Science Advisory Report 2010/076

Biophysical Overview of the Laurentian Channel Area of Interest (AOI)

Summary

• The Laurentian Channel AOI varies in depth from 100 to 500 m, with the basin of the Laurentian Channel being the deepest. Adjacent banks in the study area south of Newfoundland vary from 100 to 200 m in depth.
• Surficial and shallow geology attributes may be sufficient for broad-scale generalizations related to habitat associations of species of interest that interact with the bottom. In general, mud and clay characterize deeper areas, while sand and gravel occur mainly on the banks. Bedrock geology has strong potential for hydrocarbon discoveries.
• The occurrence of sea ice is infrequent in the study area, occurring only during maximum extent years (less than 10 of the last 30 years). The Laurentian and Hermitage Channels and areas to the west of St. Pierre Bank have some of the warmest bottom water temperatures in the Region (2-7 °C), while St. Pierre Bank and regions to the east are somewhat cooler than this (-1 to 1 °C). Circulation in the area is also unique.
• Plankton assemblages in the AOI are similar to other inner shelf areas of the Grand Banks; however, calanoid copepods and macrozooplankton show very different seasonal cycles of abundance and long term changes in the AOI.
• Sensitive habitats occurring in the AOI are represented by various species of corals. However, of the corals occurring in the AOI, sea pens have been recorded in the greatest numbers and with the greatest diversity; and have also been described as having their highest regional concentrations within the Laurentian Channel (just west of the study area).
• Of the fish species of interest, only black dogfish (Centroscyllium fabricii) and the northern wolfish (Anarhichas denticulatus) occur more frequently within the AOI (69% and 52% inside respectively) than outside the AOI within the study area, based on DFO trawl surveys.
• At least 20 species of cetaceans have been observed both nearshore and offshore in the study area, with the most frequently observed species being humpback, fin, and minke whales. Most cetaceans occur either seasonally (during spring/summer) or as transients in the study area, although some may also occur there year-round.
• Leatherback sea turtles (Dermochelys coriacea) are the most frequently occurring sea turtle in the study area, where the south coast of Newfoundland is one of the most highly-frequented leatherback foraging areas in Atlantic Canada.
• Porbeagle sharks (Lamna nasus) and basking sharks (Cetorhinus maximus) move into the study area around May-June, with movement out of the study area to areas further south occurring in late fall. One of only two known mating grounds for porbeagle occurs in the AOI.
• Uncertainties and knowledge gaps identified within the biophysical overview can be attributed to either information that was not considered for various reasons, e.g., due to scale; non-Regional databases; and migratory species, as well as information that was unknown or unavailable, e.g., survey data for certain species or times; and habitat associations.
• Oceanographic monitoring of two standard AZMP lines can inform the physical, chemical, and biological oceanography of the study area – although these are not monitored consistently during spring and fall surveys. Continuous Plankton Recorder (CPR) data provide retrospective information on plankton abundance.
• Annual multispecies research vessel (RV) surveys can inform the status and trends of primarily demersal species within the study area. However, these occur only during spring in 3P (the study area) as opposed to during spring and fall as in other areas surveyed in the Region.
• Various components of fishing, oil and gas activities, and vessel traffic have been identified as being of potential risk to some species of interest either spatially or temporally.

This Science Advisory Report is from the Fisheries and Oceans Canada, Canadian Science Advisory Secretariat, Regional Advisory Process of November 9-10, 2010 on Biophysical Overview of the Placentia Bay Grand Banks Large Ocean Management Area (LOMA) Area of Interest (AOI).  Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

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