Complex sentence: After 15 years of research and development into hatchery production of spat, the industry still remains almost completely reliant on wild spat, because collecting wild spat is markedly cheaper than breeding mussels in a hatchery.
Split into simpler sentences: After 15 years of research and development into hatchery production of spat the industry still remains almost completely reliant on wild spat. This is because collecting wild spat is markedly cheaper than breeding mussels in a hatchery.