Pesca amadora marinha e suas implicações ambientais
This dissertation is divided in two chapters, in the first chapter we evaluated the species targeted by sport spearfishers in Brazil from three geographic regions (NE, SE and S). We evaluated the trophic category of these species and assessed eventual changes in the trophy fish size over time as p...
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| Formato: | Dissertação |
| Idioma: | por |
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/25692 |
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| Resumo: | This dissertation is divided in two chapters, in the first chapter we evaluated the species targeted by sport
spearfishers in Brazil from three geographic regions (NE, SE and S). We evaluated the trophic category of
these species and assessed eventual changes in the trophy fish size over time as possible indicators of
ecological disequilibrium. We used an online questionnaire distributed over social media, mainly
Whatsapp. The questionnaire addressed, besides the fish targeted, if spearfishers acknowledge some
possible impact caused by this type of fishing and other related environmental conservation aspects of this
activity. It also assessed if spearfishers were aware of regulatory initiatives and if they were ever required
to comply with them through enforcement. The survey results showed a downward trend in the weight of
the largest fish caught and in the median trophic level over time. Carnivorous fish were the preferred target
of the spearfishers (coinciding with the results of beach sport fishing, practiced with pole and line, described
in the second chapter). The geographic regions differed in numbers of target species, with the northeastern
fishers targeting a higher number of species. Overall, spearfishers’ perception on conservation, impact and
regulation did not vary between regions, despite a slight tendency of southern spearfishers being more
subjected to enforcement. In the second chapter, we reconstructed the historical catches (1975-2016) of
sport fishing practiced with pole and line on the beaches of the state of Rio Grande do Norte, using available
bulletins and other secondary sources, besides some direct tournament observation along 2016. Missing
data were inferred using average values calculated from the years that had the original information. The
reconstructed data were presented for two types of tournament: for fish small and over 100g, resulting in
total catches per year and CPUE (Capture per Unit Effort). Whenever available, the trophic level of the
species was also registered for evaluation of changes over time. The results showed a large variation in the
number of championships over the years, with the total catch per year varying directly according to the
number of tournaments. No trend was observed regarding fish weight, which was always low. Nevertheless,
the trophic level of the targeted species decreased over the decades. Although this type of fishing removes
small amounts of fish compared to commercial fisheries, a better understanding of it could support the
evaluation of their targeted fish stocks (e.g., as shown here in the decreased trend of trophic level). It should
also be considered that, despite small, this is a selective removal that may, potentially, alter the structure of
the food chain, the reproduction of some species, and phenotypical and genotypical aspects of the targeted
species, for selecting small and often pre-reproductive individuals. Together, both chapters build an
important and unique body of knowledge regarding recreational fishing in Brazil, which is largely
unknown. This knowledge gap impairs decision-making by managers, preventing possible improvements
in policies regarding stock conservation and the marine ecosystem as a whole. We expect that the results
provided here can support better regulation of these activities and knowledge transmission between
academia, managers and fishers. |
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