470 
Temporal trends (2000-2011) and influences 
on fishery-independent catch rates 
for loggerhead sea turtles ( Caretta caretta ) 
at an important coastal foraging region 
in the southeastern United States 
Email address for contact author: arendtm@dnr.sc.gov 
1 Marine Resources Division 
South Carolina Department of Natural Resources 
217 Fort Johnson Road 
Charleston, South Carolina 29412 
2 Marine Extension Service 
University of Georgia 
715 Bay Street 
Brunswick, Georgia 31520 
Abstract — Seasonal trawling was 
conducted randomly in coastal 
(depths of 4.6-17 m) waters from 
St. Augustine, Florida, (29.9°N) to 
Winyah Bay, South Carolina (33.1°N), 
during 2000-03, 2008-09, and 2011 
to assess annual trends in the relative 
abundance of sea turtles. A total of 
1262 loggerhead sea turtles (Caretta 
caretta ) were captured in 23% (951) of 
4207 sampling events. Capture rates 
(overall and among prevalent 5-cm 
size classes) were analyzed through 
the use of a generalized linear model 
with log link function for the 4097 
events that had complete observations 
for all 25 model parameters. Final 
models explained 6.6% (70.1-75.0 
cm minimum straight-line carapace 
length [SCLmin]) to 14.9% (75.1-80.0 
cm SCLmin) of deviance in the data 
set. Sampling year, geographic sub- 
region, and distance from shore were 
retained as significant terms in all 
final models, and these terms collec- 
tively accounted for 6.2% of overall 
model deviance (range: 4.5-11.7% of 
variance among 5-cm size classes). 
We retained 18 parameters only in a 
subset of final models: 4 as exclusively 
significant terms, 5 as a mixture of 
significant or nonsignificant terms, 
and 9 as exclusively nonsignificant 
terms. Four parameters also were 
dropped completely from all final 
models. The generalized linear model 
proved appropriate for monitoring 
trends for this data set that was laden 
with zero values for catches and was 
compiled for a globally protected spe- 
cies. Because we could not account for 
much model deviance, metrics other 
than those examined in our study 
may better explain catch variability 
and, once elucidated, their inclusion 
in the generalized linear model should 
improve model fits. 
Manuscript submitted 29 November 2011. 
Manuscript accepted 28 August 2012. 
Fish. Bull. 110:470-483 (2012). 
The views and opinions expressed 
or implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National Marine 
Fisheries Service, NOAA. 
Michael D. Arendt (contact author ) 1 
Jeffrey A. Schwenter 1 
Jessica Boynton' 
Albert L. Segars 1 
Julia I. Byrd 1 
J. David Whitaker 1 
Lindsey Parker 2 
Analysis of temporal trends in capture 
rates is a significant part of conduct- 
ing stock assessments (Hilborn and 
Walters, 1992). Capture rates gen- 
erated through fishery-independent 
methods are ideal; however, fishery- 
dependent data sets are also suit- 
able provided that historical shifts 
in fishing practices are accounted for 
(Walters, 2003). Although the value 
of monitoring capture rates increases 
with expanded temporal scope, the 
temporal scope of a data set often 
is abbreviated by economics. Conse- 
quently, resource management deci- 
sions often rely on an assortment of 
observations compiled across a variety 
of sources. Provided that heteroge- 
neous data sets span a gamut of time 
and interface well, such practices are 
not inherently problematic. However, 
vast temporal gaps or intricacies that 
preclude the bridging of data sets can 
be problematic for the assessment of 
long-term patterns and, ultimately, 
for effective resource management, 
particularly for long-lived species. 
Sea turtles (order Testudines) are 
long-lived marine species that have 
come to represent the link between 
anthropogenic activities and their ef- 
fects on sea turtle populations (Mu- 
sick, 1999). Annual monitoring of 
nests and eggs has generated data 
sets with durations that approximate 
the assumed generation time for some 
cohorts (Troeng and Rankin, 2004; 
Balazs and Chaloupka, 2004; With- 
erington et al., 2009). Conversely, 
challenges associated with the col- 
lection of sea turtle data in aquatic 
environments have resulted in less 
information on abundance trends for 
life history stages between hatchling 
and adult (NRC, 2010). Despite ex- 
tensive characterizations of inciden- 
tal capture of sea turtles in fisheries 
(Wallace et al., 2010a) and subse- 
quent evaluation of mitigation mea- 
sures (Brewer et al., 1998; Gilman 
et al., 2006; Murray, 2011), few tem- 
poral analyses of fishery-dependent 
captures exist. Notable exceptions in- 
clude 2 assessments (both spanning 
8-year periods) of loggerhead sea tur- 
tle ( Caretta caretta) catch from pelag- 
ic longline fisheries in the southwest- 
ern Atlantic Ocean (Pons et al., 2010) 
and from neritic pound-net fisheries 
in the northwestern (NW) Atlantic 
Ocean (Epperly et al., 2007). Pub- 
lished accounts of temporal trends in 
