Dataset: tucker catch - CGoA LTOP
Deployment: GP0108

Zooplankton catch data from Tucker trawl from CGOA LTOP cruises, 2001-2003

Co-Principal Investigator:

Edward D. Cokelet (National Oceanic and Atmospheric Administration, NOAA-PMEL)

Kenneth O. Coyle (University of Alaska Fairbanks, UAF)

Seth L. Danielson (University of Alaska Fairbanks, UAF)

Edward V. Farley (National Oceanic and Atmospheric Administration - Alaska Fisheries Science Center, NOAA-AFSC-Auke)

Scientist:

Jamal Hasan Moss (University of Washington, UW)

Contact:

Jamal Hasan Moss (University of Washington, UW)

BCO-DMO Data Manager:

Nancy Copley (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

U.S. GLOBEC Northeast Pacific (NEP)

Deployment Synonyms:

GP0101

Data URL:

https://www.bco-dmo.org/dataset-deployment/452180/data

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Description

Zooplankton counts for tucker trawls in the Gulf of Alaska during 2001 - 2003
co-PI: Edward D. Cokelet (NOAA/OAR/PMEL)
co-PI: Edward V. Farley (NOAA/NMFS)
co-PI: Seth Danielson (IMS, U. Alaska - Fairbanks)
co-PI: Ken Coyle (IMS, U. Alaska - Fairbanks)
updated July 2008

Marine Ecosystem Monitoring in the Northern Gulf of Alaska web site
GAK1 Time Series web site
cruise reports web site

GLOBEC 2000: Gulf of Alaska Long-Term Observation Program
T. Weingartner, L. Haldorson, R. Hopcroft, K. Coyle, T. E. Whitledge (all at University of Alaska, Fairbanks), T. Royer (Old Dominion University)

This project is to conduct the Gulf of Alaska Long-Term Observation Program (GOA-LTOP) as part of Phase II of the Northeast Pacific (NEP) GLOBEC program. The GOA shelf supports a rich ecosystem that includes many commercially important fisheries. The basis for this productivity is enigmatic for the GOA shelf is deep, forced by downwelling-favorable winds, and fed by a massive nutrient-poor coastal freshwater discharge. Both the winds and the freshwater discharge are intimately linked to the strength and position of the Aleutian Low. The GOA ecosystem experiences substantial physical and biological changes on decadal and interannual time scales. Although some of these changes are correlated with various climatic indices a mechanistic understanding of climate change and ecosystem response is unavailable. The generic goal of this LTOP is to understand and quantify temporal (seasonal and interannual) and spatial (cross- and along-shelf) variations in the thermohaline, chemical, and biological properties and relationships of this shelf. Our proposal supports GLOBEC goals that will help: 1) retrospective studies interpret historical data, 2) design a cost-effective long-term monitoring program, 3) provide the seasonal and interannual context for concurrent mesoscale and process studies, and 4) provide boundary conditions and data sets for model evaluation. This 5-year project entails 4 field years and a fifth year for data analyses and synthesis. The field effort involves seven, 9-day interdisciplinary cruises/year in the northern GOA. The study area encompasses the 220-km long, Seward Line (sampled in the 1970s) that extends across the shelf and slope and high resolution sampling of the Alaska Coastal Current (ACC), upstream, downstream, and within Prince William Sound. The ACC is an important shelf habitat for yoy salmon migrating from nursery areas in the sound and into the GOA. The sampling effort (Table A) is year-round and motivated by seasonally significant physical and biological events affecting yoy pink salmon.

Table A. Sampling schedule and rationale for GOA-LTOP. (Key for Winds, Discharge and Stratification: S=strong; M=moderate; W=weak; D=downwelling winds; U=upwelling winds; V=variable; L=low; H=high) Deep water moves onshore during the July-August upwelling period.

Month	Sampling				Physical Rationale			Biological Rationale
Month	CTD	Nutrients	Zoo	Fish	Winds	Disch	Strat	Biological Rationale
March	X	X	X		D S	L	W	Zooplankton migrate from depth (at shelfbreak); transported inshore.
April	X	X	X		D M	L-M	W V	Phytoplankton bloom
May	X	X	X		D M-W	M	M V	Maximum oceanic copepod biomass.
July	X	X	X	X	D/U W	M-H	S	Maximum zooplankton abundance; YOY salmon enter shelf.
August	X	X	X	X	D/U W	M-H	S	Maximum YOY salmon abundance on shelf.
October	X	X	X	X	D S	H	H	YOY salmon on shelf.
December	X	X	X		D S	M	M	Fall-winter pre-conditioning for spring nutrients, small zooplankton.

The sampling protocol follows GLOBEC guidelines and uses gear types and techniques similar to those in the Oregon LTOP that is also a part of the NEP-GLOBEC program. Most of the research will be conducted from the R/V Alpha Helix. Fish sampling will be done from a chartered trawler in July, August, and October. Both vessels will work together during these cruises so that the fishing charter can verify fish targets detected on the acoustics array towed from the Alpha Helix.

This page was last updated on September 22, 2000.

Maintained by:
Hal Batchelder [hbatchelder@coas.oregonstate.edu
College of Oceanic & Atmospheric Sciences
Oregon State University
Corvallis, OR 97331-5503
phone: 541-737-4500; FAX 541-737-2064

Methods & Sampling

Dataset acquisition description

The OCC/GLOBEC survey occurred along the coastal waters of the Gulf of Alaska and in Shelikof Strait, AK during 2001-2004. Transects sampled during the survey were perpendicular to shore and extended from nearshore across the continental shelf to oceanic waters beyond the 200-m shelf break. The survey was conducted aboard the contract fishing vessel F/V Great Pacific during 2001-2002 and 2004, and aboard NOAA Ship Miller Freeman during 2003.

Fish samples were collected in a 198-m long mid-water rope trawl with hexagonal mesh wings and body, and a 1.2-cm mesh liner in the codend. The rope trawl was towed at 6.5 to 9.3 km • hour-1, at or near surface, and had a typical spread of 40-m horizontally and 15-m vertically. All tows lasted 30 minutes and covered 2.8 to 4.6 km, and sampling was done during daylight hours; however, tows occurred during night as part of a 24-hour repeat sampling of a single station for one day during 2001 and 2003.

Once the net was hauled aboard, salmon and other fishes were sorted by species and counted. Standard biological measurements including fork length, body weight, and sex were taken from sub-samples of all salmon species. Sub-samples of juvenile pink (Oncorhynchus gorbuscha), chum (O. keta), and sockeye (O. nerka) salmon were frozen whole for laboratory analyses of food habits, otolith hatchery thermal marks (pink and chum salmon), and genetic analysis (chum salmon).

Plankton samples were collected using a 1-m2 Tucker trawl fitted with a 505-um mesh net that was towed near surface (approximately 1 knot) for 5 minutes (2001-2003 surveys). During 2004, plankton samples were collected using a WP-2 net fitted with a 253-um mesh net that was deployed vertically to a depth of 100-m depth. The volume of water filtered by the net was estimated using flow meters. Plankton samples were transferred into vials, preserved in 5% formalin onboard the ship, and stored until a laboratory analysis was completed.

Data Processing Description

Dataset Processing Description

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-0109078	NSF Division of Ocean Sciences
unknown NEP NOAA	National Oceanic and Atmospheric Administration

Instruments

Tucker Trawl

Supplied Description:

Plankton samples were collected using a 1-m2 Tucker trawl fitted with a 505-micron mesh net that was towed near the surface (for approximately 1 knot) for 5 minutes.
Volume of water filtered by each net was estimated by flow meters and the plankton samples were preserved in 5% formalin.

Instrument Type

Generic Name: Tucker Trawl

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/NETT0161/

Generic Description:

The original Tucker Trawl, a net with a rectangular mouth opening first built in 1951 by G.H. Tucker, was not an opening/closing system, but shortly thereafter it was modified so that it could be opened and closed. The original had a 183 cm by 183 cm flexible rectangular mouth opening 914 cm long net with 1.8 cm stretched mesh for the first 457 cm and 1.3 cm mesh for last 457 cm. 152 cm of coarse plankton or muslin netting lined the end of the net. Tucker designed the net to collect animals associated with the deep scattering layers, principally euphausiids, siphonophores, and midwater fish. (from Wiebe and Benfield, 2003). Currently used Tucker Trawls usually have 1-m2 openings and can have a single net or multiple nets on the frame.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
year	year, e.g. 2004 in the format YYYY	unitless	year
haul_id	Tow identification. First 4 numbers represent year, second 4 numbers represent haul number during year specified. in the format YYYYxxx	unitless	tow
yrday_local	Local day and decimal time, as 326.5 for the 326th day of the year, or November 22 at 1200 hours (noon).	dimensionless	yrday_local
month_local	Numerical month of year, local time. in the format mm	unitless	month_local
day_local	Numerical day of the month, local time. in the format dd	unitless	day_local
time_local_start	Starting time of observation, local time , 24 hour clock. in the format HHMM	unitless	time_start_local
lat_start	latitude at starting time of measurement (west is negative)	decimal degrees	lat_start
lon_start	longitude at starting time of measurement (west is negative)	decimal degrees	lon_start
lat_end	latitude at end time of measurement (south in negative), in decimal degress	decimal degrees	lat_end
lon_end	longitude at end time of measurement (west is negative)	decimal degrees	lon_end
station	CSE = Cape St. Elias CC = Cape Cleare GAK = Gulf of Alaska, Seward Line CCH = Cape Chiniak GP = Gore Point CK = Cape Kekurnoi IB = CKA = Cape Kaguyak IP = Icy Point CN = Cape Nukshak OC = Ocean Cape	text	sta_id
depth	depth of tow	meters	depth
duration	duration of tow	seconds	no_bcodmo_term
habitat	Habitat: Continental Shelf Continental Slope Nearshore Offshore of Continental Shelf	text	no_bcodmo_term
vol_settled	volume of settled plankton sample	milliliters	no_bcodmo_term
disp_vol	displacement volume (biovolume) of plankton net samples	milliliters	disp_vol
taxon	Taxonomic group or entity. This may be a family, class, genus, species, etc.; usually this parameter will contain a mixture of taxonomic entities.	text	taxon
sex	Classification by sex (male/female).	text	sex
count_aliq	Number of individuals found in fraction of sample examined.	dimensionless	count
aliquot	Denominator of fraction of sample examined, e.g. 4 is one quarter (1/4).	dimensionless	samp_fraction_denom
count_total	Total number of individuals counted in the sample, calculated as the aliquot times the count in that aliquot.	dimensionless	count
comments_catch	Comments pertaining to the organisms in the sample.	text	comment
comments_tow	Comments pertaining to the sampling, not the animals in the tow.	text	comment
cruiseid	Cruise identifier	unitless	cruise_id

Database

Contribute Data

Dataset: tucker catch - CGoA LTOP
Deployment: GP0108

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: tucker catch - CGoA LTOPDeployment: GP0108

Dataset acquisition description

Dataset Processing Description

Dataset: tucker catch - CGoA LTOP
Deployment: GP0108