196 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Meeting these three criteria was necessarily a 

 compromise with the characteristics of the fishing 

 fleet. Throughout the period of our study, yellow- 

 tail were taken entirely by otter trawlers ranging 

 in size from about 10 to 75 gross tons. The ma- 

 jority of these vessels, and the most successful, 

 were those of about 25 to 40 gross tons, which 

 could carry a crew of 4 to 6 men and make fairly 

 regular trips of 3 to 6 days' duration. 



All of the vessels fishing for yellowtail used 

 similar gear, but since every fisherman has his 

 ideas of how an otter-trawl net should be rigged, 

 probably no two were identical. Essentially, how- 

 ever, they used lightweight trawl nets of cotton 

 or manila twine with head ropes ranging in length 

 from 50 to 70 feet and with foot ropes of chain, 

 perhaps protected by a wrapping of old rope but 

 never with large rollers. Usually, the doors were 

 attached on pennants from 1 to 3 fathoms from 

 the net. Vignernon-Dahl gear was never used. 



During the period of study, the yellowtail 

 fishery was only one of the major fisheries in the 

 area and a large proportion of the fleet turned 

 from one fishery to another as the markets and 

 the fish dictated. Early in the yellowtail fishery 

 many of the fishermen who had formerly sought 

 the winter flounder would regularly return to that 

 fishery in the spring season from April to June. 

 Other vessels occasionally interspersed their fish- 

 ing for yellowtail with periods of fishing for 

 whiting, scup, or other species. The larger ves- 

 sels (of more than 50 gross tons) usually sought 

 yellowtail only in the winter when the weather 

 was too rough for them to go to Georges Bank for 

 sea scallops or haddock, and the crews preferred 

 to fish the nearby yellowtail grounds. Our study 

 of yellowtail abundance was further complicated 

 by the fact that other species of fish were some- 

 times abundant near the yellowtail grounds and 

 vessels on the same trip would catch a mixture of 

 several species. 



After several attempts to select particular ves- 

 sels from the fleet, which would provide a con- 

 tinuous record, we found that no sizeable part of 

 the fleet had fished throughout the period studied. 

 We therefore decided to select vessels of 26 to 50 

 gross tons. This range in weight included the 

 majority of the vessels, but it eliminated the very 

 small ones which were most affected by the sea- 

 sonal weather changes and likewise the very large 



ones which usually entered the fishery only in 

 periods of poor weather. Vessels in this group 

 fished only part of the time for yellowtail 

 flounders, and many times they landed a mixture 

 of yellowtail and other species; consequently, we 

 further restricted our data to landings comprised 

 of more than 75 percent yellowtail. 



Most of the vessels fished day and night while 

 on the fishing grounds, although a few of the 

 smaller ones fished only during daylight hours. 

 It was decided to select as a unit of effort a day 

 of 24 hours actual fishing on the grounds and to 

 consider the small amount of entirely daylight 

 fishing according to the actual time fished. Infor- 

 mation on fishing effort was obtained almost en- 

 tirely at the port of New Bedford, where the cap- 

 tain of each vessel landing was interviewed to 

 determine where he had fished, what he had 

 caught, and how long he had fished in each sta- 

 tistical subarea to the nearest tenth of a day. 



The interviews were commenced in October 

 1942 and were obtained a few days each week 

 until the early part of 1943 after which they were 

 made daily (except for some interruptions caused 

 by personnel changes). Prior to October 1942, a 

 considerable number of cooperating captains had 

 kept detailed logbook records, which made it 

 possible for us to estimate the catch per unit of 

 effort during the first 3 quarters of 1942. 



Despite the restriction on size of the vessels, 

 condition of the catch, and necessity of landing 

 the catch at New Bedford, a considerable percent- 

 age of the total catch has been included in our 

 data. The percentage of the landings included in 

 the catch per unit-of-effort data was low (1.4) 

 during the early months of 1942 when only log- 

 book records were available, but rose to 16.7 per- 

 cent during the last quarter of 1942 (table 22). 

 Subsequently, it varied from 14.1 percent in 1944 

 to as much as 39.2 percent in 1948. In order to 

 reduce the effect of sampling variation during the 

 first 3 quarters of 1942 and during the second 

 quarter of 1945, we have included the catch and 

 adjusted days fished for trawlers of between 5 and 

 25 gross tons. The days fished were multiplied 

 by 0.796, the ratio of the catch per day of the 

 small trawlers to the catch per day of our selected 

 group during the period 1943 to 1947. Consider- 

 ing the generally substantial proportion of the 

 landings included and the fact that the New Bed- 



