PROGRESS IN BIOLOGICAL INQUIRIES, 1937 H 



Fluctuations in total catch have been due to changes in the abun- 

 dance of haddock on the banks and to changes in the amount of fishing 

 effort expended. Fluctuations in abundance, as measured by ''catch 

 per day,'' have been primarily due to differences in the numbers of 

 young haddock produced during successive spawning seasons, com- 

 bined with a rapid depletion of the stock of older fish due to the very 

 intensive fishery. 



' Growth rate on the various fishing gromids is studied through the 

 analysis of length frequency data and scales regularly collected on 

 the Boston Fish pier and at sea on commercial trawders and on 

 research vessels. Because of the limited amount of time available 

 for the study of growth rates only general conclusions may be drawn. 

 The growth rates on the different parts of Georges Bank differ con- 

 siderably among themselves, but when samples are considered en- 

 masse^ the growth is seen to be considerably greater than on the 

 Nova Scotian banks, especially for the younger sizes. Over the entire 

 haddock range covered by the New Egland fishing fleet growth 

 appears to be greatest in the South Channel region and least on 

 Banquereau. 



Passive migrations of haddock eggs and larvae have been studied 

 through the systematic sampling with plankton nets of the Qgg and 

 larval population in the South Channel-Georges region and through 

 the determination of ocean currents by the use of drift bottles, water 

 temperatures, and densities. It has been found that the principal 

 spawning center is on eastern Georges Bank, with a smaller one in 

 South Channel. The eggs from eastern Georges Bank drift to the 

 southwest, Avhei'e they hatcli, part of the larvae being caught in a 

 current circling to the northeast around Georges Shoals. These 

 young fish presumably go to the bottom in this region, and by the 

 end of the winter are found principally on southeastern Georges 

 Bank. The eggs and larvae not caught in the northeast current are 

 carried to the westAvard toward Long Island, where they presumably 

 perish, for no young haddock have been found on the bottom in this 

 region. The data indicate that no appreciable number of eggs and 

 larvae reach Georges from otlier banks, demonstrating that this area 

 is a self-contained imit insofar as the supply of young is concerned. 



Most of the information concerning the active migrations of older 

 fish is derived from analysis of length and age data. Kesults indicate 

 that there is no movement of young haddock between Georges and 

 the Nova Scotian bank, but that a limited intermixture of the older 

 fish takes place. For practical considerations the populations of 

 the areas east and west of the Fundian Channel may be considered 

 independent. 



The relatiA'e abundance of year classes is being determined through 

 the age analysis of the commercial catch and of material collected on 

 the AtJantk trawling trips in 19^55 and 193G through the cooperation 

 of the Woods Hole Oceanograpliic Institution. The haddock work 

 is urgently in need of facilities for continuing such deep sea trawling 

 to determine the abundance and distribution of 1-, 2-, and 3-year-old 

 haddock, as it is becoming more and more evident that major changes 

 in botli the distribution and size of the catcli depend on the abundance 

 of these smaller sizes during tlie previous year. 



