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https://access.afsc.noaa.gov/data-zips/32318_GAP_1996_Trawlex_chronic-effects-other.zip |
https://access.afsc.noaa.gov/data-zips/32318_GAP_1996_Trawlex_chronic-effects-other.zip |
Data bundled in 32318 parent project archive including: 28202-AFSC/RACE/GAP/McConnaughey:
Trawlex Chronic Effects-1996-Other 28204-AFSC/RACE/GAP/McConnaughey: Trawlex Chronic
Effects: Bottom Trawl Catch Effort Data from NORPAC for Years 1973-2001 28208-AFSC/RACE/GAP/McConnaughey:
Trawlex Chronic Effects: Trawlex (1996) Macrofauna CPUE (count/hectare) 28210-AFSC/RACE/GAP/McConnaughey:
Trawlex Chronic Effects: Trawlex (1996) Macrofauna CPUE (weight/hectare) --- |
download |
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https://forum.earthdata.nasa.gov/app.php/tag/GCMD%2BKeywords |
GCMD Keyword Forum Page |
Global Change Master Directory (GCMD). 2026. GCMD Keywords, Version 24. Greenbelt,
MD: Earth Science Data and Information System, Earth Science Projects Division, Goddard
Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA).
URL (GCMD Keyword Forum Page): https://forum.earthdata.nasa.gov/app.php/tag/GCMD+Keywords |
information |
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https://www.afsc.noaa.gov |
Website |
Website for this organization |
information |
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https://www.fisheries.noaa.gov/about/alaska-fisheries-science-center |
Alaska Fisheries Science Center Website |
AKFSC Home Page |
information |
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https://www.fisheries.noaa.gov/inport/item/28208 |
Full Metadata Record |
View the complete metadata record on InPort for more information about this dataset. |
information |
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Data were entered into a spreadsheet and converted to point features in ArcGIS.
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Point features were converted to line features based on feature and vertex ID to represent
the starting and ending locations of each trawl deployment. Catch and other environmental
data, such as depth and temperature, were then spatially joined to each line segment
based on a key field identifier from the original data.
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1996-08-01T00:00:00 |
Macrofauna sampling was conducted aboard two identical 40 m chartered stern trawlers,
the sister ships FV ??Aldebaran?? and FV ??Arcturus??. Each is powered by a 1525 hp
main engine and fitted with a variable pitch propeller and propeller nozzle. Macrofauna
were sampled with identical 83?112 eastern otter trawls, selected to ensure relatively
large samples of patchily distributed organisms and to minimize clogging of the opening
by large macrofauna (e.g. sea stars). These nets have a 25.3 m headrope and a 34.1
m footrope and have been the standard sampling gear used for annual NMFS groundfish-crab
surveys in the EBS since 1982. The trawl was towed behind 1000 kg steel V-doors and
54.9 m paired dandylines. Each lower dandyline has a 0.61 m chain extension connected
to the lower wing edge to improve bottom-tending characteristics. For this study,
the standard trawl was modified to improve catchability and retention of macrofauna.
It was equipped with a tickler chain and a hula skirt, and had a 3.8 cm liner covering
both wings and the entire bottom body, with complete coverage top and bottom of the
intermediate and codend. An acoustic net mensuration system and a mechanical bottom
contact sensor were used to assess net configuration and collect performance data
for area-swept and catch-per-uniteffort (c.p.u.e.) calculations. Each vessel sampled
adjoining HF-UF stations (??pairs??) by towing the trawl through the centre of a 1
nm2 cell for 1.39 km (i.e., 3 knots for 15 min). Catches were fully processed in the
field by sorting macrofauna to the lowest possible taxon and then weighed and enumerated
separately. Weights were determined using a motion-compensated precision electronic
balance. Biogenic substrate, such as empty gastropod and bivalve shells, and identifiable
egg masses were also weighed, so as to provide a more complete characterization of
the benthos. Prior to analysis, catch data were lumped into larger taxonomic groups
to resolve classification differences between the vessels and to reduce the number
of dependent variables. Bottom trawl catches (CPUE)are standardized according to
area swept, as determined with Scanmar ascoustic system and GPS coordinates of vessel.
Catch values are counts of organisms/hectare.
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