90 tr.S. BUREAU OF FISHERIES 



While improving the accuracy of predictions of the abundance of 

 2-year olds would rectify the most serious fault of the present fore- 

 casting system, there still would remain the question of how to predict 

 the abundance of yearlings. Prior to their appearance in the fishery 

 as yearlings, mackerel are too small to be the object of a commercial 

 fishery; hence this means of appraising their abundance is lacking, and 

 this category has been omitted from the predictions. Since yearlings 

 often provide a large portion of the commercial yield, it would be 

 useful to have them included. The most promising means of arriving 

 at an estimate of their abundance is by annually estimating the num- 

 bers of mackerel surviving to the late larval stage. This involves 

 special technique and must be pursued through a number of years to 

 ascertain the relation between abundance of late larvae and the 

 abundance of yearlings a year later. 



To provide data on this subject, the Bureau's research ship Albatross 

 II has been detailed to surveys of the spawning grounds during such 

 portions of the last five spawning seasons as she could be spared from 

 •other duties. The early years were exploratory, to ascertain the time 

 and place of spawning, and to design gear and devise methods that 

 would give reliable measures of the relative abundance of larvae. It 

 was not until the season of 1932 that equipment and methods were 

 developed that could be expected to provide reasonably reliable results. 

 The report on this season's operations may be considered as an outline 

 of the minimum requirements. 



From May until July the Albatross II was cruising almost contin- 

 uously, visiting each of some 30 stations at about weekly intervals. 

 As spawning begins first in the more southerly regions and gradually 

 progresses northward, the area of survey was shifted correspondingly. 

 During May the work was mainly at stations in the offing of Virginia, 

 New Jersey, and New York. By June it was extended to southern 

 New England waters. At each station hauls about one-quarter mUe 

 in length were made diagonally from below the 30-meter level to the 

 surface. In the early season when larvae were small a 1 -meter net 

 with 0.6-millimeter mesh was used; later, when the larvae exceeded 8 

 millimeters in length, a 2-meter net with 1- to 2-millimeter mesh was 

 also used. Although the Albatross II was taken out of service dur- 

 ing the latter part of June, because of the lack of operating funds, 

 the season's observations were extended into the latter part of July 

 with the Atlantis which was kindly assigned to this work by the 

 Woods Hole Oceanographic Institution. Altogether 239 stations 

 were occupied, at which 372 hauls were made. The larval mackerel 

 from all hauls have been counted and measured, but personnel has 

 not been available for the clerical labor involved in computing the 

 relative abundance at each stage, so that results cannot yet be 

 reported. 



A continuation of such surveys during successive years might en- 

 able forecasts of abundance of yearlings to be made, but with the 

 withdrawal of the Albatross II from active service, this feature of the 

 work must be held in abeyance and the mackerel predictions must 

 continue to contain this element of uncertainty. 



The matter of preventing extremes of fluctuations by relieving 

 intensity of fishing effort on the successful classes so that they may 

 continue abundant enough to bridge the gap caused by a series of 

 reproductive failures, is further from attainment than predictions, 



