黄河口近岸海域鮻渔业生物学特征研究

Biological characteristics of Liza haematocheila in the shallow coastal waters of the Yellow River estuary

关键词:  黄河口  定置网  鮻  渔业生物学特征

Key words:  Yellow River estuary  Set nets  Liza haematocheila  Fishery biological characteristics

摘要:

为探究黄河口近岸海域鮻(Liza haematocheila)的渔业生物学特征及资源状况，本研究根据2020年4—11月黄河口渔业生产定置网的采样数据，研究了黄河口水域重要渔业种类鮻群体的体长体重分布、体长–体重关系、繁殖、生长和死亡等渔业生物学特征和开发率。结果显示，鮻体长分布范围为45~460 mm，优势体长组为55~185 mm；体重范围为2~1100 g，优势体重组为2~80 g。方差分析表明，鮻的平均体长、体重均存在显著的月间差异；各月及全年鮻的体长–体重关系均呈显著的幂函数关系，生长类型为负异速生长。黄河口近岸海域，鮻在7月肥满度最大，而6月最小；产卵盛期为4—5月。鮻的生长速率为0.31 a−1，总死亡系数为1.42 a−1，自然死亡系数估算结果为0.51 a−1，捕捞死亡系数为0.91 a−1，其开发率为0.64，鮻种群资源被过度利用。定置网渔业生产对于黄河口渔业资源有一定的破坏作用，尤其对幼鱼和补充群体资源影响较大，应对定置网渔业生产采取必要的管理措施。

Abstract:

In recent years, fishery species have decreased in size and quality in the Yellow River estuary seas due to the effects of climate change and human activities, such as water and sediment regulation of the Yellow River, overfishing, and sewage discharge, among others. At the same time, the fishery resource structure has changed greatly: Small-sized fish with low value, shrimps and crabs became the main catches. To conserve natural resources and maintain local fishery harvests, conservation efforts such as stock enhancement and fishing quotas have been employed. Research on the biological characteristics of important fish can provide a scientific basis for the rational utilization and stock enhancement of fishery resources in the future, and it can also offer support for making relevant fishery policies. Liza haematocheila is an economically important fishery species in the Yellow River estuary and mainly feeds on zooplankton, phytoplankton, and organic detritus, which limits eutrophication and promotes energy and carbon cycling at the ecosystem level. The species plays an important role in ecosystem function and the maintenance of biodiversity. This study investigated the biological characteristics of L. haematocheila to provide a scientific basis for its conservation and rational utilization in the Yellow River estuary. Furthermore, it can provide basic biological data for the study of ecological restoration in the Yellow River estuary. This study evaluated the distribution of body length and weight, the relationship between body length and weight, reproduction, growth, death, and development. All of the analyses were based on sampling data from set nets between April and November 2020. The body length range of L. haematocheila was 45~460 mm, the average body length was 149 mm, and the modal body length range was 55~185 mm. The body weight range was 2~1100 g, the average body weight was 83 g, and the modal body weight range was 2~80 g. Both the average body length and body weight were the highest in May and the lowest in September. Overall, small individuals were the most common, and individuals with a body length of less than 200 mm accounted for more than 78%. Analysis of variance showed significant monthly differences in both average body length and weight of L. haematocheila. The relationship between body length and body weight showed a strong correlation within and between months [W=3.17×10‒5L2.82, (R2=0.980 5, n=984)]. The growth of L. haematocheila was negatively allometric, with the growth of body length being faster than that of body weight. The body condition of L. haematocheila decreased with time, though it increased in July and fluctuated with a downward trend from July to November. The nadir body condition was observed in June (1.102±0.173) and the peak body condition was observed in July (1.535±0.467). The rate of gonadal development varied from month to month, and the proportion of individuals who did not reach gonadal maturity was large, with an undeveloped gonad proportion of more than 50% per month. There was a peak spawning period from April to May. The growth curve of L. haematocheila was fitted, and its growth parameters were estimated using the ELEFAN method. The total death coefficient of the population was estimated using a length-converted catch curve, the natural death coefficient was estimated using the empirical formula of Pauly, and the population development rate was calculated. The results indicated that the asymptotic length (L∞) of L. haematocheila was 608 mm, the growth rate (K) was 0.31 a−1, total death coefficient (Z) was 1.42 a−1, natural death coefficient (M) was 0.51 a−1, fishing death coefficient (F) was 0.91 a−1, and its population development rate (E) was 0.64. The L. haematocheila resource was overfished in the shallow coastal waters of the Yellow River estuary, and its open fishing length (L50) was only 57.4 mm in this production survey. Fixed-net harvesting led to overfishing in the Yellow River estuary from April to November 2020, with juvenile fish and supplementary stocks experiencing the greatest impact. We should reconsider the management strategies for L. haematocheila in the Yellow River estuary, and promote stock enhancement at the same time. Artificial propagation technology for L. haematocheila should be considered for supplementing L. haematocheila in the Yellow River estuary seas. Research on the release time, release of krill size, population characteristics, growth, and development should be addressed to provide an informed and scientific basis for stock enhancement.