In search of traditional bio-ecological knowledge useful for fisheries co-management: the case of jaraquis Semaprochilodus spp. (Characiformes, Prochilodontidae) in Central Amazon, Brazil

The jaraquis (Semaprochilodus spp.) are the most abundant group in the fishing landing in Manaus. However, just command and control management strategies have been used by the fishery governmental agency in the region without the power to enforce centralized decisions. The fishermen and their culture represent a source of information on dynamics of the resources and aquatic environments, fundamental in making possible the co-management of the fishing resources. The present study aims to contribute to management through identification of common information available in scientific and traditional knowledge about the jaraquis' bio-ecology. There were 57 semi-structured interviews recorded with fishermen of Manaus and rural areas of Manacapuru in 2002 concerning biological and ecological aspects. Similarity was observed between scientific and traditional knowledge in the following items: size of first sexual maturation, spawning type, parental care, trophic relationships and migratory behavior, as well as in some aspects of the mortality and growth of the species. However, there was less ethnoicthyological information on fecundity and the determination of the age and growth of adult fish. Common information would be used preferably by agencies to start an effective and technical dialogue with commercial and riverine fishermen to design management plans in a decentralized strategy

Response of Prochilodus nigricans to flood pulse variation in the central Amazon

The influence of the flood pulse on fish populations has been posited, but infrequently tested or quantified. Here, we tested the effect of habitat on population size, using Prochilodus nigricans as a case study species. Floodplain habitat was based on the littoral zone area occupied by P. nigricans to feed. The magnitude of this habitat in each hydrological year, the moving littoral (ML), was expressed as the sum of daily littoral areas during the advancing flood pulse, using satellite-based passive microwave data. Annual population size was estimated by age class, using a dynamic age-structured model (MULTIFANCL) based on catches, effort and fish length frequencies from the Manaus-based fishery over 12.75 years. The principal null hypothesis was that the ML, using three lag times, had no effect on population size of a single age class of P. nigricans. The population size at 29 months of age was positively related (p = 0.00030) to floodplain habitat (ML) earlier in the same year, when the fish were 21-27 months old. The result implies a density-dependent relationship for the population with respect to its feeding habitat. Potential mechanisms governed by flood pulse variation and habitat quality for this and other species using floodplain habitats are discussed

Estimation of growth parameters of five fish species (Actinopterygii) caught in the central Amazon

For some tropical fishes, the information on growth parameters is still scarce, and few or no records are available in FishBase. Therefore, the objective of this study was to estimate the growth curves for Brycon amazonicus (Spix et Agassiz, 1829), Piaractus brachypomus (Cuvier, 1818), Prochilodus nigricans Spix et Agassiz, 1829, Semaprochilodus insignis (Jardine, 1841), and Semaprochilodus taeniurus (Valenciennes, 1821), and to build the auximetric plots for each of the families to which these species belong: Characidae, Prochilodontidae, and Serrasalmidae. Samples were obtained from commercial catches landed in the Port of Manaus. Growth parameters were estimated using the Electronic Length Frequency Analysis (ELEFAN) routine of the Length Frequency Distribution Analysis (LFDA) program. Twenty-six sets of growth parameters were thus estimated, and 66 further sets were located in the literature and FishBase. Prochilodontidae and Serrasalmidae showed a strong inverse relation between the variables composing the auximetric plots. © 2018, Scientific Society of Szczecin. All rights reserved

In search of traditional bio-ecological knowledge useful for fisheries co-management: the case of jaraquis <it>Semaprochilodus </it>spp. (Characiformes, Prochilodontidae) in Central Amazon, Brazil

Abstract The jaraquis (Semaprochilodus spp.) are the most abundant group in the fishing landing in Manaus. However, just command and control management strategies have been used by the fishery governmental agency in the region without the power to enforce centralized decisions. The fishermen and their culture represent a source of information on dynamics of the resources and aquatic environments, fundamental in making possible the co-management of the fishing resources. The present study aims to contribute to management through identification of common information available in scientific and traditional knowledge about the jaraquis' bio-ecology. There were 57 semi-structured interviews recorded with fishermen of Manaus and rural areas of Manacapuru in 2002 concerning biological and ecological aspects. Similarity was observed between scientific and traditional knowledge in the following items: size of first sexual maturation, spawning type, parental care, trophic relationships and migratory behavior, as well as in some aspects of the mortality and growth of the species. However, there was less ethnoicthyological information on fecundity and the determination of the age and growth of adult fish. Common information would be used preferably by agencies to start an effective and technical dialogue with commercial and riverine fishermen to design management plans in a decentralized strategy.</p

Close to extinction? The collapse of the endemic daggernose shark (Isogomphodon oxyrhynchus) off Brazil

The daggernose shark, Isogomphodon oxyrhynchus is endemic to the northern of South America from Trinidad and Tobago to Tubarão bay in Maranhão state (Brazil) where collapsed since the 1990’s, due to several gillnet fisheries for teleost fishes, fisheries targeting sharks, including the daggernose shark, itself, and trawling for shrimp. Based on gillnets with meshes 80–>200 mm, we analyzed the intrinsic and extrinsic vulnerabilities of the species through different scenarios investigating the species’ resilience. Samples were collected from December 1989 to September 1991, off the coast of Maranhão. Mortalities were M=0.188 and Z=0.653 for males and 0.725 in females. Only a scenario without fishing allowed for the population to remain in equilibrium. The survival of young specimens between 1 to 6 years was critical to sustainability according to elasticities that exceeded 70%. The intrinsic rebound (rz) of 0.039, demonstrated the species low resilience. An unsustainable exploitation was revealed for different ages at first capture (tc) when the maximal yield per recruit (YPR) provided Fmax (0.15), below the actual F=0.47 in 1991 when an exploitation rate E=0.72 was obtained. Using data collected in 1980/1990 the species was globally categorized in 2006 as critically endangered (CR) similar to assessments in Brazil in 2004. After a three-generation period the species, which did not recover, is now collapsed matching the predicted quasi-extinction condition which claims for urgent and effective conservation measures

Landscape variables affecting fishery yield in lake systems of the Central Amazon region, Brazil

According to fisheries data, lakes are important systems for fish production in the Amazon basin. However, there is no information about the relationship between landscape variables and fishing yield that allows foresight into potential resource exploitation in this environment. The present study aims to evaluate this relationship with the hypothesis: lakes of different shapes give the same fishery yield in the Amazon, after considering the effects of lake size, distance to the river, fishing effort, fuel and ice used. Fishery data from 1994 to 1996 were analyzed with regard to 3228 trips on 50 lakes of the main white water tributaries of the Amazon basin. Analysis of covariance was applied to test this hypothesis. With variables such as fishing grounds access, fishing effort and lake shape the model explained a significant 72% of variabilities in the fisheries yield. Fishing yields among lake systems were different, thus the null hypothesis was rejected (P < 0.05). Results indicate that dendritic lakes far distant from the main river have greater productivity than floodplain lakes because there are more habitats of fish refuge for reproduction and feed available to the fish; there are also more limitations to access by predators. © 2008 Blackwell Verlag

What are the main local drivers determining richness and fishery yields in tropical coastal fish assemblages?

ABSTRACT Seasonal ecological effects caused by temperature and photoperiod are typically considered minimal in the tropics. Nevertheless, annual climate cycles may still influence the distribution and abundance of tropical species. Here, we investigate whether seasonal patterns of precipitation and wind speed influence the structure of coastal fish assemblages and fishing yields in northeast Brazil. Research trips were conducted during the rainy and dry seasons using commercial boats and gear to sample the fish community. Diversity was analyzed using abundance Whittaker curves, diversity profiles and the Shannon index. Principal Component Analysis (PCA) was used to analyze associations between the abundance of species and various environmental variables related to seasonality. A total of 2,373 fish were collected, representing 73 species from 34 families - 20 of which were classified as both frequent and abundant. Species richness was greater and more equitable during the rainy season than the dry season - driven by changes in the precipitation rather than to wind speed. Species diversity profiles were slightly greater during the rainy season than the dry season, but this difference was not statistically significant. Using PCA was identified three groups of species: the first associated with wind speed, the second with precipitation, and the third with a wide range of sampling environments. This latter group was the largest and most ecologically heterogeneous. We conclude that tropical coastal fish assemblages are largely influenced by local variables, and seasonally mediated by annual changes related to precipitation intensity and wind speed, which in turn influences fishery yields

Dinâmica populacional da matrinxã Brycon amazonicus (Characidae) na Amazônia Central Population dynamics of matrinxã Brycon amazonicus (Characidae) in Central Amazon

<abstract language="eng">The matrinxã, Brycon amazonicus (Spix & Agassiz, 1829) is one of the most important fishery resources of the Amazonas state. Its population dynamics in Central Amazon was analyzed based on total landing and biometry data registered in the main landing port of Manaus, between 1994 and 2002. Growth and mortality rates were estimated separately for the rivers Purus, Madeira and Solimões. Differences in size structure and growth curves suggest that different population units exist among these rivers, requiring individualized evaluation and fisheries management strategies. The analysis of the yield per recruit does not indicate overexploitation. However, the highest relative exploitation rate was observed in the Madeira river. The suggested management strategies are related to restrictions to the fishery in the main fishing grounds during the migratory dispersal period, instead of restrictions during reproductive periods