A Marine Protected Area Along The Boundary Between U.S. And Canada on Georges Bank? Time for a second look.

In the late 1990s, an effort was made to convince the US and Canadian governments to  establish a 10 kilometer wide  joint marine protected area along their Georges Bank Boundary. Below,  read the scientific paper that stimulated the effort.   The plan would use  the US National Monument process to protect a 5 kilometer wide strip on its side, while the Canadian Government would use its Ocean Act to similarly protect a 5 mile wide strip along its side of the Georges Bank border.

Rationale:  the strip would serve as a scallop egg producing reserve, with its larvae  reliably seeding the rest of Georges Bank with scallop. The proposal, however,  received sufficient congressional opposition to pressure the Clinton Administration into declining to sign the National Monument  Executive Order. Canada then dropped its side of the proposal.  

RATIONALE FOR A MARINE PROTECTED AREA ALONG THE INTERNATIONAL BOUNDARY BETWEEN U.S. AND CANADIAN WATERS IN THE GULF OF MAINE Original article here.  Click on "Full-Text available"

RICHARD McGARVEY(l) and J.H. MARTIN WILLISON
Biology Department, Dalhousie University, Halifax, N.S. Canada B3H 4Jl. 1 Present address: South Australian Research and Development Institute, 2 Hamra Ave., West Beach, SA 5024, Australia.
FROM: Marine Protected Areas and Sustainable Fisheries, Editors: Nancy Shackell and JH Martin Willison, Science and Management of Protected Areas Association

SUMMARY We propose a marine protected area along the ICJ international boundary (the "Hague line") separating U.S. and Canadian Atlantic waters. This line passes through the Gulf of Maine and the intensively fished Georges Bank. The area included in the proposed reserve contains a variety of habitats representative of the Gulf of Maine. 

We propose that a strip be protected against exploitive , uses. The width of the protected area would be a matter for negotiation but might be set at 10 km: 5 km on each side of the boundary. This marine reserve would serve four principal functions: (I) to preserve marine, mainly benthic, biodiversity in these biotically rich coastal habitats in a small but long zone of untrawled bottom; (2) to enhance important benthic fisheries, notably scallops, by leaving a subpopulation to grow to advanced adult ages at which egg production is much greater than by adults at average time of harvest in the present fishery; (3) to provide a buffer zone to reduce encroachment of scallopers and trawlers from one nation into the waters of the other, and to facilitate enforcement against these territorial violations; and (4) to provide untrawled bottom for benthic ecological study.

1. INTRODUCTION
The marine ecosystem of the Gulf of Maine region lies on the Atlantic coastal shelf north of Cape Cod, east of Maine and west and south of Nova Scotia (Fig. 1). At the outer edge of the Gulf of Maine lies a very large and shallow region, Georges Bank (Figs. 1 and 2). This bank has an area within the 60 m depth contour of about 33,700 km2, about the size of Rhode Island, Connecticut, and Massachusetts (1). Primary productivity on Georges Bank, in particular, is among the highest in the North Atlantic, measured at 455 grams carbon fixed per year per square meter (2). Catch rates, particularly of groundfish (including haddock and cod) and scallops, were historicly among the highest as well. The best fishing at present, for both scallops and groundfish, lies along the Northern Edge and Northeast Peak of Georges Bank, predominantly in Canadian waters (see Fig. 2).

Current understanding provides two reasons for the biological richness of Georges Bank waters. First, strong tides sweep back and forth across the large eastward-extending shallows of the bank. The high turbulence of this movement creates zones that are fully mixed, all the way to the bottom, which continuously replenishes the surface with settled nutrients, stimulating the growth of phytoplankton, and thus providing rich production for the marine trophic web. 

Secondly, as water surges over this shallow ridge into and out of the deeper Gulf of Maine to the north, water moves north and south about 45 km with the tides twice daily (3), a total of about 180 km, together with a residual average displacement clockwise around the Bank of about 7 km. For scallops, this clockwise gyre has the crucial effect of retaining spawn on the Bank; scallop eggs and larvae drifting freely with the currents in their pelagic phase during the first month of life. The predominant movement of water along the Northwest Atlantic coastal shelf from Arctic waters to Cape Hatteras is southward with the Labrador Current. Iles and Sinclair (4) have advanced the theory that coastal zones of high retention and turbulent flow which yield higher productivity and greater repro ductive integrity, like Georges Bank, play a principal role in sustaining marine populations over many generations. Sinclair and others (5) have advanced this same hypothesis for sea scallops in the Northwest Atlantic.

The history of these fishing grounds is much like that of waters off Newfoundland and other rich Northwest Atlantic coastal zones. Before the international boundary between the USA and Canada was established in a mediation ruling by the International Court of Justice in The Hague in 1977, the most intense fishing was by foreign fleets, principally large factory trawlers, which in the early 1970s peaked at highly excessive levels. Levels of catch for a variety of species reached levels often two to three times previous highs. This crisis was, at that time, a principal motive behind the declaration by the USA of a 200-mile coastal fishing exclusion zone, which was soon adopted worldwide, and led to the establishment of the Hague line (6, see Fig.1).

Since 1977, most fishing in these waters has been by US and Canadian fleets on their respective sides of the line. Rapid capitalization for new vessels with more powerful engines and fishing tchnologies, particularly for groundfish and scallops, ensued after 1977. 

The groundfisheries, as a result, never recovered. On the U.S. side catch rates for haddock are presently about 2% of their early 1960s average. Scallops have fared better on the Canadian side, due principallyto sound management facilitated by close cooperation between the major scallop vessel operators and Department of Fisheries & Oceans managers and fishery scientists. There is, nevertheless, agreement that a greater yield per recruit (5,7,8) would result from an older average age of capture of sea scallops (Placopecten magellanicus).

In this proposal, we shall focus on this example of the Georges Bank population, whose fishery is worth about $100 million annually to the USA and Canada. It is relevant to focus on scallops for three reasons: cross-border fishing disputes have centered on this species; detailed data are widely available, and spatial zone protection can be expected to be particularly beneficial to scallop fishery because, unlike fish, scallops rest on the bottom, swimming short distances only to escape.

2. POTENTIAL BENEFITS OF A PROTECTED ZONE ALONG THE HAGUE LINE

2.1 Location of the protected area
The potential benefits of marine protected areas are reviewed elsewhere in this volume. As Bohnsack (9) has stated "they enhance fisheries, reduce conflicts, and protect resources". After we realized the probability that a protected area might help to enhance and stabilize the Georges Bank scallop fishery, one of us had a lucky encounter with Kirk Munro, a fisherman, who suggested that the Hague line might be acceptable to the commercial fishing community as a protected area location. The reasons are politically complex, but include the reduction of conflicts to which Bohnsack referred (see above).

The Hague line intersects Georges Bank within the region which is rich in scallops (Fig. 2). The evidence of the present study suggests that protection of as little as 8-10% of the productive part of the bank would have a substantial effect on scallop recruitment throughout the bank. A protected zone along the entire length of this line, about 10 km wide (5 km within each of the national jurisdictions), as shown approximately in Fig. 1, may suffice to enhance and stabilize the scallop fisheries in both the USA and Canada. For this protected zone to be effective, all commercial and destructive activities must be excluded (for discussion, see Ballantine, this volume), with the exception of defined shipping lanes.

We can expect that once a protected area has been established along the Hague line for a sufficient time it would be effective in the enhancement of other species of commercial value (for discussion, see 9). The protection of representative spawning habitat and nursery grounds is important for many species. By extending the protected area throughout the Hague line (Fig. 1 ), a representative cross section of the habitats of the Gulf of Maine would be protected, providing for conservation of much of the benthic diversity of this biologically diverse region.

2.2 Conflict reduction.
A commonly-shared cross-boundary ecological preserve in the Gulf of Maine region may facilitate closer cooperation between the USA and Canada in dealing with acing these ecosystems, caused principally by overfishing. There is a precedent on land for USA-Canada cooperative management of a protected area. The Waterton-Glacier International Peace Park, which lies along the continental divide, spans the Montana-Alberta border.

A zone excluding fishing vessels from this boundary should greatly assist bilateral enforcement against illegal cross-boundary incursions, in particular by American scallopers, which has become a sore point with Canadian fishers and public alike. Encroachment of vessels into the protected zone would no longer be internationa incidents since responsibility for enforcing the exclusion would be retained by authorities of the home nation of these vessels on each side of the border. A 10 km protected zone should make aerial observation and coastal patrols significantly more effective.

2.3 Fishery Productivity When a fishery collapses due to overfishing, the reason is that egg production of the adult population has been reduced to the point that it is insufficient to replenish the population in subsequent generations. Most eggs do not survive to age 2; for scallops in the present population, survival chances are roughly 1 in 10 million (10). Other factos which affect population size are less influential. Environmental factors mediated by fluctuations in currents during time of spawning and larval drift strongly influence this survival rate from year to year. However, these external factors are independent of stock size, and thus should average out over many spawning seasons. Density dependent factors, which limit recruitment of juveniles to the adult population due to overcrowding and competition for food, are probably relatively minor in a heavily fished population because population densities are below peak values.

Average recruitment should, therefore, vary linearly, or a bit less than linearly, with egg production. 82% of the average annual total recruitment to Georges Bank from 1977 to 1988 occurred on the Northern Edge and Northeast Peak of the bank (10). For this scallop population, regression analysis has shown that recruitment is highest in years when scallop production is highest (11). This suggests that greater egg production in this region tends, on average, to result in greater numbers of younger scallops recruiting to the fishable stock.

The USA-Canada boundary along the proposed protected zone runs directly through this region of maximal effective spawning, lying a bit south and east of the zones of densest scallop abundance (12).

It is difficult to predict whether the average density of females per m2 in the protected zone would rise due to dramatically reduced mortality of adult scallops of fishable size or whether density dependent effects, which will also come into play when the region is unfished, would reduce recruitment even more, thus reducing the numbers per m2. Both effects would be felt strongly, and only measurements made after the establishment of this zone could provide the answer.

However, as a first guess, it is reasonable to suppose that the two effects balance and average annual densities in protected and fished areas would be roughly the same. Since we are interested in long- term averages, we may further limit ourselves to considering the long-term average age structure, which we approximate by the steady state age structure. The latter is obtained from the reported average level of natural mortality, M=0.1 (13,14,15), together with fishing mortality, for scallops age 5 and older, of F = 0.966, where this rate of capture is presumed to rise with age up to age 5 (10,13,16,17). Under these assumptions we may calculate the fractional increase in total scallop egg production per female.

The number of eggs spawned by an average female, can be calculated from

where the survivals {l(a)}, at each adult age, a, from 2 to 20, are derived as outlined above for the exploited and protected zones, and fecundities { m(a)}, are obtained from field measurements by MacDonald and Thompson (18) and Langton et al. (19) as reviewed by McGarvey et al. (10). Fig. 3 illustrates these relationships. In Fig 4, the numbers of eggs produced by scallops of each age, considering the increase in mortality and decrease in survival with age, are plotted. They peak around ages 10 to 17.

The results of the calculation of Eq. 1, indicate that an average female in the present exploited population produces 15 million eggs in an annual spawning, while in a protected zone, due to the higher average age of the females, the number is 153 million eggs, a factor of 10 times greater. If scallops aged 3 and 4 do not contribute substantially to total viable egg production, as the indirect evidence noted above hints, this factor would be 21. The most likely value lies somewhere in between.

Fishing effort often focuses on the aggregations of older individuals because of meat-count regulations designed to raise average harvested size. Using the same methods used to calculate average eggs released per female, the average age of a scallop in the exploited fishery is estimated as 3.1 years, versus 7.9 years in a protected zone.

By allowing scallops to live and reproduce over a natural lifespan, the eggs per female would thus increase by an order of magnitude or more in this proposed protected zone. Its location in or near the regions of highest density and recruitment make this choice of location ideal for the goal of enhancing scallop production. Tidal flows are highly turbulent and variable, and the lengthwise extension of the protected zone across the Bank should allow for larval drift to most regions of the N orthern Edge and Northeast Peak, and to the Southeast Part. This proposal thus fits well with Apollonio' s general call (22) for "biologic management" of the fisheries resources of Georges Bank.

The question remains whether healthy natural adult scallop beds supplying arich source of spawn annually would actually result in greater recruitment. The evidence of a significant stock-recruitment relationship in the Northern Edge and Northeast Peak (II), where the protected zone is proposed, implies that greater egg production should yield, on average, linearly proportional increases in recruit numbers in that region. Canadian scallop fishing effort, reported in hours of time a scallop drag is being towed along the bottom, is sufficient in a typical year to roughly cover the entire Canadian side to the 110 m depth contour. It is therefore difficult to imagine that density dependent competition and crowding is a substantial limiting factor, particularly in the locations of highest scallop abundance where most effort is directed. Thus, more spat settling on each region of favorable habitat would be expected to yield a nearly proportional increase in recruits, though wide fluctuations in the currents above the US-Canada line during spawning season would also be expected to yield substantial variability in survival of eggs originating in the protected zone from year to year.

A number of factors imply that we have conservatively estimated the higher average fecundity of females in the protected zone. First, it was assumed that senescence increases natural mortality rapidly for scallops above age 16, as shown in Fig. 3, implying reduced egg production in Fig. 4, for ages 17 to 20. No evidence has been reported for this assumption. Second, we know that intensive exploitation of scallops begins at about age 3.25 by Canadian statistics (20). By age 4.25, numbers are typically reduced to less than 10%, and by age 5.25, less than 1% survive relative to the abundance at age 3.0 (20, Tables 6 and 7). These very steep declines in abundance, observed directly by scientific survey, imply values of mortality greater than those assumed in the results graphed in Figs. 3 and 4. If future fishing pressure is as great, the proposed protected zone would have an even greater relative effect on the production of spawn than shown in Fig. 4.

2.4. Ecological restoration and study
There would be considerable benefits to science and to fisheries monitoring if part of the productive region of Georges Bank, and other representative parts of the Gulf of Maine, were free from human disturbance. This would allow natural restorative processes to come into effect in those regions which had been subject to disturbance, while protecting other regions against future impacts. Protection from the deleterious effects of benthic fisheries is crucial in this regard. Bottom trawls and dredges disturb benthic habitats considerably; a typical scallop dredge, for example, weighs about a ton and is estimated to kill approximately as many scallops left on the bottom as it brings up (21).

Of benefit to the scallop fishery would be the ability to do controlled field experiments and measure natural mortality, growth, fecundity, predation, and density dependent effects. At present, this is possible only in regions, such as coastal inlets, where scallop densities are not sufficient to support a commercial fishery .Improved measurements of these variables would be of great value in managing the scallop fishery.

It would also valuable to know what effects continuous disturbance and, in some cases, local devastation have on the nature of the benthic ecosystem. Without adequate control sites, such as would be provided by the proposed protected area, we have no means to measure these effects. As a result, there is sometimes more rhetoric than objectivity in marine environmental management.

REFERENCES

1 R.H. Backus andD.W. Bourne, in: R.H. Backus and D.W. Bourne (eds), Georges Bank, M.I. T. Press, Canlbridge MA, 1987, p.356.

2 J.E. O'Reilly, C. Evans-Zetlin and D.A. Busch, in: R.H. Backus and D. W. Bourne (eds.), Georges Bank, M.I. T. Press, Cambridge MA, 1987, pp. 220-233.

3 B. Butman, J. W. Loder and R.C. Beardsley, in: R.H. Backus and D. W. Bourne (eds.), Georges Bank, M.I.T. Press, Cambridge MA, 1987, pp. 125-138.

4 T.D. Iles and M. Sinclair, Science 215 (1982) 627-633.

5 M. Sinclair, R.K. Molm, G. Robert and D.L. Roddick, Can. Tech. Rep. Fish. Aquat. Sci. 1382 (1985) 113 p.

6 D.R. Christie, in: R.H. Backus and D.W. Bourne (eds.), Georges Bank, M.I.T. Press, Canlbridge MA, 1987, pp. 469-473.

7 J.A. Posgay, Int. Comm, Northw. Atl. Fish" Ser. 1016, Doc. 73 (1962) 20 p.

8 F.M. Serchuk, P. W .Wood, J.A. Posgay and B.E.Brown, Proc. Nat. Shellfisheries Assoc. 69 (1979) 161-191.

9 J.A. Bohnsack, Oceanus 36 (1993) 63-71.

10 R. McGarvey, F.M. Serchuk and I.A. McLaren, J. Northw. Atl. Fish. Sci. 13 (1992) 83-99.

11 R. McGarvey, F.M. Serchuk and I.A. McLaren, Can. J. Fish. Aquat. Sci. 50 (1993) 564- 574.

12 G. Robert, G.A.P. Black and M.A.L. Butler, Canadian DFO Atlantic Fisheries Research Document 93/15 (1993) 33 p.

13 L.M. Dickie, J. Fish. Res. Board Can. 12{1955) 797-857.

14 A.S. Merrill and J.A. Posgay, Int. Comm. Northw. Atl. Fish. Res. Bull. 1 (1964) 88-106.

15 B.A. Macdonald andIR.J. Thompson, J. Exp. Mar. Bioi. Ecol. 101 (1986) 285-299.

16 J.F. Caddy, ICNAFRedbook 1972(3), 79-86.

17 R.J. Smolowitz and F.M. Serchuk, Proc. World Symposium on Fishing Gear and Fishing Vessel Design, Marine Institute, St. John's, Newfoundland, November 21-24, 1988, 13 p.

18 B.A. Macdonald and R.J, Thompson, Mar. Ecol. Prog. Ser. 25 (1985) 295-303.

19 R. W. Langton, W .E. Robinson and D. Schick, Mar. Ecol. Prog. Ser. 37 (1987) 19-25.

20 R.K. Mohn, G. Robert and G,A.P. Black, Canadian Atlantic Fisheries Scientific Advisory Committee Research Document 89/21 (1989) 26p.

21 J.F. Caddy, J. Fish. Res. Board Can. 25 (1968) 2123-2141.

22 S. Apollonio, in: R.H. Backus and D. W. Bourne (eds.), Georges Bank, M.I. T. Press, Cambridge MA, 1987, pp. 508-511.

FROM: MARINE PROTECTED AREAS and SUSTAINABLE FISHERIES
Proceedings of the symposium on marine protected areas and sustainable fisheries conducted at the Second International Conference on Science and the Management of Protected Areas, May 16-20, 1994, Dalhousie University, Halifax, Nova Scotia, Canada.

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