245
device, and a VHF transmitter (mm130, ATS Co.,
Australia) connected to a mount. The fl oats were
used to adjust the weight of the systems to near
neutral in seawater to avoid putting extra weight
on the fi sh.
Four Japanese sea bass caught in Tokyo Bay
between 25 and 27 October 2011 (ID1: total
length (TL), 60.8 cm; ID2: TL, 52.3 cm; ID3: TL,
57.5 cm; ID4: TL, 56.4 cm) were kept in a cage at
the mouth of the Obitsu River for 24 h. They
were outfi tted with the data collection equipment
by sewing the mount to their backs with a surgical needle and biodegradable thread. The fi sh
were then released about 500 m upstream from
the river mouth (35°24′57″N, 139°54′26″E). The
releasing device was set to cut a plastic cable that
fi xed the system to the mount at a scheduled time,
which allowed the system to fl oat to the surface.
The fi rst system was retrieved by tracking signals from the ultrasonic transmitter with a
receiver (VR100, Vemco Co., Canada) on a boat.
The second system was retrieved about 14 h after
release by surveying radio signals emitted from
the system with Yagi antenna receivers (Ham
Center Sapporo Co., Japan) on a boat and on
the shore. The fi rst system is referred to as
the tracking survey and the second as the releasing survey.
Three-axis acceleration was recorded at
32 Hz, and swimming depth, water temperature,
and salinity were recorded at 1 Hz. Data were
downloaded from the loggers to a computer and
analyzed using an Igor Pro (ver. 6.0 J,
WaveMetrics, Lake Oswego, OR, USA) and Igor
Filtering Design Laboratory (IFDL: ver. 4,
WaveMetrics) software.
During the tracking survey, we visually
observed the surrounding land and sea environments. In the releasing survey, we observed the
surrounding environment at the time of retrieval.
We also surveyed the salinity distribution in the
Obitsu River with a salinity–temperature–depth
device (ASTD102, JFE Advantech Co., Japan)
during the tracking and releasing surveys. To do
Fig. 1 Map of the studied area in Tokyo Bay
Measurement of Fish Habitat Use by Fish-Mounted Data Loggers for Integrated Coastal…
device, and a VHF transmitter (mm130, ATS Co.,
Australia) connected to a mount. The fl oats were
used to adjust the weight of the systems to near
neutral in seawater to avoid putting extra weight
on the fi sh.
Four Japanese sea bass caught in Tokyo Bay
between 25 and 27 October 2011 (ID1: total
length (TL), 60.8 cm; ID2: TL, 52.3 cm; ID3: TL,
57.5 cm; ID4: TL, 56.4 cm) were kept in a cage at
the mouth of the Obitsu River for 24 h. They
were outfi tted with the data collection equipment
by sewing the mount to their backs with a surgical needle and biodegradable thread. The fi sh
were then released about 500 m upstream from
the river mouth (35°24′57″N, 139°54′26″E). The
releasing device was set to cut a plastic cable that
fi xed the system to the mount at a scheduled time,
which allowed the system to fl oat to the surface.
The fi rst system was retrieved by tracking signals from the ultrasonic transmitter with a
receiver (VR100, Vemco Co., Canada) on a boat.
The second system was retrieved about 14 h after
release by surveying radio signals emitted from
the system with Yagi antenna receivers (Ham
Center Sapporo Co., Japan) on a boat and on
the shore. The fi rst system is referred to as
the tracking survey and the second as the releasing survey.
Three-axis acceleration was recorded at
32 Hz, and swimming depth, water temperature,
and salinity were recorded at 1 Hz. Data were
downloaded from the loggers to a computer and
analyzed using an Igor Pro (ver. 6.0 J,
WaveMetrics, Lake Oswego, OR, USA) and Igor
Filtering Design Laboratory (IFDL: ver. 4,
WaveMetrics) software.
During the tracking survey, we visually
observed the surrounding land and sea environments. In the releasing survey, we observed the
surrounding environment at the time of retrieval.
We also surveyed the salinity distribution in the
Obitsu River with a salinity–temperature–depth
device (ASTD102, JFE Advantech Co., Japan)
during the tracking and releasing surveys. To do
Fig. 1 Map of the studied area in Tokyo Bay
Measurement of Fish Habitat Use by Fish-Mounted Data Loggers for Integrated Coastal…