12 U. S. BUREAU OF FISHERIES 
The Grand Bank fishery still seems to be beyond the practical 
range of our fleet. Several scouting trips were made to this area 
during 1939, but the distance is so great that the catches ordinarily 
do not justify the extra time and fuel consumption. 
The unfortunate trend toward concentration of the fishery on 
small haddock has continued, and in recent years the fleet has taken 
an increasing quantity of scrod haddock. This size category made 
up 25 percent of the total catch in 1937, 32 percent in 1938, and 
38 percent in 1939. On Georges Bank alone, the proportion ran 
even, higher—43 percent in 1939. The increased capture of scrod is 
definitely prejudical to the future of the haddock fishery, since had- 
dock of the small sizes affected are growing rapidly, and another 
year on the bank would increase materially the poundage in the 
sea available to the fisherman. The increased concentration on scrod 
will reduce even further the supply of haddock available. 
It was demonstrated early in the present investigation that al- 
though the great decline in catch immediately following 1930 was 
partly due to economic factors, the principal cause was the scarcity 
of haddock as compared to earlier years. The major problems to 
be solved are the detection of the causes of the scarcity, whether due 
to natural conditions or to the commercial fishery, and the deter- 
mination of how these causes could be controlled so that the fishery 
might be restored and maintained at the most productive level. 
In attacking these problems, a consistent program of investiga- 
tion has been pursued which stresses the following points: (1) The 
collection and compilation of present and past records to show the 
total quantity of haddock taken by the commercial fishery from 
each of the principal fishing grounds. (2) The development and 
application of an index of abundance to show accurately the changes 
in the stocks of fish, rather than changes in gear or fishing methods. 
(3) A determination of the relative success of reproduction from 
year to year and its relationship to measurable features of the natu- 
ral environment. (4) A determination of the interdependence of 
haddock stocks through study of the passive movements of eggs 
and larvae and the migration of bottom stages. (5) A study of 
features of the biology of the species, such as growth rates, mor- 
tality rates, and distribution, that are needed to interpret the various 
population data. (6) An analysis of modifications in fishing pro- 
cedure to determine the most practical and effective methods for 
obtaining an optimum yield. This involves experiments with sav- 
ings gear, the charting of nursery grounds, and related projects. 
Extensive records of fishing activities of the otter-trawl fleet from 
1914 to the present were accumulated from various public and _ pri- 
vate sources. After considerable analysis, a method of calculating 
the relative abundance from year to year was developed which gave 
consistent results in spite of changes in fishing intensity from month 
to month and from year to year. By use of this method an index 
of abundance, or availability, was nearly completed for 1914-37. 
This index demonstrates that in the Georges Bank region regular 
cycles in abundance of commercial-sized haddock occurred in the 
early years of the fishery before the fishing intensity had become 
severe. These cycles of 7 to 9 years in length were caused by sim- 
ilar cycles in the success or failure of the survival of young to 
commercial size. The cycles in the survival of young tentatively 
