1 EXECUTIVE SUMMARY
One of the fundamental rationales for the existence of marine science is to support research leading to a
wise use of marine resources. While our basic knowledge of the ocean, its physics, and the nature of
its ecosystems have progressed remarkably in the past few decades, our ability to provide reasonable
advice as to the response of any fishery to the combination of exploitation and the effects of climate
change is still rudimentary. This document provides the outline of a program required to make a
quantum leap forward in this area using the best tools available to modern molecular biology,
statistics, physical oceanography, acoustics and population biology. The target fisheries and region for
study is the northwestern Atlantic shelf edge with its extremely productive banks.
The banks of the northwestern Atlantic such as the Grand Banks and Georges Bank have been
exploited as one of the major fisheries resources on the globe since at least the 1500s. This trend has
continued to the present, with 1988 New England landings of cod, scallops and pollock amounting to
$133.4 million dollars. Combined, this is approximately equal to the value of the lobster harvest for
that period. The groundfish on Georges Bank are at their lowest stock size since estimates were
begun. A rise in populations of pelagic species such as dogfish and skates suggests that the place
which groundfish hold in the ecosystem may be being replaced. Furthermore, the most recent National
Marine Fisheries Service report on the status of fishery resources off the northeastern United States
concludes in the case of scallops that "current fishing effort is far beyond what the resource can
sustain." Much of the stock decline is due to the effects of overexploitation. The effects of fishing on
stocks, are, however, strongly influenced by variations in the physical and biological environment
within which the fishery exists.
Climatic effects on fisheries have been reasonably well established in a number of regions although the
exact processes by which these effects occur are not well understood in any situation. It is also well
established that climate variations can substantially modulate the influence of exploitation and, within
the extremes suggested in the recent climate record, can completely eliminate regional fisheries without
any effects of fishing. These climatic variations range from the effects of the last ice age, which
probably reduced the viable habitat for the species mentioned above by up to 90% through a
combination of lowering temperature, salinity, and sea level and increases in sea ice cover; to
historically documented decadal time scale fluctuations in winds, sea temperature and salinity that have
a correlation with cod stock declines in recent decades. There is ample evidence for a broad range of
climatic fluctuations in the past and some grave doubts about future variations tied to natural cycles and
the effect of man through greenhouse warming and modifications to the marine environment tied to
In order to extract an understanding of the interactions between the physical environment, the primary
and secondary producers in the marine ecosystem and the higher trophic level species relevant to
commercial fisheries, a multidisciplinary approach is necessary. The GLOBEC Canada/U.S. Meeting
on Northwest Atlantic Fisheries and Climate was held to consider the advent of such a
multidisciplinary program on Georges Bank, and to recommend specific scientific elements which
might be included in a full-fledged field program under the aegis of GLOBEC during the early 1990s.
The following recommendations are intended to serve as guidelines, not as mandates, for formulation
and implementation of the field study. These were made with strong consideration given to the ten
necessary criteria for GLOBEC study sites.
1.2 Site Selection
Georges Bank is an ideal location in which to study the potential effect of global climate change on
marine planktonic populations. Global climate models predict that significant changes are likely to take
place there. The banks along the edge of North America from Georges Bank to the Grand Banks sit at
the edge of the boundary between the subpolar and subtropical gyres. They are therefore sensitive to
fluctuations in the current systems - the Gulf Stream and Labrador Currents - which form this
boundary. Variations in these current systems are likely to be some of the strongest signals expected as
part of global climate change.
Target species should emphasize cod and include haddock. Local populations should be defined by
frequent surveys, molecular and biochemical techniques, with a focus on locating key spawning sites.
A key objective of population dynamics is to study the development of larvae with respect to the onset
of seasonal vertical stratification. Process studies should focus on mechanisms controlling population
dynamics, such as how food and feeding may change with climate, how adults locate spawning sites,
and how the population is retained or exported from the area. Historical data should be exploited to a
greater degree. A Historical Data Working Group should be established to make quality data sets
available to the community; paleoecological studies should be encouraged. Modeling is particularly
required for understanding the physical dynamics of Georges Bank, annual energy budgets of the
target species, distinguishing between the effects of fishing pressure and climate change, and as a
means to improve statistical techniques. New technology is needed to improve hardware and software
for hydroacoustics, and to develop a variety of techniques relying on biochemistry and molecular
biology to provide indices of physiological state such as growth, feeding, and reproduction.
Target species should emphasize Calanus finmarchicus and include Pseudocalanus spp. and
Centropages spp. Local populations of Calanus' are thought to overwinter in the nearby Gulf of
Maine; the dynamics of their spring-time advection onto Georges Bank should be studied in detail.
Population dynamics studies should focus on understanding reproduction, growth and mortality in
relation to physical transport processes. Process studies should be aimed at understanding how local
physics controls the distribution of zooplankton, and what processes control overwintering. Historical
data are not as abundant as for fish, but are sufficient to determine the magnitude of signal required to
detect effects of climate change. Modeling studies could make new sampling technology (e.g.,
acoustics and optics) more effective by helping to understand the relation between animal size and
physiology; population dynamics could be better understood through coupled biological/physical
numerical modeling. New technology is needed to rapidly assess physiological state, and to rapidly
sample distributions of zooplankton from both moored and mobile platforms.
Target species should include sea scallops (Placopecten magellanicus), but the focus might best be on
types of meroplanktonic larvae and types of benthic habitat. Local populations could be studied by
comparing a variety of larval types (e.g., feeding vs. non-feeding larvae, spring vs. fall spawners).
Population dynamics studies should focus on larval dynamics of any species which might produce
distinguishable cohorts of easily identifiable larvae from a well defined adult population, and should
not necessarily be restricted to scallops. Process studies should focus on understanding the relation
between fundamental population dynamics parameters (e.g., growth, reproduction) and physical and
biological forcing functions such as tides, storms, food availability and temperature change. Historical
data are less abundant than for other groups, but efforts should be undertaken to use what data do
exist. Modeling studies could help to understand how local physical processes favor different
reproductive strategies, what causes interannual variation in scallop recruitment, and how changing
physical and biological factors affect larval life histories. New technology is acutely needed to rapidly
sample and identify larvae of different species.
1.6 International Interactions
GLOBEC activities should be coordinated with existing international studies including WOCE,
NOAA's Atlantic Climate Change Program (ACCP), and the Joint Global Ocean Flux Study
(JGOFS). The Georges Bank initiative should be closely coupled with two new Canadian programs;
these are the Ocean Production Enhancement Network (OPEN), a $25.4M, four-year program
focusing on cod and scallops in the waters off Nova Scotia and Newfoundland and in the Gulf of St.
Lawrence, and the Northern Cod Science Program (NCSP), a $43M program focused on fisheries
oceanography off northern Newfoundland and the Labrador coast. An ICES working group on Cod
and Climate Change (CCC) and the new SCOR working group on pelagic biogeography present
opportunities for broadening GLOBEC's activities across the North Atlantic.
1.7 Field Program Logistics
The group endorsed a broad outline of a field program involving three basic means of studying
Georges Bank: (1) Bank-scale survey cruises, (2) Process-oriented cruises, and (3) Moorings The
recommended program would be carried out over a three-year period, with most effort focused in the
first and third years.
The next step in the implementation process will involve the establishment of an implementation
committee to provide the details of setting up a U.S. experiment. It is hoped that this will take place
over the next year and come up with a plan for a program starting in the 1992-1993 time frame.