Influence of tides and winds on fishing techniques and strategies in the Mamanguape River Estuary, Paraíba State, NE Brazil - PDF

Anais da Academia Brasileira de Ciências (2012) 84(3): (Annals of the Brazilian Academy of Sciences) Printed version ISSN / Online version ISSN Influence

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Anais da Academia Brasileira de Ciências (2012) 84(3): (Annals of the Brazilian Academy of Sciences) Printed version ISSN / Online version ISSN Influence of tides and winds on fishing techniques and strategies in the Mamanguape River Estuary, Paraíba State, NE Brazil DANDARA M.M. BEZERRA 1, DOUGLAS M. NASCIMENTO 2, EMMANOELA N. FERREIRA 1, POLLYANA D. ROCHA 3 and JOSÉ S. MOURÃO 4 1 Programa de Pós-Graduação em Ciências Biológicas, Zoologia, Departamento de Sistemática e Ecologia, Centro de Ciências Exatas e da Natureza, Universidade Federal da Paraíba, Campus I, Bairro Castelo Branco, Cidade Universitária, João Pessoa, PB, Brasil 2 Programa de Pós-Graduação em Etnobiologia e Conservação da Natureza (PPGEtno), Departamento de Biologia, Universidade Federal Rural de Pernambuco (UFRPE), Rua Dom Manoel de Medeiros, s/n, Dois Irmãos, Recife, PE, Brasil 3 Departamento de Biologia, Universidade Estadual da Paraíba, Av. Baraúnas, 351, Campos Universitário Bodocongó, Campina Grande, PB, Brasil 4 Departamento de Biologia, Universidade Estadual da Paraíba, Av. Baraúnas, 351, Campos Universitário Bodocongó, Campina Grande, PB, Brasil Manuscript received on May 3, 2010; accepted for publication on April 28, 2011 ABSTRACT This work was carried out in two small fishing communities, Barra de Mamanguape and Tramataia, Northeastern Brazil. The aim was to study these traditional fishermen s knowledge and perception about tide and wind classifications, as well as their fishing strategies and techniques. Our research methodology involved various techniques: free interviews and semi-structured ones, guided tours and direct observations. The results obtained show the fishermen s classification of the tides according to the phases of the moon: breaking tide, flushing tide, dead tide and big tide designated technically these last as neap tide and spring tide, respectively. Wind is also an essential factor for the fishermen to make successful catches, and they classify it according to direction: North, South, East, Southeast, Southwest, Northeast and Northwest. The data show that fishermen's knowledge can also be useful in devising plans for management and conservation studies for this estuary. Key words: Artisanal fishing, ethnoictihology, fish, fishing communities, lunar-tide cycle. INTRODUCTION Within the context of the relation society-nature, in the universe of fishermen it is possible to encounter evidence of mechanisms of a natural and cultural order, which can guarantee the reproduction of their social, historical, economic and cultural Correspondence to: Dandara Monalisa Mariz Bezerra system (Cunha 2004). This author draws attention to the indicator systems, a combination of winds, tidal con ditions and the moon phases, signalling favorable or non-favorable conditions for fishing, as truly natural mechanisms interposed in the fishing universe. The mechanisms are elaborated or socially acquired, based on observation, experimentation and cosmo-vision. 776 DANDARA M.M. BEZERRA et al. Thus, the climatic factors that most directly intervene in fishing activity are the winds and the periodicity of the tides. According to Kuparinen et al. (2009), lunar cycles are commonly believed to affect fishery catches through changes in the behavior and movements of fishes, to affect feeding, vertical distribution and catchability of several marine and freshwater fishes. These meteorological elements constitute two fundamental occurrences in the functioning of fishing strategies, playing primary limiting roles, given that, depending on their intensity, they can impede fishing activity and modify fishing plans in short, medium and long terms (Allut 2000). This same author states that only meticulous knowledge on the dynamics of meteorological factors and the aspects related to fishing allows fishermen to have a degree of response to their environment, enabling them, to a certain extent, to make forecasts. Time, atmosphere and tidal cycles have precise meanings in fishing activity (Cardoso 2001). However, since the beginning of time, the observation of the sky has always served as a knowledge base for all societies, submitted in conjunction with the cyclical movement of phenomena like day and night, the moon phases and the seasons. The indigenous, since long ago, have perceived that hunting, gathering, fishing and agricultural activities depend on to seasonal fluctuation, and they have sought to unveil the fascinating mechanisms that govern these cosmic processes in order to use them in favor of the survival of their communities (Afonso 2006). The scientific community knows very little about the astronomy of traditional communities and its relation with their knowledge on meteorological processes. It constitutes treasure facing extinction just like biological resources. In this perspective, Cordell (1974) was one of the pioneers in the study of the classification that the fishermen from Arembepe - BA make for tidal movements associated to the various lunar phases. However, few studies show this theme, like Cordell (1974), Mourão (2000), Nishida (2000), Sanches (2001), Alves and Nishida (2002), Godefroid et al. (2003), Ramires and Barrella (2003), Nishida et al. (2006a, b) and Ono and Addison (2009). Ono and Addison (2009) studied rich traditions of fishing made by Tokelauan from New Zealand focusing on fishing practices, technologies and materials and related them to fish ecology, demonstrated the wisdom of this community and could serve as an example for many island communities where fishing is quickly changing under the pressures of modern life. All this knowledge and perception of natural phenomena have allowed the traditional fishermen to build up their know-how and techniques to exploit the resources in their environment and adapt themselves to it. Consequently, traditional fishing shows a great diversity of technique and strategy according to the range of species to be caught (Netto et al. 2002). This variation in the use of devices is related to the kind of environment exploited and the target species (Maia and Rocha-Barreira 2008). Chaves and Robert (2003) studied a variety of fishing techniques used in many regions of the Brazilian coast, such as drag, cast, emalhe nets (mesh net) and espinhel (long line), among others. Silvano (2004) states that just on the Paraná coast, more than 15 different methods of fishing can be recognized, some of which are remarkable for their economic importance. The fishing strategy can be defined by a combination of instruments, target species and geographical location, plus, the influence of abiotic factors (Montenegro et al. 2001). According to Cordell (1974), the determination of where and how to fish every day is generally based on a set of pre-determined environmental information, and the origin of this information is the perception that fishermen know the cyclical regularity of tides, which affects both the mechanical operations of the fishing methods and the distribution of the species throughout the estuary. The lunar phase can exert an influence on the specific composition of a region s ichtyofauna, either because of the variation caused by the nightlight or because INFLUENCE OF TIDES AND WINDS ON FISHING TECHNIQUES, NE BRAZIL 777 of its action on the variation in tide level (Quinn and Kojis 1981, Rooker and Dennis 1991, Godefroid et al. 2003). Besides these, the reproductive activities related to the lunar cycle, such as the aggregation for spawning, can cause significant effects on the temporal variation regarding fish abundance (Johannes 1978, Godefroid et al. 2003). The traditional ecological knowledge represents multiple facets of know-how accumulated over many generations of intense interaction between people and the natural world (Drew 2005), enabling important contributions vis-à-vis with the recent awareness about loss of biological diversity, the need to know and comprehend the tropical ecosystems, as well as the cooperation with management programs (Berkes 1999, Drew 2005, Anwani and Vaccaro 2008). This research aimed to describe the way traditional fishermen from the communities of Barra de Mamanguape and Tramataia, located on the shores of the Mamanguape River Estuary, on the Paraíba State coast, NE Brazil, classify the tides and the winds, as well as the influence of these factors on their fishing strategies and techniques. MATERIALS AND METHODS The Mamanguape River Estuary MRE (Fig. 1) is located on the septentrional part of the Paraíba coast, around 80km from the city of João Pessoa. It covers an area of 5,721 ha of mangrove bounded by latitudes S to S and longitudes W to W (Paludo and Klonowski 1999). The fishing communities studied were Barra de Mamaguape and Tramataia, located in the Barra de Mamanguape Área de Proteção Ambiental - APA [Environmental Protection Area], on the shores of the MRE. These settlements are basically formed by a mixture of Indian, black and white racial Fig. 1 - Map of the localization of the Mamanguape River Estuary MRE. 778 DANDARA M.M. BEZERRA et al. elements, and they conduct extractive activities in the area around the Mamanguape River (Paludo and Klonowski 1999, Mourão and Nordi 2003). The field work was carried out in the period of November 2006 to March 2007, with two trips per month. 23 male fishermen were altogether interviewed, 15 from the Barra de Mamanguape community and 8 from the Tramataia community, with ages ranging from 25 to 67. The research project was submitted to the Ethics Committee in Research of the State University of Paraíba and approved (protocol number: ). In addition, the fishermen were asked if they wanted to take part in the study. All of them were free to withdraw from the research at any time. Initially, mutual trust and rapport between researcher and interviewee were established through free non-organized interviews (Costa-Neto and Marques 2000). For the free interviews, the snowball technique (Bailey 1982) was used, in which each informer indicates others who know about the researched subject. Semistructured interviews followed this one, enabling the gathering of fishing data concerning the knowledge of techniques and strategies related to the tides, moon, winds and the seafood caught. The mesh of fishing nets was measured between adjacent knots using a metal ruler with 1mm graduations in order to relate its size to its catch selectivity. The interviews were recorded manually and with the aid of a cassette or MP3 recorder, and then transcribed. These recordings can be found at the Ethnoecology/Ethnobiology Nucleus of Paraíba State University. Besides the interviews, a direct observation technique was used (Stebbins 1987), in which the researcher is a non-participant observer. The aim was to provide a better understanding of the fishing techniques and strategies, to learn about the local denominations for the tide and the winds to and make the photographic registration. For the analysis and control of data, some were performed tests to verify the consistency and validity of the replies in synchronic and diachronic situations; the first lot occurred when the same question was posed to different people in a very short space of time, and the second when a question was repeated to the same individual in a distinct period of time. The data were analyzed using qualitative emicist and ethicist approaches (Costa-Neto and Marques 2000), in which the traditional knowledge was compared to the corresponding and/or co-related knowledge found in the scientific literature. The behavior was evaluated according to the environmental implications that arose, and the thoughts deduced by looking for possibilities of cognitive/behavioral linking. TIDES CLASSIFICATION RESULTS By means of the interviews, it was possible to organize the way the traditional fishermen classify the effect of the moon on the periodicity of the tides. Figure 2 shows that the breaking tide corresponds to the amplitude variation between the tides when they start to decrease; flushing tide means the amplitude variation between the tides when they start to increase; dead tide means the minimum amplitude variation between the tides that occurs in the days when the sun and the moon pull at right angles to the earth; the big tide happens when there are the greatest amplitude variations between high and low tides. The tide called head of dead water means the last days of the 'dead tide' as the moon starts to change to waning crescent phase. The big tide is responsible for as causing the highest and lowest amplitude of water level and has a strong flow: during the big tide, it influences the kind of water flow and the water into that enters mangrove, making the flow more intense in the estuary and spreading out over the croas (sandyclayloam shores) (Eufrásio - fisherman). The dead tide is thus nominated because the low and high tide oscillations are minimal and the flow is weaker: the dead tide lowers the water and decreases its flows less (Bio Aristóteles - fisherman). The breaking INFLUENCE OF TIDES AND WINDS ON FISHING TECHNIQUES, NE BRAZIL 779 Fig. 2 - Classification, according to the knowledge, of the fishermen from MRE of tidal movements associated with the lunar cycle. tide is distinguished by the daily lowering of the tide level and the water flow until it reaches the same stage as the dead tide : it s getting less water (Caroba - fisherman). The flushing tide means a gradual increase in the water level and flow until it reaches the big tide level: water s coming and getting higher (Vermelho - fisherman). Besides the tides mentioned, the MRE fishermen also named the tides according to the water level in relation to the sand banks (high tide, low tide, thick tide of flood, thick tide of ebb, low tide of flood, low tide of ebb), to the lunar phases (tide of moon, tide of quarter), and to the period of occurrences (dark tide, twilight tide) (Table I). THE TIDAL INFLUENCES ON FISHING TECHNIQUES AND STRATEGIES The fishing nets made of nylon can be used for four different modalities: cerco, caceia, de espera and de zangaria fishing. Siege fishing ( cerco ) is aimed at mullets (M. curema) and usually performed by three fishermen. They identify the shoals; with a rowing boat, cast a mullet net ( tainheira ) and follow the shoal movement until the net almost surrounds it. Then a fisherman beats the water with a wooden rod to drive the shoal towards the net. The same type of net is also used to catch sauna, the youthful stage of a mullet; also it catches sardines (Clupeidae), catfish (Ariidae) and tamataranas (M. curvidens, M. incilis, M. gaiamardianus). This strategy is used at low tides of big tides or syzygy, when the fishermen manage to visualize the shoals more easily. The fishing of caceia consists of a strategy in which the fishermen pay out the net, allowing the current to take it until a certain point where the fish get trapped in it. The nets used can be the mullet net, which captures M. curema, Centropomus undecimalis, Pomadasys ramosus and other species of the families Ariidae and Gerreidae; gillnet ( sauneiro ), which captures species of the families Ariidae e Mugilidae and gillnet ( caçoeira ), which catches species of the families Ariidae, Centropomidae, Gerreidae, Mugilidae and Sciaenidae. In these cases, the suitable tides are high tides of big tides and the flushing tide, because these tides provide the current needed in the transportation network by water. Another strategy used by the fishermen is the zangareia, which is characterized by the vertical fixing of a mullet net, which starts laid 780 DANDARA M.M. BEZERRA et al. TABLE I Classification system of the tides according to fishermen (23 interviewees) from the MRE and its characteristics and correlation with the scientific classification of tides. Classification according to the fishermen Characteristics Scientific classification Big tide Occurs with the full and new moon. Spring tide Dead tide Breaking tide Flushing tide Dark tide Twilight tide Occurs with waning moon and crescent moon Occurs with the passages of the full moon from the waning moon and new moon to crescent moon. Occurs with the passage of waning to new moon and crescent to full moon. Corresponds to the dawn period; occurs with the new moon. Related to the tide at the beginning of night time. Neap tide High tide or full tide Maximum level of the high tide. High tide. Low tide or dried tide Minimum level of an ebb tide. Low tide. Thick tide of flood Thick tide of ebb Low tide of flood Low tide of ebb Head of dead water The tide rises and its level crosses half of the beach; it is close almost to being a high tide. The tide is decreasing in water volume after the high tide. The tide is increasing its level from the low tide. The water level is falling; it is close to the low tide. Presents the end of the neap tide, when the moon starts to change phase from full moon to new moon. Flood tide Ebb tide. Flood tide. Ebb tide. Slack water longitudinally inside the stern of the canoe; in the bow area, a tocheiro (kerosene lamp) is attached to make the fish jump as a reaction to the light reflection. This fishing strategy usually catches species of the families Belonidae and Mugilidae. The gillnets can also be set to stay in a vertical position to reach a great part of the water column. This fishing strategy is used in dead tides and in flushing and breaking tides, as the current is slow. Fishing activities with nets made of silk line, like the mesh net of silk ( tomada ) (Fig. 3A) and the drag-net ( arrasto ) (Fig. 3B), are also organized according to the tides. The mesh net of silk is employed in the period of the syzygy, flushing and breaking tides, with three stages: (1) the mesh net of silk is set when the tide is low; Laguncunlaria racemosa ( mangue manso ) rods are inserted and the net is fixed on the muddy soil; (2) at the peak of the INFLUENCE OF TIDES AND WINDS ON FISHING TECHNIQUES, NE BRAZIL 781 high tide, the net is raised and attached to the top end of the rods; (3) in the following low tide, they remove the fish trappped by the net. This network captures species of the families Ariidae, Centropomidae, Gerreidae, Mugilidae and Sciaenidae. The drag-net is most often used in the breaking and flushing tide, preferably in tidal ranges of lower amplitude, when the sandy-clay-loam banks are exposed with a shallower estuary depth, so the fishermen can drag the net to the shore of the estuary or to the banks. This technique usually catches species in the families Ariidae, Clupeidae, Gerreidae, Sciaenidae, Trichiuridae, Dasyatidae, Gymnuridae, Myliobatidae and Rhynopteridae. The cast net ( tarrafa ) (Fig. 3C) is generally used in the flushing or breaking tide, while the long line (Fig. 3D) with hooks can be used in all types of tides. The castes net catch species such as Mugil curema, Centropomus undecimalis and Pomadasys ramosus, and also other species of the families Ariidae, Clupeidae and Gerreidae, while the long line catches species in the families Ariidae, Dasyatidae, Gymnuridae, Myliobatidae, Rhynopteridae and Serranidae. Regarding the net technique, it was noticed that the fishing net needle ( agulheira ), gillnets, mullet nets and cast nets are selective because they have meshes compatible with the adult size of the fish they catch, so the ecological impact is lower. The nets with 20mm or less are the ones for catching fish in the youth and adulthood stages of various species (e.g. the drag-net and the mesh net of silk). In particular, the fishing net needle must be considered special, because, although its mesh is in the millimeter range, it does not constitute a predatory technique as its size is related to adult needle fish (Belonidae). Fig. 3 - A- Tomada net (gillnet) exposed at low tide on the MRE. Photo: José Mourão, 2000; B- fishermen using drag-net on the MRE. Photo: Silvia Soares, 2008
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