Bottom Trawl Survey
ArcGIS Feature Service
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InPort Metadata
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Description
The Northeast Fisheries Science Center (NEFSC) Bottom Trawl Survey (BTS) is the primary source of synoptic, shelf-wide, multiseason, annually repeated fish and oceanographic data on the Northeast U.S. Shelf. Furthermore, it is the primary data source of relative abundance data for 48 stock assessments (and an important component of an additional 6 assessments), as well as the source of population demography, maturity, and stomach contents data for the region. It is also a reliable source of other biological samples, as requested, from internal and external partners. The objectives of the NEFSC BTS are twofold: (1) to monitor trends in biological parameters (e.g., recruitment, biomass, growth, maturity, mortality) and geographic distribution of fish and invertebrates of the Northwest Atlantic Continental Shelf; and (2) collect and monitor ecosystem-level data for broad-scale oceanographic and environmental changes. The BTS is fully standardized, including sampling gear construction and performance, vessel(s), standard operating procedures, and spatiotemporal sampling consistency. Survey catch is identified to species level for all fish and a subset of invertebrates (i.e. decapods, cephalopods, some bivalves), and aggregate catch weights are recorded for each species. Biological samples and individual weights are collected for subsampled fish, subsampled invertebrates, and all protected species. The gear captures smaller size classes than commercial gears, and therefore provides estimates of cohorts before they enter the fishery, as well as critical samples of immature fish to inform maturity curves. Oceanographic sampling includes a vertical conductivity, temperature, and depth (CTD) cast at all trawl stations, oblique bongo plankton tows at a subset of stations, and continuous measurement of additional variables via a surface water flow-through system.
Spatial Extent
Layers
| id | name | type | geometryType |
|---|---|---|---|
| 0 | SMIT_BTS_STRATA | Feature Layer | esriGeometryPolygon |
Fields
SMIT_BTS_STRATA
| name | alias | description | dataType |
|---|---|---|---|
| OID | OID | Original object ID | esriFieldTypeBigInteger |
| SURVEY_NAME | Survey name | Name of NEFSC scientific survey | esriFieldTypeString |
| AREA_SQNM | Area (sq nm) | Area of strata in square nautical miles | esriFieldTypeBigInteger |
| DEPTH_M | Depth (m) | Average depth of strata in meters | esriFieldTypeString |
| STRATA | Strata | Strata ID | esriFieldTypeString |
| N | n | Sample count | esriFieldTypeBigInteger |
| STRATA_NUM | Strata number | Strata ID number | esriFieldTypeString |
| REGION | Region | Strata region ID | esriFieldTypeString |
| SECTOR | Sector | Strata sector ID | esriFieldTypeString |
| SAMP_FREQ | Sampling frequency | Frequency of strata sampling | esriFieldTypeString |
| EARLIEST_T | Earliest tow | Year of earliest tow in strata | esriFieldTypeString |
| LATEST_TOW | Latest tow | Year of latest tow in strata | esriFieldTypeString |