DFO Maritimes Research Vessel Trawl Surveys Fish Observations (OBIS Canada)

This is the OBIS-formatted view of the Canadian Department of Fisheries and Oceans (DFO) Maritimes Research Vessel Trawl Surveys. This data is created using a Structured Query Language (SQL) program run against the DFO production database. Refer to the parent metadata record for more information about the surveys.

This OBIS product reports the abundance and weight of demersal fish species captured by a variety of trawl gear and vessles. Catch data appear in the "observedindividualcount" and "observedweight" OBIS fields and have been normalised for distance towed. The swept area of each tow can be found in the "samplesize" field of the OBIS schema. Care should be taken when using multiple types of gear since the catchability of different fish species varies from gear to gear. The OBIS field "locality" contains the DFO stratum number where each tow was conducted. The OBIS field "collectioncode" identifies which survey series each data record comes from. Strata statistics required to derive stratified random estimates of catch abundance and biomass can be found on the OBISCanada website or upon request.