New Feature! Indian Island Naturalists Notebook

Striped perch and Shiner perch give live birth!

Striped perch and her golden newborn, Indian Island, June 25, 2013

Russel Barsh and the Indian Island Marine Health Observatory team

Everyone knows that fish lay eggs, right? Well, not our two local surfperch species! Shiners and Stripeys, as our volunteers affectionate them, return to Indian Island each summer by the thousands to mate and give live birth to clutches of up to six, or even more tiny “babies” that pop out one by one. But don’t expect these newborn fish to be helpless like the babies of mammals. They are perfect copies of their parents and can immediately swim and eat for themselves!

Paleontologists have found evidence that internal fertilization and internal hatching and brooding of young is actually a very old phenomenon in the fishes. Fossils of fish with fully formed juveniles inside them are as old as 400 million years! But only a small proportion of fish species rely of this trick to give their offspring a head start in life.

Mature surfperch generally begin congregating in the eelgrass around Indian Island in June and birth in July, leaving behind swarms of gold and silver juveniles the size of quarter-dollars that remain in the vegetated shallows, feasting on small crustaceans such as heptacarpid shrimp (green “grass shrimp”) and gammarid amphipods (“sand fleas”), until the water cools down in the fall.