AFSC/RACE/GAP/McConnaughey: Trawlex Chronic Effects: UAF Infauna

Benthic communities are structured by dynamically interacting factors that determine habitat quality. Since benthic macrofauna demonstrate strong and often narrowly defined affinities, forces altering (or disturbing) the environment will be of considerable importance to their distribution and abundance. Commercial fishing with mobile gear, such as bottom trawls and dredges, and the physical disturbance that results, is widespread in continental shelf areas. Because of its prevalence and the potential for adverse effects, there have been numerous attempts to quantify sea-floor exposure at various spatial scales. The well documented development of commerical fisheries in the eastern Bering Sea (EBS) since 1954 presents a unique opportunity for studying trawling impacts. The Crab and Halibut Protection Zone 1 (CHPZ1; also known as management area 512), located north of the Alaska Peninsula in Bristol Bay, has a long and complex history of trawl prohibitions that extend from 1959 to the present. Using detailed accounts of closures and fishing activity, it is possible to reconstruct historical effort and identify essentially pristine areas immediately adjacent to areas that have been heavily fished with bottom trawls. This physical arrangement permits an examination of chronic disturbance by bottom trawls, without confounding environmental effects that result from geographic separation. Sampling locations were preselected on the basis of historical fish effort. Starting positions for commercial bottom trawls (n=392 743 through July 1996) were spatially joined with a 1 nm2 grid to calculate total number of trawls per nm2, and thus identify heavily fished (HF) and unfished (UF) areas along the boundary of the CHPZ1 (NORPAC fishery observer database maintained at the NMFS Alaska Fisheries ScienceCenter, Seattle, Washington). HF and UF cells on opposite sides of the boundary line were paired a priori on the basis of spatial proximity and were generally separated by 1 nm to allow for prior navigational discrepancies. A total of 42 pairs was identified at the northeastern corner of the CHPZ1. In 1997, 54 grab samples were obtained using a 0.05 m^2 Sutar van Veen (SvV) sampler deployed from the FV Golden Dawn at many, but not all, of the paired sites in the sandy, high-current northeast corner of management area 512. An additional 28 grabs were acquired in the central region of management area 512 as part of a completely different BACI project while sampling protocols were being ironed out in the early stages of the effort. This point file contains the weights (g) of various infauna obtained from 83 grab samples.

The eastern Bering Sea has experienced rapid and intensive development of commercial trawl fisheries. Because of good record keeping and the relatively brief history of fishing it is possible to reconstruct the spatial and temporal patterns of exploitation. Previously unfished (UF) areas can be identified and directly compared with heavily fished (HF) areas to investigate long-term consequences for the benthos. Using this approach, macrofauna populations in a shallow (48 m average) soft-bottom area were studied during 1996 with subsequent bottom grabs being obtained at each site in1997.

Loaded by FGDC Metadata Uploader, batch 7274, 10-09-2015 14:24

The following FGDC sections are not currently supported in InPort, but were preserved and will be included in the FGDC export:

- Spatial Reference Information (FGDC:spref),

- Spatial Data Organization Information (FGDC:spdoinfo)

Effects of Chronic Bottom Trawling on the Size Structure of Soft-Bottom Benthic Invertebrates. American Fisheries Society Symposium 41:425?437, 2005

unknown

none

The United States Government shall not be held liable for improper or incorrect use of data described and/or contained herein. These data and related graphics are not legal documents and are not intended to be used as such. The Alaska Fisheries Science Center gives no warranty, expressed or implied, as to the accuracy, reliability, or completeness of these data. Spatial information may not meet National Map Accuracy Standards. The information contained in these data is dynamic and may change over time. Original data were compiled from various sources. The data are not better than the original sources from which they were derived. It is the responsibility of the data user to use the data appropriately and consistent within the limitations of geospatial data in general and these data in particular. It is strongly recommended that these data are directly acquired from an Alaska Fisheries Science Center server and not indirectly through other sources which may have changed the data in some way. Although these data have been used (processed) successfully on a computer system at the Alaska Fisheries Science Center, no warranty expressed or implied is made regarding the utility of the data on another system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data.

Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.3.0.4322

see Abstract, process steps

IT Security and Contingency Plan for the system establishes procedures and applies to the functions, operations, and resources necessary to recover and restore data as hosted in the Western Regional Support Center in Seattle, Washington, following a disruption.