submerge the entire assembly and to prevent 

 it from drifting, even in areas with 1- to 

 2-knot tidal currents. 



Three plastic foam buoys about 14 inches 

 (35.6 cm.) long and 5 inches (12.7 cm.) in 

 diameter were used in each set--a subsur- 

 face buoy, a surface buoy, and a trailer 

 buoy. The subsurface buoy held the three 

 midwater pots in position relative to the 

 bottom, and the surface buoy held the top 

 pot in position relative to the surface. The 

 trailer buoy, on a 12-foot (3.7-m.) line at- 

 tached to the surface buoy, facilitated our 

 recovering the gear. 



The pots were built with plastic pipe and 

 covered with fine-woven nylon mesh (fig. 2). 

 They were 22 inches (55.9 cm.) in diameter 

 and 14 inches (35.6 cm.) high and had four 

 funnel-shaped entrances. A line clip fastened 

 to the frame was used to attach the pot to 

 the nylon loop on the line. The pots weighed 

 2.2 pounds (1.0 kg.) and had a slight tendency 

 to sink in sea water. Chopped herring was 

 put in a bait box suspended in the pot. De- 

 tails of the materials and construction of 

 the pots are described by McBride and Barr 

 (1967). 



The anchor, bottom pot, and surface and 

 trailer buoys were attached to the line be- 

 fore a set was started. As the line was 

 dropped, the resistance of the pots in the 

 water slowed the rate of descent so that 

 the rest of the pots and the subsurface buoy 

 could be attached easily. 



1 



The string of pots was retrieved in three 

 steps. First the trailer buoy and the surface 

 buoy were pulled onto the deck by hand. The 

 line was then passed over an open block 

 (suspended over the side by a davit- -fig. 3) 

 and around a hydraulic windlass. The rest 

 of the line and the attached gear were then 

 pulled up by the windlass. One man un- 

 snapped the pots and the subsurface buoy as 

 they appeared, and another coiled the line. 



EFFECTS OF TIDES ON OPERATION 

 OF GEAR 



When a vertical series of shrimp pots is 

 fished where tides are present, it is im- 

 possible to maintain constant distances from 

 each pot to both the surface and the bottom. 

 The average diurnal tide range in Kachemak 

 Bay is 18.2 feet (5.5 m.) (U.S. Coast and 

 Geodetic Survey, 1966). We designed the sur- 

 face-to-bottom pot fishing gear to absorb the 

 effects of this change in water depth in the 

 upper quarter of the line. The bottom pot 

 was held on bottom by the anchor, and the 

 three midwater pots were maintained at 

 nearly constant positions relative to the bot- 

 tom by the lift of the subsurface buoy im- 

 mediately above the fourth pot. The surface 

 pot was maintained in its position relative 

 to the surface by the surface buoy (the sur- 

 face buoy was occasionally submerged during 

 high-water periods), but the distance from 

 the bottom and from the other pots changed 

 as the depth of the water fluctuated. It was 

 especially important to maintain a constant 

 distance between the bottom pot and the next 

 pot above because it is here that the greatest 

 differences occurred in species composition 

 of the catch (fig. 4). 



sg^sMfpS^i^ 



■ - 



Figure 2. — Pot used in surface-to-bottom string of pots 

 set to fish for shrimp, Kachemak Bay, Alaska. 



EFFECTIVENESS OF THE TECHNIQUE 



Sampling in Kachemak Bay with all gear 

 revealed the presence of many species. The 

 most common and abundant species of the 

 family Pandalidae were Pandalus borealis 

 (pink shrimp), P. goniurus (humpy shrimp), 

 and P_. hypsinotus (coonstripe shrimp). P. 

 platyceros (spot shrimp) and PandalopsTs 

 dispar (sidestripe shrimp) occurred less fre- 

 quently but were abundant at some locations. 

 Pandalus danae and P. stenolepis were taken 

 only occasionally and were never abundant. 

 Several species of the families Hippolytidae 

 and Crangonidae were abundant in most areas 

 of Kachemak Bay. 



Surface-to-bottom pot fishing caught most 

 of the species of shrimp known to be present. 

 All species except those in the family 



