McBride et al : Changes in size and age at maturity of the northern stock of Lopholatilus chamae/eonticeps 
163 
Age (years) 
Figure 2 
Maturity ogives for (A) female and ( B ) male Tilefish 
(Lopholatilus chamae/eonticeps) in 1978 (solid line) and 
1982 (dashed line), at the height of the expansion of 
the modern fishery. Maturity was determined by mac- 
roscopic appearance of the gonad. Raw data were ex- 
tracted from Grimes et al. (1988: tables 5 and 6). For 
model fitting, a generalized linear model and the logit 
link function in R software were used. The predicted 
curves together with the median age at maturity (A 50 ) 
are depicted by sex and year. 
individual level, such responses can signal a decline in 
fishery yields and reproductive potential at the popu- 
lation level (Law, 2000; Fitzhugh et al., 2012; Cooper 
et al., 2013). Therefore, such data can be important to 
monitor and include in stock assessments (Caselle et al., 
2011; Collins and McBride, 2011). In particular, the pos- 
sibility that fishing selects for a certain genotype and 
may thereby cause fishing-induced evolution can be a 
grave concern in terms of rebuilding fisheries to be sus- 
tainable (Conover, 2000; Heino and Dieckmann, 2008; 
Enberg et al., 2011). 
Materials and methods 
Field collections 
During 2 trips by commercial fishing vessels targeting 
Tilefish in 2008, 688 Tilefish were sampled on 16 dif- 
ferent days of normal longline operations. The first trip 
occurred in June, offshore of southern New England, 
where fish were collected between 70° and 72°W at 
depths of 104-280 m (Fig. 3). The second trip occurred 
in July, offshore of southern New England and farther 
south, where fish were collected between 70° and 74°W 
at depths of 119-283 m (Fig. 3). This geographic cover- 
age overlapped all the major fishing areas by the Tile- 
fish fishery north of the Carolinas (Turner et al., 1983; 
Kitts et al., 2007). 
Fish were identified on the basis of taxonomic char- 
acters summarized by Able (2002). Fork length (FL) 
was measured to the nearest centimeter, and sex and 
maturity were determined macroscopically for 421 
males and 267 females. Macroscopic determination of 
maturity followed Idelberger (1985; Table 1), which 
conforms to the standard maturity classifications used 
in the region (Burnett et al., 1989). To reduce cluster 
sampling in high-density areas, especially where fish 
from the same longline set may have had similar age 
or reproductive status, at least one fish of each sex was 
sampled for each 1-cm interval (Wigley et al., 1999; 
Helle and Pennington, 2004). This sampling strategy 
resulted in a broad range of fish sizes that was similar 
to the size composition in the landings, and, if any- 
thing, this strategy increased the number of larger, 
older fish to aid in fitting the maturity data to a model 
(Fig. 4). 
Gonad histology 
To confirm macroscopic evaluations of sex and matu- 
rity, gonad tissue was taken from 157 males and 67 
females and fixed in 10% buffered formalin (Fig. 4B). 
Fixed tissue was prepared according to standard par- 
affin embedding techniques, stained with hematoxylin, 
and counterstained with eosin. Histological sections 
collected from 3 locations (anterior, medial and poste- 
rior) within the ovary lobe for 15 females were initially 
examined, but there was no effect of location on the 
most advanced stage of oocyte development, as also re- 
ported by Erickson et al. (1985); therefore, no further 
attention was given to the intragonad location. 
The sexual pattern, meaning the functional expres- 
sion of sexuality by individuals, was characterized on 
the basis of gonad histology. Morphological features 
noted were the presence of a remnant ovarian lumen 
