Bradbury et a I.: Daily and seasonal activity patterns of female Tautogolabrus adspersus 
647 
from fish tagged with ultrasonic transmitters 
(Bradbury et al., 1995). Female cunners occupy small 
home ranges (300-2,353 m 2 ) and exhibit seasonal 
variation in the size of their home range. The larg- 
est home ranges occur during June and July, a time 
when cunners are replacing energy stores depleted 
during winter torpor (Bradbury et al., 1995). This is 
also the time of year with the longest photoperiod 
and hence with the maximum potential foraging pe- 
riod for a diurnal species. 
In this study, we report on the daily activity pat- 
terns of the female cunners in Conception Bay. Cun- 
ners at the northern extent of their range are of in- 
terest because their prolonged winter torpor may 
reduce annual foraging time. We expected that as 
the photoperiod decreased, female cunners would be 
active for more of the diurnal period, both to maxi- 
mize growth and increase energy stores in prepara- 
tion for six months of winter torpor. 
Methods 
Tracking 
A fixed hydrophone array tracking system ( Bradbury 
et al., 1995) was used to monitor the activity of eight 
female cunners tagged with ultrasonic transmitters 
in Broad Cove, Conception Bay. The system provided 
positional information (fixes) on a tagged fish once 
every 15 seconds. The change in the quality of the 
transmitter signal when a tagged cunner sought shel- 
ter by going under a boulder or into a crevice be- 
tween two rocks enabled us to monitor activity-inac- 
tivity patterns accurately in much the same way as 
Chapman et al. (1975) had done with Norway lobster 
(Nephrops norvegicus). For a description of the track- 
ing system, tagging procedure, and study site see 
Bradbury et al. (1995). With our tagging procedure, a 
tag holder and dummy tag were initially attached to 
fish in the field. After a week (minimum period), a fish 
with a tag holder and dummy tag was recaught by a 
diver, and the dummy transmitter was replaced with a 
functional one. The latter procedure involved handling 
the fish for 1-2 min, from capture to release. 
Tagged cunners were from 194 to 250 mm in total 
length (Table 1). At this size female cunners in Con- 
ception Bay are sexually mature (Pottle and Green, 
1979a). Fish were tracked from June until Novem- 
ber, i.e. during most of the period between the end 
and start of winter torpor. Lightning damage to the 
tracking system limited the amount of tracking that 
could be done in August. Individual fish were tracked 
for 4 to 32 days during which they all remained in 
the area encompassed by the hydrophone array. For 
Table 1 
Total length and tracking dates for female cunner tagged 
with ultrasonic transmitters in Broad Cove, Conception 
Bay, Newfoundland. 
Fish 
identification 
Total 
length 
(mm) 
Tracking 
dates 
Track 
duration 
(days) 
A 
194 
17 Jun-30 Jun 
14 
5 Jul-6 Jul 
2 
B 
215 
18 Jun-4 Jul 
17 
C 
250 
28 Jun-21 Jul 
24 
D 
235 
12 Jul-21 Jul 
10 
E 
195 
15 Aug- 18 Aug 
4 
F 
225 
30 Aug-22 Sep 
16 
G 
245 
23 Sep-20 Oct 
22 
H 
240 
21 Oct -24 Nov 
32 
the duration of the tracking period, information on 
water temperature, sea state, tidal phase, and cloud 
cover was available on a daily basis, as described by 
Bradbury et al. (1995). 
Activity-inactivity 
A tagged cunner was determined to be active or in- 
active based on information from the tracking sys- 
tem. If a strong transmitter signal was received, and 
positional information was obtained, the subject was 
considered active. If, on the other hand, signals were 
weak and no positional fix could be determined for 
more than 3 min ( 12 possible fixes), the fish was con- 
sidered inactive. With scuba or snorkel equipment, 
divers documented over a period of >20 h that cun- 
ners had retreated into cracks and crevices or un- 
derneath objects when transmitter reception was 
poor. These observations also showed that female 
cunners do not “rest” on the substrate in open sites. 
During the night, cunners seek shelter and un- 
dergo a period of nocturnal quiescence during which 
positional fixes cannot be obtained. The first and last 
positional fixes of the day therefore marked the be- 
ginning and end of diurnal activity. Onset of diurnal 
activity was expressed as the number of minutes 
before or after sunrise, whereas cessation of diurnal 
activity was expressed as the number of minutes 
before or after sunset. The duration of diurnal activity 
for an individual was defined as the total elapsed time 
between the onset and cessation of its daily activity. 
Cunners also entered shelter (became inactive) at 
various times throughout the day; sites where cun- 
ners were inactive are termed day-rest sites. The 
duration of each inactive period (the time between 
