Catch of a lifetime: White Sturgeon (Acipenser transmontanus)

Catch of a lifetime: White Sturgeon (Acipenser transmontanus)

by Stephanie Hansen

steph s1

On Saturday March 16th, while working aboard the R/V Brownlee, I had the most amazing catch of my life: a white sturgeon! In the year and a half I have worked for MSI there has only been one other white sturgeon caught. As we pulled up the net, I could feel the weight of a big catch, and looking down into the otter trawl (the type of net we use) I knew something magical was in the water. Once it was on board, I quickly realized it was a white sturgeon. These fish are huge; mine was over 4 feet long, weighing about 100-150 pounds. They are the largest freshwater fish in North America and can weigh over 1,500 pounds, be 20 feet in length, and live for over 100 years! Clearly mine was a baby, our captain said it was between 10 and 20 years old.

 

steph smile s2Sturgeons start off their lives in fresh water and then move into saltier water later in life. The fish that move from fresh to salt water, and then back to fresh water to spawn are called anadromous. It takes between 15 and 25 years for a sturgeon to fully mature and begin the spawning process. White Sturgeon move to rivers in the spring and spawn from May to June. They broadcast spawn, which means they release their eggs into the water, the eggs get fertilized and then the fertilized eggs attach to the rocky bottom to hatch. Females can produce anywhere from 100,000 to 4 million eggs! They spawn every 4-11 years, with the older females producing more eggs and waiting longer between spawning. Hatching can happen anytime from 4 days to 2 weeks depending on water temperature.

 

The white sturgeon is an ancient species that has not changed much over evolutionary time. They are bottom dwelling fish that spend their time rummaging on the seafloor for food. steph s barbUnlike most other fishes, its taste buds are on the outside of its mouth. These taste buds, along with barbels (feelers) under the sturgeon’s snout, help the fish select food, and a toothless mouth sucks it up. Young white sturgeon primarily feed on algae and aquatic insects while remaining in rivers and estuarine environments. Adult white sturgeon primarily feed on fish, shellfish, crayfish, and on various aquatic invertebrates, clams, amphipods, and shrimp.

 

These fish are classified as bony fish, but much of their skeleton is made of cartilage. It has no scales, but “scutes” instead. Scutes are actually large modified scales that serve as a type of armor or protection. They can have anywhere between 58 and 74 scutes along their body which can be razor sharp. This is why in the pictures I am wearing a rain coat on a sunny day!

 

I was very happy to catch this giant prehistoric fish, and everyone on board was too!

You never know what you can see out on the Bay! Come to Earth Day on the Bay and find out.

A full day of fun on land awaits, including your choice of three trips on the Bay aboard the Brownlee!

http://www.sfbaymsi.org/earthday.html

Earth-Day-on-the-Bay2009-Lo

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