A voluntary conservation agreement reduces the risks of lethal collisions between ships and whales in the St. Lawrence Estuary (Québec, Canada): From co-construction to monitoring compliance and assessing effectiveness

Abstract

Lethal collisions with ships are limiting the recovery of several at-risk whale species worldwide. In the St. Lawrence Estuary (Quebec, Canada), the endangered blue whale and of special concern fin whale are among the migratory species subject to collisions with large ships. In 2011, a working group composed of representatives from the maritime industry, the government, non-governmental organizations, and academia was created to explore solutions to mitigate ship-whale collisions in the St. Lawrence Estuary. Adopting an adaptive risk management framework, the working group took advantage of the best available scientific data and tools to co-construct realistic collision mitigation options and evaluate their likely benefits for whale conservation and costs for the industry. In 2013, the working group recommended the implementation of voluntary measures to mitigate collision risks, consisting of a slow-down area, a no-go area, and a caution area; a recommended route was added in 2014. Along with the voluntary framework, the working group agreed to continuously monitor compliance with and assess effectiveness of these mitigation measures. After the fourth year of implementation, voluntary measures showed encouraging results, with a reduction of up to 40% of lethal collision risks with fin whales in the highest density area. This reduction in risk is mainly related to ship speed reduction in the slow-down area from 14.1 ± 2.6 knots in 2012 to 11.3 ± 1.7 knots since 2014. The presence of a mandatory pilotage area overlapping with the slow-down area was instrumental to facilitate communication about the mitigation measures, with the pilotage corporation sitting as a regular member of the working group. This resulted in significantly slower speeds in the slow-down area for ships with a pilot from the pilotage corporation onboard compared to those without (-0.8 knots, p-value < 0.001). It is also likely to explain the weaker compliance of the maritime industry with the no-go area located outside of the mandatory pilotage area. Other factors of success include: the continuous dedication of the government to a voluntary and transparent participatory process; the use of available data, tools and institutions; the presence of an environmental certification program representative in the working group; and the adoption by consensus of an adaptive risk management approach. The traditional regulatory approach to conservation is often blamed for its focus on deterring negative behaviors, doing nothing to encourage and reward positive ones. In agreement with other case studies, the benefits of the voluntary measures implemented in the St. Lawrence Estuary include the pro-active commitment from the industry (which is likely to reduce conflicts with regulators), the greater flexibility and freedom that allowed to come up with cost-effective and tailored-made mitigation measures, and the fast achievement of conservation gains. More importantly perhaps, the human and working capital built throughout the concertation process have the potential to be a fundamental cornerstone in dealing with more complex issues such as the chronically increasing level of underwater noise in whale habitats.

Fig 1. Study area.

St. Lawrence Estuary and the Saguenay River, Québec, Canada (Figure created by the authors. Data sources: Canadian Hydrographic Service; Parks Canada; Fisheries and Oceans Canada; Group for Research and Education on Marine Mammals; and ESRI).

Fig 2. Voluntary operational measures to mitigate collisions between ships and whales in the St. Lawrence Estuary as of 2017.

(Figure created by the authors. Data sources: Canadian Hydrographic Service; Parks Canada; Fisheries and Oceans Canada; and ESRI).

Fig 3

Histograms of transits distance-weighted average speed in the speed reduction area when the voluntary measures were active (left panel) and inactive (right panel) for the 2012–2016 period. The difference between these distributions is statistically significant (Kolmogorov-Smirnov test, D = 0.538, p-value < 0.001). The 11.8 knot threshold corresponds to a 50% probability of lethal injury in case of a collision [16].

Fig 4

Boxplots of ship transits distance-weighted average speed in the speed reduction area from 2012 to 2016 when the voluntary measures were inactive (left panel) and active (right panel). The number of yearly ship transits considered are reported in Table 4.

Fig 5

Proportion of ship transits using the no-go area completely (dark) or partially (light) during the active (blue) and inactive (red) period of the measures from 2012 to 2016.

Fig 6

Boxplots of transits distance-weighted average speed within the no-go area during the 2012–2016’s inactive period (left panel) and the 2013–2016’s active period (right panel) of the voluntary measures.

Fig 7. Proportion of transits complying with the recommended route (RR) (i.e. travelling north of Île Rouge).

Panel a shows the percentages of transits north of Île Rouge (RR) during summers of 2012 to 2016 and panel b shows monthly percentages in 2013. Red dots indicate the periods when the voluntary measures are inactive whereas blue dots indicate periods when they are inactive.

Fig 8. Reduction in the risk of lethal ship strikes for the four most abundant baleen whale species relative to the whole area of the voluntary measures (blue shades) and to the speed reduction area only (yellow shades) compared to August 2012 (i.e. during the “whale season” before the implementation of the voluntary measures).