American Fisheries Society 113 



half of Ajiril tlu' water tcnipcrature ranoecl from 43° to 50°, 

 tlie second half from -43° to 56°. The average temperature for 

 the month of ]\IaY was 57.75°. The first week the average tem- 

 ])eratiu\' was (i()°. the seeond 58°, the tliird 57°, the fourth 5(i° 

 and it will lie noted that the greater take of eggs Avas in the 

 second week of ^May. In June the average temperature was 

 (n.;S°. First week (30°, second week ()1°, tliird week G-i° and 

 the fourth week (U°. 



The gi-eatest munlier of fish within ahout 24 hours of hidng 

 ri])e was (hu'ing the third aiul fourth weeks in ]\Iav with the 

 tt'm])ei'ature average helow 58° and there was also during that 

 ])erio(l a notahle decrease in the numlier of shad caught. Tlu^ 

 greatest luiiiihci- of shad caught throughout the season was in the 

 two weeks in dune and I have no douht judging hv the nundier 

 of fish caught by the three gillers in our own net that the catcli 

 would have heeii much larger in the third week for each net that 

 was in operation caught a much laig'er percentage than before. 



If water pollution had been a very heavy factor in determin- 

 ing the run of shad there could not have been any great increase 

 in 1907 over jirevious years for the reason that th? river is ju-t 

 as badly polluted today l)y the cities of Philadelphia, Camden 

 and Trenton as in former years and if anything the oil nuisance 

 at Point Breeze was worse. The only eliVct that I could see in 

 regard to the pollution was that after the water temperature be- 

 came highest in June, tlie (ish caught in the neighborhood of 

 Torrcsdale tasted strongly of the pollution. The data therefore 

 in tlic |iossession of the department leads to the conclusion that 

 nature ratluT than man is responsible for the marked fluctuation 

 in the v\m (vl' shad in the Delaware river. 



( A])j)lause. ) 



DISCUSSIOX. 



Dui'ing the reading of the ])a])i'r. iMr. ]\leehan made the f(d- 

 lowiiig comments : 



(1) 1 might add here that those eggs taken in Bay, were 

 taken late in the season. 



(•3) Washington Park Fishery is below Philadelphia. 



(3) ■ Showing that with the tem])erature of the water going 

 beyond G4° or 65°, as it did, the eggs were likely to be bad. 



