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Puget Sound Marine Sta. Pub. 



Vol. 1, No. 11 



cent solution of formalin and three days later, after carefully drying 

 them, they were weighed. These weights are recorded in table 10. The 



Table 10. A comparison of the weights of fish taken Apr. 9 



average weight of the fish from the dark trough according to these esti- 

 mates is 18 per cent greater than that of the average weight of those 

 from the light. 



The increasing unevenness in growth is well brought out in a compa- 

 rison of the weights of the 10 largest and the 10 smallest from each group 

 last taken from the troughs : 



The 10 largest from dark weighed 12.290 grams 



The 10 smallest from dark weighed 6.440 grams 



The 10 largest from light weighed 10.390 grams 



The 10 smallest from light weighed 4.750 grams 



The 10 largest from the dark itrough were 90.83 per cent heavier 

 than the 10 smallest from the same trough, while the 10 largest from 

 the light trough were 118.73 per cent heavier than the 10 smallest from 

 the light. From these figures it is seen that the fish in the dark not only 

 average larger but they are more uniform in size. 



With a view to eliminating as far as possible any error that might 

 arise from the method of removing the water and the chance that a single 

 sweep of the strainer might take a group of fish not representing the 

 average in each trough, a still larger number were weighed April 10. 

 This time nine different groups were weighed, each being taken by a 

 single random sweep of the strainer. The fish were weighed alive and 

 each group weighed was returned to the trough from which it had been 

 tfikcn before the next group was caught. It is probable that many of 

 the fish were weighed more than once. Table 1 1 gives the result of this 



Table 11. Comparative zceights of a large number taken from each 



group Apr. 10 



