Add Maximum Sustainable Yield and Fishery Collapse lecture (#763)

* Add Maximum Sustainable Yield and Fishery Collapse lecture (#755)

New lecture lectures/msy_fishery.md, slotted under Nonlinear Dynamics
after solow. Builds the deterministic Schaefer MSY model (logistic
growth, 45-degree diagrams, sustainable yield, MSY via grid search and
optional calculus), then adds environmental randomness to show why a
constant MSY quota sits on a knife-edge and collapses, versus a
self-correcting constant-effort policy. Includes the Peruvian anchovy
and Atlantic cod collapses, plus exercises on precautionary quotas and
large-r logistic chaos.

Adds schaefer1954, gordon1954, may1976, clark1990 to quant-econ.bib.

Closes #755

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Revise MSY lecture: rename effort to e, yield to y*(e), add early graphic

- Rename effort symbol E -> e and sustainable yield Y(E) -> y*(e)
  throughout prose, math, and code, matching the x*(e) notation.
- Introduce y*(e) graphically with a growth-vs-harvest figure right
  where it is defined, marking x*(e) and y*(e) at effort e=20.
- Shrink the two 45-degree diagrams by 10% (figsize 5.5 -> 4.95).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Implement TODOs in revised first half of MSY lecture

- Add a figure showing the shape of the logistic growth curve G(x);
  move the G definition above it.
- Refactor plot_45 to take the one-year map as a function argument, so
  the no-fishing 45-degree diagram works before fishing/effort and the
  update() function are introduced; update both call sites to pass
  lambdas.
- Add the two-effort 45-degree diagram (staircases omitted) showing
  x*(e) falling with effort.
- Fix the multi-effort growth-vs-harvest figure: use explicit efforts
  [12.5, 25, 37.5] and G(K/2) for the y-limit (e_msy/MSY are not yet
  defined there), and fix the label typo.
- Restore the grid-search computation of e_msy, MSY, x_msy in the MSY
  section.
- Drop the under/over-fishing framing from the yield-effort curve per
  review note, since under randomness no constant policy is fully safe.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Align MSY lecture with QuantEcon style guide; fix two typos

Following manual/styleguide (figures.md, math.md, references.md):

- Remove all embedded matplotlib titles (ax.set_title / fig.suptitle)
  and add mystnb figure captions + names to every figure cell.
- Keep the figure box: drop all ax.spines[...].set_visible(False).
- Standardize data-line widths to lw=2; drop figsize from standard
  single-panel charts (keep square figsize on the cobweb diagrams and
  the stacked stochastic panel as justified exceptions).
- Label the two policy panels with in-axes text rather than titles.
- Use {cite:t} for in-sentence citations (Schaefer/Gordon/Clark,
  Following Schaefer, analyzed by May); keep {cite} for parenthetical.
- Fix typos: "according the" -> "according to the"; "called
  intrinsic" -> "called the intrinsic".

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Reflow msy-policies figure caption

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Fix LaTeX PDF build: drop figure floats inside solution blocks

The mystnb figure captions on the two code-cells inside the
{solution-start}/{solution-end} dropdowns produced LaTeX figure floats
nested in a directive, triggering "! LaTeX Error: Not in outer par
mode." Per the admonitions style guide (use image, not figure floats,
inside exercise/solution directives for PDF builds), remove the caption
metadata from those two solution cells; the top-level captioned figures
are unaffected. Verified with a local pdflatex build (24-page PDF, no
error).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Restructure MSY lecture around quotas; fix yield-effort build break

Reframe as "Fishery Management: Quotas and MSY": compute the MSY after
introducing the yield-effort dome, add Dynamics and Adding randomness
subsections, list x/r/K under the growth equation, and credit the
"Maths from the past" discussion.

Fix the reorder regression: the yield-effort figure referenced MSY in
set_ylim before MSY is computed (NameError); use y_grid.max() instead.
Also fix two typos ("sevaral" -> "several"; missing question mark).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Add MSY success story: Pacific Coast lingcod recovery

Insert a new section before "Randomness, risk and collapse" so the
lecture shows MSY-based management working before discussing its
failures. Uses RAM Legacy Stock Assessment Database series for U.S.
Pacific Coast lingcod (B/B_MSY and F/F_MSY, 1928-2009): sustained
overfishing drives biomass to ~0.27 B_MSY, then an MSY-anchored
rebuilding plan (overfished 1999, rebuilt 2005) pulls F below F_MSY and
biomass recovers and overshoots -- the model's negative feedback in real
data. Includes honest caveats that tee up the randomness section.

Vendor the small series as datasets/lingcod_msy_recovery.csv (read
locally, no build-time download); add pandas import and the ricard2012
bib entry.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Use default color cycle for data series; minor prose/tense fixes

Per QuantEcon convention, let matplotlib pick data-series colors (C0/C1
standard pair) instead of hard-coding C0/C3; reserve explicit color for
reference elements only (black 45-degree line/cobweb/markers/guides,
grey milestone lines). Markers now follow their line via get_color().
Lingcod overfishing band switched from red to neutral grey.

Also fold in the user's prose edits (overview rewording, G(x)
definition, hide-input on plot_45, simplified update equation, tightened
lingcod narrative) and fix a past/present tense slip in that narrative.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: jstac

lectures/_static/quant-econ.bib

@@ -2917,3 +2917,54 @@ @incollection{sargent1989least
   year={1989},
   publisher={Cambridge University Press}
 }
+
+@article{schaefer1954,
+  title={Some aspects of the dynamics of populations important to the management of the commercial marine fisheries},
+  author={Schaefer, Milner B.},
+  journal={Bulletin of the Inter-American Tropical Tuna Commission},
+  volume={1},
+  number={2},
+  pages={23--56},
+  year={1954}
+}
+
+@article{gordon1954,
+  title={The economic theory of a common-property resource: the fishery},
+  author={Gordon, H. Scott},
+  journal={Journal of Political Economy},
+  volume={62},
+  number={2},
+  pages={124--142},
+  year={1954},
+  publisher={University of Chicago Press}
+}
+
+@article{may1976,
+  title={Simple mathematical models with very complicated dynamics},
+  author={May, Robert M.},
+  journal={Nature},
+  volume={261},
+  number={5560},
+  pages={459--467},
+  year={1976},
+  publisher={Nature Publishing Group}
+}
+
+@book{clark1990,
+  title={Mathematical Bioeconomics: The Optimal Management of Renewable Resources},
+  author={Clark, Colin W.},
+  edition={2nd},
+  year={1990},
+  publisher={Wiley}
+}
+
+@article{ricard2012,
+  title={Evaluating the knowledge base and status of commercially exploited marine species with the {RAM} Legacy Stock Assessment Database},
+  author={Ricard, Daniel and Minto, Coilin and Jensen, Olaf P. and Baum, Julia K.},
+  journal={Fish and Fisheries},
+  volume={13},
+  number={4},
+  pages={380--398},
+  year={2012},
+  publisher={Wiley}
+}

lectures/_toc.yml

@@ -47,6 +47,7 @@ parts:
   chapters:
   - file: scalar_dynam
   - file: solow
+  - file: msy_fishery
   - file: cobweb
   - file: olg
   - file: commod_price

lectures/datasets/lingcod_msy_recovery.csv

@@ -0,0 +1,83 @@
+year,B_over_Bmsy,F_over_Fmsy
+1928,3.859289617,0.12815534
+1929,3.842213115,0.177669903
+1930,3.825136612,0.198058252
+1931,3.790983607,0.19223301
+1932,3.756830601,0.142718447
+1933,3.756830601,0.224271845
+1934,3.705601093,0.14368932
+1935,3.705601093,0.170873786
+1936,3.671448087,0.133009709
+1937,3.671448087,0.173786408
+1938,3.654371585,0.146601942
+1939,3.637295082,0.127184466
+1940,3.637295082,0.145631068
+1941,3.637295082,0.117475728
+1942,3.637295082,0.067961165
+1943,3.654371585,0.131067961
+1944,3.654371585,0.132038835
+1945,3.654371585,0.130097087
+1946,3.637295082,0.216504854
+1947,3.603142077,0.430097087
+1948,3.50068306,0.462135922
+1949,3.398224044,0.413592233
+1950,3.31284153,0.45631068
+1951,3.227459016,0.453398058
+1952,3.142076503,0.350485437
+1953,3.090846995,0.246601942
+1954,3.073770492,0.290291262
+1955,3.056693989,0.308737864
+1956,3.039617486,0.355339806
+1957,3.005464481,0.526213592
+1958,2.920081967,0.539805825
+1959,2.851775956,0.466990291
+1960,2.800546448,0.417475728
+1961,2.74931694,0.449514563
+1962,2.698087432,0.386407767
+1963,2.663934426,0.391262136
+1964,2.629781421,0.340776699
+1965,2.612704918,0.413592233
+1966,2.578551913,0.518446602
+1967,2.527322404,0.57961165
+1968,2.476092896,0.612621359
+1969,2.407786885,0.575728155
+1970,2.339480874,0.850485437
+1971,2.237021858,1.077669903
+1972,2.117486339,1.563106796
+1973,1.929644809,1.766990291
+1974,1.741803279,1.951456311
+1975,1.572745902,1.951456311
+1976,1.449795082,2.077669903
+1977,1.321721311,1.485436893
+1978,1.270491803,1.941747573
+1979,1.166325137,2.718446602
+1980,1.00068306,3.378640777
+1981,0.840163934,3.378640777
+1982,0.712090164,3.504854369
+1983,0.594262295,2.67961165
+1984,0.544740437,2.805825243
+1985,0.488387978,3.951456311
+1986,0.403005464,3.854368932
+1987,0.37568306,4.019417476
+1988,0.37397541,4.310679612
+1989,0.358606557,4.834951456
+1990,0.3125,4.553398058
+1991,0.285177596,4.32038835
+1992,0.268101093,4.174757282
+1993,0.256147541,3.485436893
+1994,0.266393443,2.27184466
+1995,0.315915301,2.019417476
+1996,0.365437158,2.038834951
+1997,0.396174863,1.815533981
+1998,0.425204918,1.300970874
+1999,0.479849727,1.398058252
+2000,0.539617486,0.63592233
+2001,0.650614754,0.49223301
+2002,0.800887978,1.029126214
+2003,0.988729508,1.291262136
+2004,1.243169399,0.195145631
+2005,1.656420765,0.261165049
+2006,2.083333333,0.249514563
+2007,2.510245902,0.144660194
+2008,2.885928962,0.093203883
+2009,3.193306011,