Complex sentence: Fear of dependence on fishing licenses and threats from overfishing, illegal fishing and fish market price fluctuations have increased interest on oil drilling as an alternative source of revenue; exploration efforts have yet to find "exploitable reserves".
Split into simpler sentences: Fear of dependence on fishing licenses and threats from overfishing, illegal fishing and fish market price fluctuations have increased interest on oil drilling as an alternative source of revenue. However, exploration efforts have yet to find "exploitable reserves".