{ "version": "1.0.0", "checked": "2026-10-21", "scope": "Atchafalaya Basin largemouth-bass size-limit history and evidence. This is an attributed synthesis of agency reports and published research, not a reanalysis of raw fish records.", "timeline": [ { "year": "1992–1993", "label": "Emergency protection after the fish kill", "detail": "After Hurricane Andrew caused a major fish kill and bass were stocked, a 14-inch minimum length rule was adopted to protect surviving and stocked bass and allow spawning before harvest.", "source": "LDWF Atchafalaya Basin Management Plan (2023), regulation history; LDWF March 4, 1993 commission minutes", "url": "https://www.wlf.louisiana.gov/assets/Resources/Publications/Freshwater_Inland_Fish/Inland-Waterbody-Management-Plans/Atchafalaya-Basin-MP-B-2023.pdf" }, { "year": "1997", "label": "Temporary rule becomes permanent", "detail": "LDWF says the minimum length limit was renewed without a sunset clause, with popular support. The original emergency recovery rationale had become a continuing management policy.", "source": "LDWF Atchafalaya Basin Management Plan (2023)", "url": "https://www.wlf.louisiana.gov/assets/Resources/Publications/Freshwater_Inland_Fish/Inland-Waterbody-Management-Plans/Atchafalaya-Basin-MP-B-2023.pdf" }, { "year": "2010–2011", "label": "Preference and population evidence diverge", "detail": "An LDWF mail survey received 663 questionnaires. A contemporaneous Louisiana Sea Grant summary reported support among respondents for keeping the 14-inch minimum and 10-fish daily limit. LDWF's biological evaluation separately concluded the 14-inch minimum was ineffective for increasing larger bass.", "source": "LDWF 2010 Atchafalaya, Henderson and Verret Black Bass Survey; LDWF 14-inch evaluation; Louisiana Sea Grant Lagniappe (August 2011)", "url": "https://www.wlf.louisiana.gov/assets/Resources/Publications/Freshwater_Inland_Fish/2010_Atchafalaya_Henderson_and_Verret_Black_Bass_Survey.pdf" }, { "year": "2013–2015", "label": "The 14-inch minimum is repealed", "detail": "A later Louisiana study-group report records that the 14-inch minimum was repealed effective June 20, 2013; a seven-fish daily limit was in effect for two years, then the statewide 10-fish daily limit applied. This was a bundled policy change, not an isolated test of length limit alone.", "source": "Louisiana Senate Concurrent Resolution 154 study-group report", "url": "https://www.dnr.louisiana.gov/assets/OCM/ABP/SR154.ReportA.pdf" }, { "year": "1987–2009 data; published 2011", "label": "Flood-pulse timing is linked to bass abundance", "detail": "A peer-reviewed basin-wide analysis found age-one bass proportions associated with the previous year's flow magnitude and age-two proportions associated with flood magnitude two years before sampling. That lag complicates simple rule-versus-year comparisons.", "source": "Alford (2011), River Research and Applications, doi:10.1002/rra.1610", "url": "https://doi.org/10.1002/rra.1610" }, { "year": "2005–2022", "label": "A long, variable monitoring record", "detail": "LDWF reports fall electrofishing relative-weight observations for 4,326 largemouth bass across 2005–2022. Its management plan also says the 1991–2008 age/length evaluation did not show the 14-inch rule increasing the number of larger fish. The released aggregate is not a raw annual size-structure table.", "source": "LDWF Atchafalaya Basin Management Plan (2023), Figures 5–6 and age/growth discussion", "url": "https://www.wlf.louisiana.gov/assets/Resources/Publications/Freshwater_Inland_Fish/Inland-Waterbody-Management-Plans/Atchafalaya-Basin-MP-B-2023.pdf" }, { "year": "2026-08-01", "label": "A new rule takes effect in a defined area", "detail": "Act 460 sets a 12-inch minimum total length and five black bass per day within its specified geographic boundary. The new package has been in effect only since August 1, 2026; this review contains no post-change biological evaluation.", "source": "Louisiana Act 460 / SB 111 and official legislative effective-date record", "url": "https://legis.la.gov/Legis/ViewDocument.aspx?d=1480143" } ], "reported_observations": [ { "measure": "Mean age at which Atchafalaya largemouth bass reached 14 inches total length", "value": "3.4 years", "period_or_scope": "LDWF 14-inch evaluation; agency report summary", "interpretation": "Reported by LDWF; not recalculated here." }, { "measure": "Age structure", "value": "Seldom reached five years", "period_or_scope": "LDWF 14-inch evaluation; agency report summary", "interpretation": "Reported by LDWF; not an annual survival estimate." }, { "measure": "Fall electrofishing relative-weight observations", "value": "n = 4,326", "period_or_scope": "2005–2022", "interpretation": "Fish count for the plan's relative-weight series; not 4,326 independent regulation experiments or a count of trophy bass." }, { "measure": "Flood-stage duration linked to optimized annual relative abundance in Alford's model", "value": "121–157 days per year at Butte LaRose stage ≥3.6 m", "period_or_scope": "1987–2009 basin-wide analysis", "interpretation": "Model result reported in the paper abstract; this is not a fishing forecast or rule threshold." } ], "creel_patterns": [ { "period": "1989–1991", "label": "Before the 14-inch minimum", "no_catch_percent": 17.3, "released_all_percent": 37.1, "harvested_and_released_percent": 36.0, "harvested_only_percent": 9.6 }, { "period": "1996–2009 survey years", "label": "14-inch minimum in force", "no_catch_percent": 18.3, "released_all_percent": 50.9, "harvested_and_released_percent": 28.8, "harvested_only_percent": 2.0 }, { "period": "2013–2014 (18 months)", "label": "After 14-inch minimum removal", "no_catch_percent": 22.8, "released_all_percent": 34.2, "harvested_and_released_percent": 25.7, "harvested_only_percent": 17.3 }, { "period": "2019", "label": "Five-year follow-up", "no_catch_percent": 16.4, "released_all_percent": 37.7, "harvested_and_released_percent": 37.7, "harvested_only_percent": 8.2 } ], "derived_creel_contrasts_percentage_points": [ { "comparison": "14-inch-rule survey years minus pre-rule survey years", "measure": "Anglers releasing every bass caught", "difference": 13.8, "interpretation": "Our subtraction of LDWF's rounded Figure 16 percentages; descriptive, not a causal effect estimate." }, { "comparison": "14-inch-rule survey years minus pre-rule survey years", "measure": "Anglers harvesting bass without releasing any", "difference": -7.6, "interpretation": "Our subtraction of LDWF's rounded Figure 16 percentages; descriptive, not a causal effect estimate." }, { "comparison": "2019 follow-up minus 2013–2014 survey", "measure": "Anglers harvesting bass without releasing any", "difference": -9.1, "interpretation": "Our subtraction of LDWF's rounded Figure 16 percentages; this behavioral category was closer to the pre-rule value in 2019." } ], "limits": [ "The 2011 evaluation and the 2023 plan's cited age/length period overlap; they are not independent replications.", "The 2005–2022 relative-weight count is an aggregate condition series, not a downloadable annual age/length dataset or a causal test of the 2026 rule.", "Creel Figure 16 percentages classify interviewed anglers by whether they caught no bass, released all, both harvested and released, or harvested only. They are behavior categories, not fish-level catch rates or size distributions; source sample sizes and uncertainty intervals were not available in the indexed excerpt.", "The 2013 size-limit repeal coincided with a temporary daily-bag change, and the 2026 law changes both size and daily harvest limits.", "Flood magnitude, water levels, storms, oxygen events, recruitment and fishery sampling all vary among years and can confound before/after comparisons.", "The direct LDWF 2011 and 2023 PDF endpoints returned access errors during this review. Exact statements are attributed to agency reports as exposed in official indexed text; complete methods, tables and figure data were not independently audited.", "This analysis concerns largemouth bass evidence. Act 460 applies to black bass (Micropterus spp.) and hybrids in its statutory area." ] }