WCI Patagonia Expedition Update 1994

Whale Conservation Institute (wci@vmsvax.simmons.edu)
Mon, 20 Nov 1994 12:43:41

On the Right Track
 
by Vicky Rowntree
 
In September 1994, we embarked on our twenty-fifth field season
studying the southern right whales (Eubalaena australis) which
appear annually off the shores of the Peninsula Valdes, Argentina.
Females come to the protected bays of the Peninsula to rear their
young during the calvesU first months of life.  For me, 1994 was a
wonderful home-coming, my first return in five years.  I found the
Peninsula changed.  The largest town, Puerto Madryn, has grown
enormouse
population grew as well in my absence. There were 1375 whales in
the population in 1988; with a growth rate of 7.1% per  year, there
are now around 2000 whales.  The increase in whales was apparent; I
heard a nearly constant serenade of whale blows, snores and
splashes through the night from inside my tent.
 
John Atkinson and Kim Marshall conducted the annual aerial
photographic census of the whales.  We survey the whales by flying
over them in a small plane and photographing the individually
distinctive white patterns (callosities) on the heads of each whale
we encounter.  As usual, it was windy for most of our time at the
Peninsula, with many days of high waves and whitecaps.  Survey
attempts are fruitless on days like this because the callosity
patterns on the whalesU heads are awash with white water.  Finally,
with most of the field season behind us, we woke to a calm day.  We
were able to coordinate the plane, fuel and pilot and Kim and John
surveyed the entire 500 kilometer perimeter of the Peninsula over
the following two days.
 
The surveys revealed two new findings: 1) the concentration of
whales in Golfo Nuevo had shifted from the area it had occupied for
the past ten years to an area 50 km to the west, near the busy
industrial port of Madryn,  and 2) a concentration of what appeared
to be sub-adult right whales (with few calves) just to the north of
the Peninsula.
 
The right whales in Golfo Nuevo have moved away from an area
which is the center of a rapidly growing whale-watch industry.  The
reason for the shift is not apparent.  However, Mariana Martinez
Rivarola, Alicia Tagliorette and Claudio Compagna of the Argentine
conservation organization Fudacion Patagonia Natural (FPN) have
been studying the interactions between whales and whale-watch
boats through the time of the shift and may soon be able to comment
on the possible effects of disturbance from whale watch activities.
The concentration of whales to the north of the Peninsula is very
intriguing.  Chris Clark and Peter Thomas, who conducted research
for their PhD.s at Peninsula Valdes, saw mothers abandon their one-
year-old calves in the groups of mothers with newborn calves.  Sub-
adults are curious, boisterous and often seen in vigorous surface-
active groups.  Analysis of the air flight photos will tell us if sub-
adults are indeed forming their own concentrations at the Peninsula.
If so, these groups of adolescents will be particularly interesting to
study.
 
For the first time at the Peninsula, a concerted effort was made
to collect data and tissue samples from dead whales are washed
onto the beaches.  Mariana Martinez Rivarola of FPN led the effort
this year and we worked with her and Alejandro Arias to collect
data.  Eight dead calves were found; measurements and tissue
samples were collected for genetics, toxins, isotope and tissue
structure analysis.  We  have been concerned about the pox-like
marks, which are appearing on an increasing number of whales (39%
in 1990.)  Unfortunately, none of the stranded individuals had the
pox-like marks, so we were unable to make progress in
identification of the cause of these marks. Tissue samples collected
from stranded individuals can reveal fascinating information about
the whales, such as how the whales at Peninsula Valdes are related
to other right whales in the southern hemisphere, where the whales
go when they leave the Peninsula, baseline toxin levels and the types
of diseases carried by the population. Information on deaths is an
important part of a population model, and until this year, data had
only been collectable on a sporadic basis. The data Mariana collects
from stranded whales will make a valuable contribution to our
knowledge of right whales at Peninsula Valdes.
 
One of the most disturbing sights at the Peninsula this year was
the at times incessant attacks on whales by kelp gulls. The gulls
land on the whales and gouge pieces of skin from their backs. Roger
Payne commented that the whalesU reactions to the attacks were
more violent than any he has ever seen.  An attacked whale flinches,
suddenly arching its back and swims off rapidly underwater, its
speed indicated by the swirls of footprints on the water surface
from the motion of its flukes.  The gull tracks the whale from
overhead, awaiting the next surfacing.  Peter Thomas studied this
behavior in 1984. He once saw a gull peck the same whaleUs back 178
times in five minutes.  In 1984, the attacks were restricted to a
small region within Golfo San Jose and aimed almost exclusively at
mothers.  This year, we watched attacks in other regions of Golfo
San Jose as well as in Golfo Nuevo.  The gulls are also being less
selective.  We saw them attack all whales, including calves. Thomas
concluded that the responses of the whales to gull attacks, such as
frequent rapid travel and resting postures with the back held
underwater, may exact a serious energetic cost from nursing
mothers who have little energy to spare.  He also noted that when
whales flee the gulls, they often swim away from the protection of
shallow water bays.  The possibility that gulls could drive the
whales from the Peninsula was discussed at a workshop convened by
FPN on the problems facing right whales at Peninsula Valdes.  Plans
were designed to investigate this possibility.
 
On a happier note, I spent many wonderful hours sitting on the
cliffs, watching different whales.  I was often assisted by people
who just wanted to watch and learn more about whales.  At first,
people appeared overwhelmed by all that was before them; but as
they sat, following one whale and repeatedly recording particular
categories of behavior, a brilliant light appeared to go off inside
them and by the end of the afternoon, they were transformed by the
peaceful time they had spent getting to know another animal.  Some
of my most thrilling moments involved encounters with old friends.
A large mother who we first identified  with a calf in 1972
(PV#145) was back again 22 years later with a very rambunctious
calf.  The mother had an orca scar on her lip and her calf had orca
scars on the tips of its tail - a reminder that though orcas are not
often seen, mothers must be constantly on guard for orca attacks.  I
spent another morning watching a mother who was rolling at the
surface with a male.  I was delighted when I finally identified her as
13-71, a whale that was born in 1971 and had returned in 1994 with
her sixth calf.
 
As I folded up my tent in the pouring rain of my last day, I cried
too.  I wanted more time at the Peninsula where I had been one with
the weather, rising with the sun, embroiled in the windUs fury,
warmed in the protected pockets of sand, and guided to my tent by
starlight so bright that it reflected across the whalesU backs into
the night.