December 20, 2011
The following document was presented by Micheal Comeau (DFO Science) in the Moncton, Southern Gulf Lobster Advisory Committee meeting on December 1st, 2011.
Discussion Document
Biodegradable Panels for Lobster Traps
Southern Gulf of St. Lawrence
• A research project was carried out in the southern Gulf of St. Lawrence between 2009 and 2011 to assess the efficiency of several proposed materials (i.e., several gauges of cotton twine, fence wires, hog rings and wooden headers) that could be used as biodegradable panels by harvesters to avoid or minimize ghost fishing of lobster traps.
• The existing configuration of biodegradable panels indicates that they are ghost fishing with lost traps capturing lobsters with a catch-per-unit-effort of up to 5 kg (12 lbs) per lost trap was observed during monthly visits.
• Gauges 21, 30, 60 and 96 of untreated cotton twine were used in the study. All showed a steady degradation related to soak time based on tension tests for their breaking point with the faster degradation in colder water.
• In 2009 gauges 30, 60 and 96 were used on lost traps at a depth of 30 feet. None of the twine broke up by its own before the winter period. There was an exception in North Rustico but this was related to the condition of the old wooden traps that collapsed from strong wind in the fall.
• On the wire traps in Caraquet, fence wires and hog rings were also studied in 2009. Although some were rusted and disappeared, others were observed still attached undisturbed following the winter period.
• The study was modified in 2010 by adding a set of traps at a depth of 60 feet, and using 21 gauge cotton twine and wooden headers.
• Cotton twine is more efficient as a biodegradable panel in deeper water as both gauges 21 and 30 completely disappeared following the winter period. Furthermore, 21 gauge cotton twine could breakup within about 100 days.
• Where the escape mechanism is also used as the biodegradable panel, the use of hog rings is inconsistent at shallow depths and performed poorly in deeper waters creating ghost fishing. The same is true of wooden headers. Consequently, they are considered unreliable material for efficient biodegradable panels. .
Conclusion
• The most reliable and efficient material for a biodegradable panel for lobster traps is the gauge 21 cotton twine. It will be strong enough to withstand two months of regular fishing activity in the Gulf, but it could breakup within 100 days if continuously submerged and will completely disappear after the first winter.
• The biodegradable panel should be place in each single parlor and be independent from the escape mechanism to insure its efficiency.
• Untreated gauge 21 cotton twine is reliable, but all the other material examined (i.e., higher cotton twine gauges, fence wires, hog rings and wooden headers), are inconsistent as an efficient biodegradable panel for lobster traps even the following year after the winter period.
EKME 2456013
Telephone: (902) 566-4050
Fax: 902-368-3748
Follow us
Instagram:
@peifishassoc
Facebook:
@princeedwardislandfishassoc