Katy Perry and Justin Trudeau photographed kissing on Perry's yacht

Photographs taken late last month show pop singer Katy Perry and former Canadian prime minister Justin Trudeau kissing aboard Perry’s private yacht off the coast of Santa Barbara, California, renewing public attention on reports that the two have been romantically linked since midyear. The images, taken by a passenger on a nearby whale‑watching boat, show Perry in a dark swimsuit and Trudeau shirtless as the pair embraced on the yacht’s upper deck.

A passenger who witnessed the encounter said the singer pulled her yacht alongside the smaller boat and the two “started making out,” adding that they only recognized Trudeau after seeing the tattoo on his upper left arm. The tattoo, a Haida raven, is a distinctive marking Trudeau has displayed in public. The yacht was identified as Perry’s 24-metre vessel, the Caravelle.

The photographs follow weeks of speculation after the pair were first publicly linked in July, when they were seen dining together in Montreal. Trudeau was later photographed attending one of Perry’s concert dates in Canada, and the two were reported in public settings in the city in subsequent days. Neither Perry nor Trudeau has issued a public statement about their...