Life History and Ecological Notes on the Tubenose, Aulorhynchus flavidus, a Hemibranch Fish of Western North America

Abstract

The tubenose, or tube-snout, Aulorhynchus flavidus Gill, attains a length of at least 165 mm, but the mean standard length of adults examined was 142.9 mm. The range of the tubenose is Sitka, Alaska, to Punta Banda, Baja California, and diving observations reveal them to be present through the year in southern California. The fish have been observed and collected in rocky crevices, kelp beds, eel grass, and over sand bottom. They are found from the surface to 100 feet. They feed on small, free-swimming organisms. The major spawning area studied is considered for a possible correlation of the peculiar conditions there with spawning habits. The tubenose mainly establishes its nest on and attaches its eggs to the giant kelp, Macrocystis pyrifera. The nests are closely guarded by males who actively drive off intruders. The nest building habit and territorial behavior is reminiscent of that of the sticklebacks, and the morphological evidence of the close relationships between the two groups is in part confirmed. Egg masses have been observed from depths of 17 to 120 ft, but most commonly 35 to 58 ft. The presence of eggs and young fish during the entire year suggests that spawning is not seasonal. It is probable that the tubenose serves as an important link in the food chain of some California game fishes.