. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 192 WILLIAM C. SUMMERS Loligo pea lei (Woods Hole) o Mean size of stxed squid UNSEXED & UNCOUNTED. VIII IX MONTH FIGURE 1. Monthly range of size class means, proposed age groups and occurrences of age groups near Woods Hole, Massachusetts. The data represent 8,437 squid from 45 col- lections in the years 1967-1970 and are a composite for males and females assuming a 1:1 sex ratio. The range of sizes for one year olds has been stippled for emphasis. Open dots indicate the mean size of all sexed squid (those with a dorsal
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 192 WILLIAM C. SUMMERS Loligo pea lei (Woods Hole) o Mean size of stxed squid UNSEXED & UNCOUNTED. VIII IX MONTH FIGURE 1. Monthly range of size class means, proposed age groups and occurrences of age groups near Woods Hole, Massachusetts. The data represent 8,437 squid from 45 col- lections in the years 1967-1970 and are a composite for males and females assuming a 1:1 sex ratio. The range of sizes for one year olds has been stippled for emphasis. Open dots indicate the mean size of all sexed squid (those with a dorsal mantle length of seven centimeters or larger). See text for further interpretation of the figure. centimeters were specifically excluded from the quantitative results because they were generally a distinctive size class, their relative abundance was known to in- crease markedly over the inshore season (Summers, 1968) and because of probable escapement (reduced efficiency of the trawl net in collecting smaller squid). Open dots in Figure 1 indicate the mean size of sexed squid; this value is remarkably constant after the middle of May and stays within the range 1H to 144 cm for seven months. The mean size can be misleading because it in- cludes both sexes and varying proportions of different age groups. Sexual dimorphism in mantle length has been reported for L. pealei (Verrill, 1882; Haefner, 1964) ; our results indicate that males exceed the length of contemporary females by cm at nine months, cm at 12 months and 4—5 cm at 20 months. The mean size is useful in comparing unbiased samples of L. pealei with no segregation other than the exclusion of young-of-the-year individuals. Three age groups are shown in Figure 1. One year olds (age group 1) are intermediate in size and age among these groups and most numerous among the sexed squid over the inshore season; the range of their size class means has been stippled in the figure for emphasis. Two year old squid arrived i
Size: 1924px × 1298px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
