90 THE SCALLOP FISHERY 



81.48 per cent., and the shore 60.18 per cent. The actual gain in volume 

 for each locality would be raft 662 per cent., Stage Harbor 475 per 

 cent., shore 293 per cent. (Fig. 88). 



(4) In comparing the growth of penned scallops during 1906 at 

 Chatham, Powder Hole, Monument Beach and Marion in reference to 

 the natural conditions, the pens with the best circulation of water 

 invariably showed the fastest growth, as can be observed in detail by 

 referring to the table under artificial growth. 



(5) The Stage Harbor Set. An excellent opportunity for observ- 

 ing the effect of current on the growth of young scallops was found at 

 Stage Harbor in 1906. The set was located at the entrance to Stage 

 Harbor on a flat extending about 90 yards from the east shore to the 

 channel, which curves close to Harding's Beach, on the opposite side. 

 Thick eel grass covered this flat except near the channel, where it grew 

 scatteringly. The water at mean low tide is from 6 to 9 inches deep 

 over most of the flat, gradually deepening at the edge of the eel grass 

 toward the channel. The rise and fall of the tide is about 2 l /2 feet. 

 At low course tides the greater part of the flat is exposed. The differ- 

 ence in the flat is mostly due to the tide, which sweeps in and out of the 

 harbor at every rise and fall, so that there is a strong current always 

 running in the channel. The result is to give that portion of the flat 

 near the channel more current than the portion further away, and the 

 part near shore hardly any. The young scallops were evenly distributed 

 over the flat, although the channel portion was not so heavily set. The 

 growth of scallops of the 1906 set was followed by dividing the flat 

 into three sections, passing from the shore to the channel, each roughly 

 30 yards wide, and by measuring the average size of scallops in each 

 of these sections at different dates. Four measurements were made, 

 Oct. 26, 1906, April 4, 1907, May 1, 1907, and July 1, 1907. By calcu- 

 lating the difference in the rate of growth and size at each date, the 

 following figures were obtained. Giving the area near the channel 

 (the area of fastest growth) 100 per cent., the middle portion would 

 have a value of 87.04 per cent., while the shore section would have 

 77.79 per cent. These figures conclusively show the effect of location 

 on the growth of scallops, as in this case scallops of the same set mani- 

 fested a much greater growth when situated near circulating water. 

 Placing the same in measurements as taken July 1, 1907, when the 

 scallops were exactly one year old, we would have in current portion 

 scallops 42.81 millimeters in size, middle, 37.77 millimeters, shore, 32.95 

 millimeters, showing a difference of nearly 10 millimeters between the 

 current scallops and the shore, possibly 70 yards apart and of the same 

 set. Computing the growth of the standard scallop (25 millimeters) for 

 each of these areas for a definite period, the following comparative 

 gains in volume, 482 per cent., 280 per cent., and 146 per cent, were 

 obtained (Fig. 87). 



