Background
Information
The wire crab trap dramatically affected the Gulf of Mexico blue
crab (Callinectes sapidus) fishery. By the middle 1950s,
crab traps were widely accepted throughout the Gulf of Mexico
and came to dominate the fishery as the main gear type used. The
total number of traps has increased because of increases in the
number of trap fishermen and an increase in the number of traps
used per fisherman. Adoption of the crab trap improved fishing
efficiency, but exacerbated problems associated with derelict,
abandoned, or lost traps. Problems include ghost fishing,
bycatch mortality, and user group conflicts. |
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Ghost fishing occurs
when blue crabs or bycatch are caught and retained inside the
derelict trap. Fishing practices and physical characteristics of
crab traps contribute to derelict trap impacts by either
facilitating trap loss or magnifying ghost fishing mortality.
Traps are effective in capturing blue crabs but inefficient with
respect to size selection. Ghost fishing mortality is directly
related to the ability of a trap to retain blue crabs and
bycatch. |
| The replacement of
galvanized wire by vinyl-coated wire resulted in more durable
traps with a longer ghost fishing period. Traditionally,
hexagonal mesh traps have dominated the fishery, but now one and
one-half inch square mesh traps have become popular in Louisiana
and other areas. These traps are constructed of a heavier gauge
wire and may lead to higher rates of ghost fishing mortality,
longer ghost fishing periods, and greater potential for vessel
or motor damage than hexagonal mesh traps.
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Origin of Derelict Traps
- Abandonment of traps by
fishermen who leave the fishery seasonally or permanently
- Improper disposal of old traps
- Loss of actively fished traps
resulting from
- tides, currents, or storms
- deterioration of floats,
lines, or knots
- negligence by fishermen in
assembling and maintaining floats and float lines
- clipping of float lines by
vessel propellers
- intentional cutting of
float lines by vandals
Number of Derelict
Traps
Annual estimates of trap disposal
and overall trap loss due to inadvertent loss or theft:
- 30-50% in Florida
- 20-50% in Alabama
- 20-30% in Mississippi
- up to 100% in Louisiana - (257
lost traps/year/fisherman)
- 35-50% in Texas - (103 lost
traps/year/fisherman)
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Although an accurate
count of derelict traps is unavailable, a rough estimate can be
generated using the number of fishermen, average traps per
fisherman, and trap loss rate. Recent numbers of licensed
commercial crab fishermen by state and the average number of
traps fished by each fisherman are:
- 2,381 fishermen using 152 traps
each in Florida Gulf waters
- 174 fishermen using 150 traps
each in Alabama
- 256 fishermen in Mississippi -
no estimate on the number of traps used per fisherman
- 3,347 fishermen using 250-270
traps each in Louisiana
- 259 fishermen using 200 traps
each in Texas
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Conservatively assuming
a total of 5,000 commercial blue crab fishermen, fishing 200 traps
each, and losing 25%
approximately
250,000 derelict traps are added to the Gulf of Mexico each year.
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| Impacts
of Derelict Traps
Negative impacts created by derelict
traps include:
- mortality of blue crabs and
bycatch
- user group conflict
- visual pollution
- negative impacts to sensitive
habitats
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Ghost
fishing continues until the trap deteriorates sufficiently for
holes to develop in the wire mesh, allowing captured animals to
escape. The life expectancy of vinyl-coated wire traps averages
two years or more. Blue crab ghost fishing mortality in Louisiana
averaged:
- 25.8 crabs/trap over one year
- 17.3 crabs/trap in traps without
escape rings over a three-month period
- 5.3 crabs/trap in traps with
escape rings over a three-month period
Assuming that Louisiana fishermen
lose 30-50% of their traps each year and a mortality rate of 25.8
crabs per trap,
this
ghost fishing rate leads to a loss of 4 to 10 million blue crabs
each year in Louisiana.
Other animals besides crabs are
captured in blue crab traps. Important recreational fish species
found in crab traps include spotted seatrout, red drum, black
drum, and southern flounder. In addition to fish, diamondback
terrapin, river otter, and raccoons have also been observed in
derelict traps.
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| Conflicts between crab
fishermen and other groups have occurred as the number of derelict
traps have increased. For example, derelict traps may pose
navigation hazards to waterfowl hunters, recreational fishermen,
pleasure boat operators, and shrimp fishermen, and may entangle
hooks of recreational fishermen. Economic costs may also be
incurred because of derelict traps. Derelict traps can damage
shrimp gear and result in loss of catch and fishing time. |
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Derelict crab traps are visually unattractive. Exposed derelict
traps in the water or along shorelines may be aesthetically
degrading to other user groups.
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| Derelict Trap Removal Programs
Texas, Louisiana, Mississippi, and
Alabama have instituted derelict traps removal programs to address
the problems that derelict traps create. Partial funding for
these programs was made possible in 2004 by funding from the NOAA
Community-based Restoration Program. The following links
contain information on the Louisiana
program, the Mississippi
program, and the Alabama
program.
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A detailed report on the
derelict crab trap problem.
For more derelict crab trap photos, view the derelict crab trap photo page. |
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