While results from tissue samples from stranded whales on
Otago's coast this summer are still to come in, it is
unlikely they will shed any further light on the cause of the
whales' deaths, the Department of Conservation says.
As part of the investigations into why the whales stranded,
scientists are seeing whether any effects from seismic
testing in the area at the time can be detected.
Doc has a voluntary agreement with those undertaking seismic
testing that they fund necropsies for any marine mammal
deaths while they are testing.
The strandings of nine orcas on a beach near Tuatapere and a
long-finned pilot whale at Kaka Point in February were
uncommon but not unusual, Doc marine and species threat
technical adviser Dave Lundquist said.
Records showed there were strandings around New Zealand about
every 15 years.
While the necropsies were often inconclusive, even in
best-case circumstances, Doc was doing its best to detect if
the strandings were caused by acoustic trauma from seismic
''If it's possible to detect it, we will detect it, but it's
very hard to detect.''
That was because the small bubbles in the whale's inner ear
that indicated such trauma were also found once it had
The results from the one Orca tested were inconclusive. The
stranding might have been caused by acoustic trauma but
because the whale had been dead for several days before
testing, it was hard to say.
''The pilot whale was similar - there was nothing
The whale had parasites in its inner ear and while that could
affect its ability to navigate, in other cases such parasites
Once the final tissue samples were completed, Doc would
release its full report on the deaths, but Mr Lundquist
believed it was ''unlikely to shed more light''.
Doc made the ''best effort'' to monitor the effect of seismic
testing on marine mammals with observers on
ships and other measures, but it might never be able to rule
out acoustic trauma as a possible cause of death.
''We'll never be able to rule it out, as there is a large
amount of uncertainty around it.''