夏季西南大西洋阿根廷无须鳕异尖线虫幼虫感染情况研究

阿根廷无须鳕(Merlucciushubbsi)是西南大西洋最主要的捕捞物种之一,近年来其捕捞产量持续上升,异尖线虫幼虫(Anisakidlarvae)是寄生于阿根廷无须鳕最常见的寄生虫之一,本研究为了解西南大西洋阿根廷无须鳕感染异尖线虫幼虫的情况,于2022年10月至2023年2月夏季阿根廷及马尔维纳斯群岛(福克兰群岛)专属经济区外的公海海域共捕获435尾阿根廷无须鳕,对其进行生物学实验,采集寄生虫进行形态学鉴别,最后记录数据并进行分析。结果显示, 99.08%的阿根廷无须鳕均感染异尖线虫幼虫,平均感染强度为(19.56±24.76)条/尾, 44.37%的样本鱼感染异尖线虫幼虫的数量在1～10条之间。性腺成熟度为I～IV的样本鱼感染异尖线虫幼虫的平均感染强度分别为(9.89±10.67)条/尾、(13.83±14.74)条/尾、(25.86±22.17)条/尾、(50.61±56.78)条/尾;样本鱼腹腔、肝脏和胃感染异尖线虫幼虫的平均感染强度分别为(9.20±10.01)条/尾、(8.61±13.74)条/尾、(4.34±5.10)条/尾。统计分析结果显示,性腺成熟度为IV期的样...

Infections of anisakid larvae in Merluccius hubbsi from the southwestern Atlantic Ocean in summer

Merluccius hubbsi is one of the most prominent fishing species in the southwestern Atlantic Ocean, and its catch has been increasing continuously in recent years. Owing to its delicate taste and rich nutritional value, it is very popular among nationals and is one of the major chilled fish imported in China. Anisakid larvae are one of the most common parasites of Merluccius hubbsi. Available data show that its infection rate can be as high as 90% or more, and the intensity of the infection is also high. Parasite infection not only draws nutrients from the host fish but also affects the aesthetics of the fish and reduces its economic value. This study aimed to understand the infection of M. hubbsi by anisakid larvae in the waters of the Southwest Atlantic, to perform biological experiments on M. hubbsi, to collect parasites for morphological identification, and to record and analyze the data. Samples for this study were collected from sampling sites in open ocean waters outside the exclusive economic zone of Argentina and the Malvinas Islands during the summer months of October 2022 to February 2023, with a total of 435 individuals. The results showed that the infection rate of M. hubbsi infected by anisakid larvae was 99.08% and the mean intensity of infection was (19.56±24.76) fish/tail. The higher the sexual maturity of M. hubbsi, the higher the mean intensity of infection of anisakid larvae was; the mean intensity of infection of anisakid larvae was as high as (50.61±56.78) fish/tail when sexual maturity was stage IV. The sites of infection of anisakid larvae were the abdominal cavity, liver, and stomach. The infection intensity of anisakid larvae was significantly higher in the abdominal cavity and liver than at other sites (P＜0.05). This study showed that the abundance and intensity of M. hubbsi infection by anisakid larvae in the Southwest Atlantic was high, which was related to the stable ecosystem of its living sea area, large host population size, and suitable environment for survival. As the host matures, the range and number of feeding objects increase, and the parasite accumulates in the host during this process; it mainly parasitizes the abdominal cavity where the environment is suitable and the area of parasitism is large, and the liver and stomach, which have high nutritional value, are suitable for its growth, development, and stable parasitism. In summary, the number of M. hubbsi infected with anisakid larvae was related to sexual maturity and different infection sites in the sample fish, and the number of infections was correlated with fork length and body weight. This study provides a basis for understanding the growth characteristics and factors influencing anisakid larval infection of M. hubbsi.