Final answer:
Male pipefish produce relatively few sperm because of their polyandrous mating system, which focuses reproductive success on offspring care and gestation rather than quantity of sperm.
Step-by-step explanation:
The male pipefish produces relatively few sperm due to the polyandrous mating system of the species, where one female mates with several males. The males have developed adaptations for better investment in offspring care rather than in spermatogenesis, seeing that they carry and protect the fertilized eggs in a pouch until birth. This strategy shifts reproductive success towards quality of care and gestation over the quantity of sperm produced.