JAMIESON and CAMPBELL: SCALLOP FISHING IMPACT ON LOBSTERS 



by the divers when the drag was finally lowered. 

 When the drag was on the bottom, divers swam 

 along the outside edge of each lead line with a 2 m 

 rod, noting all scallops and lobsters encountered in 

 the 2 m wide unfished "path" (120 m^). The divers 

 then positioned themselves on the drag and noted 

 the number of lobsters in the drag path during the 

 tow, which covered on average 975 m (SD = 221). 

 When the tow terminated, the divers searched the 

 drag path between the lead lines (70.8 m-) and col- 

 lected the scallops and lobsters encountered. Scallop 

 height (edge of hinge to distal edge of the valves) 

 and lobster carapace lengths were measured to the 

 nearest millimeter with a measuring board and ver- 

 nier calipers, respectively. Location (loran C 

 readings), bottom type (Fig. 1), water temperature, 

 and marine plant presence were noted. Tbw distance 

 and speed were calculated from loran C readings 

 (Jamieson 1982) and averaged 4.6 kn (SD = 1.9) in 

 May and 4.3 kn (SD = 1.7) in July. Average tow dura- 

 tion was 6.9 min. 



Lobster Abundance and Distribution 



Four study areas (Ikble 1; Fig. 1) were located by 

 loran C and were selected after bottom types were 

 characterized from scuba diving observations. The 

 areas were 1) recently heavily fished scallop ground, 

 2) recently lightly fished scallop ground, 3) ground 

 with large rocks with no recent scallop fishing, and 

 4) typical lobster ground in waters deeper than areas 

 1-3 with no scallop fishing. Fifty, three bow, single 

 kitchen and parlor design lobster traps with 121 mm 

 diameter entrance ring and 31-34 mm lath spaces 



were set in each area. Each trap was baited with 

 salted gaspereau (or alewife), Alosa pseudoharengiis, 

 and/or Atlantic herring, Clupea harengus harengus. 

 The traps were set in groups, two traps per buoy, 

 within a 1 km radius of the center of the area (Tkble 

 1). The mean interval between trap hauls from 22 

 June to 30 July was 3 d (1-7 d range). Each trap was 

 reset as close as possible to the original site of each 

 trap set. 



The sex and carapace length (CL in mm) of each 

 trapped lobster was recorded. Once a week, the ter- 

 minal quarter of a pleopod endopodite was removed 

 with scissors from each of 70-140 lobsters of various 

 size groups, and placed in a vial containing seawater. 

 The pleopod method described by Aiken (1973) was 

 used to determine the molt stage of each lobster. 



The bottom and surface water temperatures were 

 recorded for each area and time fished. To observe 

 lobster movement and growth, a total of 2,002 lob- 

 sters (ca. 500 lobsters/area) were measured and tag- 

 ged (Tkble 1) with a sphyrion tag (Scarratt and Elson 

 1965) and returned to the water within 10 min and 

 0.5 km of the capture site During the 10 August-10 

 October fishing season, lobster samples were obtain- 

 ed at-sea from commercial lobster fishing boats at 

 a number of locations within and near areas 1-4. 



One-way analysis of variance was used to compare 

 the mean number of lobsters per trap haul in each 

 area during a 1-wk sampling period and to compare 

 the mean distance moved for lobsters from the dif- 

 ferent study areas. 



From tagged lobsters recaught during the study, 

 movement and direction statistics of tagged lobsters 

 were analyzed by methods Jones (1959) and Saila 



Table 1.— Summary of Egmont Bay lobster tagging experiment, 22 June-30 July 1981. 



'No scallop fishing. 



^Number of tags returned up to 30 October 1981 including tags witfiout recapture locations. 



579 



