FA-65615 / Ecological population dynamics / Member archive

Baranov catch and age-structured survival: plus group · case 05

Old fish disappear from the stock after one year in the oldest class.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Z_a = F_a + M; catch_a = F_a/Z_a*N_a*(1-exp(-Z_a)) (0 when Z=0); survivors N_a*exp(-Z_a) age one year; the last class is a plus group; next year starts with recruits at age 0; return [catch rounded 3, next vector rounded 3, total catch rounded 3]; at least two age classes.

Why this case matters

Population projections set harvest quotas, conservation status and pest-control timing; a wrong update order, boundary or rate conversion silently changes management advice.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: haddock four ages	`[[86.394, 141.649, 107.875, 53.937], [900.0, 740.818, 363.918, 148.976], 389.855]`	`[[86.394, 141.649, 107.875, 53.937], [900.0, 740.818, 363.918, 223.463], 389.855]`	Failed

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