| Show female of the salmon family builds and defends the nest male does guard duty how salmon build and defend their nests Is described in the annual report of the smithsonian institution by leonard P schultz assistant curator of fishes of the united states national museum it is essentially a labor of the female of the species he finds with the m male ale standing guard and occasionally sio nally giving a little help the completed nests are depressions in a stream bottom each with a small mound of sand or grav gravel of on the downstream side the depth and d size of a nest depend on the size of the fish which constructs it the shape of her body and the rate of flow 0 of f the water ever the spot A pair of these fish dr schultz chose the landlocked species of salmon known as for or his observations ions choose a time for building their nest when there are no other fish around to molest them the female will turn over on her side and vigorously flex her tall from tour four to six times against the bottom this motion carrying her a foot or more upstream eam the tall of the fish bsh during these movements corne comes a 1 it contact with the bottom and vigorous hydraulic forces are set up by the upward movement of the tall which lift the gravel and sand off 00 the bottom the material thus disturbed is carried by the swift current down stream the smaller particles fax fai chest and the larger stones but a few inches before they settle if undisturbed dr schultz observed a female in 20 minutes may complete as many as 70 separate nest build ing acts with intervals of from lour four seconds to a little more than a minute between them from a few hours to a few days are required to build a single nest pit the male usually stands by idly |
