Dataset: salmon_juv_diet
Deployment: MF0310

juvenile salmon diet, 2001-2003

Principal Investigator:

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

Scientist:

Jamal Hasan Moss (National Oceanic and Atmospheric Administration - Alaska Fisheries Science Center, NOAA-AFSC-Auke)

Contact:

Jamal Hasan Moss (National Oceanic and Atmospheric Administration - Alaska Fisheries Science Center, NOAA-AFSC-Auke)

BCO-DMO Data Manager:

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

Project:

U.S. GLOBEC Northeast Pacific (NEP)

Data URL:

https://www.bco-dmo.org/dataset-deployment/452216/data

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Description

GLOBEC 2000: Factors Affecting the Distribution of Juvenile Salmon in the Gulf of Alaska
J. Helle (NMFS/AFSC, Auke Bay Laboratory)
E. D. Cokelet (Pacific Marine Environmentla Laboratory),
E. V. Farley, Jr. (NMFS/AFSC, Auke Bay Laboratory),
A. B. Hollowed (NMFS/AFSC),
P. J. Stabeno (Pacific Marine Environmental Laboratory)

"Remarkable changes in atmospheric, oceanic and biological conditions have occurred in recent decades in the North Pacific Ocean including declines in the marine survival of some salmon stocks. Fishery scientists generally agree that in the first few months after leaving freshwater, salmon survival and growth are linked to oceanic variability. The purpose of this research is to focus National Marine Fisheries Service studies on the GLOBEC region, augment oceanographic measurements and determine what biological and physical factors influence the distribution of juvenile salmon. Three general hypotheses are explored in this proposal: (1) juvenile salmon prefer the buoyancy-driven Alaska Coastal Current (ACC) at the head of the Gulf of Alaska, (2) they associate with oceanic temperature, salinity, current and prey fields, and (3) they migrate landward of Kodiak Island in the ACC rather than seaward in the Alaskan Stream. Annual, summer cruises aboard a chartered fishing vessel will catch juvenile salmon on 10 transects between Yakutat Bay and Kodiak Island. The vessel will be outfitted with a thermosalinograph to measure sea-surface temperature and salinity, and with an Acoustic Doppler Current Profiler (ADCP) - each operating continuously for fine-scale resolution. Modeled tidal currents will be removed from ADCP measurements to reveal the mean flow fields. At each trawl site, temperature and salinity profiles will provide water-column properties, and bongo-net hauls will give zooplankton distributions. Stomach samples from juvenile salmonids will be analyzed in the laboratory for diet composition and compared with zooplankton distributions. Analysis of salmon otoliths for hatchery thermal marks and Genetic Stock Identification techniques will be used to determine the home stream of hatchery and wild stocks in the Gulf of Alaska and their distribution with respect to oceanographic regimes. Retrospective analysis of catch per unit effort versus oceanographic and prey factors will reveal what affects the distribution of pink, chum, coho and sockeye salmon in the study region. Proxies for bio-physical factors will be developed and compared with salmon-run size."(project proposal)

Data Collection Details:
Types: CTD profiles, ADCP profiles of ocean current, juvenile salmonid catch statistics from trawls, salmonid stomach samples analyzed for diet composition, salmonid otolith analyses, Genetic Stock Identification, zooplankton distributions from bongo-net hauls
Platform: Chartered fishing vessel
Spatial extent: 10 transects perpendicular to the coast between Yakutat Bay and Kodiak Island
Temporal extent: ~2 weeks each July-August of 2001-2004.

Methods & Sampling

Dataset acquisition description

Fish samples were collected with a 198-m-long mid-water rope trawl with hexagonal mesh wings and body, and a 1.2-cm mesh liner in the codend (Fig. 2, Table 1). The rope trawl was towed at 3.5 to 5 kt, at or near surface, and had a typical spread of 40-m horizontally and 14-m vertically. All tows lasted 30 minutes and covered 1.5 to 2.8 nautical miles. All fish sampling was done during daylight hours. Sometimes this meant that salmon trawls preceded CTD casts. For reference, sunrise occurred at 06:04 ADT and sunset at 22:27 ADT on 1 August 2003 at 58o N. Alaska Daylight Time (ADT) is 8 hours earlier than Greenwich Mean Time (GMT).

Data Processing Description

Dataset Processing Description

Salmon and other fishes were sorted by species and counted. Standard biological measurements including fork length, body weight and sex. Scale samples from a preferred area (to document age and growth) were taken from subsamples of all salmon species. Subsamples 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). Tissues and otoliths were also saved from immature and maturing chum salmon to determine stock distribution and migration of these salmon. All other fish species were counted; juvenile rockfish (Sebastes spp.) and sablefish (Anoplopoma fimbria) were frozen whole for laboratory analyses.

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

Midwater Trawl

Supplied Description:

Fish samples were collected using a midwater rope trawl, which is 198-m long, has hexagonal mesh in wings and body, and has a 1.2-cm mesh liner in the codend. The rope trawl was towed at 3.5 to 5 kt, at or near surface, and had a typical spread of 40-m horizontally and 14-m vertically. All tows lasted 30 minutes and covered 1.5 to 2.8 nautical miles. All fish sampling was done during daylight hours.

Instrument Type

Generic Name: Midwater Trawl

Acronym: TrawlMid

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/23/

Generic Description:

A mid-water or pelagic trawl is a net towed at a chosen depth in the water column to catch schooling fish such as herring and mackerel. Midwater trawl nets have very large front openings to herd schooling fish toward the back end where they become trapped in the narrow "broiler". The sides of the deployed net are spread horizontally with two large metal foils, called "doors," positioned in front of the net. As the trawler moves forward, the doors, and therefore the net, are forced outward, keeping the net open.
This instrument designation is used when specific make and model are not known.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
year	year of sample collection	unitless	year
haul_id	First four numbers represent year, second four numbers represent haul number during year specified in first four numbers	unitless	haul_id
sta_id	Abbreviation for transect name and station number along a particular transect.	unitless	sta_id
control_id	First four numbers are year; following six numbers are individual fish identification numbers.	unitless	sample
month_local	month, local time	unitless	month_local
day_local	day, local time	unitless	day_local
time_start_local	starting time of haul, local time , 24 hour clock	HHMM	time_start_local
yrday_local	local day and decimal time, as 326.5 for the 326th day of the year, or November 22 at 1200 hours (noon)	unitless	yrday_local
lat_start	latitude at starting time of measurement (west is negative), in decimal degrees	decimal degrees	lat_start
lon_start	longitude at starting time of measurement; in decimal degrees (negative denotes West)	decimal degrees	lon_start
distance_start	distance from start of the transect?	nautical miles	no_bcodmo_term
depth_start	depth at the start of the haul	meters	depth_begin
temp_start	water temperature at measurement depth	degrees Celsius	temp
time_end_local	ending time of haul, local time , 24 hour clock	HHMM	time_end_local
lat_end	latitude at end time of measurement; in decimal degrees (negative denotes South)	decimal degrees	lat_end
lon_end	longitude at end time of measurement; in decimal degrees (negative denotes West)	decimal degrees	lon_end
depth_end	depth at the end of the haul	meters	depth_end
temp_end	water temperature at measurement depth	degrees Celsius	temp
habitat	nearshore, shelf, slope, or offshore	unitless	no_bcodmo_term
name_common	common name: chum, pink or sockeye	unitless	common_name
species	genus and species name of the fish	Genus and Species	species
comments_diet	comments pertaining to the salmon stomach contents	unitless	comment
comments_haul	comments pertaining to the haul	unitless	comment
distance_end	distance along the transect at the end of the haul?	unitless	no_bcodmo_term
weight_wet	wet weight	grams	weight_g
sex	M = male; F = female	M or F	sex
pred_stom_wgt	predator stomach weight	grams	no_bcodmo_term
pred_full	Objective measure of how full the stomach was. (1 = least full, 7 = most full)	unitless	no_bcodmo_term
prey_wgt	prey weight	grams	no_bcodmo_term
prey_dig	Objective measure of how digested prey in diet is (1 = most fresh; 5 = most digested)	unitless	no_bcodmo_term
prey_count	number of prey found in stomach contents	count	no_bcodmo_term
prey_id_nodc	prey identification, NODC standard name	unitless	taxon
prey_nodc_common_name	prey common name, using NODC standards	unitless	common_name
cruiseid	cruise identifier	unitless	cruise_id

Database

Contribute Data

Dataset: salmon_juv_diet
Deployment: MF0310

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: salmon_juv_dietDeployment: MF0310

Dataset acquisition description

Dataset Processing Description

Dataset: salmon_juv_diet
Deployment: MF0310