A Population Assessment of Lake Sturgeon in the Namakan River ...

Of the 430 fish captured, 407 were biologically sampled for total length (376 for fork
length) while weight and girth information was obtained from 373 and 370 fish
respectively. Sex and maturity data was obtained from only 27 fish, including 6 mature
(developing) males, 14 mature (ripe) males, 4 mature (developing) females and 3 mature
(gravid) females. Sample size was too small to conduct a separate analysis by sex and
maturity. Mean total length of fish captured was 1,211 mm (605-1,746 mm), while
mean fork length was 1,092 (531-1,577). Mean round weight was 11,858 g (1,100-
36,350 g) and mean girth was 442 mm (195-766 mm). A total of 362 fish (88.9%)
exceeded 1,000 mm in total length, and 56 fish (13.8%) exceeded 1,400 mm. Length
composition of the catch is provided in Figure 6 (based on percent of fish in 100 mm size
bins) and Figure 7 (based on number of fish in 20 mm size bins). The majority of the
catch (25.8%) in Figure 6 was in the 1100 mm size bin (1100 to 1199 mm), while 27 fish
from Figure 7 were observed in the 1190 size bin (1180-1200 mm).
Age determination was completed for 349 fish, providing a mean age of 26.1 years (range
of 7-61 years). Figure 8 provides the age composition (%) of the catch for all fish
sampled from spring 2006 to fall 2008, with no age adjustments made based on the year
of sampling. The majority of the catch (80%) was between 16 to 33 years of age, with
age 21 fish representing the highest proportion at 7.2%. Meanwhile, Figure 9 provides
the year class composition based on the number of fish sampled, with adjustments made
to the year of actual recruitment. The majority of the catch (86%) originated from annual
recruitment over the 20 year period from 1972 to 1991; however consistent annual
recruitment did occur over the period from 1963 to 1995. The highest representation
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