Dataset: sublegal lobster traps

Name: Testing of trap styles for capture of sublegal sized lobsters from unknown lobster boat NEC-RB2005-1 in the Southwest Harbor, Mt. Desert Island, Maine from 2006-2007 (NEC_ProjDev project)
Published: 2009-06-29
Keywords: oceans

Cite This Dataset

Project:

Northeast Consortium: Project Development (NEC_ProjDev)

Program:

NorthEast Consortium (NEC)

Principal Investigator:

Robert C. Bayer (University of Maine - The Lobster Institute, UMaine-LI)

Student:

William J. Fike (University of Maine - The Lobster Institute, UMaine-LI)

Data Manager:

Rachel Feeney (Northeast Consortium, NEC)

BCO-DMO Data Manager:

Nancy Copley (Woods Hole Oceanographic Institution, WHOI)

Nancy Copley (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

29 June 2009

Version Date:

2009-06-29

Validated:

Yes

Current State:

Final with updates expected

Testing of trap styles for capture of sublegal sized lobsters from unknown lobster boat NEC-RB2005-1 in the Southwest Harbor, Mt. Desert Island, Maine from 2006-2007 (NEC_ProjDev project)

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Description

"Designing and Testing a Sublegal Lobster Sampling Trap"

P.I.: Robert Bayer

Master's Thesis by William Fike

The objective of this study was to design a trap to fill a gap in the collection of data concerning lobster abundance. The trap design should allow sublegal sized lobsters to enter the trap while excluding legal sized lobsters. It is believed that the larger legal sized lobsters inhibit the smaller lobsters from entering the traps and therefore these smaller sized lobsters are not represented in the data collected at this current time. Having the ability to base stock size estimates on smaller size lobsters will help individuals estimate future catch.

See final report

Methods & Sampling

Sample Trap Head Name	Head Design	Number of type made	Number of Hauls	Purpose	Results
Large High	plastic covered wire mesh large horizontal opening high angle	7	1	Catch sublegal lobster, exclude legal size lobster.	Caught lots of crabs
Large Low	plastic covered wire mesh large horizontal opening low angle	7	1	Catch sublegal lobster, exclude legal size lobster.	Caught one lobster, lots of crabs
Small High	plastic covered wire mesh small horizontal opening high angle	7	1	Catch sublegal lobster, exclude legal size lobster.	Caught lots of crabs
Small Low	plastic covered wire mesh small horizontal opening low angle	7	1	Catch sublegal lobster, exclude legal size lobster	Caught one lobster, lots of crabs
Vertical Opening	plastic covered wire mesh vertical rectangular opening	1	Several in one day, used video camera	Discover crab capabilities of entering different head designs.	Showed the ability of crab to access traps
Chalmers	cloth mesh head opening has no wire ring	4	24	Catch sublegal lobster, exclude legal size lobster and crabs.	Caught sublegal lobster, excluded legal size lobster, caught crabs
Fike 1	cloth mesh head has wire ring with 2.5 inch opening	4	24	Catch sublegal lobster, exclude legal size lobster and crabs	Caught sublegal lobster, excluded legal size lobster, caught crabs
Square	Trap has no head instead one inch openings are present around the trap	4	4	Openings in the trap simulates mesh of standard legal trap, discover if sublegal lobster move freely through the mesh.	Caught no lobsters or crabs
Fike 2	cloth mesh head has wire ring opening of 1.75 inches	4	20	Discover the smallest size head opening that lobster will enter through.	Caught 2 very small lobsters and no crabs

Data Processing Description

The data was entered into Microsoft Excel. All data that was recorded while at sea was transferred to a spreadsheet (See Appendix). Data was organized in Excel for the purpose of entering the data into the statistical program Systat. The Systat program was used to conduct an Analysis of Variance for analyzing each trap type: ventless, Fike 1, Fike 2, and Chalmers trap. The dependent variable was lobster carapace length (mm), with trap type, date, location, soak period, and number of crabs in trap as independent variable (Table 2). Insignificant main effects (P>.05) were removed and a reduced model was evaluated. Three variables, depth, bottom type, and catch, which is the number of lobsters caught in each trap, were found not significant and were removed. The Analysis of Variance was then run a second time, excluding these three variables (Table 3). Effects of trap type, soak period, number of crabs, and location on lobster size were included in a prediction equation (Table 4). A final model included significant main effects with interaction terms between main effects (Table 5). Results were presented graphically.

Data Files

File
juv_lobster_traps.csv (Comma Separated Values (.csv), 27.82 KB) MD5:4623b946549fc46daae2bef70428a70f Primary data file for dataset ID 3137

More Information about this dataset

Funding Sources

Funding Source	Award Number
National Oceanic and Atmospheric Administration	NA05NMF4701257

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
NEC-RB2005-1		2006-11-18	unknown lobster boat	Robert C. Bayer (Principal Investigator) William J. Fike (Student) Rachel Feeney (Data Manager)	data info

Instruments

Lobster Trap

Supplied Description:

All sample traps were constructed of 0.5" inch square shrimp mesh plastic covered wire with outside dimensions of 24" inches long, 12" inches wide, and 10" inches high. The size of the trap is approximately 1/6th the volume of a legal size trap. The sample trap heads were rectangular openings that were all 4" inches wide with the large opening 2" inches tall and the small size 1.5" inches tall. There were two head angles one with a rise of 5" inches and a run of 7" inches. The second head angle has a rise of 2.5" inches and a run of 7" inches. Eight trap variations were constructed for a total of 32 sample traps. These traps were set and hauled with each string including four different sample traps and one ventless trap as a control.

Instrument Type

Generic Name: Lobster Trap

Acronym: Lobster Trap.

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/90/

Generic Description:

A lobster trap (often called a lobster pot) is a baited trap which traps lobsters or crayfish and is used in lobster fishing. A lobster trap can catch multiple lobsters at once and can be a various sizes. An opening permits the lobster to enter a tunnel of netting and proceed into a "chamber" or "kitchen", where there is bait, and then into the "parlor" from which it cannot escape.

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
trap_design	see above for description of the lobster trap modifications		no_bcodmo_term
date_local	local month, day and year		date_local
day_local	day, local time		day_local
month_local	month of year, local time		month_local
year	year, reported as YYYY, e.g. 1995		year
yrday_local	local day and decimal time, as 326.5 for the 326th day of the year, or November 22 at 1200 hours (noon)		yrday_local
site	a harbor in Maine		site
tide	relative state of tide		no_bcodmo_term
depth_feet	depth in feet that trap was set at	feet	depth
bottom_type	description of sea bottom		no_bcodmo_term
soak_time	duration of trap collecting period in hours unless otherwise described.	hours	sog
length	length of carapace	millimeters	length
legal_sublegal	whether the lobster was of legal (82.5 mm) or sublegal carapace length.		no_bcodmo_term
num_crabs	number of crabs found in trap		no_bcodmo_term
comments	free text comments		comment

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Dataset: sublegal lobster traps