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Review of the Effectiveness of Recovery Measures for St. Lawrence Estuary Beluga


Review of the Effectiveness of Recovery Measures for St. Lawrence Estuary Beluga

Review of the Effectiveness of Recovery Measures for St. Lawrence Estuary Beluga (PDF, 1.26 MB)

Table of Contents

7. Conclusions

When the review to estimate the potential for recovery of the SLE beluga population was conducted after SARA listing in 2005, the population was considered to be stable or increasing at a maximum of 1% per year (Hammill et al. 2007). The subsequent DFO review in 2013 revealed that at the time of SARA listing the population was actually already on the decline and had been doing so since about 2000 (DFO 2014). The major changes in population dynamics and trends at that time coincided with a worsening of several environmental parameters that were considered to already be unfavorable to beluga recovery; and thus the situation deteriorated further. These included: further decreases in prey availability relative to long-term averages for the Gulf of St. Lawrence; a warming climate; chronic exposure to shipping traffic, and disturbance from increasing whale-watching activities in parts of the beluga Critical Habitat; high levels of a larger number of contaminants (e.g., PCBs, DDTs, PBDEs); and episodic harmful algal blooms. The population is now considered Endangered and is still declining. From this, we conclude that collectively, recovery measures implemented following the first Recovery Plan (Bailey and Zinger 1995) and those implemented after SARA listing have not succeeded in abating threats sufficiently to allow population growth and recovery.

Data that has become available through the recent DFO review (DFO 2014) has not identified any additional threats to the SLE beluga recovery that were not included in the recovery strategy. However, it has changed our perception of the relative importance of the previously identified threats. High contamination, high noise levels and potential for disturbance, and shortage of food supplies continue to be considered the main threats to SLE beluga recovery. However, shortage of food supplies, which was viewed as a likely imminent but undocumented threat at the time the Recovery Strategy was published in 2012, is now seen as one of the main factors likely involved in the current decline of the population (Plourde et al. 2014; DFO 2014; Williams et al. in press). Similarly, harmful algal blooms were considered a potential threat of medium concern. While there was no evidence that two of the three harmful algal blooms documented over the past two decades (see Scarratt et al. 2014) increased mortality in SLE beluga, the die-off of several beluga and other marine species in 2008, most likely as a result of a harmful algal blooms (Scarratt et al. 2014), has brought a very concrete perspective to the potential effects of such events on population dynamics, and has raised the level of concern for this threat.

Recovery measures implemented to date have been a mix of science/research and management-based measures. While nothing has really been done since 2005 to increase beluga access to food supplies, or to effectively mitigate noise and disturbance, we can conclude that recovery measures aiming at reducing legacy organochlorines in the beluga environment have been effective at reducing mortality from cancer in beluga. However, these efforts were counterbalanced by parallel exponential increases of other toxic chemical compounds (e.g., PBDEs), which might today be at least partly responsible for the high incidence of peripartum problems in females and newborn calves.

A cumulative model incorporating the top threats with the exception of harmful algal blooms (i.e., food supply shortage, high contamination, and noise and disturbance from marine activities) and their effect on population dynamics failed to determine which of these three threats needed to be the most urgently addressed to allow the population to grow (Williams et al. in press). Instead, this analysis indicated that simultaneous and aggressive mitigation of all three threats is needed in order for the population to maintain the necessary resilience to cope with effects from the warming climate. This report proposes recovery measures to abate threats. However, scientific evidence to identify the level below which a threat is no-longer likely to induce biologically significant effects on SLE beluga are generally lacking. Therefore, our capacity to even qualify the benefits for the population from specific recovery measures is also limited. Notwithstanding this, abating the three main threats is under our control, cannot harm the population, and provides the best chance for population growth.

To abate the threat from contaminants, there is a need to undertake actions promptly to reduce, or further reduce, levels of PBDEs and other flame retardants, and to enhance control over the discharge of other highly toxic substances (e.g., PAH, Mirex, PCBs, DDTs), in areas located upstream or within the beluga habitat.

Given that noise attenuates with distance, and in general with vessel proximity, the most effective way to reduce threats from noise and disturbance is to increase the distance separating ships, ferries and small crafts from the beluga or their important habitats. The replacement of ferries by road infrastructure at the mouth of the Saguenay Fjord would result in high and immediate gains for abating one of the top threats contributing to the prevention of recovery, as it would remove thousands of vessel transits each year in important beluga habitat where ensonification is the highest and the most chronic (McQuinn et al. 2011). Priority should also be given to re-examining the placement of shipping lanes and the pilot station as it is probable that adjustments could be made that would result in significant and rapid gains in terms of quieting important beluga habitats. In parallel, there is also a need to limit beluga interactions with recreational and whale-watching vessels, or activities resulting from marine development projects. An extension of the limit to beluga approaches (i.e., the 400 m no-boat zone) for sectors located outside of the SSLMP by including this measure in the Marine Mammal Regulations, and the creation of exclusion zones (e.g., acoustic refugees) in and outside the limits of the SSLMP, combined with adequate enforcement and awareness campaigns, would be highly effective at rapidly abating threat from noise and disturbance. These high priority measures are particularly important to implement promptly, considering the foreseen increase in noise and marine traffic as a result of recently implemented, or recently proposed, projects to expand oil and mineral transportation from ports located upstream or within the beluga habitat.

Effects of a warming climate on ecosystem structure and prey availability for beluga are difficult to prevent on the short-term. However, actions aiming at increasing standing stocks of potentially important prey of beluga, such as herring, rainbow smelt, tomcod, American eel, and some of the groundfish species, could provide beluga with a greater access to prey. Such actions include reductions of removals by existing fisheries, or even possible bans on additional forage species fisheries, and increased protection of spawning sites. Promptly completing the research on diet and habitat use would help identify key prey species, and focus management actions on the most important species.

The 2008 harmful algal bloom strikingly highlighted how these events can affect survival and population dynamics. Eutrophication through the increase in nitrogen and urea levels in water in particular, and climate change, which has circumstantially been identified as the cause for novel algal bloom episodes, may make these events more frequent (Anderson et al. 2012). Therefore, there is a need to implement regulatory actions to reduce inputs of some nutrients such as urea-enriched compounds (e.g., from agricultural fertilizers, improperly treated effluent) in the beluga habitat or upstream of it, to help limit the occurrence of these deadly events.

In parallel to these actions, performance indicators need to be instated and monitored to assess trends in threats and how they are affecting beluga health over time in order to inform adaptive management; currently very few such indicators exist (see Appendix 1). Indicators are especially needed for monitoring beluga exposure to contaminants and to vessel noise, interactions with vessels, and access to adequate prey. Monitoring programs exist to document population dynamics and trends, distribution, level of some threats (e.g., collision, entanglement), and causes of mortality. A monitoring program also existed within DFO for contaminants, but this program was abolished in 2014 and was not transferred to other institutions, which might impair our capacity to monitor recovery measure effectiveness in the future. The 2013 DFO review has demonstrated the importance of these programs, as they helped understand the complex and combined interactions among natural and human stressors.

These monitoring programs should also be accompanied by scientific research (see Tables 3-8 for specific data gaps) to provide the context needed for interpreting trends and to ensure that focus of recovery measures remains on components that are the most likely to contribute to abating threats. The development of models and other predictive tools would be particularly useful to test the effects of various management scenarios (e.g., traffic rerouting, speed reductions) on the level of specific threats, or on the probability of biologically significant effects on SLE beluga.

By virtue of its location downstream of important industrial centers, and the variety of valued socio-economic activities it supports, the SLE and its marine species are exposed to a myriad of human stressors. Currently, there is no mechanism for integrated spatial planning of activities in the SLE, or for setting stressor-specific management objectives, as there is no centralized tracking of authorized activities or projects, or their cumulative impacts on specific species. This is especially relevant for activities or projects that occur outside of the SLE beluga habitat, but that generate impacts in the beluga habitat (e.g., through increased marine traffic). There is an urgent need for a strategic (or programmatic) review to define upper limits to the level of specific threats we are willing to accept, and to provide context for current or planned activities and development projects that add to those threats. Such a review is especially needed for activities and projects that generate noise and disturbance, as it would provide a framework for setting management objectives in terms of noise levels or amount of traffic not to be exceeded, while improving spatial and temporal planning of economic activities such as shipping and marine development projects, and the assessment and management of their cumulative or aggregated effects on the beluga and its habitat.

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