Magnetic Remanences in Salmonid Fish

Abstract

In connection with indications of magnetic-field detection in migrating salmon, measurements of magnetic remanences were carried out for various salmonid fish, i.e., chum salmon, coho salmon, kokanee, masu salmon, yamabe, amago, rainbow trout, brown trout, Japanese char, and lake trout. Whether the species is migratory or not, none of the fish examined appears to contain magnetic materials in a special tissue related to the sensory mechanism, at least within the detection limits of the SQUID magnetometer. The natural remanent magnetization and the induced remanent magnetization were of the orders of 10-8-10-7 e.m.u. and of 10-7-10-6 e.m.u. respectively. These values are 0.01 to 0.1 times those reported for bees, pigeons, dolphins, and woodmice. © 1986, The Japanese Society of Fisheries Science. All rights reserved.