MEPS 242:215-228 (2002)  -  doi:10.3354/meps242215

Distributions of larval rockfishes Sebastes spp. across nearshore fronts in a coastal upwelling region

Eric P. Bjorkstedt1,2,*, Leslie K. Rosenfeld3,**, Brian A. Grantham1,***, Yehoshua Shkedy1,****, Joan Roughgarden1,4

1Department of Biological Sciences, Stanford University, Stanford, California 94305, USA
2National Oceanic and Atmospheric Administration (NOAA) Fisheries, Santa Cruz Laboratory, 110 Shaffer Road, Santa Cruz, California 95060, USA
3Monterey Bay Aquarium Research Institute, Pacific Grove, California 93935, USA
4Department of Geophysics, Stanford University, Stanford, California 94305, USA
*Correspondence address: Santa Cruz. E-mail: Present addresses: **Naval Postgraduate School, Code OC/Ro, Monterey, California 93943, USA ***Department of Zoology, Cordley 3029, Oregon State University, Corvallis, Oregon 97331, USA ****Israel Nature and Parks Authority, 3 Am Veolamo Street, Jerusalem 95463, Israel

ABSTRACT: We sampled larval fishes along cross-shelf transects off Granite Canyon, California, USA, during the upwelling seasons of 1993 and 1994 to determine whether coastal upwelling fronts affect the cross-shelf distribution of larval rockfishes Sebastes spp. during the earliest period of planktonic life. Rockfish larvae occurred in relatively high densities near surface fronts and were distributed in patches oriented along sloping pycnoclines contiguous with surface fronts. Qualitative comparisons between observed distributions of larval rockfishes in relation to hydrographic structure and predictions from models of plankton distributions at convergent fronts support the hypothesis that convergent circulation contributes to observed distributions. Our results indicate that (1) coastal upwelling fronts influence larval rockfishes at an earlier life history stage than has previously been documented, and (2) the influence of upwelling fronts on distributions of larval rockfishes is similar to the influence of hydrographic fronts on distributions of larval fish reported for a variety of oceanographic settings. In light of the plausible effects of upwelling fronts on larval transport and ecology, our findings suggest that upwelling fronts merit further investigation for their potential role in translating variability in upwelling dynamics into fluctuations in recruitment to coastal rockfish populations along the west coast of North America.

KEY WORDS: Larval fish distribution · Coastal upwelling · Upwelling fronts · Recruitment mechanisms · Rockfishes · Sebastes

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