Canadian Snow Crab Trawl

Trawl survey data used primarily for assessing the status of snow crab stocks in the southern Gulf of St. Lawrence are available at OBIS. The OBIS compiled data includes species name, individual count, lat/lon, and some environmental correlates like depth and salinity. 

Dataset Location: OBIS Canadian Snow Crab Trawl

Direct Download: OBIS Canadian Snow Crab Trawl

Site Location: Southern Gulf of St. Lawrence, Canada

Site(s) Georeferenced: Yes

Timespan: 1988 - 2009

Sampling Frequency: annual; local fishery offseason early July to mid September

Data Collection Summary / Methods: From OBIS metadata - "Nephrops bottom trawl towed over the bottom during 5 minutes at a speed of approximately 2 knots. A scanmar (1989-1998) or netmind (1999-present) hydro-acoustic instrumentation system is used to monitor the status of the trawl, such as depth, trawl opening width and height. On board computer systems record the position, time and status of the trawl (Moriyasu et al, 1998)."

Data collected: Original data includes location, stock assessment, trawl depth and openning

OBIS data schema: species name, individual count, date, location, temperature, depth, salinity, nitrogen, oxygen, silicate.

Known Issues: No survey was conducted in 1996. 

From OBIS metadata- "Throughout the years, the snow crab survey has covered an ever widening range of the Southern Gulf of St. Lawrence area. In 1989 for instance, there were 155 stations mostly within Area 12. Since then the survey has grown to cover all fishing grounds in the Southern Gulf of St. Lawrence (Area 12, E, F, and 19) with over 300 stations.

Three successive boats have been used since the first survey. , The side trawler 'Emy Serge' from 1988 to 1998, followed by two stern trawlers, the 'Den C Martin' from1999 to 2002, and the 'Marco Michel' from 2003 to present. No boat comparisons were completed during the transitions. Because the fishing efficiency of the gear used is not yet known for snow crab, abundance is considered as relative compared to the absolute abundance.

Best Practices: Abundance can only be used as a relative indicator of absolute abundance because the trawl vessel and ger varies througout the dataset.
 
Conditions for use: 'freely available' and 'open-access' as per OBIS: http://iobis.org/about/vision

Citation/ Distributing Author: Wade, Elmer J. Snow crab research trawl survey database (Southern Gulf of St. Lawrence, Gulf region, Canada) from 1988 to 2010. OBIS Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada, 2011, Version 1, Digital. Retrieved from http://www.iobis.org

Supplemental resources: 

Moriyasu M, Wade E, Sinclair A, Chaisson Y. 1998. Snow Crab, Chionecetes opilio, stock assessment in the southwestern Gulf of St. Lawrence by bottom trawl survey. In Proceedings of the North Pacific Symposium on Invertebrate Stock Assessment and Management. Ed by Jamieson GS, Campbell A, 125 Can. Spec. Publ. Fish Aquat. Sci., NRC Research Press (1998), pp. 29–40. <link>

Hebert et al 2014. The 2012 assessment of the snow crab ( Chionoecetes opilio ) stock in the southern Gulf of St. Lawrence (Areas 12, 19, 12E and 12F). http://publications.gc.ca/collections/collection_2014/mpo-dfo/Fs70-5-201...

Dawe et al 2010. Capture efficiency of a multi-species survey trawl for Snow Crab (Chionoecetes opilio) in the Newfoundland region. http://www.sciencedirect.com/science/article/pii/S0165783609002525

Hébert, M., E. Wade, M. Biron, P. DeGrâce, J.-F. Landry and/et M. Moriyasu. 2010. The 2009 assessment of snow crab, Chionoecetes opilio, stock in the southern Gulf of St. Lawrence (Areas 12, 19, 12E and 12F). DFO Can. Sci. Advis. Sec. Res. Doc. 2010/091. vi + 85 p.

Siddeek, M.S.M., Wade, E. and Moriyasu, M. 2008. Proposed harvest control rule for managing the snow crab stock in the southern Gulf of St. Lawrence, Canada. Fisheries Research, 95: 268-279.

Caddy, J.F., Wade, E., Surette, T., Hebert, M. and Moriyasu, M., 2005. Using an empirical traffic light procedure for monitoring and forecasting in the Gulf of St. Lawrence fishery for the snow crab, Chionoecetes opilio. Fisheries Research, 76: 123-145.

 Available via the EcoData Retriever: No