The MCE results were successful at identifying areas of significant sightings and shipping overlap, as well as areas where large numbers of threatened species are present. The MCE results for the shipping model and the tourism model with differently assigned weighting values are presented in Figures 15 and 16 below. Spatial patterns of the high risk category of the commercial shipping MCE layer outlines spatial patterns of high shipping density and high cetacean sightings density seen in the specified criteria. Therefore, each of the 3 alternative commercial shipping routes generated were successful at reducing the number of higher risk cells ships go through compared to the current commercial routes. The success of minimizing the number of risk cells is highlighted in the Table 9 and Figures 12-14 below. The structure of the routes are different than that of traditional pathways, due to the fact that the routes are avoiding high risk areas. The result of this structure difference is the proposed routes having a longer length than the current routes, these routes are depicted in Figure 17 below. Proposed route 1 is affected the least as it is only 2 km longer than the current shipping route, whereas proposed routes 2 and 3 are 6 km and 7 km different respectively. New proposed marine tourism routes are represented in Figure 18, below.
Table 9: Statistics for the three current routes and their proposed changed routes, with their corresponding number of cells assigned, and associated level of risk.
Proposed route 1 of Victoria to Vancouver reduced high risk cells the most, reducing the extreme risk cells from 2% to 0% in the commercial route, high risk cells reduced by 15%, and moderate risk cells reduced by 18%. In total, the proposed route 1 is 79% low risk cells, and the current commercial route is 43% low risk cells, these values are displayed visually in Figure 13 below. Proposed route 1 has the highest percentage of cells in the low risk category leading proposed route 2 by 14% and proposed route 3 by 19%. With a length difference of 2 km, proposed route 1 is the most successful of the generated routes in that it reduces a significant amount of high risk cell crossings and is not significantly longer than the current commercial route, adding 2 km to the 148 km route. The least cost pathway tool considered where the existing routes are, the threatened species distributions, the common areas for other species to be located and the protected areas. While accounting for all of those factors and still aiming to create the shortest and most feasible route the least cost pathway tool was able to create new routes that significantly reduced the high risk cells. Based on the reduced travel over higher risk cells, and only a small increase in travel length, proposed route 1 is the most successful pathway generated for the specific study area.
Figure 12: Graph comparing risk levels of current commercial shipping route 1 and it's proposed alternative route.
Proposed route 2 Nanaimo to Vancouver is moderately successful, reducing high risk cells by 8%, and moderate risk cells by 13%, (Figure 14). The route increases in length by 6 km or 12% of the total route length. A 6 km increase in length decreases the feasibility of the route for commercial shipping, because it is an added mileage and time expense to the company.
Figure 13: Graph comparing risk levels of current commercial shipping route 2 and it's proposed alternative route.
Proposed route 3 West Shore to Vancouver reduces the most extreme risk cells of any route, reducing them to 0% from 8%. High risk cells are reduced by 8%, moderate risk cells are increased by 11%, these amounts are visually represented in Figure 15 below. This route is successful in reducing high and extreme risk cells, unfortunately the moderate risk cells increase by 11%. Alternative route 3 also increases the route by 7 km or 12%, compared to proposed route one with a 1% increase in length.
Figure 14: Graph comparing risk levels of current commercial shipping route 3 and it's proposed alternative route.
Figure 15: Map of the MCE commercial shipping vessel risk layer, high risk being high density of shipping and cetaceans.
Figure 16: Map of the MCE marine tourism sightings likelihood layer, high likelihood meaning there is a dense number of cetacean sightings in that area.
Figure 17: Map showing the proposed new routes for commercial shipping vessels.
A different approach was taken to calculate proposed routes for marine tourism. Using the cetacean sightings point density layer, two destinations were created: a northern and southern marine tourism destination. These two destinations are located in dense sighting areas. The sightings criterion for the MCE are re classified to encourage travel towards high density sightings areas. Four proposed marine tours were generated, three traveling to the southern sighting destination and one to the northern, these routes are depicted in Figure 18 below. Southern marine tourism company ports used in this study are Ocean Ecoventures, Sidney Whale Watching, White Rock Sea Tours. The northern marine company is Prince of Whales Whale Watching. All routes have a variant structure, similar to those generated for the alternative commercial routes. To mediate this the routes can be simplified to reduce cost of time and energy expenses. The southern routes generated well, but the northern route did not hug the coastline like it should have, deeming it the most unsuccessful of the proposed marine tour routes.
Figure 18: Map showing the proposed routes for marine tourism.
Other Mitigation Applications:
The MCE conducted in this study identifies high risk areas for marine cetaceans regarding commercial vessel density. The identification of high risk areas can propose speed reduction zones as well as introduce alternate shipping routes. Speed reductions to under 10 knots are being recommended by organizations to reduce the likelihood of lethal strikes in densely populated waters (Australian Government, 2017; Coastal Research Institute, 2016).
The larger baleen (toothless, krill and plankton eating whales) are the type of whales that are larger and slower moving and when struck by large vessels they often suffer severe head traumas (Conn and Silber, 2013). If large vessels reduced their speed to 10 knots in the areas where threatened species exist in high numbers, the larger and slower moving cetaceans would have more time to react and may be able to swim out of the way from large vessels (Vanderlaan & Taggart, 2007; Australian Government, 2017; Coastal Research Institute, 2016).
In a study conducted by Williams et al. released in March 2017 smaller cetacean species such as dolphins and porpoises defense response was examined. These species often swim in fast bursts when spooked by approaching vessels (Williams et al. 2017). This action uses their oxygen stores far quicker and causes them to need to surface more frequently, increasing the risk of a ship strike (Lawson & Lesage, 2013; Williams et. al, 2017). The distress this causes to these animals increases their likelihood of becoming stranded as they can become totally panicked and exhausted. (Williams et al. 2017). This is another factor to consider for the reduction in the speed of large vessels as it may potentially reduce this defensive behavior in smaller cetacean species.