in the net mouth is plotted against the number 

 of revolutions (N) obtained in the calibration 

 distance tow. These data are shown as triangles. 

 A linear regression analysis performed on the 

 data points produced the regression line shown in 

 Figure 2. The slope of the line (regression coef- 

 ficient) was taken as a measure of the filtering 

 efficiency of the 3-m IKMT and had a value of 

 92%. Although the filtering efficiency determined 

 by this study applies to the specific net described 

 in this note, it can probably serve as a guide to 

 the filtering efficiency of most 3-m IKMTs and 

 enable a better quantitative estimate to be made 

 of the actual population density of organisms 

 sampled. 



Acknowledgments 



We wish to thank George Botseas for computer 

 calculations and graphs. This task was sponsored 

 by Naval Ships Systems Command, Code 302-4, 

 under Subproject Number SF 52552004. 



Literature Cited 



Aron, W. 



1962. Some aspects of sampling the macroplankton. 

 Rapp. P.-V. Reun., Cons. Perm. Int. Explor. Merl53:29- 

 38. 

 Aron, W., and S. Collard. 



1969. A study of the influence of net speed on catch. 

 Limnol. Oceanogr. 14:242-249. 

 Aron, W., N. Raxter, R. Noel, and W. Andrews. 



1964. A description of a discrete-depth plankton sampler 

 with some notes on the towing behavior of a 6-foot 

 Isaacs-Kidd Mid-water. Trawl and a one-meter ring net. 

 Limnol. Oceanogr. 9:324-333. 

 Backus, R. H. 



1972. Midwater fish distribution and sound-scattering 

 levels in the North Atlantic Ocean (U). U.S. Navy J. 

 Underwater Acoust. 22(3):243-255. Office of Nav. Res., 

 Code 468, Arlington, Va. 22217. 

 Barkley, R. a. 



1964. The theoretical effectiveness of towed-net samplers 

 as related to sampler size and to swimming speed of 

 organisms. J. Cons. 29:146-157. 

 1972. Selectivity of towed-net samplers. Fish. Bull., U.S. 

 70:799-820. 

 Brooks, A. L. 



1972. Ocean Acre; Dimensions and characteristics of the 

 sampling site and adjacent areas. NUSC (Nav. Under- 

 water Syst. Cent.) Tech. Rep. 4211. 

 Clarke, G. L., and D. F. Bumpus. 



1950. The plankton sampler — An instrument for quanti- 

 tative plankton investigations. Limnol. Oceanogr. 

 Spec. Publ. No. 5., Revised 1950. 

 Clutter, R. I., and M. Anraku. 



1968. Avoidance of samplers. In D. J. Tranter (editor), 

 Part I, Reviews on zooplankton sampling methods, 

 p. 57-76. UNESCO Monogr. Oceanogr. Methodol. 2, 

 Zooplankton sampling. 



Friedl, W. a. 



1971. The relative sampling performance of 6- and 10-foot 

 Isaacs-Kidd Midwater Trawls. Fish. Bull., U.S. 69:427- 

 432. 

 GiBBs, R. H., Jr., C. F. E. Roper, D. W. Brown, and R. H. 

 Goodyear. 



1971. Biological studies of the Bermuda Ocean Acre. 

 I. Station data, methods and equipment for Cruises 

 1 through 11., October 1967-January 1971. Rep. to the 

 U.S. Naval Underwater Systems Center, Contract 

 No. N00140-70-C-0307. Smithson. Inst., Wash., D.C. 

 20560. 



Harrisson, C. M. H. 



1967. On methods for sampling mesopelagic fishes. In 

 N. B. Marshall (editor). Aspects of marine zoology, 

 p. 71-126. Academic Press, N.Y. 



Isaacs, J. D., and L. W. Kidd. 



1953. Isaacs-Kidd Midwater Trawl. Final report. Scripps 

 Inst. Oceanogr. Ref 53-3, Oceanographic equipment rep. 

 no. 1. 

 King, J. E., and R, T. B. Iversen. 



1962. Midwater trawljng for forage organisms in the 

 Central Pacific 1951-56. U.S. Fish Wildl. Serv., Fish. 

 Bull. 62:271-321. 

 Krueger, W. H., and G. W. Bond. 



1972. Biological studies of the Bermuda Ocean Acre. IIL 

 Vertical distribution and ecology of the bristlemouth 

 fishes (Family Gonostomatidae). Rep. to the U.S. Naval 

 Underwater Systems Center, Contract No. N00140-72-C- 

 0315. Univ. of Rhode Island, Kingston, R.I. 02881. 



Murphy, G. I., and R. I. Clutter. 



1972. Sampling anchovy larvae with a plankton purse 

 seine. Fish. Bull., U.S. 70:789-798. 

 Pearcy, W. G., and R. M. Laurs. 



1966. Vertical migration and distribution of mesopelagic 

 fishes off Oregon. Deep-Sea Res. 13:153-165. 

 Tranter, D. J., and P. E. Smith. 



1968. Filtration performance. In D. J. Tranter (editor), 

 Part I, Reviews of zooplankton sampling methods, p. 

 27-56. UNESCO Monogr. Oceanogr. Methodol. 2, Zoo- 

 plankton sampling. 



Vannucci, M. 



1968. Loss of organisms through the meshes. In D. J. 

 Tranter (editor). Part I, Reviews on zooplankton sam- 

 pling methods, p. 77-86. UNESCO Monogr. Oceanogr. 

 Methodol. 2, Zooplankton sampling. 

 Wiebe, p. H., and W. R. Holland. 



1968. Plankton patchiness: Effects on repeated net tows. 

 Limnol. Oceanogr. 13:315-321. 



New London Laboratory 



Naval Underwater Systems Center 



New London, CT 06320 



New London Laboratory 



Naval Underwater Systems Center 



New London. CT 06320 



On exchange from 

 R.A.N. Research Laboratory 

 Garden Island, N.S.W. 2000 

 Australia 



A. L. Brooks 

 C. L. Brown, Jr. 



P. H. Scully-Power 



621 



