基于多元变量的南极磷虾拖网作业状态影响因素分析

拖网作业过程中的网位、网身状态、拖网整体状态是评价拖网性能优劣的重要指标。以南极磷虾拖网为例，通过测量拖网不同部位（上纲、第3~4节网身连接处和网囊口上部中点）深度，以部位间深度差表示拖网作业状态，分析捕捞操作、海洋环境和渔获量对拖网作业状态的影响，确定中层拖网作业过程中状态的变化趋势。结果表明：（1）上纲与第3~4节网身连接处深度差范围为-0.20~8.02 m，上纲与网囊口上部中点深度差范围为6.49~30.16 m；（2）曳纲长度、拖速、风速、150 m水层流速对磷虾拖网上纲深度影响显著（P< 0.05）；上纲深度与曳纲长度和150 m水层流速呈正相关关系，与拖速呈负相关关系，随风速增加，上纲深度先减小后增大；（3）拖速、200 m水层流速和浪高对上纲与第3~4节网身连接处深度差影响极显著（P< 0.05）；上纲与第3~4节网身连接处深度差具有随拖速和200 m水层流速的增加，先增大后减小的趋势；其中拖速2.6 kn和200 m水层流速0.3 kn时，上纲与网囊口上部中点深度差最大，2 m浪高时，深度差最小；（4）渔获量与上纲和网囊口上部中点深度差呈正相关关系；（5）曳纲长度是影响拖网作业状态的最重要因素，其次是拖网速度、风速、浪高和水流速度。

Factors influencing the trawling status of Antarctic krill fishery based on multivariate analysis

The net position, net body status and overall status of trawl are important indices to evaluate the trawling performance during trawling operation. The trawl operation status of an Antarctic krill trawl is expressed by the depth difference between the different parts of the trawl (headline, section 3-4 net body connection, upper midpoint of the cod-end mouth). In order to determine the trawling status of midwater trawl, the effects of fishing operations, marine environment and catch on the status of trawling operations were investigated in this study. The results show that: (1) The depth difference between the headline and the section 3-4 net body connection range from -0.20 to 8.02 m, and the depth difference between the headline and the upper midpoint of the cod-end mouth range from 6.49 to 30.16 m; (2) Warp length, towing speed, wind speed and water velocity at 150 m depth have significant effects on the depth of the headline (P< 0.05); The headline depth is positively correlated with the warp length and water velocity at 150 m depth; There is a negative correlation between the headline depth and towing speed, and the headline depth decreases first and then increases with the increase of wind speed; (3)Towing speed, water velocity at 200 m depth and wave height have significant effects on the depth difference between the headline and the section 3-4 net body connection(P< 0.05); The depth difference between the headline and the section 3-4 net body connection increase first and then decrease with the towing speed and water velocity at 200 m; When the towing speed is 2.6 kn and the water velocity at 200 m is 0.3 kn, the depth difference between the headline and the section 3-4 net body connection is the largest, and the depth difference is the smallest when the wave height is 2 m; (4) The catch is positively correlated with the depth difference between the headline and upper midpoint of the cod-end mouth; (5) Warp length is the most important factor affecting the status of trawling operations, followed by towing speed, wind speed, wave height, and water flow velocity.