Plainfin Midshipman

Spawn at night in spring and summer. There are 2 different types of male plainfin midshipman: type I males are much larger and they make and guard nests in sandy or muddy bottoms near rocky areas in shallow waters. The male uses his fins or mouth to scoop out a hollow. Type I males make 3 different kinds of sounds: hums, grunts, and growls. The hum is used to attract females, while a male will grunt at any intruders while guarding his nest. Type II males are smaller, sneakier males. Rather than make their own nest to guard, their reproductive strategy is to sneak into a Type 1 male’s nest and release sperm. Along with females, Type II males can only make growls, but not the hums or grunts that Type I males make. During the spawning season, Type 1 males start humming shortly after dusk, humming for as long as 14 minutes. Attracted by the humming, a female will enter the male’s nest, and he will stop humming. She will spend up to 20 hours laying her sticky 70-200 eggs in his nest. He fertilizes them as she lays them and when she’s done, he kicks her out of the nest, and he starts humming again to attract more females, while caring for those eggs by brushing and fanning them. A single nest can contain 2,000 eggs from many females. During low tide, when the eggs are exposed to the air, the male will splash them to keep the eggs moist. It takes 40-45 days for the eggs to hatch. The juveniles hatch at 0.2 or 0.3 inches long but stay attached to the rocks for weeks, until they reach 0.6-0.7 inches long. Once they are free-swimming, they stay in shallow waters, either on sand or eelgrass, burying into the sand during the day and coming out at night to feed.

They can reach a maximum length of 16 inches and live to at least 5 years old.