Fishers’ knowledge on the coast of Brazil

Ethnobiology includes the labelling of organisms (ethnotaxonomy), their recognition by diagnostic characteristics (diagnostic characters) and their cultural classification, which implies their grouping according to a set of criteria following a classification system [1]. The understanding of clusters of organisms, the criteria of group formation, along with higher hierarchical forms, such as ‘life forms’, forms a body of theory that helps understand the human classification of nature and human cognition concerning nature ‘discontinuities’ [2]. A study on Brazilian fishers [3] has shown that fishers form fish groups, hierarchically, based on morphology, ecology and fish behaviour. Among the multiple questions raised in ethnobiological studies, one approaches how the knowledge people have about nature varies with culture, experience, or expertise [4]. Another question addresses if human perception is selective, by focusing better on more salient items (or organisms). Salient organisms can be beautiful, colourful, big or cultural relevant organisms, among other attributes [5]. Therefore, the way people name and classify nature is also associated to human perception, expression and cognition. It has been shown, for example, that people tend to classify nature often up to a genus level (primary lexemes), represented by generic names [1].

The reason why multiple ethnobiology studies have been done with fishers is exactly due to their direct contact with a wide range of organisms, and especially in tropical countries, where there is a high diversity of species. Specifically, the ethnotaxonomy and classification systems of fish by artisanal fishers have been widely studied, including several studies in coastal Brazil [3, 6‐14]. Understanding how fishers name fish, along with other information they have about the ecology and biology of species, could help us grasp part of the human cognition. Human perception abilities, such as when observing nature, is an important attribute and might be concentrated on more salient organisms (e.g.: beautiful, colourful useful, big organisms). Such understanding could also help us in other ways. For example, target species seem to be those that fishers focus their daily attention [3, 15]. If we conclude that fishers know considerably more about target species than about non-target ones, consequences for managing fisheries are manifold. For example, fishers’ knowledge regarding fish diversity could be useful to monitor temporal or spatial changes in fish species composition or abundance [16], as well as to compare fishers’ knowledge with official fish landings statistics [17]. Furthermore, fishers’ knowledge on ethnotaxonomy could improve inventories of fish diversity, at least for target species [3].

Ethnoecology, or more specifically ethnoichthyology, meaning the knowledge fishers have about fish biology and ecology, has also been studied in Brazil. Ethnoichthyology is a subdivision of ethnozoology [18]. Besides more basic research questions from ethnozoology and ethnoichthyology, the simple need of information about fish is of great importance: in particular, the lack of information on fish from the Brazilian coast is striking, also because the collection of data on fish landings on this coast is unreliable. Some studies have focused on fishers’ knowledge of spawning and migration of coastal fishes [19]. Some other studies have also examined fishers’ knowledge of trophic interactions in SE Brazil [20‐22]. Particularly, there is increasing interest in having fishers contribute their knowledge to the management of fisheries [23, 24].

However, studies are generally local or regional and cover specific fishing communities. Collecting data is time-consuming, and there are few studies that encompass larger areas to permit broader comparative analysis of fishers’ knowledge [18, 25, 26]. We thus developed an ethnobiological study encompassing several fishing communities in major coastal areas of Brazil (northeast, southeast and south). We also developed a comparative method: instead of using locally landed data, we used identical pictures of fish at all studied sites.

Our objectives were to obtain knowledge on general patterns of fishers’ folk nomenclature and classification processes. We also tested with quantitative data two hypotheses regarding factors influencing fishers’ knowledge on coastal fish species: 1) fishers’ knowledge will be positively related to fish size (see also [5]) so larger fish would be better known; and 2) fishers’ knowledge will be positively related to economic importance of fish species, so fish with high economic importance would be better known. Finally, we suggest these data are worth to environmental agencies and researchers, in order to improve the management of target species.

Five coastal communities were studied between 2004 and 2005: two from the northeast (Porto Sauípe and Itacimirim, in Bahia State), two from the southeast (Itaipu at Niterói and Copacabana at Rio de Janeiro, Rio de Janeiro State) and one from the south coast (Pântano do Sul, Florianópolis, in Santa Catarina State) (Fig. 1). These sites were visited in earlier studies [27] (Fig. 1).

We chose the fish species to be studied according to their commonness, rarity, and usefulness (for example, eaten and sold, among others.). This information was obtained from fish landings we had from earlier research at these areas [27]. We expected to find more information on common species (target species) rather than on rare ones. For that reason we used prior information on landings to identify the target and rare species. Probably we could expect more knowledge on salient species; but target species, being also salient, are testable. We expanded an earlier study in which 24 pictures were shown to fishers at some sites in Brazil [3, 12]. In the present one, we showed pictures of 38 fish species to fishers. The fish pictures were randomly ordered, and the same order was presented to all interviewees (Fig. 2). One of the pictures was a control (a freshwater fish of no occurrence at the study sites, the Pseudoplatystoma fasciatum, Pimelodidae).

We only interviewed fishers who were over 35 years old and who had lived in the community being studied for the last 20 years. We conducted interviews at landing points and at fishers’ residences. Information regarding fishing activities and on fishers, is available [27]. The interview protocol, after the verbal consent of the interviewer, included the fish identification of the picture (folk name), knowledge of the fish diet, of the fish habitat, among other questions. The last protocol included placing the fish (based on the order number) on a table, or at the floor, and asking the fisher to form groups as they perceived them (for example, groups of fish considered by fishers to be ‘cousins’ or ‘relatives’). The questionnaires are deposited in the FIFO’s archives, labeled PEMVIMSA 005 (Fisheries and Food Institute, located at Ecomar, Unisanta, Santos, SP, Brazil). Interviews included 34 fishers from Bahia State (22 from Porto Sauípe and 12 from Itacimirim), 35 from Rio de Janeiro State (12 from Itaipu, Niterói, and 23 from Copacabana, Rio) and 23 from Santa Catarina State (Pântano do Sul, Florianopolis), with a total of 92 fishers.

We compared our data on fishers’ knowledge about fish biology and classification with the scientific literature that is available and synthesized in Fishbase [28], amongst others, which are references cited along the text (see also Additional file 1).

We tested the two hypotheses regarding the influences of fish size (hypothesis 1) and value (hypothesis 2) on the local fishers’ knowledge. These hypotheses were tested by using two measures of fishers’ knowledge (the dependent variables in the analyses): number of doubts (when the fisherman answered ‘I do not know’) and homogeneity of identification of fish species. Number of doubts was adopted as an inverse indicator of knowledge: the higher the number of doubts, the lesser the knowledge, following an approach adopted in previous ethnobiological studies [3, 18, 29]. The homogeneity of answers was measured as the total number of interviewed fishers who cited the most mentioned name for the fish species in each studied community, calculated from data in Table 1. This is a direct indicator of knowledge: a higher number of fishers mentioning the same name for a fish indicates that this fish is better known, as it shows higher homogeneity within the population and is more readily recognized by fishers [3]. The economic value of fish species (independent variable) was assigned based on previous studies on fish preferences [26, 30] and on the expertise of the authors. Each species was classified as low, medium or high priced fish. The other independent variable, fish size, was gathered from the Fishbase website [28], measured as maximum reported length for each species. We checked normality of the continuous variables (fish size, number of doubts, number of fishers reporting main fish name) and the variable number of doubts was log transformed to perform the statistical analyses. The number of doubts (Log transformed) and number of fishers mentioning the main fish name were compared among three economic categories (high, medium low) of fish species through an Analysis of Variance (ANOVA). The number of doubts (Log transformed) and number of fishers mentioning the main fish name were related to fish size (cm) through linear regression analyses. We checked the relation of these two dependent variables [number of doubts (Log transformed) and number of fishers mentioning the main fish name] through Pearson correlation analysis.

The results of the study are here in the same sequence used to show the pictures to the fishers (1 to 38). We interviewed a total of 92 fishers in the three study areas in the coast of Brazil: NE, SE and S. Our results indicate similarities in the fishers’ identification of the generic ranking and the groups of fish formed by the fishers.

Fishers’ nomenclature follows regional names, particularly when comparing the northeast and southern coasts of Brazil (SE and S). Besides, there are also linguistic variances of the same name, along with regionalisms per area (SE and NE). Generic names are the most common, represented by primary lexemes. Fishers’ knowledge of the habitat and diet of fish appear to be particularly concerned with target species, which are species that fishers encounter most often; such knowledge can be needed to achieve good catches. Fishers must know where to locate the fish and which bait to use. Fishers also group fish, and their groupings are similar in the three areas; again, the groups cited most often are those groups that include most important fish. Finally, we can conclude that fishers showed a comparatively higher knowledge of target species compared to less important species (not consumed, or not sold, for example). Overall, fishers showed good knowledge about most of the studied fish species considering an analogy with the scientific literature and for some species fishers’ knowledge may be the sole source of information available. These results reinforce the relevance to include fishers’ knowledge in fisheries management.