Snow Crab Tagging DFO Science Bedford Institute of Oceanography
Tag Options Spaghetti Tags Acoustic Tags
Strengths Spaghetti Tags Shows long-term movement / migration Allows for females or other life stages Tag lasts as long as animal is alive Not overly expensive / labour intensive (opportunistic) Familiar to fishermen Weaknesses Only terminal moult animals Only works for animals captured by fishery Dependent entirely on recapture reporting Affected by political motivations, misreporting, sheer laziness, apathy Not retained through moult
Spaghetti Tags Traditional tagging method ~18,000 tags applied on the Scotian Shelf in last 10 years In past, tags removed from captured animals Currently, tag number recorded and tagged animal returned to the water Majority of returns from within the CFA with some exceptions
Tags Released: 399 + 375(CFA19)
Tags Released: 698
2304 tags released 129 captured in NENS 1 captured in Gulf Released in 2014, 2015 and 2016 NENS
3993 tags released 321 captured in NENS 93 captured in Gulf 1 captured in SENS Released in 2011, 2012 and 2013 NENS
Unknown number of releases 49 captured in NENS 36 captured in Gulf Released in 2000, 2001 and 2002 NENS
3468 tags released 89 captured in SENS Released SENS in 2014, 2015 and 2016
3993 tags Released 98 captured in SENS 8 captured in NENS 3 captured in Gulf Released SENS in 2011, 2012 and 2013
Unknown number of releases 239 captured in SENS 15 captured in NENS 5 captured in Gulf Released SENS in 2000, 2001 and 2002
Acoustic Tagging and Tracking
Acoustic Tagging Acoustic transmitters attached to individual animals Can be surgically implanted (fish) or externally attached (crab, lobster, etc.) Various sizes available- trade-off of battery and signal strength V13 for snow crab has ~5 year lifespan
Strengths Acoustic Tagging Shows long-term movement / migration Not dependent on tag recapture reporting Allows for females or other life stages Long tag life (~5 years) Can describe movement of an animal in space and time over ~5 year time span Weaknesses Very expensive Labour intensive Needs receivers to be detected Very little history Not retained through moult
Fixed Receivers Detection Methods Attached to float above seafloor, released acoustically to surface Some downloaded remotely through water, some manually -- require annual maintenance and can be fouled in gear ++ Constant sampling and exact positioning
Area 19 Receivers 6 receivers deployed in Area 19 August 2015. Retrieved 5,,downloaded and redeployed in August 2016 Cabot Strait Line Maintained by Ocean Tracing Network Last downloaded in May 2016. Emera Array Required to do habitat usage studies as part of Environmental Assessment Last downloaded May 2016 St.Anns Bank Lines 2 receiver lines between CFA 23 & GBH. Extended to 46 receivers in 2016.
Wave Glider Detection Methods Self powered by wave action Remotely programmed and steered Limited maneuverability in current or rough seas ++ Constant sampling and directed effort
Completed in June 2014 Detected 2 of the 27 released in 2013
Detected 6 of our crab in November 2016
Detected over 20 our animals in October & November 2016
Acoustic: Calculated Routes
Proposed Emera Corridor 27 tags released in summer of 2013, repeated in 2015 14 one side of line, 13 on other Proof of concept of acoustic tagging Begin to collect movement data previous to any Emera work CFA 19 16 released in summer of 2015, 19 in August 2016. Want to see If two way movement exists.
Detections 10 detections on Cabot line from 2013 release, last detection in September 2014 Numerous Detections on the Emera array. 2 animals detected on the Area 19 receivers. All animals in 19 were also detected on the Cabot line. To date, there have been no detections of animals tagged in Area 19
30 tags released in August of 2015 in the Glace Bay Hole. Trying to determine movement characteristics.
Wave Glider detected 9 animals as well as 1 fisherman re-release. Southern most detection was from November of 2015. The rest were from October/November 2016
33 crab tagged in Area 23, South of St.Anns bank in October 2015. 30 more released in April of 2016. Trying to determine movement between areas and within St.Anns bank AOI. 6 females + 1 male tagged in June 2016 Scatarie Bank.
Wave Glider detections, one in 2015 and one in 2016. 9 fisher re-releases. 1 detection by environmental noise project.
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