# Temporal and Spatial Variation Characteristics of the Fish Biomass Particle-Size Spectra in the Shandong Province Area of the Yellow River

## TL;DR

This study analyzed seasonal and spatial changes in fish biomass in the Yellow River's Shandong section, finding that human activities like overfishing are stressing fish populations and reducing stability.

## Contribution

The study provides new insights into seasonal and spatial variations in fish biomass particle-size spectra and their implications for sustainable fishery management.

## Key findings

- Fish biomass particle-size spectra showed significant seasonal and spatial variations in the Yellow River's Shandong section.
- Human activities, especially overfishing, are causing a shift toward smaller, fast-growing fish species and reducing community stability.
- The estuary area had the least external disturbance and supported larger fish species compared to upstream regions.

## Abstract

This study examined changes in fish communities in the Shandong section of the Yellow River from summer 2022 to spring 2023. Small fish dominated in the spring and summer, medium fish in autumn, and large fish in winter. Upstream areas had more small fish, while the estuary, with fewer disturbances, supported larger species. Human activities, especially overfishing, caused severe stress on fish populations, shifting them toward smaller, fast-growing species and reducing stability. This research highlights the need to protect fish populations and offers insights for the sustainable management of Yellow River fish resources, benefiting biodiversity, food security, and local livelihoods.

Based on the data from a continuous fishery resource survey conducted in the Shandong province area of the Yellow River from the summer and autumn of 2022 to the winter and spring of 2023, this study constructed fish biomass particle-size spectra. It compared and analyzed the differences in the characteristics of the fish biomass particle-size spectrum parameters across four different seasons in various survey areas. The results indicated that the fish biomass particle-size spectra in the Shandong province area of the Yellow River exhibited significant seasonal and spatial variations. Overall, the shape of the Sheldon-type biomass particle-size spectra across the four seasons showed a unimodal pattern. The peak values in spring and summer ranged between 32–64 g, while in autumn, it reached 64–128 g, and in winter, it was 1024–2048 g. The dominant species shifted from small individuals in spring and summer to larger individuals in autumn and winter. The fitted curves of the standardized biomass particle-size spectra for the four seasons displayed a dome-shaped parabola, generally arranged from high to low in the biomass particle-size spectra lines from spring to winter, with winter experiencing the least external disturbance. In terms of the regional distribution, the peak particle-size classes for fish in the areas of Gaocun, Dong’a, and Gaoqing all corresponded to the particle-size class of 16–32 g, predominantly featuring small fish species such as Carassius auratus and Pseudobrama simoni. In contrast, the peak particle-size class in the estuarine waters corresponded to 512–1024 g, mainly comprising larger fish species like Cyprinus carpio, Hypophthalmichthys molitrix, and Liza haematocheila. The differences in the standardized biomass particle-size spectra among the four regions were not significant, but the curvature of the estuarine waters was the highest, indicating the least external disturbance. The abundance–biomass comparison (ABC) curve suggested that the fish community in the Shandong province area of the Yellow River is in a severely disturbed state.