FISHERY BULLETIN: VOL. 83. NO. 4 



time specific Nevertheless the extent of sea scallop 

 gear damage to American lobsters in Egmont Bay 

 was measured, and this permits estimation of the 

 damage to lobsters on similar substrate types in 

 other locations. In the nonfished area there was no 

 significant difference in the lobster abundance 

 between the May and July observations, whereas 

 there were significant differences in relative seasonal 

 lobster abundance in the fished areas. In western 

 Northumberland Strait at the time of this study, 

 scallop fishing occurred primarily between late April 

 and late June, with a minor amount of fishing 

 between mid-October and winter freeze-up 

 (Jamieson et al. 1981c). There was limited scallop 

 fishing during July. If lobsters were displaced by 

 scallop dragging during May and June, normal 

 seasonal lobster densities could be reestablished by 

 late July. It is unclear whether the greater density 

 of lobsters in the fished areas in July was due to nor- 

 mal seasonal migration onto these grounds or to the 

 absence of scallop fishing. Data from tagged lobsters 

 suggested that some immigration may have occurred 

 from the deeper water areas of the Strait, but it also 

 appeared that overall abundance on the scallop 

 grounds may have been reduced by scallop dragging 

 activity. Predators have been reported to be at- 

 tracted to the disturbed substrate in a drag's path 

 (Caddy 1973), but how this relates to lobsters is 

 unclear. 



The trapability of lobsters is a function of many 

 variables (Elner 1980), making the quantification of 

 lobster abundance difficult in the four trap study 

 areas. There was a lower percentage of short lobsters 

 and a larger mean carapace length in Area 4 than 

 in the other areas (Tkble 5). When large lobsters were 

 trapped there were generally fewer small lobsters 

 in the traps (Tkble 5), but this may have resulted from 

 agonistic behavior (Cobb and Tkmm 1975) rather 

 than relative density. Water temperature increases 

 may also have affected behavior and possibly had 

 major modifying effects on lobster growth and/or 

 movement. McLeese and Wilder (1958) documented 

 an increase in lobster rate of movement with in- 

 creasing temperature, but what effect this had on 

 the average direction of movement during the study 

 period is unclear. The mean movement rate of 

 lobsters in our study (Tkble 7) was similar to that 

 reported by Saila and Flowers (1968) for mature 

 lobsters off Rhode Island. Saila and Flowers (1968) 

 showed that the coefficients of directed movement, 

 V and V, are sensitive to changes in movement pat- 

 terns at various life history stages, and hence are 

 a possible function of lobster maturity level and the 

 sex ratio used in their calculation. These potential 



influences were not considered here because of 

 limited duration of the study and the relative close 

 proximity of release and recapture areas which were 

 probably not optimal to permit extensive data 

 analysis. 



There probably was a directed movement of tag- 

 ged lobsters from area 4 (deeper water) into Egmont 

 Bay. This may have contributed to the increased 

 CPUE during July-October. Tfempleman (1936) found 

 there was some movement during the summer with 

 lobsters congregating in the relatively shallow in- 

 shore water areas of Northumberland Strait and that 

 some lobsters moved offshore in the fall. The 

 disproportionate sex ratio of legal-sized lobsters 

 observed in the present study suggested a 

 geographic distributional difference between the 

 sexes of lobsters after maturity during July-August. 



Lobster trapability, and hence estimated abun- 

 dance, can be influenced by molt stage. Many legal- 

 sized lobsters appeared to have molted between 

 August and September, and while the data are in- 

 sufficient to support the fact that a molt may have 

 occurred prior to or during the experimental fishing 

 period (late June-July), other investigations have 

 presented evidence in the literature that lobsters in 

 this area do molt in late spring (Tfempleman 1934, 

 1936; Wilder 1963). If, in fact, two molts did occur 

 during the study period, this along with increased 

 water temperature increasing lobster movement 

 (McLeese and Wilder 1958) could partially explain 

 the rapid increase in CPUE during July. However, 

 no soft-shelled lobsters were observed during July, 

 while soft-shelled lobsters were quite frequently en- 

 countered in fishermen's traps during the August- 

 September fishing season. 



The seasonal nature of the fisheries minimizes the 

 impact of scallop gear on lobsters because lobsters 

 are in low abundance on scallop ground at the time 

 of greatest scallop fishing activity. Commercial con- 

 centrations of scallops and lobsters also appear to 

 be largely separated spatially (Figs. 2, 3). What then 

 is the likely economic impact in Egmont Bay of 

 scallop fishing on lobsters, and how does this com- 

 pare to the value of the exploited scallop resource? 

 No reported commercial scallop fishing was reported 

 in 1980 off Red Head, but vessel logs recorded that 

 1,509.4 kg of adductor muscle meat were taken near 

 West Point (scallop log areas 77 and 78 combined, 

 Jamieson et al. 1981c). Average CPUE was about 2.4 

 kg/h • m "\ indicating that 629 h • m of effort was ex- 

 pended. In our study, a total of 8.2 h-m of research 

 effort was expended in May on the fished grounds 

 and 22 lobsters were observed behind the drag in 

 the drag path. Drag velocities over the bottom in 



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