Egg Flies

catastrophes such as floods.  In areas where fish are spawning, eggs are often more prevalent than aquatic insects in a foraging trout's diet. 
   Deschutes Redsides dine all winter on white fish eggs.  Alaskan rainbows get a seasonal boost from the roe of spawning salmon.  Trout and steelhead often congregate down stream of the redds of spawners of their own race.  All salmonids, especially Rainbows, Cutthroats, Dolly Varden and Rocky Mountain white fish are egg eaters.   
    Fish eggs come in many sizes and colors.  White fish eggs are 1/8" diameter and are transparent yellowish pink.  Eggs from spawning resident

rainbows are usually 3/16" in diameter and are translucent yellowish orange.  Steelhead eggs are about 1/4" in diameter and exhibit the same coloration as their land locked cousins.  Coho salmon eggs are nearly identical to steelhead eggs.  Chinook salmon eggs are the same color but range to nearly 3/8" in diameter.  Chum salmon eggs are slightly larger but lighter in color.

   All eggs change color as the embryo inside them develops.  Trout and salmon eggs go through a similar metamorphosis.  First the tiny eyes of the fish inside the egg forms a dark spot.  Then the darker reddish-orange yoke sack starts to form.  In later stages the silvery form of the fish is seen through the outer membrane of the egg.

   If the egg is unfertilized it dies quickly and turns an opaque whitish-pink.  Silt collecting on the outer skin of the egg can give it a grayish cast.  If the egg is allowed to drift long enough, it will be attacked by fungus and algae and become greenish.  Trout and steelhead may become selective to these different egg nuances.