Sutherland and Richards: Aging Lophius americanus based on length-mode progression of a strong cohort 19 
Table 2 
Details for samples of goosefish (Lophius americanus) collected from June 2015 through September 2018 along 
the Atlantic coast of the United States from Virginia to Georges Bank and used in this study. Sources of samples 
include surveys of the NOAA Northeast Fisheries Science Center (NEFSC), the NEFSC Study Fleet program, 
and the NEFSC Fisheries Monitoring Operations Branch (FMOB). SD=standard deviation; TL=total length. 
Known No. of samples Total Mean 
age S|) LS Sr = a no. of length (SD) 
Month (years) NEFSC surveys Study Fleet FMOB samples (em TL) 
2 14.5 (0.7) 
3 28.0 
1 29.7 (3.9) 
33.5 (1.9) 
36.7 (2.1) 
34.0 (2.9) 
36.8 (2.3) 
38.6 (1.9) 
37.2 (1.5) 
37.2 (0.8) 
37.8 (1.6) 
40.3 (2.1) 
42.0 (2.0) 
44.8 (1.9) 
42.7 (0.6) 
51.8 (3.6) 
September 
May 
June 
July 
August 
September 
October 
November 
December 
January 
February 
March 
April 
May 
July 
April 
WNHNNNN DD FH RRP RR Re HO 
Marginal increment analysis 
A total of 74 illicia were examined in the 
marginal increment analysis, including 
61 illicia that had only one ring inside the 
edge (ages from 1+ to 2 years). The nar- 
rowest MIR widths were measured in illi- 
cia from fish sampled in May—July 2016 
and in April 2017; maximum MIR widths 
were measured in illicia from fish sam- 
pled in December 2016 (Fig. 7). Monthly 
sample sizes ranged from 1 to 12 fish. 
Diameters of various marks in illi- 
cia were compared against fish length 
(Fig. 8). The mean diameter of the set- 
tlement check was 0.078 mm (95% con- 
fidence interval [CI]: 0.075—0.081 mm); 
the diameter of the settling check 
increased with fish length (linear 
regression: slope=0.0005, P=0.04, coef- 
ficient of determination  [r”]=0.05). 
Ring count (illicia) 
Ring count (vertebrae) 
The first ring was visible inside the 1 2 3 1 2 3 
edge in fish as small as 24-28 cm TL Knownjage (years) ISIN EBD (FOEUS) 
and had a mean diameter of 0.259 mm Figure 5 
(95% CI: 0.253—0.265 mm); the diame- Accuracy of ring counts versus known ages from readings of (A) illicia and 
ter of the first ring increased with fish (B) vertebrae of goosefish (Lophius americanus) captured along the Atlantic 
length (linear regression: slope=0.0017, coast from Virginia to Georges Bank between September 2015 and April 2018. 
P=0.0005, r?=0.12). Illicium diameter The diagonal lines represent equivalence. Points have been jittered to improve 
increased linearly with fish length (lin- the visibility of overlapping data. 
ear regression: r7=0.85). 
