FISHERY BULLETIN: VOL. 87, NO. 1 



U 



S= 



-t-» 

 03 



XI 



■an 



S 



6 

 13 



'to 



.3 



.2 



.1 







-.1 



-.2 



-.3 



.6 

 .4 

 .2 

 

 -.2 

 -.4 

 -.6 



Larvae < 10 d post-first feeding 



4 5 6 7 8 9 



Larvae > 25 d post-first feeding 



5 6 7 8 



Transect Number 



West coast 



East coast 



Figure 12.— Regressions between relative growth rates and transect number for Macruronus 

 novaezelandiae larvae <10 d postfirst-feeding and those >25 d postfirst-feeding. Correlations 

 are significant at P < 0.01 for both age classes of larvae. 



and transect 8, off the southeastern coast, for ex- 

 ample, is about 400 km. Hence, the minimum time 

 it should take a larva drifting passively in the main- 

 stream of the current to reach transect 8 would be 

 approximately 20 days. In fact, the shortest inter- 

 val between release time and recovery of one of our 

 drift cards on the southeastern coast was only 15 

 days suggesting that at least occasionally larvae 

 could be transported around the southern end of 

 Tasmania very quickly. Total ages of larvae collected 

 at transect 8 varied from 22 to 41 days, averaging 

 31 days in 1984 and 32 days in 1985. As few larvae 

 are likely to traverse a perfectly direct path between 

 the spawning groimds and transect 8, the mismatch 

 between predicted minimum and observed average 

 ages is probably reasonable and the hypothesis that 



larval distributions are the result of passive advec- 

 tion seems plausible. 



The range of ages of larvae at each point along 

 the advection route appears to reflect, in part, 

 spawnings by M. novaezelandiae at sites north and 

 south of the primary spawning area, in part, the 

 distribution of the larvae relative to the main axis 

 of the Zeehan Current, the location of which is like- 

 ly to vary with time, and, in part, variations in the 

 strength and direction of that current. Baines et al. 

 (1983) noted that the manifestation of the current 

 may often be overridden by direct wind effects, 

 which is supported by our observations. The drift 

 rate and direction of our drogue varied as an imme- 

 diate function of wind speed and direction. C. 

 Fandry (fn. 6) suggested that wind affects move- 



42 



