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Spawning Biomass of the Central Stock of Northern Anchovy (Engraulis Mordax) Estimated from the Daily Egg Production Method off California in 2017
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2018
[PDF-1.60 MB]
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Description:The 2017 daily egg production method (DEPM) survey for the Central Stock of northern Anchovy (CSNA, Engraulis mordax,) was conducted in March/April off California from about San Diego, California (32.55°N) to north of San Francisco, California (ending at 38.06°N, north of CalCOFI line 60). The survey covered a total area of 130,816.2 km2 . Northern anchovy spawned in waters ranging from 11° to 17°C, averaging 14.14°C. Eggs, larvae and adults were most abundant between 32.75°N and 34.04°N (San Diego, CA to Los Angeles, CA), indicating that the stock was mostly concentrated in the Southern California Bight (SCB) and spawning dynamics were similar to those observed in the 1980s. The survey area was stratified based on eggs collected from a Continuous Underway Fish Egg Sampler (CUFES) into an High and a Low Density regions, having egg density > and ≤ 1 egg/min, respectively. The daily egg production in the High density area (20,675 km2 ) was estimated to be 19.30/0.05m2 (CV = 0.23) using eggs and yolk sac larvae collected from Pairovet and Bongo nets. In the Low Density area, daily egg production was 0.45 eggs/0.05 m2 (CV = 0.65) when estimated as a function of the ratio (defined as q) of egg density in the Low and High Density areas.
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Rights Information:Public Domain
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