A Pesca de Emalhe e de Espinhel de Superfície na Região Sudeste-Sul do Brasil

Publisher: Série Documentos Revizee, ISBN: 85-98729-14-0

ABSTRACT Drifters operated from Itajaí-Navegantes (Santa Catarina State) and Ubatuba (São
Paulo State),between 1993 and 1997 years.Panel mesh size ranged from 12 to 40 cm
(opposite knots, streched) and net length from 1.130 m to 7.560 m.Hammerheads
(mainly Sphyrna lewini, Griffith & Smith, 1834) were the target species , due to its
highly valuable fins in the international market. They represented 77,8% and
28,5% of the total driftnet landings in Itajaí-Navegantes and Ubatuba respectively.
In 1995, the high fishing effort applied by drifters from Itajaí and Navegantes
(72 .216 km of net length estimated), plus the patchy distribution of the adult
hammerheads during the reproductive season, led to a steep yield decline the
following years.

The monofilament longline fishery, based in Itajaí and Navegantes (Santa
Catarina State, Brazil) was described, focusing on sharks and finning. Between
2000 and 2002 years, sharks represented more than 50% of the total longline
landings in Santa Catarina State, being the carcasses for domestic market and fins
exported to Asia. Steel wires used at the gangions are the main responsible for the
high shark rate capture. The blue shark (Prionace glauca), is the most important
species. A seasonal pattern was presented for blue sharks, hammerheads,
billfish, albacores and swordfish catches. Longline survival was high for sharks
(more than 50%) and most of them are sacrificed aboard. Higher hammerhead
catches used to happen in the second quarter of the year.

The hammerheads catch dynamics (Sphyrna lewini and Sphyrna zygaena)
was studied through covariance analysis (ANCOVA) on longline data for the fleet
based in Itajaí and Navegantes (Santa Catarina State, Brasil). Catch and effort
observations (n � 596) were used for the period 1996-2001.Year, season, and area
effects were tested in the model, being the natural logarithm of the fishing effort
(hook number) the covariable. The adjusted means by the model showed higher
hammerhead catches during winter (related to Sphyrna zygaena), spring and
summer (related to Sphyrna lewini).There was a low variation in the hammerhead
catches between 1996 and 2001 years. An area over the continental slope,
between 200 and 3.000 m depth and limited by 30° – 35° S latitudes, yielded the
best catches. The logarithmic relationship between catch (Kg) and effort (hook
number) is linear and positive.

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    ABSTRACT: Movement patterns of scalloped hammerhead sharks in the vicinity of El Bajo Espiritu Santo, a seamount in the Gulf of California, were determined by tracking by ultrasonic telemetry 13 sharks and marking 100 sharks. The 13 tracked sharks swam back and forth along the seamount ridge throughout the day. They did not swim in different directions to reduce swimming effort when currents changed from a parallel to a perpendicular orientation to the ridge. Sharks tracked up to 8 km away into the pelagic environment soon returned to the seamount. From such trackings and repeated observations of marked sharks over periods of several weeks, it is believed that most sharks disperse and return to the seamount in a rhythmical fashion. The separate departures of individual hammerheads in five paired trackings indicated that the sharks left the seamount either in small groups or singly. For these reasons, we argue that the social system of the scalloped hammerhead shark can be described as a refuging system.
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