I would think that whether or not the ROK Navy found any rocket debris that this is what they would be telling the media in order to not let the North Koreans know whether or not they recovered debris:

 South Korea’s navy made little progress in recovering North Korean rocket debris on its third straight day of attempts Sunday, officials said.

About 10 South Korean navy vessels were searching international waters of the Yellow Sea off the country’s west coast, but did not find anything presumed to be rocket fragments, a military official said.

The official said the recovery operation could take time as there is much floating waste in the area.

“No major progress has been made in recovering” any debris, said another official at the Joint Chiefs of Staff, adding that no Chinese or Russian vessels had been spotted near the site of the fallen rocket fragments.  [Yonhap]