DOI: 10.25921/1k6d-tf95
title: NOAA/WDS Paleoclimatology - California Current Splitnose Rockfish Otolith Growth Data

description: Analysis of monthly coastal upwelling intensities revealed two seasonal and biologically relevant upwelling 'modes' in the California Current Ecosystem (CCE). The first mode reflected upwelling during the summer months and was characterized by low-frequency (multidecadal) processes, including significant (P<0.01) linear trends at some latitudes. In contrast, the second mode reflected wintertime upwelling and was defined by higher-frequency variability associated with the North Pacific High and El Niño Southern Oscillation events. These modes were compared with multidecadal time series of splitnose rockfish (Sebastes diploproa) otolith growth, yelloweye rockfish (S. ruberrimus) otolith growth, Chinook salmon (Oncorhynchus tshawytscha) scale growth, and indices of Cassin's auklet (Ptychoramphus aleuticus) and common murre (Uria aalge) reproduction in the central-northern CCE. In redundancy and correlation analyses, salmon growth and Cassin's auklet fledgling success associated with the summer upwelling mode while all other time series associated with the winter upwelling mode, indicating that CCE biology was differentially sensitive to these seasonal upwelling patterns. Thus, upwelling occurred in unrelated seasonal modes with contrasting trends, atmospheric forcing mechanisms, and impacts on the biology of the CCE, underscoring the importance of seasonality when evaluating ecosystem response to climate variability and change.
description: Growth increment data from Splitnose Rockfish otoliths 
collected in the California Current System, eastern 
North Pacific. 

Otoliths were collected from splitnose rockfish (Sebastes 
diploproa) captured between approximately 36ºN 122ºW 
and 39ºN 125ºW in the California Current Ecosystem.  
Fish were collected as part of NOAA National Marine 
Fisheries Service rockfish surveys and recreational 
and commercial fishery landings between 1980 and 2008.  
Splitnose rockfish adults are largely planktivorous 
(krill and also copepods, sergestid shrimps, and amphipods) 
and are most common between 215 to 350 m depth on the 
continental shelf and upper slope, and can live to be 
at least 85 years in age. 

Otoliths were embedded in resin, mounted on a lapidary saw, 
and thin-sectioned through the dorsal-ventral axis to 0.4 mm 
in thickness.  These thin sections were polished with 2000-grit 
sandpaper and 10-um lapping film to reveal the annual increments. 
All samples were visually crossdated to ensure that all annual 
growth increments were assigned the correct calendar year of 
formation.  After visual crossdating, the dorsal half of the 
otolith was then photographed and the annual increment widths 
measured continuously from the margin to as close to the focus 
as possible using the program ImagePro Plus v. 6.0. 
Crossdating was statistically verified with the Dendrochronology 
Program Library program COFECHA using 22-year 50% frequency 
cutoff splines (rather than the default 32-year splines). 
To generate the master chronology, each otolith measurement 
time series was fit with a negative exponential function or 
linear regression with negative or 0 slope and divided by the 
values predicted, thereby removing age-related growth declines 
and standardizing each time series to a mean of one.  
These detrended time series were averaged with respect to 
calendar year.  All chronology development was conducted 
using the program ARSTAN, available at: 
http://www.ldeo.columbia.edu/res/fac/trl/public/publicSoftware.html 
70 otoliths were used to develop the splitnose rockfish master 
chronology.  The "standard" chronology from ARSTAN is reported. 
All growth-increment widths are in mm. 

Measurement type: annual growth-increment width (in mm)
1st detrending method: Negative exponential or linear regression 
with negative or 0 slope 
Collection purpose: Ecology; effects of climate variability 
on rockfish growth
Samples are stored at the Oregon State University Hatfield Marine 
Science Center, Newport, OR 97365. 

COFECHA output: 
series intercorrelation = 0.580; mean sensitivity = 0.152