Structure of Fish Eggs

When the eggs are deposited onto the redd by a female, they are very, very fragile. The outmost skin of the egg is called the porous outer shell, which is transparent, elastic, delicate and porous. This outer shell is limp, somewhat collapsed, and flaccid. These fresh eggs are also slightly adhesive, causing some of them to lump and bunch up together on the redd. Hence, our use of 3 Egg Clusters to imitate that occurrence! They also have one small hole in the outer shell called the micropyle through which sperm from a male enters the egg to fertilize the inner egg nucleus. Inside this outer shell is located the yolk inside the yolk membrane, which is also very fragile until the egg is "hardened". This yolk also contains the germinal disc which is colored and visible through the transparent outer shell of the egg.

After deposition onto the redd, this new, fragile egg begins to absorb water in the small space between the yolk and the limp outer skin. This process takes about 20 minutes and during this time the outer skin hardens, and the entire volume of the egg increases by approximately 20 %, until pressures within and without the egg and yolk are normalized. Many spawn fishermen, after taking fresh eggs from a fresh female Brown or Rainbow trout, Steelhead or Salmon use this same method of "water hardening" eggs in a small nylon sack placed in stream water for 15 to 20 minutes prior to using these fresh eggs in making up their new spawn bags to fish with.

An interesting feature of this germinal disc and the yolk is that the entire yolk mass is free to rotate within the outer shell. If you take an egg and turn it so the germinal disc is on the side of the egg, the entire yolk will then freely rotate so the the germinal disc rotates back to the top of the egg. That is why when looking at fresh eggs this disc is never in the center of the egg, but rather on an outer top edge of the egg in an eccentric, not concentric, position.

Introduction to Basic Data on Fish Eggs | Egg Sizes Versus Fish Species | Timing to Use Our Egg Patterns | Color Ranges of Eggs | Our New "Dead Egg White" Color | Recommendations on Hook Styles and Manufacturers | Why Otter's "Soft Milking Egg"© patterns Work So Well

For more information, contact:
Blue River Designs, LLC
6977 S. Madison Way
Centennial, CO 80122

All "Soft Milking Egg"® patterns are registered trademarks of Blue River Designs, LLC.
© 2017 Blue River Designs, LLC
All rights reserved.

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