large schools often in shallow water. Also, schools in 
deep water formed thick layers that covered small 
areas, schools in shallow water formed thin layers that 
covered large areas. Since commercial fishing of 
walleye pollock, sardine and anchovy by set nets and 
gillnets occurs in the survey area, the large plate- 
shaped fish schools in shallow water are thought to be 
correspond of pelagic species, like sardine and 
anchovy, and the small spindle-shaped fish schools 
near the sea bottom are thought to be correspond of 
walleye pollock during their spawning migration to the 
coast. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
School Depth av sg of S En, 
vd RD 
7 ; = eene à f d. 
m LZ X 
8 Elongation 
3 Ks e Z emat ^. 
* 7 o S sx. 
> e. ae Em 99 9 La 8 
Ser 1e Cp Log Volume 
z S sro 235 Qe S». a 
e. P d odo d e s bo [E 
$718 qw? 7 
: AA, 
2 3 — Z 7 
Figure 11 Scattergram matrix of three 
representative parameters of fish school shape. 
4.3 Application for Acoustic Fish Resource Survey 
Scanning sonar can survey larger areas than vertical 
echo-sounders. However quantitative fish resource 
surveys using sonar have not yet been developed. 
Recently acoustic fisheries surveys have combined 
scanning sonar observations with ordinary scientific 
echo-sounder observations (Misund, 1993b, 1993c, 
Misund and Floen, 1993). Misund et al. (1992b) 
demonstrated that fish-school volumes calculated by 
sonar data analysis are proportional to the area 
backscattering strength (SA) of fish schools calculated 
by scientific echo-sounders. These trials suggest the 
importance of combining geometrical information from 
sonar with quantitative information from scientific 
echo-sounders. 
Finally, if fish avoid survey ships, as shown in Figure 
10, we may underestimate fish abundances, 
especially for pelagic species. Scanning sonar 
provides  three-dimensional information of the 
distribution and movement of fish schools to ensure 
more precise estimates of fish school size. 
734 
REFERENCES 
Cervenka, P., and Moustier, C., 1993. Sidescan Sonar Image 
Processing Techniques. IEEE Journal of Oceanic 
Engineering, 18, 108-122. 
Hara, l., 1985. Shape and size of Japanese sardine school in 
the waters off the southeastern Hokkaido on the basis of 
acoustic and aerial surveys. Bull. Japan. Soc. Sci. Fish., 51, 
41-46. 
lida, K., Mukai, T., Aoki, Y., and Hayakawa, T., 1996. Three 
dimensional interpretation of sonar image for fisheries 
research. Acoustical Imaging, 22, 583-588. 
Lu, H. J., Lee, K. T., 1995. Species identification of fish 
shoals from echograms by an echo-signal image processing 
system. Fisheries Research, 24, 99-111. 
Misund, O. A., 1990. Sonar observations of schooling 
herring: school dimensions, swimming behaviour, and 
avoidance of vessel and purse seine. Rapp. P.-v. Reun. Cons. 
Int. Explor. Mer., 189, 135-146. 
Misund, O. A., and Aglen, A., 1992a. Swimming behaviour of 
fish schools in the North Sea during acoustic surveying and 
pelagic trawl sampling. ICES J. mar. Sci., 49, 325-334. 
Misund, O. A., Aglen, A., Beltestad, A. K., and Dalen, J., 
1992b. Relationships between the geometric dimensions and 
biomass of schools. ICES J. mar. Sci., 49, 305-315. 
Misund, O. A., 1993a. Avoidance behavior of herring and 
mackerel in purse seine capture situations. Fisheries 
Research, 16, 179-194. 
Misund, O. A., 1993b. Dynamics of moving masses: 
variability in packing density, shape, and size among herring, 
sprat, and saithe schools. ICES J. mar. Sci., 50, 145-160. 
Misund, O. A., 1993c. Abundance estimation of fish schools 
based on a relationship between school area and school 
biomass. Aquat. Living. Resour., 6, 235-241. 
Misund, O. A., and Floen, S., 1993. Packing density structure 
of herring schools. ICES mar. Sci. Symp., 196, 26-29. 
Misund, O. A., 1994. Swimming behavior of fish schools in 
connection with capture by purse seine and pelagic trawl. In: 
MARINE FISH BEHAVIOUR, edited. by Ferno, A. and Olsen, 
S., Fishing News Books, Oxford, pp. 88-92. 
Misund, O. A., Aglen, A., and Fronaes, E., 1995. Mapping 
the shape, size, and density of fish schools by echo 
integration and a high-resolution sonar. ICES J. mar. Sci., 52, 
11-20. 
Mitson, R. B., 1983. Fisheries Sonar. Fishing News Book Ltd. 
Farnham, Surrey, England. pp. 194-224. 
Pitcher, T. J., and Partridge, B. L., 1979. Fish School Density 
and Volume. Marine Biology, 54, 383-394. 
Reid, D. G., and Simmonds, E. J., 1993. Image Analysis 
Techniques for the Study of Fish School Structure from 
Acoustic Survey Data. Can. J. Fish. Aquat. Sci., 50, 886-893. 
Weill, A., Scalabrin, C., and Diner, N., 1993. MOVIES-B: an 
acoustic detection description software. Application to shoal 
species' classification. Aquat. Living Resour., 6, 255-267. 
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