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Mr. Studds. Dr. Read, I understand that you are familiar with 

 the use of so-called pingers to deter marine mammals from ap- 

 proaching fishing gear. We have heard some concerns expressed re- 

 cently that those things should not be relied on as the solution to 

 all of our marine mammal gear interactions, particularly since we 

 really don't know what the effects might be of the widespread use 

 of pingers. Can you explain to us how they work and give us your 

 thoughts on their use and tell us whether you think NMFS should 

 be considering a general environmental assessment on the effects 

 of these devices on the marine environment? 



Mr. Read. Certainly. Pingers work by— basically they are active 

 acoustic deterrents. They generate a sound that, in principle, is to 

 alert marine mammals to the presence of a net. In the past, 

 pingers have not been shown to be particularly useful in reducing 

 entanglement rates particularly with the animals that I work on, 

 dolphins and porpoises. There are good reasons for that. In order 

 for a pinger to be effective, an animal must know that the sound of 

 the pinger represents a danger to it. And, unfortunately, most en- 

 tanglements of dolphins and porpoises in nets, at least the kind of 

 nets that I work with, gill and drift nets, usually end up in the 

 death of the animal so it has no opportunity to learn from its expe- 

 rience. 



There are other possible problems. Animals can habituate to the 

 sounds. They can associate the sounds with a food source if they 

 are feeding on fish in the nets or around the nets like some seals 

 do. And there are practical problems like changing batteries, cost, 

 design. So I guess, in general, they haven't been shown to be very 

 useful. If we could develop a pinger system that was useful, then I 

 think we would want to be concerned about the effects on both the 

 animals that we are trying to keep out of nets and other nontarget 

 populations of marine mammals. 



In the Gulf of Maine, for example, if we were using pingers to 

 try and reduce the entanglement of harbor porpoises in gill nets, 

 we might also want to investigate what the effects of those sounds 

 were on other marine mammals like right whales and whether or 

 not we were having an effect of reducing the effective habitat that 

 animals could utilize. But I would say that the research that I have 

 seen so far doesn't suggest that we are very close to having pingers 

 that are very effective at least for small citations or for pmnipeds. 

 Mr. Studds. Was the theory that this particular noise would be 

 uniquely alarming to the critters, or was it just that any noise 

 might be? 



Mr. Read. There are a couple of different lines of work that way. 

 Some people have tried using sounds that are associated with pred- 

 ators of certain marine mammals like killer whale sounds. Some- 

 times people have just used broadband sounds. 



Mr. Studds. How about the Senate in debate? Has that been 

 tried? 



Mr. Read. No. That is probably worth a try though. 

 Mr. Studds. Ms. Young, we have been told that the NMFS pro- 

 posal to begin using current carrying capacity instead of historic 

 carrying capacity as a goal for determining stock status is a matter 

 of some concern to the environmental community. Can you explain 



