Browsing by Author "Duarte, Pedro N."
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- Annotated list of fishes caught by the R/V ARQUIPÉLAGO off the Cape Verde archipelago.Publication . Menezes, Gui M.; Tariche, Oksana; Pinho, Mário Rui; Duarte, Pedro N.; Fernandes, Ana; Aboim, Maria A.A prospective survey was carried out in October - November of 2000, in the Cape Verde archipelago, by the R/V ARQUIPÉLAGO. The main objective was to determine the species composition and relative abundance of the demersal fish resources living in the waters of the Cape Verde archipelago. A list of fishes caught with bottom longline during the survey is presented in this document, along with information about the area, depth limits and the relative abundance of the species in the catches. Ninety-seven different species from 49 families were identified from 20 long-line sets. To our knowledge, the following 12 species were recorded for the first time from the waters of Cape Verde islands: Etmopterus princeps, Etmopterus pusillus, Gymnothorax maderensis, Myroconger compressus, Laemonema robustum, Beryx splendens, Scorpaena elongata, Serranus atricauda, Taractes rubescens, Taracthichthys longipinnis, Pagrus africanus and Cathidermis sufflamen. The species Laemonema robustum, were new to the CLOFETA area.
- Staining techniques for ageing tope shark, Galeorhinus galeus (Linnaeus, 1758), from the Azores : a comparison based on precision analysis.Publication . Duarte, Pedro N.; Silva, Alexandre A.; Menezes, Gui M.; Pinho, Mário RuiA vertebrae sample of tope shark, Galeorhinus galeus (Linnaeus, 1758), stratified by sizeclasses,was used to test between different staining techniques of enhancing vertebral growth ring visibility. Four techniques were tested: alizarin red, silver nitrate and cobalt nitrate staining, and the “deep-coned vertebrae” technique. The latter was discarded due to its unsuitability for tope shark vertebrae. The cobalt nitrate original protocol was modified. Upon staining, each vertebra was subject to three replicated independent readings, by a single reader. Within-reader consistency and bias of growth ring counts determination were evaluated using four different precision indices: percent of agreement (PA), average percent error (APE), coefficient of variation (V) and index of precision (D). Results indicated that the vertebrae stained with the cobalt nitrate technique showed both better optic enhancement of growth rings and higher degree of count consistency, comparatively to the alizarin red and silver stained vertebrae. Conclusively, the cobalt nitrate was the most efficient staining technique upon tope shark vertebrae, among the methods tested herein.
- Trends in the fishery and catch patterns of kitefin shark, Dalatias licha (Bonaterre, 1788), from off Azores, through a GIS spatial analysis.Publication . Machado, Pedro B.; Pinho, Mário Rui; Duarte, Pedro N.During the last two decades the Azorean fishing community has profited from the kitefin shark fishery which in the year 2000 generated an estimated revenue of approximately €12,500. This resource has been targeted mainly by small fishing vessels operating in the Azores archipelago since the late 1970s. The vulnerability of this species to exploitation has raised the concern about the impact of the fishery on the resource. The monthly landings of three artisanal fishing vessels were monitored and possible changes to kitefin shark abundance and catch pattern, for the period between 1986 and 1998, were geographically analysed. A vector-based GIS (Geographic Information System) was constructed to evaluate the changes in the number of individuals captured and squalene oil barrels obtained through a spatio-temporal perspective. In order to investigate which were the most profitable fishing areas. An optimum fishing pathway was generated for one of the vessels in 1997 based on a raster GIS. The results indicated a decrease of kitefin shark catches in several areas around Azores archipelago and over the time period analysed. The analysis of the data in a GIS environment yield a dynamic and integrated view of the species catches off Azores in a temporal and spatial perspective.