|DFO ignores ocean
By Debbie MacKenzie
(published by the Halifax
Herald, Nov. 16,2003)
DFO RECENTLY presented findings of a 30-year ecological
survey of the Eastern Scotian Shelf ecosystem. The messages
that filtered through to the public emphasized themes of
changing trends, plus a poor prognosis for any recovery in
populations of groundfish such as the once dominant cod.
The 30-year change in marine life has been stunning.
Where there once lived many large fish of various species,
now there are virtually none. And the remnants of fish such
as cod are small and in very poor condition; they are "not
healthy." DFO reports that "groundfish appear to have lost
A plainer statement of this truth is that these fish are
starving. DFO has admitted this in many reports and studies.
However, no good reason has yet been found by science to
explain just why the fish are starving.
Besides noting the loss of groundfish, the media reported
three other themes: a spell of unusually cold water occurred
in the area between 1985 and 1993; a massive increase in the
numbers of "small pelagic" fish (herring, mackerel, capelin)
has been seen as the groundfish have disappeared; and a
large increase in numbers of grey seals in recent decades,
including the population "doubling since 1997 to almost
225,000 last year" (as reported in the Herald on Nov. 6,
neglecting the detail that seals have not been surveyed
But none of these observations brings us close to
discovering why cod are starving, because (1) the cold spell
has been over for a decade; (2) small pelagics are normally
eaten by bigger cod, and; (3) the more cod eaten by seals,
the better fed the remaining individual cod should be.
The key question raised by the starving cod pertains to
the fertility of the ocean. Despite DFO's recent collation
of 64 data sets regarding the Scotian Shelf, ocean fertility
estimation is not one of them. Dramatic plankton changes
have coincided with the changes in fish populations, yet
these have not been emphasized in media reports. These
changes include a substantial decline in zooplankton, the
tiny animals on which small fish feed, and this decline,
along with a rise in uneaten phytoplankton, is consistent
with a fall in ocean fertility.
Seaweeds are good direct indicators of ocean fertility,
and visible changes in seaweeds along this coastline confirm
this grave conclusion.
What seems to contradict the falling ocean fertility
hypothesis is the massive increase in small pelagic fish.
Fantastically, DFO reports a 400-500 fold increase in their
numbers since the early 1980s. That's not a 400-500 per cent
increase, but 400-500 fold. I remember fair numbers of these
fish in the early 1980s, and if they have undergone such a
phenomenal population explosion, the sea must be literally
swarming with them now. But it doesn't appear to be,
frankly, because it is not.
Small pelagic fish are hard to survey because they
normally swim in schools throughout the water column,
instead of collecting near the bottom. In other areas, these
types of fish are sometimes assessed with "acoustics," which
is basically sonar, or "fish-finders."
In Newfoundland, a recent unexpected acoustic finding has
been a change in the habit of capelin on the now fish-bereft
Grand Bank: scientists have recorded echoes which indicate
capelin spread only in a thin layer over the bottom, rather
than using the whole water column. If these capelin had been
assessed only with a bottom net trawl, as DFO has done on
the Scotian Shelf, a wildly incorrect impression might have
been received of how many capelin were in the sea.
This may explain the small pelagic phenomenon in DFO's
Scotian Shelf data. The maladies affecting the Grand Bank
and the Scotian Shelf are undoubtedly one and the same: it
appears that as fertility falls in an empty ocean,
everything that is left just hugs the bottom more tightly.
Debbie MacKenzie lives in Prospect and does independent
research on the fishery. On the Internet: