## 4 Discussion
### The Relationship Between the Habitat Area of Antarctic Krill, the Fishing Duration, and the Catch  
It is generally believed that high-quality habitat has a positive promoting effect on the inhabitation and reproductive activities of fishery populations. Specifically, there is a close correlation between the area of high-quality habitat and the abundance of resources. Generally speaking, the larger the area of high-quality habitat, the higher the abundance of resources tends to be; conversely, if the area of high-quality habitat decreases, the abundance of resources will decrease accordingly ([PERSON], 2018). And fishing operations carried out in areas with high resource abundance usually can catch higher fishing production. As a kind of large zooplankton, krill has obvious clustering characteristics [50] and a relatively high resource density [48]. Its resource distribution and fishing production will inevitably be affected by the suitable habitat areas of different habitats. However, there is a severe lack of relevant research on this impact effect at present. This study found that there are different relationships between the area of different suitability regions and production. By fitting the area of the unsuitable habitat zone and the production, it was found that there is a negative correlation between them. From the perspective of the \(p\) value and \(R^{2}\), there is no significant relationship, and the fitting relationship is poor. But there is a probability that when the area of the unsuitable habitat zone increases, the production decreases. And at the end of the fishing season, the area of the unsuitable habitat zone increases significantly (Figure 6a), because the vessels gradually leave the fishing ground, resulting in a decrease in the area of the suitable habitat zone. The fitting of the areas of the low, medium, and high suitable habitat zones to the production shows a positive correlation. However, the \(p\) value and \(R^{2}\) also perform poorly. There is a probability that when the area increases, the production also increases. At the end of the fishing season, the area of the suitable habitat zone decreases significantly (Figure 6b,c). These conclusions indicate that although the habitat area can reflect the level of krill production indirectly, it cannot accurately predict the specific fishing volume level. It reflects that it is still very difficult to quantify the future production level of krill based on the fishing effort of the habitat area. In contrast, there is a significant positive correlation between the fishing duration and the production. The \(p\) value and \(R^{2}\) perform well, indicating that the fishing duration is an important factor affecting the fishing production. The extension of fishing operation time can significantly increase the production [51]. A longer fishing operation time means that the fishing vessels increase the probability of encountering krill groups, and at the same time, they can obtain more catches during the period when krill are concentrated, which is intuitively reflected in the final fishing production data [34]. This reflects that the continuity and input degree of fishing activities have a direct impact on the fishing of krill resources [52]. There is a negative correlation between the non-fishing duration and the production, but both the \(p\) value and \(R^{2}\) perform poorly, and the relationship with the production is not significant. In general, the significant positive correlation between the fishing duration and the production indicates that extending the fishing operation time is an effective way to increase the krill production [50]. Therefore, future krill fishing management can focus on the optimization of the fishing duration, and then scientifically and reasonably plan the time arrangement of fishing operations to ensure that fishing vessels can efficiently go to areas with high resource density for fishing activities within a given and relatively limited time range.