[MARMAM] New papers on North Atlantic whale abundance
kinguq at gmail.com
Tue Nov 10 18:38:22 PST 2009
I would like to announce the recent publication of the following 3 papers in
*NAMMCO Scientific Publications* Volume 7, North Atlantic Sightings Surveys:
Counting whales in the North Atlantic, 1987-2001. The volume is available at
www.nammco.no, and pdf reprints are available from me at kinguq at gmail.com.
Pike, D.G., Víkingsson, G.A., Gunnlaugsson, Th. and Øien, N. 2009. A note on
the distribution and abundance of blue whales (*Balaenoptera musculus*) in
the Central and Northeast North Atlantic. *NAMMCO Sci. Publ*. 7:19-29.
The distribution and abundance of blue whales (*Balaenoptera musculus*) was
assessed from ship surveys conducted in the Central and Northeast Atlantic
in 1987, 1989, 1995 and 2001. Blue whales were most commonly sighted off
western Iceland, and to a lesser extent northeast of Iceland. They were very
rare or absent in the Northeast Atlantic. Sightings were combined over all
surveys to estimate the detection function using standard line transect
methodology, with the addition of a covariate to account for differences
between surveys. Total abundance was highest in 1995 (979, 95% CI
137-2,542)and lowest in 1987 (222, 95% CI 115-440). Uncertainty in
had little effect on estimates of abundance. There was a significant
positive trend in abundance northeast of Iceland and in the total survey
Pike, D.G., Gunnlaugsson, Th., Víkingsson, G.A., Desportes, G. and Bloch, D.
2009. Estimates of the abundance of minke whales (*Balaenoptera
acutorostrata*) from Faroese and Icelandic NASS shipboard surveys. *NAMMCO
Sci. Publ*. 7:81-93.
North Atlantic Sightings Surveys for cetaceans were carried out Northeast
and Central Atlantic in 1987, 1989, 1995 and 2001. Here we provide estimates
of density and abundance for minke whales from the Faroese and Icelandic
ship surveys. The estimates are not corrected for availability or perception
biases. Double platform data collected in 2001 indicates that perception
bias is likely considerable for this species. However comparison of
corrected estimates of density from aerial surveys with a ship survey
estimate from the same area suggests that ship surveys can be nearly
unbiased under optimal survey conditions with high searching effort. There
were some regional changes in density over the period but no overall changes
in density and abundance. Given the recent catch history for minke whales in
this area, we would not expect to see changes in abundance due to
exploitation that would be detectable with these surveys.
Pike, D.G., Paxton, C.G.M., Gunnlaugsson, Th. and Víkingsson, G.A. 2009.
Trends in the distribution and abundance of cetaceans from aerial surveys in
Icelandic coastal waters, 1986-2001. NAMMCO Sci. Publ. 7:117-142.
Aerial surveys were carried out in coastal Icelandic waters 4 times between
1986 and 2001 as part of the North Atlantic Sightings Surveys. The surveys
had nearly identical designs in 3 of the 4 years. The target species was the
minke whale (*Balaenoptera acutorostrata*) but all species encountered were
recorded. Sighting rate and density from line transect analysis were used as
indices of relative abundance to monitor trends over the period, and
abundance estimates corrected for perception biases were calculated for some
species from the 2001 survey. More than 11 species were sighted, of which
the most common were the minke whale, humpback whale (*Megaptera
novaeangliae*), dolphins of genus *Lagenorhychus*, and the harbour porpoise
(*Phocoena phocoena*). Minke whales and dolphins showed little change in
distribution or abundance over the period. There were an estimated 31,653
(cv 0.30) dolphins in the survey area in 2001. Humpback whales increased
rapidly at a rate of about 12%, with much of the increase occurring off
eastern and northeastern Iceland. In 2001 there were an estimated 4,928 (cv
0.463) humpback whales in the survey area. The relative abundance of harbour
porpoises decreased over the period, but estimates for this species were
compromised by uncorrected perception biases and poor coverage. The
ecological and historical significance of these findings with respect to
previous whaling activities and present-day fisheries is discussed.
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