. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder. Oceanography Bering 22-24 26-28 30-32 34-36 Depth (meters) 38-40 42-44 Figure 67-2. Depth-dependent density distribution of tiie S. polynyma stock off the north coast of the Alaska Penin- sula as determined during the 1977 resource assessment survey using a hydraulic clam harvester m -I r 70-74 80-84 90-94 100-104 110-114 120 124 130-134 140-144 Length (mm, by 5-mm increments) Figure 67-3. Weighted shell-length size-composition of the S. polynyma stock off the north coas
. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder. Oceanography Bering 22-24 26-28 30-32 34-36 Depth (meters) 38-40 42-44 Figure 67-2. Depth-dependent density distribution of tiie S. polynyma stock off the north coast of the Alaska Penin- sula as determined during the 1977 resource assessment survey using a hydraulic clam harvester m -I r 70-74 80-84 90-94 100-104 110-114 120 124 130-134 140-144 Length (mm, by 5-mm increments) Figure 67-3. Weighted shell-length size-composition of the S. polynyma stock off the north coast of the Alaska Peninsula, 1977. distribution during July and early August 1977 and 1978. Size, age, and sexual maturity Size, age, and maturity composition of the stock were assessed during the initial resource-assessment survey in 1977. That assessment was conducted within an area of 5,440 km^ representing 70 percent of the area occupied by the stock. Shell-length size compositions of 10,318 animals measured during that survey were weighted by catch magnitude and area within sampling blocks to determine a weighted size composition of the stock (Fig. 67-3). Weighted age composition (Fig. 67-4) was determined from the 1977 age-length key and the weighted shell-length composition presented above. All S. polynyma examined were dioecious. Males and females collected in July and August 1977 and 1978 were ripe, spawning, or recently spent. Some male and female animals as young as five years of age (mean shell length 63 mm) were found to be sexually active but represented only 10 percent of that age- group. All eight-year-old clams (mean shell length 83 mm) were sexually active; this was the youngest age-group fully recruited to the spawning population. Length-weight relationship and meat yield Length-weight data for males and females com- 15- 10- 5- t t t I IâIâr 4 6 I ' I 10 111 12 I â 1 I I 14 16 I 20 Age (years) Figure 67-4. Weighted age-composition of the S. poly- nyma stock
Size: 1690px × 1478px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1900, bookcollectionamericana, bookleafnumber596
