680 



Abstract.— Growth of otoliths of adult 

 widow rockfish, Sebastes entomelas. 

 and yellowtail rockfish, S. flavidus. in- 

 habiting the coastal waters off central 

 and northern California was reduced in 

 1983. This reduction ( 12.69, and 20.5'^r , 

 respectively) coincided with a strong El 

 Nifio event that dominated oceano- 

 graphic conditions that year. Otolith 

 growth from 1980 to 1987 was signifi- 

 cantly correlated with ocean tempera- 

 t\*re, upwelling, and sea level anomaly. 

 Specifically, in 1983, the highest ocean 

 temperature, largest positive sea level 

 anomaly, and lowest amount of coastal 

 upwelling corresponded to the smallest 

 mean otolith growth increment. 



Reduction of growth in otoliths of widow and 

 yellowtail rockfish (Sebastes entomelas 

 and 5. flavidus) during the 1983 El Nino 



David Woodbury 



Southwest Fisheries Science Center 



National Marine Fisheries Service, NOAA 



3150 Paradise Drive 



Tiburon, Calilornia 94920 



E-mail address David Woodburyignoaa gov 



Manuscript accepted 16 September 1998. 

 Fi.sh. Bull. 97:680-689 (1999). 



In 1983, one of the strongest El Nino 

 events of the century occurred in the 

 east-central Pacific Ocean (Cane, 

 1983; Rasmusson, 1984; Glynn, 

 1988). This event had strong nega- 

 tive effects on the growth of many 

 marine organisms inhabiting wa- 

 ters along the west coast of North 

 America, including giant kelp 

 (Zimmerman and Robertson, 1985), 

 yellowtail rockfish (Lenarz and 

 Wyllie Echeverria, 19861, coho and 

 Chinook salmon (Pearcy and Schoe- 

 ner, 1987), Pacific herring (Spratt, 

 1987), Pacific kelp (Germann, 

 1988), Pacific hake (MacLellan and 

 Saunders, 1995), and blue rockfish 

 (VenTresca et al., 1995). 



At.ypically narrow annuli (annual 

 growth increments) formed during 

 1983 were observed during routine 

 aging of otoliths from adult yellow- 

 tail rockfish, Sebastes flavidus (Fig. 

 1). Because otolith growth is gener- 

 ally proportional to fish growth, a 

 reduction in the width of the 1983 

 annulus could correspond to poor 

 fish growth caused by the El Niiio- 

 induced anomalous oceanographic 

 and biotic conditions present that 

 year Widths of annually formed in- 

 crements on the hard parts of ani- 

 mals and plants have been used to 

 correlate growth with a range of 

 environmental conditions. A com- 

 mon example is the relation be- 

 tween the widths of tree rings and 

 annual precipitation. In the marine 

 environment, a reduction in annual 

 shell growth of geoduck clams was 



observed to correspond with in- 

 creased pollution (Noakes and 

 Cambell, 1992). Boehlert et al. 

 ( 1989) used otolith annuli to provide 

 historical time series of growth in 

 Sebastes that were compared with 

 environmental factors. In a similar 

 study, MacLellan and Saunders 

 ( 1995 ) noted a reduction in the 1983 

 annulus of Pacific hake otoliths in- 

 habiting northeastern Pacific wa- 

 ters, attributing it to the negative 

 effect of the 1983 El Nino. 



In this study, otolith growth from 

 1980 to 1987 was measured from 

 two commercially important rock- 

 fish species: yellowtail rockfish and 

 widow rockfish (S. entomelas). 

 These species range from British 

 Columbia to southern California 

 (Gunderson and Sample, 1980). 

 They are semipelagic, associated 

 with bottom structure located on 

 the shelf. The measurements of 

 otolith growth were compared with 

 physical oceanographic variables 

 collected during the same period. 



Methods 



Otolith growth 



Otoliths from female yellowtail 

 rockfish inhabiting Cordell Bank, 

 California (Fig. 2), were collected 

 during research cruises conducted 

 from 1986 to 1992. As noted earlier, 

 during otolith age determination 

 procedures, the 1983 annulus was 



