I don't know how the US Navy does it, but the Russian Navy apparently places a premium on retrieving spent practice torpedoes such as this one:
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Admiral Berzin assures us that this is not an authorized manner of torpedo recovery, no matter HOW lost the torpedo retriever is:
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And here is Hotel II SSBN K-178 demonstrating an alternative method of practice torpedo recovery back in 1989 (click for a magnified view):
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Admiral Berzin offers a wealth of Cold War stories and more on his Livejournal page.