[Microplastics in the stomach and intestine of pelagic squid: A case study of Dosidicus gigas in open sea of Peru]. / å¤§æ´‹æ€§å¤´è¶³ç±»èƒƒå’Œè‚ é“ä¸­çš„å¾®å¡‘æ–™­­ä»¥ç§˜é²å¤–海茎柔鱼为例.

Microplastic (MP) ingestion by marine animals has been well documented, but less being known about pelagic squid. Jumbo squid Dosidicus gigas supports the world's largest cephalopod fishery and plays an important ecological role in the Eastern Pacific Ocean. In this study, D. gigas taken from the open sea of the Peruvian Exclusive Economic Zone were selected as research objects. We estimated the abundance and characteristics of MPs in the stomach and intestine of D. gigas and investigated the differences between tissues and sexes. Similar abundance and characteristics of MPs were observed in the same tissue of females and males. However, the stomach had a higher abundance of MPs with larger size than the intestine, while the MP abundance by stomach wet weight was lower than that of the intestine. The MPs were predominantly fiber-shaped, with blue or black color. The most frequent polymers were high-density cellophane and polyacrylic acid. These polymers could sink into deeper sea layers and were available for D. gigas living there during the daytime. Our findings revealed the distribution pattern of MPs in the waters of the Peruvian fishing ground. This study could improve our understanding of the MP contamination level in pelagic squid, and have implications for evaluating the ecological effects of MP on cephalopods.

[A study on feeding ecology and migration patterns of Dosidicus gigas off Peru using stable isotope analysis].

As a pelagic cephalopod and one of the main target species of Chinese distant water fishery, jumbo squids (Dosidicus gigas) play a major role in the marine ecosystems of the eastern Pacific. Understanding the feeding ecology and migration patterns of jumbo squids is of importance for better utilizing the resources. The isotopic signatures of gladius, have been proved to be a powerful tool to reveal high resolution and ontogenic variations in individual foraging strategies of squids; which is an archival tissue with no elemental turnover after formation. In this study, the growth equation of gladius proostracum was established based on the age information determined by statolith. Gladius was cut successionally by the growth curve of gladius proostracum, the stable isotopic values of the gladius profiles were determined, and the feeding ecology and migration patterns of jumbo squids during its growth process were investigated. Results showed that the jumbo squids began to migrate after 180 days of postnatal, and their trophic levels tended to decrease throughout the life span. These results demonstrated the feasibility of using continuous sampling hard tissue to study the feeding ecology and habitat transfer of jumbo squids.

[Stock assessment and management for Illex argentinus in Southwest Atlantic Ocean based on Bayesian Schaefer model].

Abstract: Bayesian Schaefer model was applied to assess the stock of Illex argentinus in the Southwest Atlantic Ocean, with the risk of alternative management strategies for the squid analyzed. Under the scenarios of normal and uniform prior assumptions, the estimated model parameters and reference points were similar, and higher than the values under the scenario of logarithmic normal prior assumption. Under the three proposed scenarios, the fishing mortalities and the total catches in 2001-2010 were lower than the reference point F0.1 and the maximum sustainable yield (MSY), indicating that the I. argentinus was in an expected sustainable exploited level but not in over-fishing and over-fished. The results of decision analysis indicated that at the same harvest rate, the stock of the I. argentinus under the scenario of logarithmic normal prior assumption in 2025 would be the lowest, and the probability of collapse would be the highest. Under the three scenarios, the harvest rate in 2025 would be all 0.6 if the catch was the maximum. However, if the harvest rate was set to 0.6, the stock of the I. argentinus after 2025 would have definite risk, and thus, the harvest rate 0.4 and the catch 550000 t appeared to be the best management regulation or the baseline case.