Since 1991, an annual fishery-independent acoustic survey of early fall (September-October) concentrations of Herring has been conducted in the sGSL. The standard annual survey area occurs in the 4Tmno areas where both NAFO Div. 4T Herring spawning components aggregate in the fall. The survey uses a random stratified design of parallel transects within predefined strata. Surveys are conducted at night and use two vessels: an acoustic vessel to quantify the fish schools biomass using a hull-mounted 120 KHz split-beam transducer, and a fishing vessel to sample aggregates of fish with a pelagic trawl (details in LeBlanc et al. 2015; see also LeBlanc and Dale 1996). Trawl samples are used to separate the estimated biomass by spawning component and age, determine species composition, and size distribution for the estimation of the target strength (LeBlanc and Dale 1996; LeBlanc et al. 2015). A standardized abundance index is generated from this acoustic survey. This index includes catch-at-age data since 1994. This survey also provides the age-disaggregated acoustic abundance index for ages 2 to 10 for spring spawners and fall spawners.

The acoustic trawl database for Lynn Canals echo-trawl survey was conducted from 2001 to 2004 throughout southern Lynn Canal in southeast Alaska. Acoustic surveys were conducted one day per month and trawl surveys were conducted every 3 months to verify acoustic signals and collect biological data. This study was conducted to study the relationship between Steller sea lions (Eumetopias jubatus) and their prey. Additional acoustic surveys were conducted throughout the winter of 2004 to 2005 on 6 consecutive days once a month in order to study forage fish hots spots. Acoustic equipment were calibrated before every trawl survey. Acoustic data were analyzed by the same qualified acoustician throughout the surveys duration with calibrations entered into the analytical software after each calibration. Trawls were used to identify the fish species associated with a specific acoustic signal and to get length weight data per species. Trawl data were also used to enumerate and identify all nekton found within the study area and to generate length frequencies, species composition and abundance by species and season. The acoustic data was use to generate biomass estimates for Pacific herring and walleye pollock. Longlines were deployed to better identify and enumerate the benthic species not usually caught in pelagic trawls.

PURPOSE: To provide demographic parameters and relative indices of abundance for Atlantic herring in NAFO Division 4T. DESCRIPTION: The experimental gillnet survey is conducted in collaboration with Atlantic herring harvesters and uses standardized multi-mesh gillnets. Gillnets are set on spawning grounds in the spring and fall. Data (fish and sample) are collected to provide: (1) relative age-disaggregated indices of abundance, (2) an indicator of relative changes in fishery selectivity over time, and (3) information on the demographic composition of herring on the spawning grounds. PARAMETERS COLLECTED: Sample: sample location; sample weight; mesh size; length frequency Biological: length; weight; gonad weight; maturity stage (biological); sex (biological); ring count (biological) USE LIMITATION: To ensure scientific integrity and appropriate use of the data, we would encourage you to contact the data custodian.

The NEFSC Advanced Sampling Technologies Research Group conducts annual fisheries acoustic surveys using state-of-the-art acoustic, midwater trawling, and underwater video technologies to improve fisheries-independent stock assessments for pelagic species. Pilot and experimental studies were conducted during 1995-97 to develop the NEFSC's fisheries acoustic capabilities. Annual NEFSC Atlantic Herring Acoustic Surveys began in 1998. NEFSC acoustic capabilities include multifrequency EK60 echosounder data, Acoustic Doppler Current Profiler (ADCP), and trawl monitoring systems. Midwater trawling, plankton sampling, and underwater video operations provide biological samples and target verification. CTD (conductivity-temperature-depth) vertical profiles are also routinely obtained during survey operations.

Fisheries acoustics data are collected from more than 200 sea-days each year aboard the FRV DELAWARE II and FRV ALBATROSS IV (decommissioned) and the FSV Henry B. Bigelow during pelagic, bottom-trawl, and marine mammal surveys. Acoustic sampling operations include continuous measurements using hull-mounted transducers and multi-frequency scientific echosounders. Biological sampling with midwater and bottom trawls, and underwater video deployments is conducted to verify species-specific backscatter and characterize sea-floor habitat. In-situ and laboratory experiments aid in understanding species-specific acoustic measurements. We are continuously developing, testing, and evaluating advanced sampling technologies during laboratory and field experiments to improve abundance estimates and map spatial and temporal distributions of fish and invertebrates. Acoustic, optic, and biological data are audited and archived in the NEFSC relational data management system.

The surveys primary objective was to collect acoustic data and trawl information to estimate midwater abundance and distribution of walleye pollock (Gadus chalcogrammus) in the Gulf of Alaska (GOA) Shumagins Region during late winter and early spring. Acoustic data were collected using five split-beam transducers (18, 38, 70, 120, and 200 kHz) and Simrad ER60 scientific echo sounders. Midwater and near-bottom acoustic backscatter was sampled using an Aleutian Wing 30/26 Trawl (AWT) and a poly Noreastern bottom trawl (PNE) with roller gear. This long-running survey has consistently provided data on the pollock population in the western GOA during winter and spring months.

The acoustic trawl database for Lynn Canals echo-trawl survey was conducted from 2001 to 2004 throughout southern Lynn Canal in southeast Alaska. Acoustic surveys were conducted one day per month and trawl surveys were conducted every 3 months to verify acoustic signals and collect biological data. This study was conducted to study the relationship between Steller sea lions (Eumetopias jubatus) and their prey. Additional acoustic surveys were conducted throughout the winter of 2004 to 2005 on 6 consecutive days once a month in order to study forage fish hots spots. Acoustic equipment were calibrated before every trawl survey. Acoustic data were analyzed by the same qualified acoustician throughout the surveys duration with calibrations entered into the analytical software after each calibration. Trawls were used to identify the fish species associated with a specific acoustic signal and to get length weight data per species. Trawl data were also used to enumerate and identify all nekton found within the study area and to generate length frequencies, species composition and abundance by species and season. The acoustic data was use to generate biomass estimates for Pacific herring and walleye pollock. Longlines were deployed to better identify and enumerate the benthic species not usually caught in pelagic trawls.