More than 3,600 tilapia fry netted in upper river fish survey

BIOLOGISTS Sabrina Drill (left) and Rosi Dagit inspect part of the tilapia haul. (William Preston Bowling)

BIOLOGISTS Sabrina Drill (left) and Rosi Dagit inspect part of the tilapia haul. (William Preston Bowling)

By Rosi Dagit

Guest contributor
Looks like we captured 3,699 fish, the majority of which were juvenile tilapia under 1 inch. Based on the few larger (up to 3 inches) fish, most appeared to be redbreasted tilapia (Tilapia rendalli), but that is not yet verified with the voucher specimens.  These fish can breed year around in warm waters, and it was quite interesting to find such young fish at this time of year, but water temperatures were 24-27 degree C. (75-81 degrees F.), which is pretty warm. They can reach up to 18 inches and live for up to seven years.
They are native to Africa, and are primarily herbivores that spawn in the substrate and guard their nests.  They are considered to be competitors with native fish for food and spawning areas, and high densities of fish can negatively impact native aquatic vegetation.
In other areas, they have not survived strong flows or colder temperatures, so it will be really interesting to see if they make it through the winter El Nino.
SEINE NETS yield 3,000 tilapia fry in Haskell Creek above Sepulveda Dam on Friday. (William Preston Bowling)

SEINE NETS yield more than 3,600 tilapia fry in Haskell Creek above Sepulveda Dam on Friday. (William Preston Bowling)

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