Dataset: Northeast US Adult Fish
Deployment: NEFSC-Bottom_Trawl

Adult fish of the Northeast U.S. Shelf Ecosystem: 1977-1987 and 1999-2008.

Principal Investigator:

Jonathan Hare (Northeast Fisheries Science Center - Narragansett, NOAA NEFSC)

Contact:

Harvey Walsh (Northeast Fisheries Science Center - Narragansett, NOAA NEFSC)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

Northeast Fisheries Science Center Bottom Trawl Survey (NEFSCBottomTrawl)

Current State:

Final no updates expected

Data URL:

https://www.bco-dmo.org/dataset-deployment/787381/data

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Description

Abundance and proportion of adult fish species of the Northeast U.S. Shelf; bottom trawl surveys were conducted by the Northeast Fisheries Science Center (NEFSC) during 1977-1987 and 1999-2008.

Methods & Sampling

Dataset acquisition description

The Northeast Fisheries Science Center (NEFSC) has conducted bottom trawl surveys for juvenile and adult fish on the NEUS Shelf over the past four decades (Azarovitz 1981). The surveys were conducted in the spring (March-April) and fall (September-October) using a stratified random design. All fish for each species were counted and weighed. Literature values of the estimated median size at maturity (50th percentile) were used for most species to determine size at maturity and only mature adults were included the catch estimates.

References:
Azarovitz TR. 1981. A brief historical review of the Woods Hole Laboratory trawl survey time series. Canadian Special Publication of Fisheries and Aquatic Sciences. 58:62-7.

Data Processing Description

Dataset Processing Description

Relative proportion (rel_proportion) of adults was calculated yearly for each of the 47 EcoMon plankton strata for the two seasons (1 = spring, 2 = fall). The number of plankton strata (n = 47) is lower than the bottom trawl survey (n = 108) as the narrow inshore stratum and the offshore shelf-break stratum of the bottom trawl survey (Azarovitz 1981) are combined in the EcoMon plankton sampling design. See the map of the EcoMon plankton strata (under Supplemental Files).

The number of adults per trawl was calculated by summing the number of fish caught greater than or equal to the estimated median size at maturity based on the swept area of the trawl. All trawls completed within a stratum, year, and season were averaged, and then this mean was multiplied by the stratum area (km2) to estimate stratum abundance (mean_abund). Thus, there were two estimates of adult abundance for each stratum per year, one for each season (spring and fall). The relative proportion of adults in a stratum and year for each season was estimated by dividing the estimated number of adults within a stratum and year in a single season by the sum of all strata from the year and season. If no samples were collected in a stratum for a year and season a 'nd' was placed in the mean_abund and rel_proportion columns.

References:
Azarovitz TR. 1981. A brief historical review of the Woods Hole Laboratory trawl survey time series. Canadian Special Publication of Fisheries and Aquatic Sciences. 58:62-7.

BCO-DMO Processing:
- Sorted data by taxa, year, season, strata.
- Replaced spaces with underscores in taxa names.
- Modified parameter names to conform with BCO-DMO naming conventions.
- Replaced 'NaN' with 'nd'.

More information about this dataset deployment

Instruments

Otter Trawl

Supplied Name:

Supplied Description:

For specific details on the adult fish collection gear, see:
Azarovitz TR. 1981. A brief historical review of the Woods Hole Laboratory trawl survey time series. Canadian Special Publication of Fisheries and Aquatic Sciences. 58:62-7. (PDF)

Instrument Type

Generic Name: Otter Trawl

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/61/

Generic Description:

Otter trawls have large rectangular otter boards which are used to keep the mouth of the trawl net open. Otter boards are made of timber or steel and are positioned in such a way that the hydrodynamic forces, acting on them when the net is towed along the seabed, pushes them outwards and prevents the mouth of the net from closing. The speed that the trawl is towed at depends on the swimming speed of the species which is being targeted and the exact gear that is being used, but for most demersal species, a speed of around 4 knots (7 km/h) is appropriate. More: http://en.wikipedia.org/wiki/Bottom_trawling

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
taxa	Species/taxonomic name.	text	taxon
year	4 digit GMT year	dimensionless	year
season	1 digit code for sample season: 1=spring and 2=fall.	dimensionless	season
strata	2 digit code for EcoMon plankton strata. See a map of the EcoMon plankton strata (PDF).	dimensionless	no_bcodmo_term
lat	Strata latitude center in decimal degrees	decimal degrees	lat
lon	Strata longitude center in decimal degrees	decimal degrees	lon
area	Strata area in square kilometers	square kilomters (km^2)	no_bcodmo_term
mean_abund	Strata mean abundance (mean number of adults)	mean number of adults	abundance
rel_proportion	Strata relative proportion (% collected in a stratum for that season and year)	percentage (%)	relative_abund

Database

Contribute Data

Dataset: Northeast US Adult Fish
Deployment: NEFSC-Bottom_Trawl

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: Northeast US Adult FishDeployment: NEFSC-Bottom_Trawl

Dataset acquisition description

Dataset Processing Description

Dataset: Northeast US Adult Fish
Deployment: NEFSC-Bottom_Trawl