Campbell et al.: Release mortality in the fishery targeting Lutjanus campechanus 
293 
to determine whether there is some potential for bot- 
tom-release devices to enhance postrelease survival or 
whether the effects of barotrauma cannot be reversed 
as was suggested by Wilde (2009). 
Season also was a significant factor that affected re- 
lease mortality and, because season is a rough proxy 
for water temperature, the data indicate a positive 
relationship between water temperature and release 
mortality of red snapper. Impairment-scaling metrics 
that evaluate sublethal effects of CAR fishing, such as 
reduction of reflex responses, also show similar rela- 
tionships with water temperature (Diamond and Camp- 
bell, 2009; Campbell et al., 2010a, 2010b). Furthermore, 
impairment-scaling metrics were linked to increased 
immediate estimates in at least 2 of those studies. Tag- 
ging data show that the lowest returns have been for 
fish tagged during summer and the highest recapture 
rates have been for fish tagged during the winter (Dia- 
mond et al. 7 ; Sauls 8 ), although tag-and-recapture stud- 
ies are heavily influenced by the timing of the primary 
effort in a fishery (i.e., winter fishing effort is low and 
may result in fewer recaptures during that time). 
Finally, in 3 projects that required field collections 
before laboratory investigations could begin, red snap- 
per were unable to be kept alive during 
collection or transport back to a laboratory 
during summer months (Parker 5 ; Burns et 
al. 6 ; Campbell et al., 2010a). Most investi- 
gations included in our meta-analysis had 
vaguely defined seasonal classifications, 
and other studies reported the months in 
which sampling took place. A single study 
reported water temperatures and thermo- 
cline strength. Vague seasonal classifica- 
tions of sampling time frames complicate 
information from transitional seasons, 
such as fall, because September water tem- 
peratures in the GOM often are more re- 
flective of summer conditions. Evidence of 
unexplained residual heterogeneity in the 
mixed-effects model might be associated 
with insufficient treatment of these ther- 
mal components; therefore, future studies 
should focus attention on this relationship. 
Another common problem found in this 
meta-analysis was that the acoustic-tagging 
and caging studies typically had limited 
sample sizes. With one exception, the cag- 
ing studies evaluated in this meta-analysis 
had depth-specific sample sizes of less than 
56 fish (Parker 5 ; Gitschlag and Renaud, 
1994; Render and Wilson, 1994; Diamond 
and Campbell, 2009). The acoustic-tagging 
study available for inclusion split 44 fish be- 
tween summer and winter sampling efforts 
(Diamond et al. 7 ). Low sample sizes can 
lead to poor estimation of effects because 
proportions are unstable at low sample 
sizes. Another issue is that, because of the 
ease of obtaining surface-release estimates, those stud- 
ies greatly outnumbered other types of studies in this 
meta-analysis. Furthermore, the sample-size weighting 
scheme in this meta-analysis lends more weight to ex- 
periments with large samples, and that weighting po- 
tentially biases outcomes toward surface-release studies. 
Acoustic or satellite tags give the ideal level of in- 
formation, but until the expense of tags and required 
monitoring systems is reduced, those studies will be 
hampered by small sample sizes and poor statistical 
power to estimate mortality. Another complicating fac- 
tor in acoustic-tagging and caging studies is that han- 
dling and abrasion can act to increase release mortal- 
ity rates (Jarvis and Lowe, 2008; Hannah et al., 2012). 
Recent development of a novel caging system to evalu- 
ate survival was effective in reduction of mortality due 
to abrasion for several rockfish species (Hannah et al., 
2012). Similarly, the use of an external acoustic tag to 
evaluate rockfish survival has shown promise in reduc- 
ing handling times and may help to increase sample 
sizes in acoustic-tagging studies (Hyde 11 ). Methods 
n Hyde, J. 2013. Personal commun. NOAA Southwest 
Fisheries Science Center, La Jolla, CA 92037. 
