[MARMAM] Three more new papers on North Atlantic whales
kinguq at gmail.com
Fri Dec 4 06:33:05 PST 2009
On behalf of myself and my co-authors, 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.
Smith, T.D. and Pike, D.G. 2009. The enigmatic whale: the North Atlantic
humpback. NAMMCO Sci. Publ. 7:161-178.
We know more about the North Atlantic humpback whale (Megaptera
novaeangliae) than we do for virtually any other cetacean, yet attempts to
use this information to describe the status of the populations in this ocean
basin have not proven satisfactory. The North Atlantic humpback has been the
subject of extensive research over the past few decades, resulting in a
of knowledge about what has proven to be a species with a very complex life
history and population structure. While several population models have been
developed to integrate the available information, the data overall are not
well described by any of the models. This has left considerable uncertainty
about population status, and has raised questions about the interpretation
some of the data. We describe 7 specific areas where puzzling or ambiguous
observations have been made; these require closer attention if population
status is to be determined. These areas raise several fundamental questions,
including: How many breeding populations are there? How much do the
populations mix on the feeding grounds? How has the distribution of animals
on both feeding and breeding grounds changed? We identify additional
research needed to address the 7 areas and these questions in particular,
so that population status might be determined.
Witting, L. and Pike, D. G. 2009. Distance estimation experiment for aerial
minke whale surveys. NAMMCO Sci. Publ. 7:111-116.
A comparative study between aerial cue–counting and digital photography
surveys for minke whales conducted in Faxaﬂói Bay in September 2003 is used
to check the perpendicular distances estimated by the cue-counting
observers. The study involved 2 aircraft with the photo plane at 1,700 feet
flying above the cue–counting plane at 750 feet. The observer–based distance
were calculated from head angles estimated by angle-boards and declination
angles estimated by declinometers. These distances were checked against
image–based estimates of the perpendicular distance to the same whale. The 2
independent distance estimates were obtained for 21 sightings of minke
whale, and there was a good agreement between the 2 types of estimates.
The relative absolute deviations between the 2 estimates were on average 23%
(se: 6%), with the errors in the observer–based distance estimates
resembling that of a log-normal distribution. The linear regression of the
observer–based estimates (obs) on the image–based estimates (img) was
Obs=1.1Img (R2=0.85) with an intercept ﬁxed at zero. There was no evidence
of a distance estimation bias that could generate a positive bias in the
absolute abundance estimated by cue–counting.
Finally, I present this paper on behalf of author Tim Smith:
Smith, T.D. 2009. Encountering whales: How encounter rates became the basis
for managing whaling. NAMMCO Sci. Publ. 7:221-243.
Declining rates of encountering whales, including both sighting and
catching, were noted by whalers throughout the 19th century, and these
declines became the first indication that whaling was adversely affecting
whale abundance. The interpretation of declines in both sighting and catch
rates proved to be a difficult scientific task. Satisfactory quantitative
methods of interpreting changes in whale encounter rates were not developed
until the second half of the 20th century. Rates of encountering whales
played a key role in the International Whaling Commission (IWC) Scientific
Committee from its beginning in the early 1950s, as well as in the US in
implementing its Marine Mammal Protection Act beginning in the early 1970s.
The development of methods of collecting and interpreting sighting and catch
data was intimately interwoven with the development of the management of
whaling and cetacean by-catches in fisheries throughout the world, but
especially within the context of the Scientific Committees of the IWC and
the North Atlantic Marine Mammal Commission (NAMMCO). Although overfishing
of whales was initially identified through the use of sighting rate data,
catch rate data provided the IWC’s Committee its first firm footing for
advice. However, it was sighting rate data that ultimately became the basis
for the scientific advice on whaling and for management advice in other
settings. This led to the development of large scale cetacean sighting
programmes, such as the IWC’s International Decade of Cetacean Research
surveys in Antarctic aboard Japanese ships, the North Atlantic Sighting
Surveys (NASS) aboard Norwegian, Icelandic, Spanish, Greenlandic and Faroese
vessels and aircraft (coordinated by NAMMCO
through its Scientific Committee from 1995), and surveys under the US’s
Marine Mammal Protection Act and the European Union’s Small Cetacean
Abundance in the North Sea (SCANS) programme. Fishery independent cetacean
sighting surveys have proven to be both central and essential to
understanding and regulating of human impacts on cetaceans.
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