ABLE ET AL.: SIDESCAN SONAR TO DETECT DEMERSAL FISH HABITATS 



With sidescan sonar, detection and mapping of 

 general habitat types such as rock outcroppings 

 and wrecks, which support populations of com- 

 mercially important species (e.g.. Grimes et al. 

 1982; Sedberry and Van Dolah 1984), could be 

 done efficiently. Sidescan sonar also could prove 

 very effective (see Wong et al. 1970) in mapping 

 the distribution and relief of a coral reef, and 

 other outcroppings which are often the habitats of 

 groupers, snappers, porgies, and grunts. 



In addition to these specific examples, general 

 characteristics of sidescan sonar are advanta- 

 geous in detecting demersal fish habitats. The 

 system has a wide effective search image (up to 

 150 m to each side for the 100 kHz Klein sidescan 

 unit) that enables it to map large areas of the 

 bottom during a single transect. With multiple 

 transects a complete picture of the bottom can be 

 obtained. Also, a sonograph could determine po- 

 tentially appropriate habitats for several species 

 simultaneously. For example, in our studies we 

 have been able to detect boulders (potential lob- 

 ster, tilefish, and cusk habitat) and vertical bur- 

 rows (potential tilefish, lobster, and conger eel 

 habitat) in the same transect of the sidescan 

 sonar. 



Verification of the various images that appear 

 on the sonograph is critical to successful opera- 

 tion of sidescan sonar for fish habitat detection. 

 We have been able to do this using observations 

 from the Johnson-Sea-Link submersibles 

 (Twichell et al. 1985; Grimes et al. 1986; Able et 

 al. 1987). However, this is an expensive option 

 and not generally available. Others have been 

 able to verify sonograph targets from underwater 

 photographs (Bouma and Rappeport 1984) or 

 underwater television (Powles and Barans 1980). 

 The simplest technique, and one that would offer 

 the most information to a fishermen, is directed 

 fishing at the location of sonograph targets of par- 

 ticular interest. 



Even with these advantages, sidescan sonar op- 

 erations are still expensive. However, a consider- 

 able body of sonograph data already exists that 

 has not been utilized by fishermen or fishery biol- 

 ogists. A large number of sidescan sonar surveys 

 have been conducted in North American waters 

 in recent years, largely as a result of exploration 

 for oil and related impact studies (Carpenter and 

 Roberts 1979; Neurauter 1979; Carpenter et al. 

 1982). We have taken advantage of one of these 

 surveys to identify possible tilefish burrows off 

 the west coast of Florida, an area in which we had 

 no prior experience. Individual burrows were 



clearly visible on sonographs (Neurauter 1979; 

 target type No. 3, fig. 39) originally made to iden- 

 tify geologic bedforms. 



ACKNOWLEDGMENTS 



A number of individuals and institutions as- 

 sisted in this effort. Greg Kennedy (Harbor 

 Branch Foundation, Inc.) and Greg Miller (U.S. 

 Geological Survey) helped to operate the sidescan 

 sonar equipment and kept it functioning prop- 

 erly. The submersible and ships crews of the 

 Johnson-Sea-Link submersibles and the RV 

 Johnson and RV Sea Diver provided their usual 

 professional operations. G. Scott (National 

 Marine Fisheries Service, Miami) provided the 

 delta distribution computer program. Helpful 

 comments on an earlier draft of the manuscript 

 were provided by Elizabeth Winget, Sally 

 Needell, and Ron Circe (U.S. Geological Survey) 

 and an anonymous reviewer. Denise Rucci and 

 Patricia Eager prepared the manuscript. This 

 work was supported by grants from the NOAA 

 Office of Undersea Research, New Jersey Sea 

 Grant, and Florida Sea Grant (No. NA80AA-D- 

 00038) and logistical support was provided by 

 Harbor Branch Foundation, U.S. Geological Sur- 

 vey and the Center for Coastal and Environmen- 

 tal Studies, Rutgers University. 



LITERATURE CITED 



Able, K W.. C. B Grimes, R A. Cooper, and J R Uzmann. 



1982. Burrow construction and behavior of tilefish, 

 Lopholatilus chamaeleonticeps, in Hudson submarine 

 canyon. Environ. Biol. Fishes 7(3):199-205. 



Able, K W , D C. Twichell, R. S. Jones, and C. B Grimes 



1987. Tilefishes of the genus Caulolatilus construct bur- 

 rows in the sea floor. Bull. Mar. Sci. 40:1-10. 

 Anderson. N R , and B. J. Zahuranec. 



1977. Oceanic sound scattering prediction. Plenum 

 Press, N.Y. 

 Askew. T. M 



1985. J ohnson -Sea-Link user's majwiaX. Harbor Branch 

 Foundation Misc. Rep. No. 17, 29 p. 

 Barans, C. A., and D. V. Holliday. 



1983. A practical technique for assessing some snapper/ 

 grouper stocks. Bull. Mar. Sci. 33:176-181. 



Belderson, R. H., N. H. Kenyon, A H. Stride, and A. R. Stubbs. 

 1972. Sonographs of the seafloor. Elsevier, N.Y., 185 p. 

 Bouma, N. H , and M L. Rappeport. 



1984. Verification of sidescan sonar acoustic imagery by 

 underwater photography. In P. F. Smith (editor), 

 Underwater photography. Scientific and engineering ap- 

 plications, p. 279-294. Van Nostrand Reinhold Co. 



Carpenter, G. B., A P. Cardinell, D. K. Francois, L. K Good, 

 R L Lois, and N T Stiles 



1982. Potential geologic hazards and constraints for 



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