THEILACKER: MORTALITY OF SEA-CAUGHT JACK MACKEREL 



Table 1.— Number of jack mackerel collected and the condition of those that were ana- 

 lyzed histologically. 



characteristics that successfully diagnosed the ex- 

 tent of starvation in 85% of the laboratory-reared 

 jack mackerel (Theilacker 1978). The technique is 

 based on a stepwise discriminant analysis (SWDA) 

 using 11 body part measurements. The analysis 

 allowed me to distinguish between individuals 

 belonging to fed and starved treatments, given a set 

 of morphological measurements that describe the 

 characteristics of the individuals in each feeding 

 treatment. The 11 body part measurements used to 

 distinguish between groups of fed and starved jack 



mackerel were 1) head length, 2) eye diameter, 3) 

 body depth at the pectoral, 4) body depth at the 

 anus, 5) head length/standard length, 6) eye 

 diameter/standard length, 7) body depth at the pec- 

 toral/standard length, 8) body depth at the anus/ 

 standard length, 9) eye diameter/head length, 10) 

 body depth at pectoral/head length, and 11) body 

 depth at anus/head length. Standard length was used 

 in the ratios but not as a unit to allow discrimina- 

 tion between feeding and starving fish of the same 

 length. 



