EVALUATION 



Field use has shown that the sampler is 

 effective and versatile. The number or organ- 

 isms captured can be related accurately to the 

 size of the area sampled. Because the top 

 layer of substrate is removed by suction as 

 the sled moves across the bottom, the sampler 

 is particularly effective in capturing young 

 shrimp that are burrowed and inaccessible 

 to conventional sampling gear. The result is 

 increased accuracy in determining juvenile 

 shrimp abundance per unit area. In addition, 

 because the device samples a narrow strip, it 

 is useful in determining zonation of juvenile 

 shrimp in the shallow waters bordering bays 

 and rivers (Costello and Allen, 1966). 



We compared the shrimp-catching efficiency 

 of the suction sampler with that of the slednet. 1 

 Tests were made in the daytime in shallow 

 water on firm sand or shell-mud substrates 

 supporting the seagrasses, Thalassia testudi- 

 num and Diplanthera wrightii . The sampler 

 and the slednet were pulled adjacent and 

 parallel to one another over the same distance 

 and the catches of young pink shrimp per unit 

 area were compared (table 1). The catches of 

 shrimp by the sampler exceeded those by the 

 slednet in 36 of 43 trials, and the average 

 catch by the sampler was almost twice that 

 by the slednet. 



The sampler is effective in capturing other 

 small benthic animals including amphipods, 

 isopods, lobsters, crabs, worms, mollusks, 

 and fish. Marine plants and substrate particles 

 larger than the mesh of the collecting bag also 

 can be obtained with the sampler. 



The catch is limited to those animals capable 

 of passing through the 7.3-cm. inside diameter 

 suction head. Although sampling efficiency has 

 not been tested for animals other than shrimp, 

 the sampler is probably quantitative for all 

 except rapidly moving epifauna or deeply em- 

 bedded infauna. Almost none of the captured 

 organisms are mutilated because they do not 

 pass through the pump. The gear is most 

 effective on level bottoms. The relatively large 

 suction head prevents most clogging. Maximum 

 operating depth is not known. 



LITERATURE CITED 



BRETT, C. EVERETT. 



1964. A portable hydraulic diver-operated 

 dredge-sieve for sampling subtidal 

 macrofauna. J. Mar. Res. 22: 205-209. 

 COSTELLO, THOMAS J., and DONALD M. 

 ALLEN. 

 1966. Florida Bay ecology project. In An- 

 nual report of the Bureau of Commer- 



Table 1. — Comparison of the numbers of pink 

 shrimp 1 caught per 6 m. 2 of bottom sampled by 

 the suction sampler and by the slednet. 



1 A hand-pulled frame trawl, similar to that described by 

 Pullen, Mock, and Rlngo (1968). 



1 Size range 20 to 86 mm. total length (tip 

 of rostrum to tip of telson). 



cial Fisheries Biological Laboratory, 

 Galveston, Texas fiscal year 1965, p. 15- 

 18. U.S. Fish Wildl. Serv., Circ. 246. 

 FUSS, CHARLES M., JR., and LARRY H. 

 OGREN. 

 1966. Factors affecting activity and burrow- 

 ing habits of the pink shrimp, Penaeus 

 duorarum Burkenroad. Biol. Bull. 

 (Woods Hole) 1 50: 1 70- 191. 

 LONGHURST, ALAN R. 



1964. A review of the present situa- 

 tion in benthic synecology. Bull. Inst. 

 Oce'anogr. Monaco 63(1317) 54 pp. (In 

 English and French.) 

 MANZ, JERRY V. 



1964. A pumping device used to collect 

 walleye eggs from offshore spawning 

 areas in western Lake Erie. Trans. 

 Amer. Fish. Soc. 93: 204-206. 

 PULLEN, E. J., C. R. MOCK, and R. D. RINGO. 

 1968. A net for sampling the inter tidal zone 

 of an estuary. Limnol. Oceanogr. 13: 

 200-202. 



MS. #2033 



GPO 89 2.892 



