A float equipped Piper PA-18-150 and float equipped Cessna 185F were involved in a midair collision at an altitude of approximately 800 feet MSL over Larson Bay, AK. At the time of the midair collision, both aircraft were being used as fish spotters for several fishing boats in the area. The PA-18-150 was destroyed and the pilot was fatally injured. The Cessna 185F received no damage and the pilot was not injured. Both aircraft were flying parallel to each other with the Piper slightly lower. According to the Cessna pilot, he spotted the Piper below him when the Piper turned to the left. The Cessna pilot said he then turned right and pulled up but his left float contacted the Piper's right wing. The impact did not seem severe according to the Cessna pilot and the only damage he noted on the Piper was to the outboard end of the right wing. The Piper, however, continued a left spiral to the water. The Cessna pilot said he thought the boats should warn the pilots on a common radio frequency when two aircraft are in close proximity.