Soak fish maw in warm water for 2 hours.
Place fish maw in a 4-quart saucepan and cover with cold water. Add 4 ginger slices and bring to a boil. Boil for 5 minutes on medium low heat and then drain fish in colander, rinsing with cold water. Squeeze out any excess water.
Cut the maw into 1/2 inch diced pieces, discarding any hard pieces.
Heat the chicken broth and the remaining 4 ginger slices in a large pot until boiling. Add the fish maw and the black mushrooms. Heat to boiling and then turn to medium low heat and simmer 10 minutes.
While soup is simmering, combine the cornstarch and water in a small bowl. Remove the 4 slices of ginger from soup. Turn heat to high and stir in the cornstarch mixture. When soup returns to a rapid boil, stir in egg white mixture a little at a time, stirring constantly with a fork until egg mixture forms threads. Taste soup at this time to see if salt and white pepper are needed. Add the shredded chicken and yellow chives; stir to mix. Turn off heat and serve.
Cook's Note: Fish maw comes dried and processed. If you purchase the dried fish maw that is unprocessed and hard as plastic, you need to deep fry in oil at 375 degrees F for a few seconds until they puff up. Then you can proceed with the soaking process in the recipe.