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Update slide deck
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quang-huynh committed Oct 11, 2024
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Expand Up @@ -830,7 +830,7 @@ Age-structure incorporates lags in stock response to exploitation pattern (selec

Low fecundity limits stock productivity. Example to illustrate:

Imagine an unfished population N = 100 adults, which produce 10 pups/adult, that's 1,000 pups (B0).
Imagine an unfished population N = 100 adults, which produce 10 pups/adult, that's 1,000 pups (B0). If pup survival to recruit life stage is 0.6, then we have 600 recruits (R0).

A population of N = 20 (0.2 B0) produces 200 pups. If steepness were 1 in a closed population, we'd have to conjure 600 recruits from 200 pups.

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Demonstration of the lagged effects on the age structure of the population.
Oscillations in age classes demonstrate of the lagged effects in the population.

Early Vitamin A fishery fished out older animals (age 30+), population recovered from younger animals (20+) invulnerable to the fishery.
Early Vitamin A fishery fished out older animals (age 30+), population recovered from younger cohorts invulnerable to the fishery.
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Estimated steady decline in population biomass

Due to differences in selectivity & maturity: declines after vitamin A fishery, subsequent recovery, and another decline
Different trend in spawning output (due to differences in selectivity & maturity): declines after vitamin A fishery, subsequent recovery, and another decline
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- Stock-recruit productivity parameter $z_\textrm{frac}$ determines height of the yield curve (2023 selectivity of discard)
- Stock-recruit productivity parameter $z_\textrm{frac}$ determines height of the yield curve (2023 selectivity, primarily discards)
- Can provide upper bound on what is plausible
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Expand All @@ -1113,10 +1113,6 @@ include_graphics("../figs/ss3/retro/ret_A0.png")
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# MCMC sampling

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class: center, middle, inverse
# Reference Points
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## Challenges fitting some population indices

- Not possible to simultaneously obtain a good fit to all three modern indices

- Synoptic survey believed to target preferred Dogfish habitat (muddy bottom) but IPHC index is more precise (mixed substrates)

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## Perception of depletion was relatively robust

- Estimated current status is inferred from the decline in indices in light of low catches relative to historical levels.


- Low fecundity limits the range of potential historical population trajectories among the sensitivity scenarios

- TODO

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