The Fraser River white sturgeon are unique fish with an interesting life history. Here are some interesting points about Fraser River white sturgeon spawning behavior.
White Sturgeon Spawning
Females do not become reproductive until they are approximately 20 years of age – this corresponds to approximately 150 cm in length (5 footer). Females may spawn every 5-10 years, depending on environmental factors and fish health. Spawning occurs in the Fraser typically in June and July (give or take), and generally coincides with post peak high water levels (freshet).
A female sturgeon can produce between 500,000 and 4 million eggs during spawning, depending on age and fish health. Older fish are generally thought to produce greater numbers of eggs.
It is thought that more than one male will participate in fertilizing the eggs of one female through communal broadcast spawning. Sturgeon do not dig a redd (nest) like salmon do, but spawn near the bottom allowing the current to mix eggs and milt. Upon fertilization, the eggs become very sticky and sink to the bottom where they will attach to rocks, sticks or other objects on the river bottom until the eggs hatch.
Sturgeon eggs require 100 ATU (accumulated thermal units) to hatch – hatch time varies and is dependent on water temperature. One ATU is equal to 1 degree Celsius in a 24 hour period. Average Fraser River water temperatures during sturgeon spawning is approximately 15 degrees Celsius, therefore 100 ATUs are achieved in 6.6 days. In comparison, many salmon species require 500 ATU, give or take depending on species.
Once sturgeon fry emerge from their egg casing, they look like a small tadpole, are merely 10 millimeters long (1/2”), grey in color and feed from a yellow/grey yolk sack for nearly 3 weeks. They are poor swimmers, and will drift in the merciless current if it were not for the safe havens found in between the river bottom’s debris and rocks (interstitial spaces). At the egg and fry stage, sturgeon are most likely heavily preyed upon by a variety of other Fraser River fish species such as pike minnow, pea-mouth chub, and various suckers.
After nearly three weeks, the fry will have used up their yolk sack, and have grown to approximately 3 cm in length. With a closer look, they will look exactly like a sturgeon should. Interestingly at this age they develop little cartilaginous teeth to assist them in feeding on insects found on the Fraser’s river bottom. These “teeth” will disappear as they become large enough to ingest larger prey items.
In the first year a sturgeon may grow to approximately 20-30 cm. They are still very vulnerable to predation by other larger fish such as pike minnows, birds such as cormorants as well as other larger sturgeon!
December through to April we offer a “Juvenile Sturgeon Tagging Day”, a trip that is both educational and informative. CLICK HERE TO LEARN MORE
We hope you enjoyed reading this fascinating information. Your guide, Marc spent a number of seasons sampling the Fraser in an effort to identify the spawning areas and preferences of white sturgeon for the Provincial Ministry that oversees fish and fish environments.
Come join us for a day of sturgeon or salmon fishing on the river, and experience all that the Fraser river has to offer!
Have fun, enjoy what we have today, and remember, you can’t catch them from the couch.
We look forward to spending quality time in the boat with all of you soon!
Best wishes to you all, from all of us!
Cheers!
Photo credits: Osprey – Colin Pacitti / Bear and Seals – John Sanderson / Eagle – Marc
Whether you are looking for a day trip fishing or you want to stay longer, we can arrange everything from your pickup at the airport in a limo, to your hotel accommodation and the best guided fishing tours in the Fraser Valley. Please contact Marc or Maggie on Toll Free: 1-877-887-4366 or use our contact form.