The following paper shows test harbour porpoise seek out key upwellings cells. The authors believe that this predictive function could be used in determining "non-competetive" sites for location of tidal power structures. Current research in the Bay of Fundy has yet to point to the importance of defining key components of the Fundy ecosystem, particularly at Head Harbour. Researchers would be well advised to review the volumes of literature that are posted on the marine mammal listserv. Canada's stance on restricted passage of LNG tankers through Head Harbour Passage could be furthered by this study which shows the importance of the abundant upwellings in Head Harbour Passage.
(MARMAM mailing list
Resolving fine-scale spatio-temporal dynamics in the harbour porpoise Phocoena phocoena
Henrik Skov and Frank Thomsen
With the development of human activities in offshore shelf waters, the harbour porpoise Phocoena phocoena has become a focal species in relation to management of human activities and marine habitat conservation efforts. In this study, acoustic and visual time series of harbour porpoise occurrence were analysed from the Horns Reef area, eastern North Sea, aiming at resolving periodicity, spatial scale of aggregation and habitat drivers in porpoises. A total of 51 fine-scale surveys and 474 d of hydrophone deployment at 2 stations were analysed by partial least squares regression and spatial modelling in relation to synoptic (spatio-temporal) data derived from a local, high-resolution hydrodynamic model. Small-scale changes in local currents reflecting upwelling driven by the interaction of the semi-diurnal tidal currents with the steep slopes of the bank were the main habitat driver identified from the acoustic as well as the survey data. Spatial modelling based on selected key predictor variables showed the distribution of harbour porpoises to alternate between 2 upwelling cells depending on the direction of tidal currents. The size of upwelling cells was less than 10 km, matching the small-scale spatial structure of survey data as revealed by geostatistical analysis. The findings may have great implications for the design of future protected areas for harbour porpoises, and they indicate that the overlap between areas of concentration of the species and areas targeted by fisheries and the offshore wind industry could be avoided without major changes to current management practices.
The paper is now available online at Inter-Research Marine Ecology Progress Series; full text is available at http://www.int-res.com/abstracts/meps/v373/p173-186/, or by emailing me (email@example.com):
DHI Water & Environment
Agern Alle 5