Preface The expedition ARK XIX/3 with the German icebreaking RV ...

survey at frequencies of 38, 70, 120 and 200 kHz. Depth ranges between 5 and
15,000m and ping rate is adjustable with maximum ping rate of 10 pings per second).
Data is displayed as an echogram (Fig. A4.8.3-2), which contains information about
the acoustical value. The range is used to specify the range used in the echogram
field and can be modified according to the bottom related echogram. To link acoustical
data with navigational data, the EK60 receives data from a Global Positioning System
(GPS) or another positioning system.
Results
Preliminary results from the survey are based on echogram observations logged
during the individual surveys and require further analysis and interpretation when the
data set is investigated in full. In general, a consistently strong signal reflection was
observed at 10-125m depth throughout the survey, suggesting that plankton exist in
this upper region of the water column. Fish aggregations were observed in particular
at both the Twin and Giant Mound areas of the survey track at depths of more than
750m. In particular, fish shoals were more common at the "Twin mounds" where a
fishing vessel was recorded in the area at the time of the survey, suggesting that the
"Twin mounds" are a target area for commercial fisheries. This was later confirmed by
video observations from the "Victor 6000" ROV when evidence of fishing gear and
nets were discovered on the seabed confirming these grounds are actively fished.
Discussion
A fisheries survey has provided information on the nature and distribution of deep-sea
fish in the Porcupine Bank area. Fish activity in mound areas is clear from first
observations. However, further investigations of the data will help quantify the
relationship between fish aggregations and mound features on the seabed and
answer questions relating to whether the nature of the mounds (live or dead) has an
influence on fish distribution.
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