MEPS 153:229-238 (1997)  -  doi:10.3354/meps153229

Demographic consequences of within-year variation in recruitment

Pfister CA

I explored the consequences of variance in the timing of recruitment to early growth and survivorship in a guild of sculpins that occupy intertidal areas on the outer coast of Washington state (USA). When I quantified the appearance of new recruits every month for 3 yr, I found seasonal peaks in recruitment for the 3 most common species in this system, although fishes recruited throughout the spring and summer months. Mark-recapture studies revealed especially strong seasonal growth patterns in 2 of the 3 species, with increased growth rates during the summer months. This effect was most pronounced for young-of-the-year fishes. As a consequence, individuals of all species reach reproductive size more rapidly and benefit from higher survivorship to reproductive size when they recruit earlier in the spring and summer. These demographic consequences of within-year recruitment variation appear driven by large-scale oceanographic events, since recruitment in all 3 species can be correlated with upwelling and/or sea surface temperature. Although these results suggest that within-season recruitment variation, via its effect on juvenile performance, may affect the population trajectories of these nearshore fishes, previous research in this system also indicates a strong role for adult survivorship patterns. Thus, understanding the net effect of pelagic events in driving population dynamics of organisms with complex life cycles requires integration of both pelagic and benthic life history events.

Cottidae · Intertidal fishes · Upwelling · Recruitment variation · Timing of recruitment · Complex life cycles · Benthic-pelagic coupling · Demographic variability

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