| Contributors | Affiliation | Role |
|---|---|---|
| Hare, Jonathan | Northeast Fisheries Science Center - Narragansett (NOAA NEFSC) | Principal Investigator |
| Walsh, Harvey | Northeast Fisheries Science Center - Narragansett (NOAA NEFSC) | Contact |
| Rauch, Shannon | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
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.
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.
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'.
| File |
|---|
adult_fish.csv (Comma Separated Values (.csv), 5.45 MB) MD5:3b01b28bfca20e147343ecde2d018854 Primary data file for dataset ID 560342 |
| File |
|---|
Azarovitz (1981) paper filename: Azarovitz1981.pdf (Portable Document Format (.pdf), 910.60 KB) MD5:aabd40787953dfe7b57d01124ca8d915 Azarovitz (1981) paper |
Figure1 EcoMon Strata Map filename: Figure1_EcoMon_StrataMap.pdf (Portable Document Format (.pdf), 267.41 KB) MD5:dbb7896d1f51d91f85460aca04ebaec9 Figure1 EcoMon Strata Map |
| Parameter | Description | Units |
| taxa | Species/taxonomic name. | text |
| year | 4 digit GMT year | dimensionless |
| season | 1 digit code for sample season: 1=spring and 2=fall. | dimensionless |
| strata | 2 digit code for EcoMon plankton strata. See a map of the EcoMon plankton strata (PDF). | dimensionless |
| lat | Strata latitude center in decimal degrees | decimal degrees |
| lon | Strata longitude center in decimal degrees | decimal degrees |
| area | Strata area in square kilometers | square kilomters (km^2) |
| mean_abund | Strata mean abundance (mean number of adults) | mean number of adults |
| rel_proportion | Strata relative proportion (% collected in a stratum for that season and year) | percentage (%) |
| Dataset-specific Instrument Name | |
| Generic Instrument Name | Otter Trawl |
| Dataset-specific 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) |
| Generic Instrument 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 |
| Website | |
| Platform | NOAA Ship Trawl-Survey-Vessel |
| Start Date | 1963-09-01 |
| End Date | 2008-12-31 |
| Description | This is a 'catch-all' deployment for 50 years of Fisheries surveys. |
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. (PDF)
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