Groeneveld et al.: Escapement of Jasus lalandu from traps 



57 



retention, r(l), by each mesh size of a lobster at its cor- 

 responding mean critical CL. For the 62-mm mesh this 

 probability is 0.014 (0.926 at the upper 95% confidence 

 limit for the critical CL); for the 75-mm mesh it is 0.002 

 (0.096 at the upper 95% confidence limit for the critical 

 CL); and for the 100-mm mesh it is 0.003 (0.099 at the 

 upper 95% confidence limit for the critical CL). 



Field trials 



Escapement from traps with 62-mm mesh was highly 

 variable both for the traps with entrance funnels left 

 open, as well as for those with entrance funnels that 

 were sealed, but was surprisingly high for the latter 

 (Fig. 5). Furthermore, it is clear that the relationship 

 between proportion of lobsters retained and CL was 

 not logistic, as it was for the larger mesh sizes (Figs. 

 5 and 6). Instead, simple, least squares regression 

 analysis indicated linear relationships between these 

 variables both for traps with open entrance funnels as 

 well as for those with entrance funnels closed (Fig. 5). 

 There was no difference between the slopes (r=1.138; 

 df=10; P=0.282; common slope = 0.795/mm), although 

 their intercepts did differ significantly (r=14.079; df = 

 11;P«0.001). 



No lobsters smaller than 62 mm CL were retained 

 in the 100-mm mesh traps with open entrances, and 

 no upper size limit was reached beyond which escape- 

 ment was completely eliminated. By contrast, when the 

 entrance funnels to the traps were sealed, no lobsters 

 smaller than 64 mm CL were retained and no lobsters 



