Operational Plan for the Restoration of Diadromous Fishes to the ...

Table 5. Results of natural recolonization model.
Generational expansion rate = 2 Generational expansion rate = 1.5
Year Population 1 Population 2 Population 4 Year Population 1 Population 2 Population 3 Population 4
1 1,000 2,500 5,000 1 1,000 2,500 5,000 40,000
6 2,000 5,000 10,000 6 1,500 3,750 7,500 60,000
11 4,000 10,000 20,000 11 2,250 5,625 11,250 90,000
16 8,000 20,000 40,000 16 3,375 8,438 16,875 135,000
21 16,000 40,000 80,000 21 5,063 12,656 25,313 202,500
26 32,000 80,000 160,000 26 7,594 18,984 37,969 303,750
31 64,000 160,000 320,000 31 11,391 28,477 56,953 455,625
36 128,000 320,000 640,000 36 17,086 42,715 85,430 683,438
41 256,000 640,000 1,280,000 41 25,629 64,072 128,145 1,025,156
46 512,000 1,280,000 2,560,000 46 38,443 96,108 192,217 1,537,734
51 1,024,000 2,560,000 51 57,665 144,163 288,325 2,306,602
56 2,048,000 56 86,498 216,244 432,488 3,459,902
Generational expansion rate = 1.25 Generational expansion rate = 1.16
Year Population 1 Population 2 Population 3 Year Population 1 Population 2 Population 3 Population 4
1 1,000 2,500 135,000 1 1,000 2,500 135,000 225,000
6 1,250 3,125 168,750 6 1,163 2,907 156,977 261,628
11 1,563 3,906 210,938 11 1,352 3,380 182,531 304,218
16 1,953 4,883 263,672 16 1,572 3,930 212,245 353,742
21 2,441 6,104 329,590 21 1,828 4,570 246,797 411,328
26 3,052 7,629 411,987 26 2,126 5,314 286,973 478,289
31 3,815 9,537 514,984 31 2,472 6,179 333,690 556,150
36 4,768 11,921 643,730 36 2,874 7,185 388,012 646,686
41 5,960 14,901 804,663 41 3,342 8,355 451,176 751,960
46 7,451 18,626 1,005,828 46 3,886 9,715 524,623 874,372
51 9,313 23,283 1,257,285 51 4,519 11,297 610,027 1,016,712
56 11,642 29,104 1,571,607 56 5,254 13,136 709,334 1,182,223
Measure 7.1: 633,300 adult shad returns in 35-40 years
DMR next modeled restoration at two fry stocking levels (Table 6). The model
assumes one adult return for each 318 hatchery fry released and 100 adult returns
for each 86 spawning adults (intrinsic rate of increase from one generation to the
next = 1.16) based on data presented in Restoration of American Shad to the
Susquehanna River: Annual Progress Report 2000. The model indicates that 12
million fry would need to be stocked annually for 41-45 years to achieve a population
of 633,300 adults in 41-50 years.
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