北部湾春季多齿蛇鲻生物学特征及其年际变化

根据北部湾渔港采样及海上调查生物学测定与数据分析，研究了北部湾多齿蛇鲻(Saurida tumbil)春季生物学特征及其年际变化。结果显示，2008~2018年春季，多齿蛇鲻个体呈小型化趋势，各年度平均体长范围为15.8~16.9 cm，平均体质量范围为48.8~77.5 g，2018年的平均体长和平均体质量比2008年分别降低了6.5%和34.5%。体长–体质量关系式中的异速生长参数b的范围为3.03~3.42，表明春季群体主要呈正异速生长状态(b>3)。性成熟体长年际变化分析表明，北部湾多齿蛇鲻存在性成熟提前的现象，雌性群体50%性成熟体长从2008年(19.0 cm)至2018年(16.6 cm)整体呈减小趋势，10年间减小比例为12.6%，其中，2011~2015年海上采样的样品对比显示，50%性成熟体长减小比例为3.8%。2008~2018年北部湾多齿蛇鲻的肥满度整体呈下降趋势，均值变化范围为1.09~1.29，渔港采样样品和海上采样样品的肥满度年际变化皆呈下降趋势。

Biological characteristics and inter-annual changes of Saurida tumbil in spring in the Beibu Gulf, South China Sea

Using data from the spring fishing port samples and bottom trawl surveys in the Beibu Gulf, the biological characteristics and inter-annual changes of Saurida tumbil were investigated. The population structure of S. tumbil in the Beibu Gulf had a miniaturization trend - the average standard length (SL) and body weight (BW) decreased from 2008 to 2018, with ranges of 15.8~16.9 cm and 48.8~77.5 g, respectively. There were also temporal variations in SL and BW; the average values decreased by 6.5% and 34.5% from 2008 to 2018, respectively. The range of the allometric parameter b was 3.03~3.42, indicating that S. tumbil had positive allometric growth (b>3) in the Beibu Gulf in spring. Analysis of the inter-annual change in length at 50% maturity (L50) in females showed that the S. tumbil population maturated before the L50, decreasing 12.6% from 2008 (19.0 cm) to 2018 (16.6 cm). Compared to 2011 (18.6 cm), the 2015 female L50 reduced by 3.8% (17.9 cm). Fatness also declined from 2008 to 2018 (range: 1.09~1.29), as evidenced by consistent downward trends in the fatness samples from both fishing methods. However, fatness had an overall increasing trend with increasing SL.