. The Canadian field-naturalist. 10 The Canadian Field-Naturalist Vol. 96 rapidly during July (Figure 3). A large variation in growth between individuals was evident, and it became greater as the summer progressed (Table 2). The average length of bullheads from the September sample was mm and the maximum length was 83 mm. The growth over the summer was similar to that of young Brown Bullhead collected in New York State by Raney and Webster (1940). Back- Calculations The back-calculated lengths for each age group at stations in the Ottawa River were tabulated (Rubec 1975) and the weighted
. The Canadian field-naturalist. 10 The Canadian Field-Naturalist Vol. 96 rapidly during July (Figure 3). A large variation in growth between individuals was evident, and it became greater as the summer progressed (Table 2). The average length of bullheads from the September sample was mm and the maximum length was 83 mm. The growth over the summer was similar to that of young Brown Bullhead collected in New York State by Raney and Webster (1940). Back- Calculations The back-calculated lengths for each age group at stations in the Ottawa River were tabulated (Rubec 1975) and the weighted mean lengths for each age are summarized in Table 3. Back-calculated lengths of males at each annulus were slightly higher than those of females from the same station. Length gains were 90 r 80 highest among bullheads from station 1 in the upper river. The younger year classes (ages II and III) at the Hawkesbury stations (5 and 6) exhibited better length gains that those from station 1, but the growth of adults was intermediate to that of the upper and lower river stations (Figure 4). Covariance analysis indicated no significant differ- ence in growth between the sexes at the six individual stations, nor between sexes for the lower river stations combined (2, 3, and 4) or Hawkesbury combined (5 and 6). Consequently, the data of both sexes was pooled to compare the growth of bullheads between stations. No significant difference was found in the growth of the sexes combined between stations 2, 3 and 4 and between stations 5 and 6. Significant differ- ences (P < ) were observed in the growth between 70 E E 60 X â z llJ _l 50 _l fe 40 30 - 20 - 10 - ⢠1972 ° 1971 OTTAWA RIVER ° 1969 BRITANNIA BAY A 1938 NEW YORK STATE. JUNE JULY AUGUST SEPTEMBER OCTOBER SEASON Figure 3. Seasonal growth of young-of-year Brown Bullhead from Britannia Bay of the Ottawa River compared with those collected by Raney and Webster (1940) from Cayuga Lake. The range in total length is given
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