Population dynamics and reproductive ecology of the redtail surfperch Amphistichus rhodoterus (Embiotocidae)

Redtail surfperch (Amphistichus rhodoterus) catch has declined throughout their central California to Washington range. Research objectives determining if temperature affected reproduction, if recreational catch-per-hour (CPH) indexed abundance, if angler catch and effort data from the 1979 to 1986 Marine Recreational Fisheries Statistics Survey (MRFSS) were detailed enough to resolve CPH differences; and developing a population model based on MRFSS angler interview data; correlating abundance and recruitment with environmental factors; and making fishery management recommendations for redtail surfperch.; In the laboratory, 30- to 40-day exposure of gestating fish to ambient and ambient plus 3{dollar}spcirc{dollar}C temperature affected offspring size and parturition timing. Horsefall Beach catches were recorded to the minute to determine the following: if handling time, inter-species hook competition, recording only successful anglers, rounding effort to 0.5 hrs., combining angler catches, or angling skill invalidated use of the tonal ratio estimate of CPH (TCPH) to index abundance; to determine if the Poisson Distribution was appropriate when modeling catch accumulation; and to estimate CPH resolution. Annual Horsefall Beach mortality was estimated from MRFSS catch-length and size at age data, and then combined with predicted gravidity to form a population model. Beards Hollow, Columbia River North Jetty, and Horsefall Beach recruit and abundance indexes were formed using MRFSS TCPH and length measurements; these indexes were correlated with annual catch, effort, and harbor seal abundance and with monthly wave height, wave period, sea surface temperature, and upwelling. TCPH can be used to index abundance and confidence intervals of {dollar}pm{dollar}1 TCPH are estimated for A. rhodoterus surf fisheries at TCPH {dollar}<{dollar}3.3.; Kalaloch Beach, Damon Point, Westport Beach, Beards Hollow, Columbia River North Jetty, Jetty Sands, Freshwater Lagoons, and King Salmon (Buhne Point) fisheries were sustainable, but decreasing length of fish was common. Horsefall Beach fisheries captured prereproductive sizes extensively, and offspring production was below population replacement. Horsefall Beach recruitment correlated positively with June upwelling from when recruits were embryos, but not with catch or effort. Columbia River North Jetty abundance correlated with spring and fall environmental conditions of the previous 18-months. Female harvest restrictions are recommended when offspring production is below replacement levels.