Results of a modeling study designed to explore the influences of physical advection and certain biological mechanisms on the distribution of cod (Gadus morhua) and haddock (Melarwgrammus aeglefinus) early life stages on Georges Bank are described. Using a late‐winter/early‐spring 3‐D circulation field driven by the M2 tidal current, mean wind stress and Scotian Shelf inflow, we examine the distribution of cod and haddock larvae spawned on the Northeast Peak of the Bank. The sensitivity to a March‐April baroclinic field is also explored. Results indicate that larvae remaining in the surface Ekman layer are generally advected off‐bank. However, downwelling associated with Ekman layer convergence near the shelf break provides a mechanism for larvae to exit from the off‐bank surface drift. Larvae below the surface layer are transported south‐westward along the southern flank of Georges Bank and are retained on the Bank if their position immediately upstream of the Great South Channel is shoalward of (roughly) the 70 m isobath. Within the Great South Channel region and between the 50 and 70 m isobaths, retention can depend on the phase of the tide. Spawning shoalward of the 50 m isobath on the Northeast Peak greatly increases the chances of retention. These results apply to passive larvae and to those with specified vertical distributions and migration based on observations. Directional on‐bank swimming at rates of 0.5 to 1 body length per second would substantially enhance shoalward displacement, resulting in larval distributions during the first 2 months that are consistent with field observations.

A numerical model is developed to examine tidal properties of the Bay of Fundy and Gulf of Maine. The model is run with a pure M 2 tidal input on the open boundary, and calibrated by adjusting the friction coefficient to achieve good agreement with inshore observations. An examination of aspects of the tidal regime is made, with particular attention paid to the upper reaches of the bay. Mean energy and work values are computed. The fundamental period of the system is estimated. The effects of tidal power plants on the tidal regime are examined.The problem of interest in this paper concerns the M 2 tidal regime in the Bay of Fundy and Gulf of Maine, and the changes in this regime brought about by tidal power plants inserted in the upper reaches of the bay. The area under consideration and its bathymetry are shown in Figures 1 and 2. In the upper reaches of the bay, the spring tidal range is over 50 ft. These high tides have often been attributed to the effects of resonance. It has been previously postulated that the natural period of the bay is close to the M 2 period (12.42 hours), and therefore, conditions of resonance exist with the North Atlantic M 2 tide, producing the high tidal range. Proudman (1953) made a rough calculation of the tidal

A simple energetic argument (Simpson and Hunter, 1974) shows that the boundary between well-mixed and stratified areas of a shallow sea in summer should correspond to a critical value of BH/U 3 , where B is the buoyancy JEUX due to solar heating, H the mean water depth and U the amplitude of the tidal current. We demonstrate the importance of this parameter in a simple model of vertical mixing, and discuss the role of many other factors affecting stratification. Examination of hydrographic data from the Bay of Fundy and Gulf of Maine, together with estimates of tidal dissipation (proportional to U 3) from Greenberg's (1978) numerical model, shows a transition from well-mixed to stratified conditions, in July and August, for H/U 3 = 70 m-2 s 3. This corresponds to a mixing efficiency of only 0.26%. Predictions are made of the changes in extent of well-mixed areas that would be caused by tidal power development. Some stratification, due to both solar heating and freshwater input, is possible in previously mixed areas which would be the headponds for two schemes. Outside the barriers the changes are less dramatic, although the merging of mixed areas over Georges Bank and Nantucket Shoals is predicted. RÉSUMÉ Un argument simple au sujet de l'énergie (Simpson et Hunter, 1974) montre que la limite entre les zones bien mélangées et stratifiées d'une mer peu profonde en été devrait correspondre à une valeur critique de BH/U 3 , B étant le flux de flottabilité causé par la chaleur solaire, H la profondeur moyenne de l'eau et U l'amplitude du courant de marée. Nous démontrons l'importance de ce paramètre par un modèle simple de mélange vertical, et nous discutons du rôle de bien d'autres facteurs qui influent sur la stratification. L'examen de données hydrographiques provenant de la baie de Fundy et du golfe du Maine, ainsi que des estimations sur la dissipation de la marée (proportionnelle à U 3), provenant du modèle numérique de Greenberg (1978), montre la transition entre des zones bien mélangées et des zones stratifiées, en juillet et

Global warming is predicted to result in a rise in sea level which will lead to increased flood risk. Two other factors that will affect high water are the existing trends in mean sea level and changing tides. We illustrate here that in the Bay of Fundy and Gulf of Maine these two are related. An analysis of long-term sea level records shows that, independent of global warming related to climate change, sea level and tidal range have been increasing in this system. Our numerical model investigation indicates that recent changes in sea level, attributed in part to post-glacial rebound, are giving rise to increasing tides. The combined effects of modern sea level rise, global warming induced sea level rise, and the expanded tidal range they induce, will produce a significant increase in the high water level, much greater than that found when considering modern climate-induced sea level changes in isolation. We are predicting a dramatic increase in the risk of flooding at higher high water during the twenty-first century.RÉSUMÉ [Traduit par la rédaction] Le réchauffement climatique devrait entraîner une hausse du niveau de la mer, d'où l'augmentation des risques d'inondation. Mais deux autres facteurs sont à l'origine de cette hausse, soit les tendances actuelles liées au niveau moyen de la mer et au changement dans l'amplitude des marées. Dans notre étude, nous démontrons que ces deux facteurs sont interreliés dans la baie de Fundy et dans le golfe du Maine. L'analyse des relevés du niveau de la mer à long terme démontre que le niveau de la mer et l'amplitude des marées sont en hausse dans ce système, abstraction faite du réchauffement causé par les changements climatiques. L'étude que nous avons effectuée au moyen d'un modèle numérique fait ressortir que les changements survenus récemment dans le niveau de la mer, attribuables en partie au relèvement post-glaciaire, expliquent l'amplitude croissante des marées. L'effet de l'élévation actuelle du niveau de la mer, conjugué à celui de l'élévation du niveau de la mer provoquée par le réchauffement climatique et de l'amplitude croissante des marées que ces deux phénomènes induisent augmenteront considérablement le niveau des hautes eaux, beaucoup plus que ce qu'indiquent les conclusions des études sur les changements du niveau de la mer induits par le climat actuel pris isolément. Nous prévoyons une augmentation importante des risques d'inondation dans des conditions de pleine mer supérieure au cours du XXI e siècle.

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