The birds and the bees and the fishes in the sea

You might already know about the birds and the bees as they relate to birds and bees…but what about the birds and the bees for the fishes of the sea? Between winter and spring is the time when most of the Aquarium’s cold-water fish reproduce, and keen-eyed visitors may be able to see signs of it in our exhibits—if they visit soon!

Keep reading to learn about three types of reproduction and what to look for on an upcoming visit to the Aquarium! FYI, reproduction for our warm-water fish doesn’t follow this same seasonal cycle; it may take place year-round and be time to lunar cycles instead of seasons.

Oviparous reproduction

How does it work? The mother lays eggs, then the young hatch out of those eggs. Ninety percent of bony fish and 43 percent of cartilaginous fish reproduce this way.

What to look for: A spotted ratfish cruising around the Underwater Dome with two egg cases trailing behind it. Also recently sighted in the same exhibit: whitish clusters of lingcod eggs. On a nearby rock, you may be able to see a male lingcod guarding more of these eggs.

spotted ratfish


Viviparous reproduction

How does it work? The young develop inside the mother, then she gives live birth (similar to human reproduction). Surf perches are some of the only true viviparous fish. Certain sharks, such as hammerheads, blue sharks and bull sharks, also reproduce this way.

What to look for: If you see blue striped perch in the Underwater Dome that are just a couple inches long, you are seeing fish that were born in the exhibit! Most of the fish that are born or hatched at the Aquarium are small enough to return to Puget Sound via the open-water system that supports the exhibits in which we feature fish native to our local waters. But these young perch are anywhere from 1.6 to 2.4 inches long at birth, too large for the open-water system, and as such are one of the few larval fish that may remain at the Aquarium for the duration of their lives.

blue striped perch


Ovoviviparous reproduction

How does it work? The eggs hatch within the mother’s body, and then she gives live birth to the young. From the outside, this looks just like viviparous reproduction. The big difference is that there is no placental connection between the mother and young—instead, the young are nourished by an egg. Rockfish are ovoviviparous—as well as rays and some sharks.

What to look for: The baby bump on a yelloweye rockfish in our Window on Washington Waters exhibit. At her mature size, she may release 500,000 live little rockfish. The young will be about one-fifth of an inch long when they’re born, which usually happens around the height of the spring plankton bloom (so those young fish have food) and at night (for protection).

yelloweye rockfish


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