Fecundity and Nuture 87 



Study 23 



THE RELATION BETWEEN FECUNDITY AND NURTURE 



IN FISHES 



Materials needed: 



1. Fishes bearing the full complement of mature eggs.* 



2. Photographs and specimens illustrating nesting habits. 

 The following nurture-types are suggested for use: 



A. Fishes that scatter their eggs widely in weedy shoals, giving them no further 



care: carp, pike, etc. 



B. Fishes that seek out better aerated situations in which to oviposit, such as 



gravel beds in the riffles of streams: suckers, trout, etc.; or that hang their 

 egg-strings up on green water weeds; as yellow perch. 



C. Fishes that make simple open nests on the bottom, place their eggs in them 



and guard the eggs until hatching is over; such as sunfishes, black bass, etc, 



D. Fishes that add to this some care for the young after hatching; such as the 



common catfish, or bullhead. 



E. Fishes that build covered nests high up in the weeds and place their eggs in- 



side, and guard the young there after hatching; such as the stickleback. 



The Record of this study may be put into a table having the following column headings: 

 Kind of fish. 



Locality whence obtained, and date. 

 Restriction of egg-laying area. 

 Preparation and construction of nest. 

 Extent of care of eggs by male and female. 

 Extent of care of young by male and female. 

 Number of eggs laid by a single female. 



* Either fresh or preserved specimens will do for this: indeed, preserved ovaries, if whole and well preserved 

 and positively determined, may be used. To save the labor of counting prodigious numbers, measure the ovary 

 and the eggs, and (using the table on the last page herein) compute totals. Get volume by immersing whole 

 ovaries in a graduated beaker of water. Deduct volume of water. Deduct 5% additional for sterile tissue in 

 the egg mass (approximate only, but near enough for the purposes of this study). To get average diameter of 

 eggs, place a line of them in the bottom of a V-shaped groove, side by side and touching, and count the number 

 to the inch: reduce that number to the fractional form used in the table. 



