5 resultados para Balaena-mysticetus

em Publishing Network for Geoscientific


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Working with subsistence whale hunters, we tagged 19 mostly immature bowhead whales (Balaena mysticetus) with satellite-linked transmitters between May 2006 and September 2008 and documented their movements in the Chukchi Sea from late August through December. From Point Barrow, Alaska, most whales moved west through the Chukchi Sea between 71° and 74° N latitude; nine whales crossed in six to nine days. Three whales returned to Point Barrow for 13 to 33 days, two after traveling 300 km west and one after traveling ~725 km west to Wrangel Island, Russia; two then crossed the Chukchi Sea again while the other was the only whale to travel south along the Alaskan side of the Chukchi Sea. Seven whales spent from one to 21 days near Wrangel Island before moving south to northern Chukotka. Whales spent an average of 59 days following the Chukotka coast southeastward. Kernel density analysis identified Point Barrow, Wrangel Island, and the northern coast of Chukotka as areas of greater use by bowhead whales that might be important for feeding. All whales traveled through a potential petroleum development area at least once. Most whales crossed the development area in less than a week; however, one whale remained there for 30 days.

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Forty-six sightings of bowhead whales have been reported from the Svalbard area between 1940 and 2009. But, only three of these sightings are reported prior to 1980. Most observations involve only one or two whales, but groups of up to seven individuals have been seen recently. Increased ship traffic, particularly cruise-based tourism, in the north undoubtedly provides more opportunities for spotting this species, and the establishment of a structured cetacean sighting programme, as well as increase in effort in documenting sightings from a wider marine user-community, likely all play a role in more records being documented in recent years. The absence of a dedicated monitoring programme for ice-associated cetaceans and the generally low scientific activity level in this field in Svalbard Waters hampers firm conclusions about the trends in abundance of bowhead whales in the Svalbard area.

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Sixty hours of direct measurements of fluorescence were collected from six bowhead whales (Balaena mysticetus) instrumented with fluorometers in Greenland in April 2005 and 2006. The data were used to (1) characterize the three-dimensional spatial pattern of chlorophyll-a (Chl-a) in the water column, (2) to examine the relationships between whale foraging areas and productive zones, and (3) to examine the correlation between whale-derived in situ values of Chl-a and those from concurrent satellite images using the NASA MODIS (Moderate Resolution Imaging Spectroradiometer) EOS-AQUA satellite (MOD21, SeaWifs analogue OC3M and SST MOD37). Bowhead whales traversed 1600 km**2, providing information on diving, Chl-a structure and temperature profiles to depths below 200 m. Feeding dives frequently passed through surface waters ( >50 m) and targeted depths close to the bottom, and whales did not always target patches of high concentrations of Chl-a in the upper 50 m. Five satellite images were available within the periods whales carried fluorometers. Whales traversed 91 pixels collecting on average 761 s (SD 826) of Chl-a samples per pixel (0-136 m). The depth of the Chl-a maximum ranged widely, from 1 to 66 m. Estimates of Chl-a made from the water-leaving radiance measurements using the OC3M algorithm were highly skewed with most samples estimated as <1 mg/m**3 Chl-a, while data collected from whales had a broad distribution with Chl-a reaching >9 mg/m**3. The correlation between the satellite-derived and whale-derived Chl-a maxima was poor, a linear fit explained only 10% of the variance.