JAMIESON and CAMPBELL: SCALLOP FISHING IMPACT ON LOBSTERS 



Table 6. — Summary statistics of distance travelled and direction moved by tagged lobsters 

 released at four areas in Egmont Bay during June-July 1981, and recaptured up to 30 October 

 1981. (Direction statistics calculated according to Jones [1959] and Saila and Flowers [1968] 

 are = mean vector angle from true north; V and V = directed movement along north- 

 south and east-west plane, respectively, negative values of V and V indicate net southerly 

 and westerly movement, respectively; R and Z = Rayleigh test statistics for randomness or 

 uniform distribution of points about a circle; * = significant at P < 0.01 indicates a non-uniform 

 distribution.) SD = Standard deviation. 



'Ligtit or no scallop fishing. 



2Value for mean distance travelled significantly different (P < 0.01 ); other values not significantly different 

 (P > 0.05). 



(Tkble 6). The Rayleigh test statistic, Z, indicated a 

 non-uniform distribution of tag returns (P < 0.01) 

 for each area of release Results of the Rayleigh test 

 should be treated with caution (Batschalet 1965) 

 since there is some evidence of bimodality. In 

 general, the returns exhibited three main directions 

 of movement for lobsters: south-west for area 1, 

 north-west for areas 2 and 3, and north for area 4 

 (Tkble 6). V and V, the north-south and east-west 

 coefficients of directed movement, measure the mean 

 daily travel of the group. Lobsters from areas 1-3 

 showed little dispersion in a north-south direction 

 in contrast to lobsters from area 4, which moved the 

 greatest in a northward direction (0.213 km/d). 

 Lobsters from all areas generally moved west, but 

 lobsters from Area 1, the heavily fished scallop 

 ground, tended to disperse furthest west per day 

 (0.132 km/d). Dispersion to the west is perhaps large- 

 ly the result of the relative proximity of the release 

 areas to the western shore of Prince Edward Island, 

 which restricted lobster movement to the east. 



Lobster Growth 



Determinations of molt stage from pleopod ex- 

 aminations indicated that lobsters may have molted 

 as early as 6-12 July (Tkble 7). Trapability of lobsters 



is affected by molt stage, with late molt stages (eg., 

 D^q; Aiken 1973) being difficult to trap. The high 

 percentage of Dg to D^ animals (stages just before 

 molting) in mid-August indicated that considerable 

 molting was imminent, and this probably affected 

 CPUE at this time Many tagged lobsters (47.8%, 

 N = 46) recaptured during the period 24 August-26 

 September had molted. 



DISCUSSION 



The results of this study are probably area and 



Table 7. — Percentage of pleopod stages of lobsters sampled from 

 Egmont Bay, July-September 1981. Pleopod stages 3.0-3.5 and 

 4.0-5.5 predict lobsters molting within 1.9-4.0 wk and 0.3-2.4 wk, 

 respectively, at 15°-19°C (Aiken 1973). Prediction of molting time 

 for pleopod stage 1.0-2.5 is unreliable but usually exceeds 4.0-10.3 

 wk. 



% of lobsters 



Pleopod stage 



Period 



1.0-2.5 3.0-3.5 4.0-5.5 



Temper- 

 No. of ature 

 lobsters (°C) 



583 



