608 U. S. BUREAU OF FISHERIES 
larve from 4 to 5.9 millimeters in length. Eggs were abundant in both bottles. 
We do know that some larve come in at certain times, but I do not think any 
of them remain long enough to be of any importance, because, obviously, the 
drift is a permanent thing. 
MACKEREL 
By O. E. SETTE 
The mackerel investigation was begun in June, 1925. Thus we have to date 
only a part of the field data for the 1925 season and all of the data for the 
1926 season. All of the material collected is not yet analyzed, so that at best 
we can present at this date only a preliminary report on limited phases of 
the subject. 
The first work was done during June and July at Woods Hole, Mass., where 
the pound-net fishermen were visited as often as possible and specimens of 
mackerel were secured in such quantities as could be handled in the labora- 
tory. The particular object in this first work was to determine the technical 
methods suitable for this species. Large numbers of fish were measured, 
weighed, sex determined, scales and otoliths collected, and their condition of 
spawning maturity determined. 
It was soon evident that the mackerel caught in the traps were generally 
much smaller in size than those taken by the offshore purse seiners, the 
trapped mackerel ranging between 20 and 30 centimeters in length, while from 
the market reports received from Boston it was evident that larger mackerel 
were. taken by the purse-seine fishery. 
In order to cover the purse-seine fishery we secured the services of Mr. 
Gregersen, who took data at Boston from August to the end of the season; 
and during 1926 we were fortunate in securing the services of Mr. Nesbit, 
who collected the material of the purse-seine and gill-net fisheries throughout 
the entire 1926 season. These data consisted of relatively accurate informa- 
tion on the time and locality of capture of each vessel’s catch. Measure- 
ments were taken daily on 20 to 100 mackerel selected at random from each 
of as many catches as possible. Scales were taken from five mackerel, selected 
at random from each of as many catches as could be handled daily, and such 
other general notes on the fishery as might pertain to the problem. During the 
1926 season 1,206 vessel skippers were interviewed, over 25,000 mackerel were 
measured, and scales were taken from about 3,509. 
Before presenting any of the data it will be necessary to describe the fishery 
in general, using as a basis our experience during the 1926 season. 
Mackerel first appeared at the Delaware capes shortly before the 15th of 
April and were caught progressively farther northward until in the latter 
part of May, when they were taken in the vicinity of Block Island. At this 
time the majority of the purse seiners left the southern fishery and outfitted 
for the so-called “Cape Shore’ fishery—that is, along the coast of Nova 
Scotia—where they fished during the first two weeks in June, returning with 
fairly good trips of mackerel about the middle of June, when they again took 
up the fishery in the Gulf of Maine, from Nantucket Shoals to the coast of 
Maine. Here they continued to make good catches until the early part of 
October, when the landings tapered off in quantity, and continued to do so until 
the middle of December, when the season finally was concluded. Summarizing. 
there are four natural divisions of the season: 
1. The southern fishery, extending from the middle of April to the first of 
-June and catching mackerel south of Cape Cod. 
2. The “ cape shore” season, from June 1 to June 15, when most of the purse- 
seiners are operating off Nova Scotia. 
3. The “summer fishery,” extending from the middle of June to some time in 
October, with the fleet operating in the Gulf of Maine. 
4. The ‘autumn ” season, from October to December, when the catch becomes 
more uncertain and the season tapers to an end with the approach of winter. 
These are the natural divisions recognized by the fisherman, and, as we shall 
see later, they seem to have biological significance. 
Referring now to Figure 17, we may present a summary of our data on sizes 
of mackerel during 1925 and 1926. The 1926 graphs are shown by the solid-line 
curves, representing the frequency distribution of sizes of mackerel in the purse- 
Seine catch. The base lines of the various distributions are plotted with ref- 
