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Pesca e ecologia do tubarão galha-branca oceânico (Carcharhinus longimanus, Poey 1861) no atlântico oeste tropical
| Content Provider | Semantic Scholar |
|---|---|
| Author | Tolotti, Mariana Travassos |
| Copyright Year | 2011 |
| Abstract | The aim of this study was to add valuable information to the knowledge of the oceanic whitetip shark, especially with regard to its distribution, relative abundance and habitat preferences in the western tropical Atlantic Ocean. Despite of being a widely distributed and abundant species this kind of information is scarce or even absent in the literature. In the first article, catch and effort data from 14,560 longline sets carried out by the Brazilian chartered tuna longline fleet, from 2004 to 2009, were analyzed. The CPUE, expressed as the number of sharks caught per thousand hooks, exhibited a tendency to increase gradually over the years, ranging from 0.04 in 2004 to 0.14 in 2007. In 2008, however, the CPUE increased sharply, reaching 0.45 and then dropping back to 0.10 in 2009. The CPUE spatial distribution by year and quarters of the year showed that the area bounded by 10°S and 20°S of latitude and 030°W and 040°W of longitude concentrated the highest values. The majority of the oceanic withetip sharks caught by this fleet were under the size of first maturity. Although the total length ranged from 50 to 320 cm, almost 80% were under 180 cm (published size at first maturity). The spatial distribution showed a concentration of larger specimens from about 020°W to 030°W and from5°S to 20°S. Another area of concentration of larger specimens seems to be present to the north of 5°N, between the same longitudes. In the second article, data on horizontal movements and temperatures and depths experienced by two oceanic whitetip sharks tagged with pop-up satellite archival tags were analyzed. Tagging occurred in late January and early February of 2010, the first whitetip tagged was a female measuring 135 cm in total length and the second was male measuring 152 cm. Both sharks had a remarkable preference for warm and shallow waters of the mixed layer, spending at least 95% of the deployment period in waters with temperatures above 26.0°C and 86% in the first 50 m. Deep diving behavior was not registered. The maximum recorded depth was 128 m and the minimum temperature was 15.6°C. Despite their narrow depth distribution, both sharks performed diel vertical migrations. Tagging and pop-off sites were not far from each other and the maximum distance traveled was 1,884 nautical miles. Daily displacement ranged from 12.86 to 20.94 nautical miles and mean swimming speed ( SE) ranged from 0.41 0.16 to 1.00 0.09 knots. The horizontal movements indicated a westward migration. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://repositorio.ufpe.br/bitstream/123456789/8480/1/arquivo424_1.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
