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Fishery Bulletin 106(4) 
89.5W 89. 0W 88.5W 88 OW 87.5W 
Figure 1 
Map of areas sampled for inshore lizardfish ( Synodus foetens) in the northern Gulf of 
Mexico from spring 2004 through spring 2005. Large polygons on the shelf indicate 
artificial reef zones. Habitats inside the artificial reef zones served as de facto no trawl 
areas. Habitats A and F are predominantly sand; habitats B and E are low relief (1-2 m) 
shell rubble; habitats C and G are high relief (2-3 m) shell habitat; and habitats D and 
H are reef habitats. Filled circles indicate sites where inshore lizardfish were sampled 
opportunistically for otolith marginal condition and age analyses. The 200-m isobath is 
shown to indicate the shelf edge. 
northern GOM. As part of a broader study examining 
the effects of habitat type and shrimp trawl bycatch on 
demersal and benthic fishes in the north central GOM, 
the objectives of the work presented here were to ex- 
amine inshore lizardfish life history and ecology and 
to estimate potential impacts of shrimp trawl bycatch 
on them. Specifically, we estimated the effect of habitat 
type and shrimp trawl bycatch on inshore lizardfish 
density, size, age, and mortality in various habitats on 
the north central GOM continental shelf. 
Materials and methods 
Inshore lizardfish were sampled within four habitat 
types in the north central GOM: sand, low-relief shell 
rubble (low shell), high-relief shell rubble (high shell), 
and reef. Habitats were mapped with sidescan sonar and 
groundtruthed with boxcores and benthic grab samplers 
during previous studies (Schroeder et al., 1988; Dufrene, 
2005; Strelcheck et al., 2005). Dufrene (2005) charac- 
terized shell rubble habitats as ridges standing 1-m 
(low-relief) or 2-3 m (high-relief) above the surround- 
ing seabed and extending up to 200 m across. Boxcore 
sediment samples revealed that ridges are composed of 
>50% calcium carbonate (CaC0 3 ), and shell fragments 
from both marine and estuarine taxa, the latter of which 
come from lower sea levels that date from the Holocene 
Epoch. Reef sites were characterized by Schroeder et 
al. (1988) as reef-like outcrops of rock rubble and shell 
hash supporting a diverse epifaunal assemblage. Each 
of the four study habitat types was found on both the 
open shelf and within an artificial reef zone (AR zone) 
off Alabama (Fig. 1). Shrimp trawling is prevalent on 
the open shelf, but the AR zone functions as a de-facto 
no trawl area (NRC, 2002, Fig. B.9 in that report). 
Therefore, by sampling inside and outside the AR zone 
the effect of shrimp trawl bycatch on inshore lizardfish 
population parameters could be tested. 
Inshore lizardfish were sampled quarterly from May 
2004 to April 2005 in the habitats described above us- 
ing a bottom trawl rigged and fished according to the 
Southeastern Monitoring and Assessment Program’s 
(SEAMAP) trawling protocol, except that trawl sam- 
ples were not taken during winter and spring 2005 in 
the high shell habitat outside the AR zone because of 
weather constraints. The sampling gear was a 12.8-m, 
four-seam semiballoon otter trawl rigged with 2.4-m 
x 1-m doors, a 54.9-m bridle, a tickler chain set 1.1 m 
shorter than the footrope, and a codend with 4-cm 
