In the official Minecraft Wiki (this site), it says that the master trades of fisherman villagers are a pufferfish and a boat.

The type of boat trade depends on the biome outfit of the villager. Plains villagers buy oak boats, taiga and snowy villagers buy spruce boats, desert and jungle villagers buy jungle boats, savanna villagers buy acacia boats, and swamp villagers buy dark oak boats.

But, as it turns out, this doesn't really apply to Bedrock Edition: Fishermen (born) in the jungle don't trade jungle boats at all; the master trade is just the pufferfish. In deserts however, they DO trade jungle boats (as the wiki suggests).