Yes a blocking net will work . See this thread. We have done repeatedly exactly what you are describing.

http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Main=5690&Number=52295#Post52295

Also Pond Boss mag has several articles on blocking nets and forage ponds.

There are other threads here on what to expect with supplemental stockings (not using a blocking net) and how to establish TShad in a pond with adult predators.