Animal traffickers are smuggling high numbers of sea horses, the strange-looking aquatic creatures, through airports and other transportation hubs. The trend comes even as governments have put new laws in place to curb the activities.

More than 5 million smuggled sea horses, valued at an estimated $21 million, were seized by authorities between 2010 and 2021, according to a study recently released by the journal Conservation Biology.

“Even this limited window reveals a global problem, showing that the true scale of illegal sea horse trade is likely much larger, ” the study’s lead author, Sarah Foster, an oceans and fisheries researcher with the University of British Columbia’s Project Sea Horse initiative, said in a written statement.

The sea horse black market is largely located in China and Hong Kong. But the study said European and Latin American authorities are now seizing more illegal batches. They are often smuggled among other illegal animal items, like pangolin scales and elephant tusks.