SCIENCE REVIEW 1987 - Bedford Institute of Oceanography

Research
weren’t always benevolent. A century ago,
at the peak of the handline fishery, the
fishermen on Georges and other fishing
banks regularly caught shearwaters as bait
- and to get a taste of fresh meat.
(Discriminating gourmets preferred Sooties
to Greaters.) But things are very different
today. Instead, we provide a gargantuan
feast of trash fish, scraps and offal, spilling
from the factory trawlers that work over
the Bank. Some seabirds - Red Phalaropes,
Razorbills - are too specialised in
their feeding habits to exploit this bonanza.
But the blizzard of Fulmars, Greater
Shearwaters, Gannets, Kittiwakes and
Great Black-backed Gulls behind every
dragger is proof that the specialists are in
the minority.
This exploitation has several long-term
implications. It undoubtedly increases
seabirds’ chances of surviving through the
winter, when food is scarcest; this is
particularly true for juvenile birds. But do
we really need more large gulls? Their
population explosion in the last 40 years
has already turned them into a menace to
the other seabirds that breed along the
coasts of New England and Atlantic
Canada. And what will happen if, to feed
our own expanding species, we overexploit
the fishery? This is becoming more and
more of a possibility, as we shift our aim
from traditional food species such as cod
and haddock, to an industrial fishery for
smelt and other small fish that can be
ground down into fish-meal to feed our
cattle and chickens. The next stage may
well be a fishery for the larger zooplankton.
The difficulty is that these small-fry are at
the base of the food-web of all the higher
marine predators on Georges Bank. Zooplankton
feed small fish, which feed larger
fish, which feed seabirds and whales. If we
take away too much of the zooplankton
and small-fry at the bottom, the whole
marine community may collapse - and
Georges Bank, now so rich, will become a
desert. We had better be very careful.
Further Reading.
BACKUS, R.H. (ed.) 1987. Georges Bank. MIT
Press: Cambridge, MA, and London, U.K. 593 p.
BROWN, R.G.B. 1986. Revised Atlas of eastern
Canadian Seabirds. I. Shipboard Surveys. Environment
Canada, Canadian Wildlife Service: Ottawa.
111 p.
BROWN, R.G.B. 1988. The influence of oceanographic
anomalies on the distributions of storm-petrels
Hydrobatidae in Nova Scotian waters. Colonial
Waterbirds 11: 1-8.
BROWN, R.G.B. and GASKIN, D.E. 1988. The
pelagic ecology of the Grey and Red-necked
Phalaropes Phalaropus fulicarius and P. lobatus in the
Bay of Fundy, eastern Canada. Ibis 130. 234-250.
POWERS, K.D. and BACKUS, E.H. 1987. Energy
transfer to seabirds. Pp. 372-373. in Backus, R.H.
(ed.) Georges Bank. MIT Press: Cambridge, MA, and
London, U.K.
POWERS, K.D. and BROWN, R.G.B. 1987.
Seabirds. Pp. 359-371 in Backus, R.H. (ed.) Georges
Bank. MIT Press: Cambridge, MA, and London, U.K.
Georges Bank - Research behind the management of habitat
and commercial resources
D.C. Gordon Jr., J.D. Neilson, and G. Robert
Introduction
D. C. Gordon
FISH stocks and their habitat are managed
with the long term goal of maintaining
their health and abundance. This article
briefly summarizes some of the research
currently underway in the Scotia-Fundy
Region in support of resource and habitat
management on Georges Bank. Georges
Bank is a large and shallow submarine
bank located on the outer continental shelf
along the southern side of the Gulf of
Maine (Figure 1). Its rich fishery resources
have long been exploited by Canadian and
American fishermen. The October 1984
International Court of Justice (ICJ)
decision granted the northeast portion to
Canada. However, while Canada won
14
J.D. Neilson G. Robert
exclusive rights to significant fishery
resources, the transboundary nature of
many of these stocks remain which gives
rise to special problems concerning both
research and management.
Primary production by phytoplankton
on Georges Bank is very high because of
near optimum conditions of light and
nutrients. It is one of the most productive
fishing banks in the North Atlantic
(O’Reilly and Busch, 1984) and supports a
diverse food web which includes both
planktonic and benthic organisms and
culminates in abundant finfish (cod,
haddock, herring, etc.) and invertebrate
(scallop, lobster, etc.) fishery resources. The
landed value of Canadian fisheries from
Georges Bank in 1986 was $63 million.
Apart from the special circumstances
surrounding the IJC decision, the environment
of Georges Bank is rather unique. Its
physical features are dominated by very
strong currents which are generated by
large volumes of water moving into and
out of the Gulf of Maine and the Bay of
Fundy in response to the tidal forces. These
currents promote vertical mixing of the
water. During the winter, most of the water
over the Bank is well-mixed from top to
bottom, while during the summer solar
heating produces stratification in water
deeper than about 60 m. The boundary
between the well-mixed and stratified areas
is marked by a seasonal tidal front. The
strong currents also help generate a
clockwise rotation or gyre over the Bank