What does the sailors' dread foreshadow?

When this great short story begins, Rainsford and Whitney are talking to each other on deck of the ship that is taking them south to do some exotic big game hunting. Whitney points out an island off to the side of their ship, and Rainsford asks what island it is. Whitney provides the name of the island, and then he says that the sailors all have a curious dread about the place.

The old charts call it "Ship-Trap Island," Whitney replied." A suggestive name, isn't it? Sailors have a curious dread of the place. I don't know why. Some superstition—

Readers have no reason to fear this island at this point, yet we also automatically assume a curious dread about the island. The current setting is night, and we are told about a creepy island with a foreboding name. The result is that readers have been alerted to the fact that this island is bad news and best left alone. As we continue reading we will discover that the early foreshadowing of this line about the dangers of the island are completely accurate. Ship-Trap Island is a dangerous place that sailors do not return from because Zaroff uses those unfortunate humans as his prey in his most dangerous game.

At the beginning of the story, Whitney tells Rainsford that the sailors and Captain Nielsen have a bad feeling about the island that they are passing. Whitney proceeds to tell Rainsford that even cannibals would not live on such a God-forsaken place and says that Captain Nielsen told him that Ship-Trap Island has an evil name among seafaring men. The atmosphere surrounding the island is foreboding and evil, which is something that Whitney comments on during his conversation with Rainsford. Captain Nielsen and the sailors' ominous feelings regarding Ship-Trap Island foreshadow the dangerous environment that General Zaroff has created on the island. After Rainsford falls off the yacht and swims to the island, he discovers that General Zaroff is hunting humans that have been shipwrecked there. Rainsford is forced to survive on the island for three days while the armed and murderous General Zaroff hunts him.