effects, then the long-term effects of noise may reduce the population's reproductive capa- 

 bilities, disrupt predator-prey relationships, or cause a population to abandon preferred 

 breeding or feeding areas. 



The above discussion deals only with the possible effects of noise on marine mammals. 

 Data are not yet available to determine the probability of such effects occurring or to evaluate 

 the severity of the effects on wild populations of animals. Damage risk criteria that have been 

 established for humans may not be appropriate in evaluating possible effects of noise on wild- 

 life (re(.63), because the amount of physiological and behavioral adaptation that occurs in 

 response to noise stimulus is unknown. 



Continuous noise levels above 90 dBA (approximately 1 1 5 dB re 1 n?a at 1 m in 

 water) have potentially detrimental effects on human performance and noise levels of less 

 than 90 dBa can be disruptive (ref 2). Until noise standards are established for wild animals, 

 we may assume that animals will be at least partially protected by applying maximum levels 

 identified for humans. 



RECOMMENDATIONS 



1. Measure the noise generated from current and future offshore drilling operations. 

 Include sensitive frequency ranges from known marine mammal audiograms. 



2. Identify lease areas where offshore oil development is anticipated. Identify 

 species of marine mammals that inhabit these areas. 



3. Identify lease areas where introduction of increased sustained noise might dis- 

 rupt a critical life cycle of marine mammals. For example, feeding, breeding, transit or 

 congregation areas. 



4. Initiate a monitoring program when a lease area is opened. Monitor both 

 acoustic and population dynamic parameters in the lease area as development progresses. 



5. Develop a program to monitor the effects of controlled introduction of noise to 

 a marine mammal population. Quantify the effects of the noise on the population. 



6. Obtain underwater audiograms of marine mammals that occur in the selected 

 lease areas. 



7. Determine the effects of noise on marine mammals under controlled conditions. 



Fletcher, JL and RF Busnel, eds, Summary and Discussion, In: Effects of Noise on Wildlife, p 303-305, 

 Academic Press. 1978. 



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