A book in a Horror Anthology series I read in the 2000's about violent seals/sea lions

[Adam]

From what I can remember the book belonged to a YA horror anthology series (although the protagonist was an adult male). In this particular story, there was an infection that had begun to spread through this small coastal town (I believe causing violent tendencies in some of the marine life). After doing some research/general mystery solving, the protagonist discovered a family of very aggressive seals. He was able to determine that the town had been disposing of its waste in the sea, which had infected most of the water's fish. Female seals had eaten these fish while pregnant, resulting in the offspring being this new breed of violent seal. The story concludes with the protagonist returning home after solving the mystery, only to see that the dinner his pregnant wife was eating was a locally caught infected fish.

I also very vaguely recall another book in the series where there were humanoid-like creatures that would come out of a foggy sea at night and drag people under the water. In the end, the protagonists are able to kill the creature, but the book ends with several more creatures coming up out of the water the following night.

I've done hours of digging, and been through lists of any YA horror anthology series I can find/ think of, but there doesn't seem to be anything that matches the plot of these stories.

I'm sorry if these details are too vague to spark anyone's memory (I read it back in middle school during the mid-late 2000s, and to add extra context I'm in Australia), but any tips on where to start looking for these stories would be massively appreciated.

[Becca]

They Came from the Sea by David Orme? It's part of a series called Zone 13.