Over time the BG will exterminate the FH and stunt without additional food and predation upon them. Gams are better at avoiding extermination but will be greatly reduced in number.

Two things happen at the same time. Adult BG and RES eat all sizes of FH and the BG offspring eat all the subsequent FH fry. With a short lifespan and high natural mortality, the number of FH maturing and reproducing gets low quickly and with few fry surviving to maturity there are not enough survivors to establish/continue.