Koob et al.: Age validation of the northern stock of Centropristis striata in the Atlantic Ocean 263 
Table 1 
States of the northeastern United States in whose waters off the Atlantic coast black sea bass (Centropristis striata) were 
captured during 2013-2017, number of samples (n), sampling years, range of final age estimates for samples, and fishery type 
in which and gear type by which fish were captured. Otoliths from sampled fish were used in marginal increment analysis and 
first annulus validation. Gear types include bottom trawl, ventless trap, gill net, and hook and line. The following collaborators 
were the sources of samples: Massachusetts Division of Marine Fisheries (MA-DMF), North Carolina Department of Envi- 
ronment and Natural Resources (NC-DENR), NOAA Northeast Fisheries Science Center (NEFSC), Northeastern University, 
Rhode Island Department of Environmental Management (RI-DEM) in collaboration with the Commercial Fisheries Research 
Foundation (CFRF) and Virginia Institute of Marine Science (VIMS), and Rutgers University. 
Final age 
Sampling range 
Capture location years (years) 
2013-2017 
2013-2016 
Massachusetts 
Massachusetts— 
North Carolina 
Massachusetts— 
North Carolina 
Maine and 
Massachusetts 
Rhode Island 2017 
New Jersey 2017 
2015-2017 
2013-2016 
on whole otoliths is difficult because of their curvature and 
the presence of broad, diffuse bands; whereas, sectioned oto- 
liths have a crisp line at the distal edge of an annulus from 
which to measure. Left-sided otoliths were selected prefer- 
entially for consistency. Otoliths were embedded with epoxy 
resin and hardener (West System’, Gougeon Brothers Inc., 
Bay City, MI) in silicone molds. Transverse sections (0.5 mm 
thick) were cut along the dorsoventral plane, containing the 
otolith core (Fig. 3A), by using an IsoMet Low Speed Saw 
with a diamond blade (Buehler, Lake Bluff, IL). All otolith 
preparation used these methods, including preparation of 
samples for MIA, first annulus analysis, and the reference 
collection. 
Otolith aging and measurements 
In black sea bass, the outside edge of the opaque growth 
zone formed in winter is considered the annulus (Dery and 
Mayo, 1988). A date of 1 January was used for year-class 
advancement. Age determinations were made under a 
compound microscope (100x magnification) by placing sec- 
tioned otoliths on a glass slide with mineral oil. Each otolith 
was aged independently by 2 experienced readers without 
knowledge of fish size, capture location, or any previous 
age interpretations. If ages differed between readers, a con- 
sensus reading was required for final age determination. 
These ages were used to group samples into the 3 age bins 
for analysis, replacing the initial determination used to bin 
samples during the sample selection. Final ages for the 
3 Mention of trade names or commercial companies is for identi- 
fication purposes only and does not imply endorsement by the 
National Marine Fisheries Service, NOAA. 
Fishery type 
Independent 
Dependent Trawl 
Independent; Trawl 
Dependent 
Independent; 
Dependent 
Dependent 
Independent 
Gear type Source 
MA-DMF 
NC-DENR 
Trawl, trap 
NEFSC 
Trap, hook and line Northeastern University 
RI-DEM, CFRF, VIMS 
Rutgers University 
Trawl, trap, gill net 
Trap, hook and line 
reference collection were made following these same meth- 
ods. To assess precision and bias, each person read otoliths 
in the reference collection (with samples randomized prior 
to each reading) before and after MIA samples were read. 
Annulus measurements were made by using Image-Pro 
Premier, vers. 9.1 (Media Cybernetics Inc., Rockville, MD), a 
compound microscope-camera system (Axiostar Plus micro- 
scope, ZEISS Microscopy, Jena, Germany, and QImaging 
MicroPublisher camera, Teledyne Photometrics, Tucson, 
AZ). A straight line was drawn along the dorsal side of the 
sulcal groove, from the otolith core to otolith edge (radius), 
and the distal edge of each opaque band was marked 
(Fig. 3B). Measurements (in millimeters) from otolith core 
to each marked annulus were generated by the software on 
the basis of a coordinate plane. 
Statistical analysis 
All analyses and visualizations for this project were run 
by using statistical software R, vers. 3.6.1 (R Core Team, 
2019). Paired ages from readings of black sea bass oto- 
liths were evaluated for precision and aging bias by using 
Chang’s coefficient of variation (CV) (Chang, 1982) and 
a modification of the Bland—Altman bias plot (McBride, 
2015). Additionally, the precision of the age estimates of 
each reader was assessed by comparing each reader’s ref- 
erence collection session and the reference collection final 
ages. A CV below 5% is recommended for precision among 
readers for aging studies (Campana, 2001; McBride, 2015). 
Coefficients of variation were produced by using the FSA 
package, vers. 0.8.25 (Ogle et al., 2019), in R. 
Marginal increments are expressed as a proportion of 
the previous year’s growth (Hood et al., 1994; Winner 
