222 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Owing to the fact that the fish appear to spawn mostly at night, 

 when the pound nets are lifted in the morning the ripe eggs have in 

 many cases been extruded before the spawn-taker could secure them. 

 The iujuries which the fish sustain while in the pound nets and during 

 the hauling of the nets appear to seriously aftect the eggs and cause 

 the non-hatching of a comparatively large percentage. Undoubtedly 

 better results may be obtained if a number of nets are fished exclu- 

 sively for this purpose, insuring the careful removal of fish at the best 

 times for taking and fertilizing the eggs. 



The eggs are very delicate and susceptible to meteorological influ- 

 ences. Their development is markedly affected by water temperature 

 and atmospheric conditions; electrical disturbances, as with other fish 

 eggs, are injurious, but to what extent and in what way are not known. 

 The largest number of ripe eggs thus far taken from a single specimen 

 is 60,000, but the average is only 20,000. 



The Chester jar, such as is used in hatching flatfish eggs, has been 

 found the best apparatus for Spanish mackerel eggs. If the jars are 

 kept clean and not overcrowded, a constant current of water does not 

 seem to be essential; of a lot of 60,000 eggs in a jar of quiet water, 90 

 per cent hatched. The cod tidal-box is also adapted to this work. 



In ordinary bay water having a density of 1.014 to 1.019, the eggs 

 are buoyant and remain at the surface until hatching ensues; but in 

 water of low specific gravity they silik and give unsatisfactory results. 

 The period of incubation is very short. Under normal conditions eggs 

 hatch in 20 to 30 hours, averaging 25 hours, at a temperature of 77° 

 or 78°. The fry are planted soon after hatching. 



HADDOCK, POLLOCK, AND OTHER GADIDiE. 



The methods of culture employed with the cod are applicable to other 

 members of the cod family having buoyant eggs. The United States 

 Fish Commission have frequently taken and hatched eggs of the pollock 

 {Pollachius virens) and the haddock {Melanogrammus ccglifiniis). Both 

 are important food-fishes, but much less valuable than the cod, and the 

 collection of eggs has generally been only supplemental to cod work. 



The pollock is found from New Jersey northward. It goes in large 

 schools, which are often found at the surface, thus differing from the 

 cod and haddock. The average weight is 9 or 10 pounds, and the 

 maximum about 30 pounds. Fishing is chiefly done from small vessels 

 and boats, and is most important in Massachusetts. The value of the 

 annual catch is about $100,000. The pollock is an excellent food-fish 

 in both a fresh and a salted condition. 



The eggs of the pollock have at times been gathered in large num- 

 bers in the vicinity of Gloucester; during some seasons about 40,000,000 

 eggs have been taken. The eggs measure about ^2 iuch in diameter. 

 The pollock spawning season includes the months of October, Novem- 

 ber, and December. The fish from which eggs are obtained are taken 



