The Humpback whale is an endangered species. There are around 10,000 to 15,000 of them
world wide. This whale can be found in all of the words oceans and they make
seasonal migrations for feeding and breeding.
During the winter months, the whales travel to the warm tropical waters
to breed. It takes a female 11-12 months
to develop the calf before it is born.
After the calf is born it consumes around one hundred pounds of milk a
day from its mother and stays with her for about a year. It will take a whale 15 years to fully
mature. During the summer months, the
whales travel to the cold arctic waters to feed.
In these cold waters they consume about 1 ton of food daily. The feeding season lasts for 120 days and
then the whales live off of stored fat for the remaining seasons. These mammals can live up to be 45-50 years
old. Since the Humpback whale is such a
long lived animal, it makes them the perfect bioindicator. Humpback whales have been used in studies to
determine the concentrations of persistent organic pollutants found in their body
and also in the different feeding areas of the whales. While consuming small fish, crustaceans, and
plankton, the whales are also consuming small concentrations of persistent
organic pollutants (POP’s). POP’s are
compounds that do not degenerate in the natural environment and build up in
systems. This build up of the POP’s
introduces the concept of bioaccumulation, which is the intake of an organic
compound at a higher rate than the rate that it is leaving the system. The POP’s are entering the marine systems
through run off, waste, and atmospheric pollution. With the help of currents and the Westerlies
these pollutants are carried and spread at a global scale.
In a study the blubber of humpback whales was sampled
from male whales at various feeding locations in the Pacific and Atlantic
Ocean. A chromatography
test was then run test for the following POP’s: PCB’s, DDT, Chlordanes, PBDE’s,
and HCH’s. The goal of this study was to
see if these pollutants were present in higher concentrations in certain
feeding locations and if the concentrations of these pollutants were of any
harm to the whales. The studied showed
that the North Atlantic contained the most contaminants
and the Gulf of Maine
specifically had significantly higher concentrations than the other areas
tested (Elfes, et. al, 2009). These high
concentrations were thought to be caused by the increased industrialization and
the increased population size (Elfes, et. al, 2009). The difference in results could also be
caused by change in prey found in the different feeding locations; for example
the whales feeding in the North Atlantic could be
consuming prey of a higher trophic level than those whales feeding in the
Pacific (Elfes, et. al, 2009). Also from
these results another observation was made.
A positive correlation between the age and concentration was found. With the increase of whale age there was an
increase of the concentrations of the POP’s (Elfes, et. al, 2009). This was perfect correlation to represent the
bioaccumulation of the POP’s in the humpback whale.
Another study also wanted to test the concentrations of
POP's in the humpback whale. Instead of
focusing on the feeding locations and age, the test compared the concentrations
of the POP’s found in female whales to those found in the calves. The goal of this was to see if the female
whale transferred some of her concentrations to the calf during the offspring development
(Metcalfe, et. al, 2003). The
concentrations of the two were found to be very similar in each of the POP’s
tested for, with no significant difference (Metcalfe, et. al, 2003). Since there was no significant difference in
the concentrations of the pollutants found in the female and calf, it was
predicted that the female whale does in fact transfer it’s contaminants to the
calf (Metcalfe, et. al, 2003). It was
stated that this could be possible through transplacental and lactational transfers
(Metcalfe, et. al, 2003).
Although there were pollutants found in all of the blubber
samples, the concentrations present were not at threatening levels to the
whales. But it is a prefect example that
POP’s do not degenerate and remain in the environment for decades. Even though several of the POP’s have been
banned from use it does not mean that they do not exist in the
environment. In fact as the economy
grows, new pollutants are being introduced into the environment. Since the humpback whale is an endangered
species, it is important to continue to monitor these concentrations in order
to ensure that no unnatural harm is being exposed to the whales.
