bow) trout, Salmo gairdneri. J. Fish. Res. Board Can. 

 33:826-829. 



Cooper, J. C, A. T. Scholz, R. M. Horrall, a. D. Hasler, 

 AND D. M. Madison. 



1976. Experimental confirmation of the olfactory hypo- 

 thesis with homing, artificially imprinted coho salmon 

 (Oncorhynchus kisutch). J. Fish. Res. Board Can. 

 33:703-710. 



Hasler, A. D., and W. J. Wisby. 



1951. Discrimination of stream odors by fishes and rela- 

 tion to parent stream behavior. Am. Nat. 85:223-238. 

 NIEMUTH, W. 



1967. A study of migratory lake-run trout in the Brule 

 River, Wisconsin: brown trout. Wis. Dep. Nat. Resour. 

 Fish. Manage. Rep. 12, 80 p. 



Scholz, A. T., J. C. Cooper, D. M. Madison, R. M. horrall, 

 A. D. Hasler, A. E. Dizon, and R. J. Poff. 



1973. Olfactory imprinting in coho salmon: behavioral and 

 electrophysiological evidence. Proc. 16th Conf. Great 

 Lakes Res., p. 143-153. 



Scholz, a. T., R. M. horrall, J. C. Cooper, and a. D. 

 Hasler. 



1976. Imprinting to chemical cues: the betsis for home 

 stream selection in salmon. Science (Wash., D.C.) 

 192:1247-1249. 



Scholz, a. T., R. M. Horrall, J. C. Cooper, a. D. Hasler, D. 

 M. Madison, R. J. Poff, and R. I. Daly. 



1975. Artificial imprinting of salmon and trout in Lake 

 Michigan. Wis. Dep. Nat. Resour. Fish. Manage. Rep. 

 80, 46 p. 

 Stuart, T. a. 



1957. The migrations and homing behavior of brown trout 

 {Salmo truttaL.). Freshwater Salmon Fish. Res. 18, 27 p. 



of lobster larvae. Personnel participating in 

 Cooperative Investigations of the Caribbean and 

 Adjacent Regions (CICAR) activities have pre- 

 pared a "Plan for Sampling the Early Develop- 

 ment Stages of Pelagic Fish during CICAR Opera- 

 tions" which describes the use of the neuston net 

 (FAO^). The Boothbay neuston net, initially 

 adopted as the standard for the Marine Resources 

 Monitoring, Assessment and Prediction Program 

 (MARMAP), consists of a pipe frame 2 m wide by 1 

 m deep with an 8.5-m long net."* Because little was 

 known concerning the sampling performance of 

 this gear, an experiment was designed to test the 

 operating characteristics of two types of frame 

 (galvanized pipe and aluminum pipe) and two 

 lengths of net (4.9 m and 8.5 m with ratios of 

 mouth to open mesh aperture areas of 1 : 6 and 1 : 1 1 , 

 respectively). The nets were of 0.947-mm Nitex^ 

 mesh. 



The results of the experiment defining the 

 operating characteristics of the two types of frame 

 and two lengths of net were described by Eldridge 

 et al. (1977). The present report will describe 

 mainly diurnal variations in catches of ichthyo- 

 neuston during the latter experiment, which was 

 conducted during 9-15 July 1973 utilizing the RV 

 Dolphin. 



Allan T. Scholz 



Laboratory of Limnology 

 University of Wisconsin 

 Madison. WI 53706 



JoN C. Cooper 



Laboratory of Limnology, University of Wisconsin 

 Present address: Texas Instruments, Inc. 

 Buchanan, NY 1 05 II 



Ross M. Horrall 

 Arthur D. Hasler 



Laboratory of Limnology 

 University of Wisconsin 

 Madison, WI 53706 



Materials and Methods 



The neuston net was towed from a boom extend- 

 ing 3 m from the starboard side of the RV Dolphin, 

 and the ship was ordered in an arc of radius 1 n.mi. 

 or less to starboard to keep the net mouth out of the 

 ship's wake. The net was towed so that one-half 

 the height (0.5 m) was in the water. 



Towing speeds of 1, 2, and 3 m/s were employed 

 with a total of 48 tows being conducted. Twenty- 

 four daylight tows were made between 1107 and 

 1627 EST and 24 night tows between 2206 and 

 0432 EST. After setting (which took an average of 

 29 s), nets were towed 10 min and then retrieved 



DIURNAL VARIATIONS IN CATCHES OF 



SELECTED SPECIES OF ICHTHYONEUSTON 



BY THE BOOTHBAY NEUSTON NET OFF 



CHARLESTON, SOUTH CAROLINA^' ^ 



The Boothbay neuston net is becoming a standard 

 gear for collection of ichthyoneuston. Sherman and 

 Lewis (1967) reported using this gear for collection 



'Contribution No. 74 from the South Carolina Marine Re- 

 sources Center. This work is the result of research sponsored by 

 the MARMAP Program, U.S. Department of Commerce, Na- 

 tional Oceanic and Atmospheric Administration, National 

 Marine Fisheries Service under Contract No. 4-35137. MAR- 

 MAP Contribution No. 117. 



^Contribution No. 451 from the Southeast Fisheries Center, 

 National Marine Fisheries Service, NOAA, Miami, Fla. 



3FA0-UNDP Fisheries Program, Mexico City. 1970. A plan 

 for sampling the eggs and larvae of the fishes of Mexican waters. 

 Unpubl. manuscr. 



■•MARMAP is now using a 0.5 x 1 m neuston net. 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



295 



