180 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



the rates computed from the S group must be near the usual rate, probably within 

 10 percent. 



Discussion of growth. — Having determined the rate of growth of the mackerel 

 through its early life, it would be interesting to have comparisons of the early growth 

 of other fishes, particularly to see if logarithmic growth is the general rule. Unfor- 

 tunately, there is a paucity of data on this subject, most of the material on growth of 

 fishes being confined to the portion of life following the larval or post-larval stages. 

 From various sources, however, it has been possible to assemble material on the early 

 growth of three other species: the herring (Clupea harengus) in the Clyde Sea area, 

 the haddock (Melanograrnmus aeglifinus) in the waters off the northeast coast of the 

 United States, and the northern pike (Esox lucius) of North American fresh waters. 



1.2 - 



1.0 



• 8 < 

 40 



< 



10 



20 



30 



40 50 



AGE, DAYS 



Figure 9. — Growth of pre-metamorphosis herring on the Clyde Sea area, after Marshall, Nicholls, and Orr, plotted logarithmically 



(upper part) and arithmetically (lower part). 



Since the data on these need to be formalized for comparison with the mackerel, each 

 will be presented in turn. 



For pre-metamorphosis herring caught by tow net and sprat trawl in the Clyde 

 Sea area in 1934 and 1935, Marshall, Nicholls, and Orr (1937, pp. 248-51) determined 

 the median lengths at successive intervals of time. Plotting the median values 

 against age, they concluded that "The points do not lie on a straight line but it is 

 obvious that, apart from four points, a straight line expresses the relationship best." 

 Their curve is reproduced in the lower part of figure 9, and the four exceptional points 

 thought by them not to have represented the main shoals are indicated by question 

 marks. When the same data are plotted logarithmically, as in the upper part of figure 



