Research Document 2017/076
Coast of Bays Metrics: Geography, Hydrology and Physical Oceanography of an Aquaculture Area of the South Coast of Newfoundland
By Donnet, S., Ratsimandresy, A.W., Goulet, P., Doody, C., Burke, S., and Cross, S.
Abstract
Upon a recent rapid increase of the finfish aquaculture industry in the Coast of Bays, an area of the South Coast of Newfoundland (nine-fold production growth from 2003 to 2013), Fisheries and Oceans Canada (DFO) carried out a research project to better understand the physical oceanography of the area. This report is the first of a series aiming to provide an oceanographic knowledge baseline of the Coast of Bays (i.e., data and analyses) to help manage and ensure the sustainable growth of the aquaculture industry. Bathymetric, topographic and hydrologic data as well as sea water temperature, tides and wind data were used to determine the geographic, hydrologic and oceanographic characteristics of the area. The area includes five major bays where the aquaculture activities are currently occurring or planned.
The results of these analyses indicate that the Coast of Bays area can be divided in three regions of distinct geographic, hydrologic and oceanographic characteristics: a deep, long and narrow fjord subject to large runoff (Bay d’Espoir), a deep and wide bay subject to less but still significant runoff (Belle Bay) and a shallower region, more exposed to the open ocean and subject to very small runoff (Connaigre Peninsula). The annual average freshwater discharge was found to be about 252 m3/s in Bay d’Espoir, about 71 m3/s in Belle Bay and about 10 m3/s in the Connaigre Peninsula and characterised by a strong seasonal cycle with a large spring freshet (April-May), a low in summer (July-August) and smaller peak in late/fall/early/winter (November-December). Tides are semi-diurnal and small, with a range of about 2 m (large tides). Thus, and due to the large volumes of the bays considered, flushing times due to tides only are large and unequal, varying from about 30 days in the Connaigre Peninsula to about 70 days in Bay d’Espoir and Belle Bay. The study area is also characterized, as a whole, by a strong heating and cooling seasonal cycle with sea-surface (0-20 m) water temperature amplitude of about 7°C. Differences among the three regions in terms of seasonal cycle amplitudes and phases as well as monthly statistics and vertical mixing estimates were found and suggest a potential effect of the freshwater input on thermal stratification. The wind climate of the area is also strongly seasonal with prevailing and strong winds from the west-northwest/northeast in winter/spring (about 35-45 km/h median speed) and prevailing and much weaker winds from the southwest in summer (about 20-30 km/h median speed). Finally, bathymetric characteristics were used to delineate the area in basins which can be used, in conjunction with other relevant factors, for aquaculture zoning management purposes.
Data used and presented in this report will be available at the Government of Canada’s Open Data website.
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