The small yellow croaker (Larimichthys polyactis) is a vital fishery resource in the southern Yellow Sea and East China Sea, yet data limitations have long hindered its robust assessment. We integrated three length-based methods—LIME, LBSPR, and LBB—to evaluate stock status using discontinuous length-frequency data spanning 1960–2024, supported by Monte Carlo sensitivity analyses. Our findings reveal a severe historical decline: the population was healthy in the 1960s, became overexploited by the mid-1980s, and has faced chronic overexploitation or near-collapse since 2000. Although all models confirmed significant depletion, LIME provided more optimistic status estimates than LBSPR and LBB. Sensitivity analyses identified natural mortality (M) as the primary driver of uncertainty in LIME, while asymptotic length (L_∞) most strongly influenced LBSPR and LBB. This study highlights a critical state of overfishing and demonstrates that a multi-method framework, combined with systematic sensitivity testing, provides a more reliable scientific basis for size-based management and the sustainable recovery of data-limited stocks.