Graves et al. : Use of archival tags to study postrelease survival of and habitat use by estuarine and coastal fishes 
379 
were not problematic for striped bass; however, 
the applicability of these results to other struc- 
ture-associated species is not known. Premature 
release of PSATs has been noted in many stud- 
ies and may become more prevalent with longer 
deployment times because of attachment methods 
and increased potential for fish-tag interactions 
(Domeier et al., 2003; Conrath and Musick, 2008; 
Graves and Horodysky, 2008). The selection of a 
specific attachment method and an appropriate 
release time will depend on the species studied and 
research objectives of the study (e.g., postrelease 
mortality, movement, or habitat use). 
Fish-tag interactions present challenges for all 
PSAT studies and may occur as predation of a tag 
mistaken for a prey item or predation of an indi- 
vidual carrying a tag. Both outcomes are extremely 
difficult to quantify and compromise study objec- 
tives. In schooling piscivorous fishes, such as adult 
striped bass, predation of PSATs is more likely 
than predation of the study individuals. We cannot 
discount that our nonreporting and weakly trans- 
mitting tags may have been victims of tag preda- 
tion; it is often impossible to discern between tag 
predation and tag failure. However, it is unlikely 
that mortality of a tagged striped bass would result 
in a nonreporting tag because the PSAT should 
surface from a dead carcass after 30 days. The 
predation of live individuals by elasmobranchs, 
as well as the scavenging of dead fish carrying 
PSATs by elasmobranchs, was inferred in previ- 
ous studies (Kerstetter et al., 2004; Kerstetter and 
Graves, 2008). In these instances, the PSATs were 
not compromised during ingestion and success- 
fully transmitted after being regurgitated, but it 
is likely that damage during such events may be a 
cause of PSAT nonreportings. 
The success of studies where PSAT technology 
is used depends upon on the quality and quantity 
of the archived data that are transmitted from 
the tag to the Argos satellite system. Reception of 
PSAT transmissions is maximized when the tag 
antenna is unobstructed and above the surface 
of the water in a vertical position. In our study, we 
obtained at least 87% of the data from tags that re- 
mained adrift for the entire data transmission period. 
There is an increased probability that tags attached to 
estuarine and coastal fishes will wash ashore during 
the transmission period that typically lasts about 30 
days. Tags beach in a horizontal position which may 
result in decreased signal reception, especially if an- 
tennae are submerged in water or fouled with algae or 
other debris. 1 Beached tags in this study transmitted 
30-90% of their data. In the case of the tag attached 
to fish 7, which beached after only four days of trans- 
mission and ceased communicating with the satellite 
shortly thereafter, the transmission of over 3000 data 
points provided more than sufficient information to 
infer survival and investigate habitat use by that indi- 
vidual. The random transmission of data packets (nine 
A 
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12 
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<3 
<5 Q _ 
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E 
,a> 
4 -I T 1 1 , 
0 10 20 30 40 50 
Percent time at temperature 
Figure 4 
Time-at-depth (A) and time-at-temperature (B) histograms 
from Microwave Telemetry X-tags deployed on eight large 
coastal migrant striped bass ( Morone saxatilis) from January 
through March 2008. Each fish was given equal contribu- 
tion. Error bars are ±1 standard error. 
consecutive time points) by the X-tags during times 
when a satellite of the Argos system is likely above 
the horizon generally results in a rapid accumulation 
of data during the first week of the thirty-day trans- 
mission period (Fig. 6). 
The two tags that were recovered while still trans- 
mitting (fish 2, 4) were carried by fish that moved 
from coastal waters into the mainstem of Chesapeake 
Bay. We timed the X-tags to release while striped bass 
were in coastal or estuarine waters before their annual 
spring spawning migration to freshwater. The release 
mechanism on the PSAT, which operates by electrolysis, 
requires a >5 ppt salinity to function, 1 which necessi- 
1 P. Howey. 2009. Personal commun. Microwave Tele- 
metry, Inc., 8835 Columbia 100 Parkway, Suites K & L, 
Columbia, MD 21045 
