598 



Fishery Bulletin 100(3) 



45 



44 



43 



I 42 



_l 



41 

 40 



r A 



39 



1960 



73 

 72 

 71 

 70 

 69 

 68 

 67 

 66 



1970 



1980 



1990 



2000 



65 

 1960 



_L 



1970 



1980 

 Year 



1990 



2000 



Figure 6 



Median (notch), interquartile range, whiskers (±1.5 times 

 the absolute value of the interquartile range), values out- 

 side the whiskers (*), and far outside the whiskers (o) of 

 the (A) latitude and (B) longitude of positive catches of 

 Atlantic herring from the autumn NEFSC bottom trawl 

 survey during 1963-98. 



erence for water temperatures that were cooler than the 

 annual shelf-wide ranges; most herring were caught at 

 bottom temperatures around 5°C during 1968-94 and at 

 about 6°C thereafter (Fig. 7A). During 1972-91, the inter- 

 quartile range in capture temperature was very narrow, 

 about 1-2°C, expanding afterwards to 2-3°C (Fig. 7A). The 

 overall range in capture temperatures increased greatly 

 in the 1990s. 



The median bottom water temperature for the conti- 

 nental shelf during autumn 1963-98 fluctuated between 



1968 1976 1984 1992 2000 



20 r B 



15 



™ 10 



_L 



1960 



1970 



1980 

 Year 



1990 



2000 



Figure 7 



Median (notch), interquartile range, whiskers (±1.5 times 

 the absolute value of the interquartile range), values out- 

 side the whiskers (*), and far outside the whiskers (o), of 

 the bottom temperature of positive catches of Atlantic 

 herring from the (A) spring NEFSC bottom trawl survey 

 during 1968-98 and (B) autumn NEFSC bottom trawl 

 survey during 1963-98. 



8° and 12°C, and ranged between 3° and 25°C with a few 

 higher observations (NMFS^). Herring were generally 

 captured in the autumn surveys at bottom water tempera- 

 tures around 8°C during 1963-76 and at about 7-8°C from 

 1983 to 1998 (Fig. 7B). The interquartile range in capture 

 temperature was about 2-4°C (Fig. 7B), again much cooler 

 than the shelf-wide ranges. 



The proportional number of locations where Atlantic 

 herring were captured during spring surveys declined 



