Turn down the noise – Seismic Surveying and what it does to cetaceans
Given their extensive reliance on the use of sound, there is concern that cetaceans may be negatively impacted by noise created by human activities, especially those which use loud sound sources like oil and gas exploration. Companies assert they can mitigate any negative impacts to animals and their habitat while biologists caution that there is extensive evidence that these noise sources can harm whales and should not be used. The Canadian government has implemented seismic exploration guidelines which they claim will adequately mitigate impacts to cetaceans. Recent research suggests that the mitigation measures are out of date and will not protect these species. Does the noise have to be turned down or are the measures good enough?
The solution will focus on the impact of Seismic Noise on Cetaceans
Solution
The Impact of Seismic Noise on Cetaceans
Abstract
Marine mammals, including right whales, are greatly
exposed to large levels of sounds during seismic surveys. These sounds may
prove to be detrimental to the hearing capabilities of these animals, such that
they cause temporary hearing impairment. As such, the normal functionality of
these animals is hampered as they fail to coordinate their interactions with
each other and the environment, which are highly dependent on communication
using sounds. The guidelines developed by the Canadian Government to govern
exploration of seismic surveys prove to be outdated and ineffective in ensuring
the safety of cetaceans from such damaging levels of sound. This paper reviews
the impact of the seismic sounds on right whales and recommends proper use of
research to develop updated guidelines that would effectively protect
cetaceans.
Introduction
There has been wide documentations of immediate behavioral reactions of marine mammals such as whales to seismic sound exposure. Such behaviors include avoidance of the areas where there is production of the sounds or reducing vocalisations. Cetaceans such as whales highly rely on sound to communicate, navigate, and find prey in their habitat (Dunlop, et al. 2013). Loud anthropogenic sources of sound including piling, military sonar, and shipping noise has been associated with behavioral changes in cetaceans across the globe. In Canada, various regulatory measures have been put in place to ensure that cetaceans are protected from the impact of seismic activities. Nevertheless, some argue that such regulations are outdated and thus less effective in protecting these animals. This paper suggests that the current seismic exploration guidelines provided by the Canadian Government are outdated and ineffective, and thus require proper research and revision.
Brief Introduction of seismic surveys
Seismic surveys are exploratory tests conducted by oil companies prior to oil drilling, to determine the availability of hydrocarbons in the ocean. This survey involves the travelling of a seismic ship back and forth across the designated area while towing airguns that produce waves of sound under the water. Such sound waves travel through the water hitting the rock at the bottom of the ocean, and then back to the ship where it is recorded using hydrophones. An estimation of the airguns’ loudness is 230 decibels at a meters distance, and is repeated in every 13 seconds, within 24 hours of operation (Braverman and Quinton 2015). It is important to note that sound travels less easily in the air than in the water. As such, the seismic noise produced by the array airguns during surveys is likely to travel for thousands of square kilometers across the ocean. The use of sonic waves in seismic surveys is important in determining the structure, location, and depth underneath valuable geological resources (Nowacek, et al. 2013). Oil companies use such information to launch campaigns such as oil exploration in the oceanic floors. Nevertheless, it is evident that such noise is higher than the normal sound levels for most cetaceans, and hence, it disturbs such animals by interfering with their communication, eating habits, navigation, and general survival (Jorgenson, Hoef and Jorgenson 2010).
Impact of Seismic Surveys on Right Whales
Cetacean heavily depend on sound for their daily activities and wellbeing. Sounds produced by these animals are used to forage, in social interactions, and when responding to predators. There is an increased concern over the survival of right whales, considering their tendency to swim close to the surface and their slow speed. This, among other factors, makes them great targets for whalers. These whales produce various sounds that may sound as a moan, a buzz, a scream, or a warble to the human ear (Castellote and Llorens 2016, Rolland, et al. 2012). In addition, the males produce a sound like a gunshot that is believed to play a major role in reproduction. To receive such signals, the right whales, just like any other cetaceans have a highly sensitive auditory system. The whales in general have more neurons devoted to hearing as compared to any other animals, an aspect that explains their highly developed neural auditory centre.
Being a mysticeti, the hearing sensitivity of the right whales is at lower frequencies as compared to other marine mammals (Rolland, et al. 2012). As such, the loud sounds produced by airguns during seismic surveys greatly affect the hearing of these animals. One of the impacts of seismic noise on these whales is that it affects their social behavior (Castellote and Llorens 2016). Considering such animals depend on specific sounds for social interaction including activities such as mating and bonding, the loud seismic noise interferes with such communication and hence interaction patterns. Seismic noise also interferes with the dive and respiratory patterns of right whales, an aspect that further leads to interferences with the feeding patterns of these mammals and contributes to their high energy costs (Klinck, et al. 2012). The vocalization patterns of right whales are also affected by anthropogenic noise. Nevertheless, there is little evidence to show that such disturbance of the vocalisation patterns affect the way such animals interact with their environment. Importantly, the communication efficiency of right whales is reduced by seismic noise. Most of the information that is communicated among right whales is functionally significant for breeding, feeding, predator avoidance, parental care, and maintenance of the social group (Cato, et al. 2013). As such, given the effect that the seismic sounds have on the vocalization patterns, communication of such information is reduced among these animals. This is an issue of great concern especially considering that these animals are at risk or predators such as sharks and orcas.
Current Mitigation Measures
The Canadian Government has established various mitigation measures to regulate seismic activities in the open waters and hence to protect marine life. Nevertheless, such measures have proven to be less effective and outdated to effectively protect marine life such as the right whales. Thus, there is need for the government to consider reviewing such measures in order to improve the standards of practice for oil companies. One of the mitigation methods included in the guidelines involves proper planning of the seismic activities (Simmonds, et al. 2014). As such, SOP provides that each of the seismic activities should be properly planned to ensure that use the least amount of energy that may be required to achieve the necessary operational objectives. In addition, the guidelines suggest that such planning should ensure that the energy propagated horizontally should also be minimized through such planning. All the energy that occurs at frequencies that are above what is considered necessary for the survey’s purpose should also be maintained at minimal levels. Nevertheless, these provision tends to be inadequate, and that it could be further improved through proper modifications. As such, this paper recommends that the guidelines should also clearly state that organizations that are preparing to conduct seismic surveys should properly plan to minimize the amount of tie that is to be taken on the survey and the size of the area that is to be surveyed (Williams, et al. 2014). This would ensure that all the involved organizations make al the possible considerations to avoid the habitat of the endangered and threatened cetaceans that have been identified and labeled as critical, especially in cases where such species are likely to be in the area at the time of the survey.
The guideline for planning also provides that proper planning should be upheld to ensure that the marine mammals are well protected from any effects and risks posed by the seismic activities. As such, the provision maintains that the planning process should be aimed at ensuring that all the animal species that have been listed as threatened or endangered according to the Species at Risk Act’s schedule 1 (Theriault and Moors-Murphy 2015). It is important to note that right whales are highly endangered species especially due to the fact that they are not only prey for sharks and other sea animals, but are the main whales hunted by human beings. As such, it is important to ensure that the few remaining of these animals are well protected from any other human made activities that would threaten their survival. Apart from the listed animals, the guidelines also insist that proper planning should be upheld to protect all the other marine species from any populating-level effect that may be considered as significantly adverse (Simmonds, et al. 2014). This provisions for planning could be considered to be highly effective in dealing with the current challenges faced by conservation efforts directed at ensuring that the marine mammals are protected from any damage or destruction.
Another important guideline provided by the Canadian government involves the establishment of safety zones to minimize sound output (Theriault and Moors-Murphy 2015). A radius of 500 meters from the air source arrays’ center is provided by the Canadian guidelines as the distance at which individuals can reliably observe cetaceans (Williams, et al. 2014). It is also required that such safety zones remain always visible and be watched by a Marine Mammal Observer considered as qualified continuously for a period not less than 30 minutes before the start up of arrays. In addition, such an observer is expected to watch over the safety zone regularly in cases where the power to be used in the seismic survey is expected to meet a threshold that would require the Canadian Environmental Assessment Act to be put into consideration for assessment (Williams, et al. 2014). However, as much as such a distance may prove to be sufficient to protect the cetaceans from physical injury, such animals are still exposed to auditory masking and behavioral disturbances, which extend past the zone. As such, this guideline fails to minimize disturbance for the animals.
In addition, another part of the guidelines that has proven to be less effective is the provision for a soft-start. This involves a gradual increase of the energy released from the sources at the seismic ships aimed at allowing the marine mammals to move away from the seismic survey region (Simmonds, et al. 2014). Canada has effected a pre-start-up period of thirty minutes. It is important to not the effectiveness of this method highly depends on the circumstances and species. In addition, there are growing concerns that this approach may result in habituation. Such habituation may prove to be even more devastating as it leads to longer exposure of the animals to the high levels of sound, hence posing a risk of chronic auditory damage. Furthermore, right whales may be attracted by the initial weak sounds, causing exposure to the stronger sounds even as they develop (Rolland, et al. 2012). As such, it is evident that the current Canadian guidelines are less effective in ensuring the safety of marine animals, especially the highly endangered right whales.
Furthermore, the Canadian guidelines on seismic exploration provide that the source-array should be shut down immediately in any cases where an endangered or threatened marine mammal has been detected moving within the safety zone (Theriault and Moors-Murphy 2015). As such, it is up to the oil company performing the seismic survey to ensure that they put in place proper monitoring techniques or methods to detect any movement of endangered marine mammals within the zone. In addition, any hunch that could lead to anticipation of the entry of the marine mammals into the safety zone, by the utilization of monitoring techniques or methods and observing of the animal’s movement patterns should lead to the shut down of the source-arrays. this approach could be considered as highly effective especially in ensuring that the endangered marine mammals are protected from any of the activities that may pose a risk to them (Theriault and Moors-Murphy 2015). Nevertheless, in the establishment of such a threshold, the Canadian government failed to observe the practicality of its implementation. It is important to note that ecological and behavioral responses and effects that constitute harassment or harm of the individual animals and the destruction of their habitat have the capacity of occurring across long ranges from the source of the sound (Williams, et al. 2014). As such, these effects require designation of mitigation measures that that would effectively detect long-range prohibited impacts. Thus, it is important for the government to revise the provided guidelines in order to ensure that the animals receive equal protection form any potential harm that may be caused by seismic activities while at a long range from the source-array, as they would while within the safe zone.
Conclusion and Recommendations
It is evident that seismic activities pose a great risk to right whales among other cetaceans due to the large levels of sounds used in these activities. The right whales hear at low frequencies and thus their exposure to high sound levels interferes with their normal hearing and hence interaction with their environment. Nevertheless, the guidelines put in place by the Canadian government to ensure that such animals are protected through regulation of the seismic surveys have proven to be futile at this point. Most of these methods are outdated and tend to open a loophole of exposure of the animals when implemented to close one.
In order for the government to develop on the current guidelines and to ensure protection of marine mammals from the effects of loud sounds from seismic surveys, this paper suggests a few recommendations. First, further research should be conducted to improve the general understanding of the actual impact of seismic noise on large Cartesians such as the right whale. In addition, greater collaboration should be promoted among regulators, academic institutions and industry stakeholders to ensure that proper use of data collected through research is well utilized in the development of up to date guidelines. This paper also suggests that there should be no use of soft-start methods during periods of darkness or poor visibility without proper utilization of PAM technology in order to confirm that cetaceans are not present. It is also important for further research to be conducted in order to determine the influence of some of the factors such as distance away from the seismic source-array on the damage inflicted on animals exposed to the produced sound waves. This would allow the government to establish more effective guidelines considering the distance away from the array that the animals should be kept and the threshold that ought to be maintained to ensure that animals are not negatively affected even though they may be away from the safe zone. On the other hand, it is important for oil and gas companies to embrace advancements in technology and invest in innovation in order to come up with other measures through which the oceanic floor can be explored without threatening cetaceans.
References
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