A bacterial disease is unlikely to be the main cause of
endangered New Zealand sea lion deaths in the Auckland
Islands, scientists say.
The Deepwater Group, which represents the squid fishing fleet
off the Auckland Islands, claimed this week Klebsiella
pneumoniae was killing Auckland Island sea lions in
''In the past, the seafood industry has been blamed as the
main threat to sea lions. But when 600 pups die each year
from disease and 15 adults are killed by fishing, it is
evident this population will continue to decline, even if
there are no further deaths from fishing,'' Deepwater chief
executive George Clement said.
''As an industry, we've invested a huge amount over the past
10 years to reduce incidental sea lion bycatch in our catch
''But this disease is a much bigger threat than fishing ever
A spokesman for the group said its claims were based on data
by Niwa and the Department of Conservation and
Scientists spoken to by the Otago Daily Times said the
situation was more complex than the Deepwater Group made out.
Massey University veterinary pathologist Wendi Roe, who
studies sea lion mortality, said it was not a simple problem
and while the bacteria might be having a severe impact on
pups, there would be some underlying cause.
''We don't have the answer. The most important thing is to
get more information and we need a big co-operative effort to
find out what the problem is.''
It was likely there were multiple factors involved, not just
one, she said.
Niwa marine scientist Dr Jim Roberts said scientists were
uncertain how the group's figure of 600 deaths was
calculated. Preliminary results from a study of population
dynamics suggested that young sea lion survival had been
highly variable with a period of low survival from 2005.
''Klebsiella infection is one of a number of
contributing factors to pup mortality.''
Research on overseas sea lion species showed multiple factors
could drive population change and these could interact.
''For NZ sea lions, disease is only one of an array of
potential factors affecting population size.
''Others include mortalities in commercial trawl fisheries,
predation by great white sharks and changes in the marine
ecosystem that can affect the abundance of the species that
sea lions like to eat.''
There were other indicators of changes in the biology of New
Zealand sea lions, such as a low proportion of females
producing pups each year and variable milk quality, he said.
Understanding the drivers of population change was a key
challenge to identifying and managing threats to the sea
''We are still in the early stages of collaborative research
that will help develop this understanding.''
University of Otago zoologist Bruce Robertson said there had
only been two pupping years where more pups died due to
Klebsiella, 2002 and 2003.
''The reality is that we have never had 600 pups die each
year of Klebsiella in any year. Even in the two years
when there was Klebsiella outbreaks, other forms of
mortality were more important.''
A University of Otago modelling study showed females of
breeding age were the demographic group driving the
population decline, not pups, he said.
''The best thing industry could do before we all grab our
drenching guns or syringes of vaccine is to show some marine
stewardship and offer to stop fishing around the Auckland
Islands for a few years to give the sea lions a chance to
rebound from their precarious position.''
A spokeswoman for Conservation Minister Nick Smith's office
said on Monday the minister's response to the Deepwater
Group's claims was coming. It had not been released