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Fishery Bulletin 120(1) 
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Ring count (illicia) 
Figure 6 
Precision of ring counts, indicated by the relationship between test and 
original counts from readings of (A) illicia and (B) vertebrae of goosefish 
(Lophius americanus) captured along the Atlantic coast from Virginia to 
Georges Bank between September 2015 and April 2018. The diagonal lines 
represent equivalence. Points have been jittered to improve the visibility of 
overlapping data. 
Growth 
Goosefish in the 2015 year class reached a modal length 
of 26 cm TL by the end of their first year of life Gn May 
2016) (Table 1, Fig. 9) and increased to 42 cm TL a year 
later (growth of 16 cm TL in that year). Growth slowed 
thereafter, with a modal length of 53 cm TL at 3 years 
(growth of 11 cm TL in the third year). Growth was most 
rapid between June and September—October. 
Discussion 
We used a strong recruitment event as a source of fish with 
known ages in order to validate the use of 2 aging struc- 
tures for goosefish. Previous studies (Jénsson’; Landa 
et al., 2013) of white anglerfish have also tracked abun- 
dant cohorts across multiple years to test aging methods. 
Those studies successfully confirmed that the illicium is an 
appropriate aging structure for white anglerfish; however, 
’ Jonsson, E. 2007. Verification of anglerfish (Lophius piscatorius) 
age estimation through comparison of length modes of age read 
fish (illicia) to length modes of large year-classes appearing in 
the Icelandic stock. ICES CM 2007/K:03, 17 p. [Available from 
website.] 
Ring count (vertebrae) 
we were not able to validate use of illicia 
for aging goosefish. 
The dominant length mode of the 2015 
year class of goosefish was first observed 
in June 2015 and remained distinct for 
more than 3 years (Fig. 4). Results from 
daily aging of 2 fish that were fortuitously 
collected in the autumn of 2015 confirm 
that fish in the length mode were mem- 
bers of the 2015 year class. Therefore, we 
were confident that fish sampled from 
within this length mode were hatched in 
2015 and could be assigned known ages 
based on this hatch year. 
In assigning known ages, we assumed 
that potential confounding issues (Cam- 
pana, 2001), such as size-selective mortal- 
ity, migration, and multiple recruitment 
events, were not factors in our study. How- 
ever, all of these issues could have played 
5 6 7 a role. For example, size-selective mortal- 
ity could either increase apparent growth 
rates if the smallest fish are removed by 
predation or decrease apparent growth 
rates if the largest, fastest-growing fish 
are removed through fishing. The 2015 
year class had attained exploitable size 
by June 2017 and was subject to discard- 
ing in 2016 (NEFSC, 2020); therefore we 
may have underestimated size at ages 
1-8. The length modes remained distinct, 
however, and assignment of known age 
was unlikely to have been biased by size-selective mortal- 
ity. Female goosefish can spawn more than once per year 
(Johnson et al., 2008; McBride et al., 2017), possibly creat- 
ing a bimodal length distribution within a year class. Still, 
there is no indication of multimodality in the size composi- 
tion of the age-0 mode (Fig. 4). Migratory movements may 
also create checks on an age structure, given that a fish 
may move between temperature regimes. Goosefish make 
seasonal inshore—offshore movements (Richards et al., 
2008; Rountree et al., 2008), and evidence indicates that 
some fish make latitudinal movements (Cadrin et al.°; 
Cadrin and Bank’). Results from tagging studies of white 
anglerfish indicate some migrations of very long distances 
(Laurenson et al., 2005), as well as more frequent seasonal 
movements (Laurenson et al., 2005; Ofstad, 2013). We 
were unable to evaluate the potential effects of migration 
on our results. 
8 Cadrin S. X, C. Bank, J. H. Grabowski, and G. Sherwood. 2017. 
Archival tagging and age validation in the mid-Atlantic, 51 p. 
2014 monkfish RSA. Project completion report. NOAA grant no. 
NA14NMF4540227. Northeast Fish. Sci. Cent., Natl. Mar. Fish. 
Serv., Woods Hole, MA. [Available from website.] 
° Cadrin, S., and C. Bank. 2019. Estimating growth and move- 
ment of juvenile monkfish, 18 p. Final project report. Award no. 
NAI16NMF4540108. Northeast Fish. Sci. Cent., Natl. Mar. Fish. 
Serv., Woods Hole, MA. [Available from website.] 
