Writing on the website of Sea Shepherd, an international non-profit marine wildlife conservation group, Gary Stokes, the group's Hong Kong coordinator, said shark fins, used to make soup, are "one of the most unpleasant commodities Hong Kong has to offer," as they are sliced off the creatures, which are thrown back into the waters to drown or bleed to death.
The group said the photographs posted on its website showed more than 10,000 shark fins dry on a roof in a quiet Hong Kong neighborhood.
Stokes wrote the New Year discovery began after a tip from a citizen saying he'd found the roof in the Kennedy Town area on the island covered with the fins. Stokes said he and some others, equipped with cameras, went in search of that location.
"Last year, I had received a similar call to come and check out a street full of fins, and the footage captured went viral," Stokes said. "Hence the traders have run to the rooftops to hide."
Stokes said their search effort was joined by two other photographers to expose the "shark-mongers of death" trying to "hide their dirty business from the world."
"The pictures are now thankfully spread far and wide, but now what," Stokes asked in his article, saying raising awareness is important to inform the un-informed.
"The problem here is that the shark fin industry barbarically slaughters millions of sharks a year unregulated and unchecked," he said. "Kill numbers are bounced about, but the truth is no one really knows precisely how many sharks are being wiped out, we just know it's a huge number!"
Stokes said sharks, as predators keep the ocean ecosystems in balance, but are slow to reproduce.
"Removing and wiping them out of existence just for the greed and bragging rights ... is absolute proof that we as a species have completely disconnected from our natural world ...," he wrote.
He urged the Convention on International Trade in Endangered Species to base shark protection status on scientific facts and not on financial greed.
Separately, the World Wildlife Fund said sharks are harvested worldwide, sometimes for their meat, but also for an even more lucrative fin trade.
The organization said in 1996 only 15 shark and related species were considered threatened, but by 2010, that number had jumped to more than 180 species.
"The demand for sharks and particularly their fins has been one of the main factors driving global shark fisheries," it said, noting Hong Kong has among the greatest consumers of shark fins.