Figure 2. — Geometric mean catch (1,000 m"^) by 

 the 70 cm and 2 m net in surface and oblique tows and 

 95% confidence intervals. Catch has been plotted on a 

 log scale. 



than 3.0 mm) rather than an increased propor- 

 tion of large larvae in the 2 m oblique tow (Fig. 

 3). 



Discussion 



No attempt was made to control the many 

 variables that could contribute to the difference 

 in abundance estimates of the two samphng pro- 

 grams; we were more interested in the relative 

 effectiveness of existing methods rather than in 

 the effects of specific variables. CSIRO esti- 

 mates based on surface and oblique tows were 93 

 and 13 times greater than corresponding esti- 

 mates by FSFRL. The most obvious and 



40 



30 - 

 20 - 

 10 



CSIRO 70 cm net 

 Surface tow, n = 230 



o 



(D 



cr 



40 



30 



20 



10 





 40 



30 



20 



10 





 50 



40 



30 



20 



10 







jn, 



CSIRO 70 cm net 

 Oblique tow, n = 53 



n 



FSFRL 2 m net 

 Surface tow, n = 79 



 I ' '  I 1 1—1 1 1 1 T- 



FSFRL 2 m net 

 Oblique tow, n = 43 



n . n. 



10 



12 



Length (mm) 



Figure .3. — Length-frequency distribu- 

 tion of tuna larvae caught in 2 m net hauls 

 (surface and oblique) by FRV Shoyo Maru 

 and in 70 cm net hauls (surface and 

 oblique) by FRV Soela. 



979 



