144 
Fishery Bulletin 108(2) 
also complicate deployment and retrieval because they 
do not wrap as evenly onto reels as unmodified sweeps. 
Potential advantages with the use of disks would in- 
clude longer usability of sweeps and reduced drag (im- 
proved fuel efficiency), both due to reduced contact of 
the sweeps with the seafloor. An important factor in 
identifying these implementation and operational issues 
early, as well as in the development of potential solu- 
tions, has been the direct participation of the fishing in- 
dustry in this research and our ability to conduct these 
tests under conditions identical to most of the important 
operational aspects of the commercial fishery. 
Acknowledgments 
The authors thank K. Hjelm, captain of the FV Cape 
Horn , and his crew for their tireless work and creativ- 
ity in helping with this research. We also appreciate 
the support of numerous Bering Sea trawl captains and 
companies in discussing, motivating, and moving our 
study forward. Scott McEntire developed the systems 
necessary for collection of video and sonar data, a criti- 
cal contribution to this project. We are very grateful to 
our sampling crew: D. Benjamin, N. Roberson, E. Acuna, 
and H. Kenney, and those from a pilot study, J. Olsen, 
J. Hagga, and C. Shavey. Our thanks are also extended 
to the many reviewers both anonymous and within the 
Alaska Fisheries Science Center, whose thoughtful com- 
ments and suggestions greatly improved this article. 
Literature cited 
Barnes, P. W., and J. P. Thomas (eds.). 
2005. Benthic habitats and the effects of fishing. Am. 
Fish. Soc. Symp. 4, 890 p. 
Bellman, M. A., S. A. Heppell, and C. Goldfinger. 
2005. Evaluation of a US west coast groundfish habi- 
tat conservation regulation via analysis of spatial and 
temporal patterns of trawl fishing effort. Can. J. Fish. 
Aquat. Sci. 62:2886-2900. 
Churchill, J. H. 
1989. The effect of commercial trawling on sediment 
resuspension and transport over the Middle Atlantic 
Bight continental shelf. Cont. Shelf Res. 9:841—865. 
Fujioka, J. T. 
2006. A model for evaluating fishing impacts on habitat 
and comparing fishing closure strategies. Can. J. Fish. 
Aquat. Sci. 63:2330-2342. 
Guyonnet, B., J. Grail, and B. Vincent. 
2008. Modified otter trawl legs to reduce damage and 
mortality of benthic organisms in North East Atlantic 
fisheries (Bay of Biscay). J. Mar. Syst. 72:2-16. 
Hannah, R. W. 
2003. Spatial changes in trawl fishing effort in response 
to footrope diameter restrictions in the U.S. west coast 
bottom trawl fishery. N. Am. J. Fish. Manag. 23:693- 
702. 
He, P. 
2007. Technical measures to reduce seabed impact of 
mobile fishing gears. In Bycatch reduction in the world’s 
fisheries (S. J. Kennelly ed.), p. 141-179. Springer, 
New York. 
Kaiser, M. J., D. B. Edwards, P. J. Armstrong, K. Radford, 
N. E. L. Lough, R. P. Flatt, and H. D. Jones. 
1998. Changes in megafaunal benthic communities in 
different habitats after trawling disturbance. ICES J. 
Mar. Sci. 55:353-361. 
Kaiser, M. J., N. Graham, C. S. Rose, and P. H. Weibe. 
2007. Ecosystem-sensitive approaches to fishing: reconcil- 
ing fisheries with conservation through improvements in 
fishing technology. ICES J. Mar. Sci. 64:1610-1611. 
Lokkeborg, S. 
2005. Impacts of trawling and scallop dredging on ben- 
thic habitats and communities. FAO Fish. Tech. Paper 
472, 58 p. FAO, Rome. 
Main, J., and G. I. Sangster. 
1981. A study of the fish capture process in a bottom 
trawl by direct observations from a towed underwater 
vehicle. Scott. Fish. Res. Rep. 23, 24 p. Marine 
Scotland, Aberdeen. 
McConnaughey, R. A., C.B. Dew, and K. Meir. 
2000. An examination of chronic trawling effects on soft 
bottom benthos in the eastern Bering Sea. ICES J. of 
Mar. Sci. 57:1377-1388. 
McConnaughey, R. A., and K.R. Smith. 
2000. Associations between flatfish abundance and sur- 
ficial sediments in the eastern Bering Sea. Can. J. 
Fish. Aquat. Sci. 57:2410-2419. 
Prena, J., P. Schwinghamer, T. W. Rowell, D. C. Gordon, K. D. 
Gilkinson, W. P. Vass, and D. L. McKeown. 
1999. Experimental otter trawling on a sandy bottom 
ecosystem of the Grand Banks of Newfoundland: analysis 
of trawl bycatch and effects on epifauna. Mar. Ecol. 
Progr. Ser. 181:107-124. 
Rose, C. S. 
1996. Behavior of North Pacific groundfish encounter- 
ing trawls: applications to reduce bycatch. In Solv- 
ing bycatch: considerations for today and tomorrow, p. 
235-241. Alaska Sea Grant College Program Report 
96-03, Univ. Alaska, Fairbanks. 
Ryer, C. H. 
2008. A review of flatfish behavior relative to trawls. 
Fish. Res. 90:138-146 
Ryer, C. H., and L. A. K. Barnett. 
2006. Influence of illumination and temperature upon 
flatfish reactivity and herding behavior: Potential 
implications for trawl capture efficiency. Fish. Res. 
81:242-250. 
Ryer, C. H., C. S. Rose, and P. S. Iseri. 
2010. Flatfish herding behavior: diel patterns of trawl 
sweep efficiency as inferred from field and laboratory 
manipulations. Fish. Bull. 108:145-154. 
Tuck, I. D., S. J. Hall, M. R. Robertson, E. Armstrong, and D. J. 
Basford. 
1998. Effects of physical trawling disturbance in a previ- 
ously unfished sheltered Scottish sea loch. Mar. Ecol. 
Progr. Ser. 162:227-242. 
van Marlen, B, M. J. N. Bergman, S. Groenwold, and M. Fonds. 
2005. New approaches to the reduction of non-target 
mortality in beam trawling. Fish. Res. 72:333-345. 
Winger, P. D., S. J. Walsh, P. He, and J. A. Brown. 
2004. Simulating trawl herding in flatfish: the role of fish 
length in behavior and swimming characteristics. ICES 
J. Mar. Sci. 61:1179-1185. 
