aos proprietários ou encarregados de barcos de pesca e pescadores de canoas motorizadas. O maior investimento dos proprietários de embarcações foi para a aquisição dos apetrechos, sendo os próprios pescadores os principais financiadores. As expedições de pesca das embarcações foram financiadas por seis agentes, sendo os principais financiadores os pescadores e o frigorífico. O combustível foi o principal item dos custos a encarecer as expedições dos barcos e, combustível e gelo, como custo encarecedor para as canoas. Os armadores e encarregados de barcos de pesca ganharam em média 0,6 e 0,5 salário mínimo, respectivamente, por expedição, e os pescadores 0,3 salário mínimo, enquanto pescadores de canoas motorizadas ganharam em média 0,5 salário mínimo.