Thursday, July 31, 2014

Oh, how times change - an illustration from the underwater noise and cetacean science field

I  was talking to a student the other day about how scientists attitudes to some cetacean conservation issues have changed, that some things that were derided a decade ago, are now accepted as scientific fact and accepted as a problem. This is especially prevalent in the issue of noise and whales and dolphins.

Here’s an interesting example I just found. In a paper I published in 2008  on the possible impacts of navy sonar we said that navy dolphins might not be the best models for responses of naive wild dolphins due to their training,  habituation to noise exposure and their noisy environment (San Diego harbour). Here's an extract:

“Using the behavioral reactions by trained, captive animals to predict the responses of wild animals may therefore be flawed. The motivations of these two groups of animals are also markedly different: wild animals are trying to forage and evade predators in order to survive, while captive animals are merely expecting a reward (fish or praise).” 

…“It is possible that the high levels of background noise in captive facilities lead to hearing impairment ... and even deafness ... either of which could potentially also result from years of exposure to sound during controlled experiments.”*

This was heavily criticized by two navy-funded scientists in a rebuttal paper:

“[they] state that such physiological measurements are debatable as to their relevance to wild animals…  An example of the overreaching zeal of the authors to denigrate ‘captive animal’ research is found on page 1251 of the article when they say “It is possible that the high level of background noise in captive facilities led to hearing impairment"** etc etc etc ...

I just found this in a paper written by one of the authors of that rebuttal noted above that was published last year (5 years later), in which the same research team  measured the responses of US navy dolphins to sonar exposure:

The researchers noted that the responses of the dolphins:

are likely not directly transferrable to conspecifics in the wild. The dolphins have years of experience under stimulus control, which is a necessary condition for the performance of trained behaviors, and they live within an environment with significant boating activity. These factors likely impact the threshold of responsiveness to sound exposure, potentially in the direction of habituation or increased tolerance to noise.”***

This is exactly the point we were trying to make 5 years previously, but we had been derided by  the same researchers accusing us of being anti-captivity zealots and bad scientists.

Schopenhauer once said that all truth passes through 3 stages: first you are ridiculed, then you are violently opposed, and then it is regarded as self-evident. I think we’ve got to stage 3 !

*Parsons, E.C.M., Dolman, S., Wright, A.J., Rose, N.A. & Burns, W.C.G. 2008. Navy sonar and cetaceans: just how much does the gun need to smoke before we act? Marine Pollution Bulletin 56: 1248-1257.
**Ridgway, S. & Houser, D.S. 2009.Marine mammal auditory research: Mischaracterization of published results. Marine Pollution Bulletin 58: 312-313.
***Houser, D.S., Martin, S.W.  & Finneran, J.J. 2013. Exposure amplitude and repetition affect bottlenose dolphin behavioral responses to simulated mid-frequency sonar signals. Journal of Experimental Marine Biology and Ecology 443: 123–133

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