Effects of Trawling and Dredging on Seafloor Habitat (2002) / Chapter Skim
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Appendix B: Regional Distribution of Fishing Effort
Appendix B: Regional Distribution of Fishing Effort
Pages 80-119
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From page 80... ...
Relatively good qualitative information is available for bottom trawl and scallop dredge fisheries, and detailed information on the location of bottom trawling, the duration of tows and the associated catches is available for most of the intensively trawled areas. However, the methods of data collection, the details maintained, and the geographic resolution differ.
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From page 81... ...
1 to 19 (276) FIGURE B.1 Distribution of bottom trawl effort in New England and mid-Atlantic regions, 1991-1993.
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From page 82... ...
Intense bottom trawling occurred from nearshore to the outer edge of Georges Bank on the extensive continental shelf and slope areas extending east between about 40°30'N and 42°N latitude. Relatively heavy fishing also occurred in the Gulf of Maine.
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From page 83... ...
About 32 percent of the area from 40.5°N to 35.5°N was swept during 1985. Trawling effort declined to the south of Long Island and occurred closer to shore as a function of shelf width and slope.
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From page 84... ...
These figures illustrate the distribution of scallop fishing effort for the years 1998 and 1999 in the New England and mid-Atlantic Bight regions. Although extensive areas of the region were dredged for scallops, the effort was considerably less than the bottom trawl fisheries.
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From page 85... ...
Current estimates of the bottom trawling effort are patchy. Only two states, Florida and North Carolina, have implemented the use of trip tickets, thus improving the collection of effort data.
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From page 86... ...
interviewed fishermen in Georgia and developed charts showing the relative distribution of shrimp trawling off the southeastern portion of the state. The figure illustrates the proximity of the trawl effort to the shoreline; most of the fishing occurs within four miles of the shoreline.
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From page 87... ...
Nance, NMFS Galveston Laboratory, provided the committee with detailed effort data for the Gulf of Mexico. Additional information was provided by Ecological Research Associates, Byran, Texas, a company involved in a voluntary sampling program that uses remote-sensing satellite positioning to track trawling in the Gulf throughout the year.
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From page 88... ...
The data were collected from vessel owners who volunteered to place positioning devices on their vessels. The graphic depiction represents only a small fraction of the total fishing effort.
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From page 89... ...
In 1998-1999, this decreased to an average of 270,864 24-hour days per year. Although the greatest portion of the fishing effort in both periods occurred in the shallower depths, O-20 m, the intensity of trawling per unit area has not always followed the same pattern.
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From page 90... ...
over a large part of the Bering Sea reflects the distribution of flounder populations in time and space over much of the large flats that extend out to near the continental break, the relatively high catch rate for the harvested species, and unobserved tows and the growing use of midwater trawls. Within any year there are open and closed seasons, limiting bottom trawling to only a portion of the year.
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From page 91... ...
Most of the trawling in the Bering Sea occurred at even shallower depths (<50 m)
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From page 92... ...
Therefore, the average number of tows per year is about one-fourth the values shown. Even during this period of relatively heavy bottom trawling, tows were not observed for large areas of the Bering Sea.
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From page 93... ...
~ ~ 1~ ... 175°O'O"W 170°O'O''W Total number of bottom trawls, Bering Sea 1999-2000 ~ 1 tow -- -- -rr m , 100 tows / 55 0 0,.~ ; ., V , ,W, · ~ ~—,~~ FIGURE B.13 Bottom trawl tows in the Bering Sea, 1999-2000.
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From page 94... ...
, i / \ 4...n ~ :: ,~ ~ ~ 1 75°0'0"W 1 70°0'0."W at-,; ,1 6,5Q.O'O"W,., i . = -, ~ ,:,w,,.~=1.,6,0,°0'~ ~ FIGURE B.14 Duration of bottom trawl tows in the Bering Sea, 1991-1994.
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From page 95... ...
As in the 1991-1994 period, most of the tows averaged 1-5 hours in length, although for some statistical blocks the average exceeded five hours. There was a dramatic decrease in long duration bottom tows compared to 1991-1994, especially in the northern Bering Sea fishing grounds.
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From page 96... ...
A few scattered grids show 50-100 tows over the period 1991-1994, but they do not necessarily represent areas where trawling occurred consistently each year.
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From page 97... ...
40°0'0"W FIGURE B.17 Bottom trawl tows in the Gulf of Alaska, 1999-2000. In the 1999-2000 distribution of tows, the map shows many areas where only one tow occurred, especially within the gullies south of Kodiak Island.
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From page 98... ...
. 1 75°0'0"W 1 70°0'0"W Average duration of bottom trawls, Gulf of Alaska 1991-1994 4~ 1 65°0'0"W 1 60°0'0"W 1 55°0'0"W 1 50°0'0"W 1 45°0'0"W 55°O'O"N40°0'0"WFIGURE B.18 Duration of bottom trawl tows in the Gulf of Alaska, 1991-1994.
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From page 99... ...
. 1 75°0'0"W 1 70°0'0"W -nnon~r~ -55°0'0" N 91 ~9 Average duration of bottom trawls, Gulf of Alaska 1999-2000 1 65°0'0"W 1 60°0'0"W 1 55°0'0"W 1 50°0'0"W 1 45°0'0"W l l l l l l FIGURE B.l9 Duration of bottom trawl tows in the Gulf of Alaska, 1999-2000.
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From page 100... ...
Bottom trawling extends west along the Aleutian Islands from Unimak Island to about 168°E. Trawling intensity is lighter than in the Bering Sea, but distinct concentrations of effort occurred during 1991-1994 in the Sequam Pass area, on Petrel Bank, and off Tanaga Island.
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From page 101... ...
, ., , , ~ \ .~ ... 170°0'0"W 165°0'0"W l FIGURE B.21 Bottom trawl tows in the Aleutian Islands, 1999-2000.
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From page 102... ...
The average number of observed tows per year during 1991-1994 was 4058.
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From page 103... ...
The average number of observed tows per year in 1999-2000 was 2738. It is estimated that only 75 percent of the tows were observed and that the average number of tows during 1999-2000 was 3650.
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From page 104... ...
4469 1 777 34025 58175 1 625 325 Gulf of Alaska 1999-2000 ~ # of grids | | Approximate area | Approximate density I I (25 km ~ (km2, (# of tows/25 km21 1 tow ~ 6 8 2 < 50 tows 1 863 50 - 100 tows 1 8 > 100 tows | 0 6821 56551 57~ ol 1 7050 2 1 575 200 o 6.5 72 o Aleutian Islands 1991-1994 | ~ # of grids | | Approximate area | Approximate density I I (25 km ~ ( k m 21 (# of tows/25 km21 1 tow ~ 5 7 2 <50 tows 1 831 50- 100tows 1 36 ;> 100tows 1 27 5721 77271 2471 5461 1 tow < 50 tows ;50- 100tows > 100 tows 1 4300 20775 900 675 9 69 202 Aleutian Islands 1999-2000 # of grids | | Approximate area | Approximate density (25 km21 ( k m 21 (# of tows/25 km21 278 4 1 3 1 8 2 2781 36471 1 304 247 6950 1 0325 450 50 9 72 123.5 FIGURE B.24 Density of trawl fishing off Alaska. This table summarizes the observed bottom trawl tows for the Bering Sea, Gulf of Alaska, and Aleutian Islands for 1991-1994 and 1999-2000.
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From page 105... ...
APPENDIX B 105 FIGURE B.25 Scallop dredge effort in the eastern Aleutian Islands, 1993-1994. Most of the scallop dredge effort is concentrated in the Bering Sea north of Unimak Pass (northeast of Dutch Harbor)
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From page 106... ...
APPENDIX B FIGURE B.26 Scallop dredge effort in the eastern Aleutian Islands, 1999-2000. The density distribution of scallop dredge tows is similar to that seen in 1993-1994, but at lower effort levels.
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From page 107... ...
In most blocks, less than 15 percent of the area is swept by dredge gear.
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From page 108... ...
706 FIGORE B.28 Ares dredged in the eastern Aleutian Islands, 1999-2000. Tab hpurc sbows the ~duchon in the manhunt of Ace Rapt by dlcd~c Ace in 1999-2000 cold r~advc to 1993-1994.
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From page 109... ...
Scallop dredge effort is concentrated in the Gulf of Alaska southeast of Kodiak Island and in the Shelikof Straits close to the mainland between Kodiak Island and the mainland. Most dredging occurs at depths <100 m.
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From page 110... ...
FIGORE B30 ScsHop dredge enbrt in the Kodiak Ares, 1999-2000. Tbc donsby ~sthbudon of scallop dlcd~c tows is Angle to tab sock in 1993-1994, but ~ lower cabs lovely.
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From page 111... ...
Few areas have more that 10 percent coverage by scallop dredging.
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From page 112... ...
APPENDIX B FIGURE B.32 Area dredged in the Kodiak Area, 1999-2000. This figure shows the reduction in the amount of area swept by dredge gear in 1999-2000 compared relative to 1993-1994.
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From page 113... ...
The reduction in effort has followed declines in the abundance of target species and subsequent Pacific Fishery Management Council reductions in quotas and fishing time. The decline continued for all three states in 2000-2001 (Randy Fisher, Pacific State Marine Fisheries Commission, personal communication)
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From page 114... ...
The major bottom trawled grounds off Washington are found off Cape Flattery and to the southwest, and from Westport to the Columbia River. The grounds off southern Washington were fished relatively heavily by vessels from Washington and Oregon ports.
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From page 115... ...
Trawl effort decreased in 1998-1999, with some redistribution of the tow density. In Washington greater effort occurs near Cape Flattery and Aberdeen in 1998-1999 relative to earlier in the decade, but effort decreased off most fishing ports in Oregon.
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From page 116... ...
State regulations prohibit trawl fishing on the continental shelf south of E1 Segundo to the Mexican border, although some trawling occurs on the offshore banks of Southern California. No trawling is allowed within state waters (3 nautical miles)
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From page 117... ...
There is a significant trawl fishery for northern shrimp. The general distribution of shrimp trawling off Oregon and Washington 1997-1999is shown.
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From page 118... ...
This map shows the range of effort in 10' x 10' statistical blocks. The most intensive effort occurs off Oregon in the vicinity of Coos Bay, between Seaside and Garibaldi, and off Pacific City.
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From page 119... ...
were calculated for the Gulf of Mexico, Bering Sea, Gulf of Alaska, Aleutian Islands, and Washington and Oregon. The 1998-2000 effort is depicted relative to the effort level in the 1991-1994 period.
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