Abstract:Precise measurement of body length and morphological dimensions in whiteleg shrimp is critical for intelligent industrial aquaculture. However, practical farming environments present significant challenges, including interference from residual feed pellets, high stocking densities, mutual occlusion, and individual adhesion. These factors often lead to inaccurate keypoint localization, false positives from feed pellets, duplicate detection, and incomplete recognition of occluded individuals. To overcome these limitations, YOLO 11-Shrimp, an enhanced model for shrimp keypoint detection was proposed. Specifically, YOLO 11-Shrimp incorporated three key architectural enhancements. Firstly, standard convolutional modules within the backbone were replaced by diverse branch block (DBB)modules to enhance multi-scale feature representation. Secondly, the coordinate attention (CA)mechanism was integrated to capture long-range spatial dependencies, thereby refining keypoint localization precision. Finally, the C3k2_OREPA module was introduced into the detection head to substitute the original C3k2 structure, facilitating more robust feature fusion and representational efficiency. Experimental results demonstrated that, compared with the baseline YOLO 11-Pose model, YOLO 11-Shrimp improved PCK0. 1 by 10. 35 percentage points and PCK0. 2 by 7. 82 percentage points. Meanwhile, false detection caused by residual feed pellets were significantly reduced, and duplicate detection under dense scenes were suppressed. Also, the shrimp keypoint shift was markedly decreased, and bounding box confidence scores became more reliable. Furthermore, an automated shrimp body length estimation system was designed. When a shrimp cannot be fully detected due to occlusion, the system can automatically estimate the body length based on visible parts. The research results can provide a methodological framework for precision monitoring in smart aquaculture for whiteleg shrimp.