Complex sentence: Although the backcross program did succeed in creating some localised angling opportunities, it never achieved any degree of success in terms of natural reproduction; the backcross was only marginally better at reproducing than was the F1 splake.
Split into simpler sentences: Although the backcross program did succeed in creating some localised angling opportunities, it never achieved any degree of success in terms of natural reproduction. The backcross was only marginally better at reproducing than was the F1 splake.