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Fishery Bulletin 97(1), 1999 



Halifax SST (Jan-Mar) 

 Halifax SST(Apr-Jun) 

 Bickerton (1 Im) 



Figure 3 



Total annual lobster catch (topi and total annual effort (middlel for east- 

 ern shore statistical districts from 1986-95. the years for which effort 

 information is available from index fishermen. Also shown for these years 

 are three temperature indices (bottom), including average sea surface 

 temperatures (SST I in Halifax harbour from January to March; average 

 SST from April to June i.e. during the lobster season; and average water 

 temperatures (11 m) at Port Bickerton during the lobster season. The 

 bars show the average temperature for the first (lower) and last (upper) 

 week of the lobster season. 



Correlation coefficients of the daily first 

 differenced CPTH data from individual 

 fishermen on the eastern shore were plot- 

 ted against distance from Port Bickerton 

 and Three Fathom Harbour (Fig. 5), situ- 

 ated about 125 km apart near the north- 

 eastern and southwestern end of the 

 study area (Fig. 1). Correlations were 

 strongest in the immediate vicinity of 

 these ports, decreased to insignificance at 

 about 50 km, then increased to a second 

 maximum at 125 km. This pattern was 

 still apparent when all ports were in- 

 cluded in the analysis (Fig. 5, bottom), but 

 the least-squares fit to the polynomial was 

 not as good, perhaps because local factors 

 influence the main spatial trend in other 

 areas. In contrast, short-term changes in 

 water temperature are strongly correlated 

 throughout the area (Fig. 6) because they 

 are caused by wind events that impact the 

 eastern shore as a whole. Apparently, the 

 correlation of catches and temperatures 

 at Port Bickerton in 1994 (Table 2) oc- 

 curred only at either end of the eastern 

 shore. To determine if this correlation was 

 truly a direct environmental influence on 

 catch, I plotted the daily correlation coef- 

 ficients of all ports against distance sepa- 

 rately for CPTH and effort (Fig. 7). The 

 fourth-order polynomials fitted to the data 

 are similar for both, indicating that the 

 similarity in catches between ports on ei- 

 ther end of the eastern shore and their 

 similarity to short-term temperature 

 changes are mainly due to similarities in 

 the daily pattern of change in effort. This 

 is confirmed by plotting the coefficients 

 for effort versus temperature directly. 

 Similar results were obtained for 1991, 

 the other year in which significant corre- 

 lations between temperature and catches 

 were found at Port Bickerton. The reason 

 why fishermen separated by 125 km have 

 similar day-to-day fishing patterns is ap- 

 parent when one examines the nature of 

 the coastline along the eastern shore (Fig. 

 1 1. The coast near Three-Fathom Harbour 

 and Bickerton is characterized by rela- 

 tively long and narrow bays generally ori- 

 ented in a north-south direction, which 

 offer more shelter than the relatively ex- 

 posed coastline between them. If the 

 winds that cause temperature decreases are 

 also those that make fishing more difficult, 



