The time series of relative abundance and age structure from the Ross Sea shelf survey provides information about year class strength, variability, and autocorrelation, and hence is an important input into the Ross Sea stock assessment.
The objectives of the survey were to (i) continue monitoring trends in Antarctic toothfish (Dissostichus mawsoni) recruitment in the southern Ross Sea (core strata A–C); (ii) continue monitoring trends in abundance of larger (large sub-adult and adult) toothfish and biological characteristics in two areas of importance to predators: McMurdo Sound and Terra Nova Bay in alternate years; and (iii) collect and analyse a wide range of data and samples from these areas (e.g., demersal fish, benthic invertebrates, stomach and tissue samples, acoustic data), which will contribute to the Research and Monitoring Plan for the Ross Sea region MPA.
The estimated relative biomass index of toothfish showed an increase to the second highest in the survey time series in 2021. Biological data and samples were collected from more than 3,100 toothfish; samples and measurements were also collected on bycatch species. A total of 268 toothfish were tagged and released with an 89.6% tagging length overlap statistic. The catch limit of 65 t was not exceeded, mainly because catches in Terra Nova Bay were lower than in previous years. Collected toothfish otoliths were aged and included in the 2021 stock assessment.
Abstract:
This paper examined eggs and larval transport pathways of Antarctic Toothfish under extreme Southern Annual Mode (SAM) events in the continental slope-shelf regions of East Antarctica using a particle tracking model. Ocean currents datasets were calculated using a coupled ocean-sea ice-shelf model output “COCO.” Model simulation results indicated transport pathways of particles released from the east side slopes in the East Antarctic regions were different between the positive and negative SAM phases. While the Antarctic slope current (ASC) generally prevailed southwestward transports of particles from slopes to inner shelves regardless of release regions under both extreme SAM events, particles released from the northeast slopes were transported offshore by the Antarctic Circumpolar Current (ACC) or inner shelves by the combination of ACC and local recirculation system. The result suggests extreme SAM events caused the change in the transport of egg and larvae in the east slopes of the East Antarctic region.
Abstract:
The diet of Antarctic toothfish, Dissostichus mawsoni, collected from the 88.1 research subarea was analyzed by metabarcoding their stomach contents. As a result of metabarcoding analyzes of 436 stomach contents, which have been collected for three years (2018, 2019, and 2021), a total of 184 haplotypes and 38 species were obtained. As shown in previous studies, the main diet of D. mawsoni was fish species and relatively much lower proportions of cephalopods and crustaceans. Among them, both Macrourus caml and Cryodraco antarcticus were the two most abundant prey species, ranging from 25.41 % to 83.96 % with 64.43 % on average, supporting their importance as a diet of D. mawsoni in the 88.1 subarea. In the previous study, Chionobathyscus dewitti, Macrourus caml, and Macrourus whitsoni were the most dominant prey items in 88.3 and 58.4 subarea. Clustering analysis showed that prey compositions clearly reflected geographical distance, indicating that metabarcoding analysis of D. mawsoni stomach contents would be one of the efficient methods to monitor ecosystem sustainability in each research area. However, in addition to the geographical distance, the water depth where the fish were collected may also be one of the critical factors for the difference in the prey compositions. Long-term surveys should be conducted for statistical significance.
Abstract:
The stocks of Antarctic toothfish, Dissostichusmawsoni were a relatively economically and ecologically important fishery resource in the waters of Antarctic. However, there is not enough data and information to assess the robust stocks and deliberate proper measurements for sustainable utilize, especially relate to diet and feeding strategy which may lead to think about ecosystem based stock assessments and fishery managements. Therefore, the Korean scientists analyze diet composition and feeding strategy of D. mawsoni in the research block 88 as a part of Korean research plan for the exploratory longline fishery for Dissostichus spp. during 2021 season. This study was carried out based on the results of stomach content identification of the D. mawsoni caught in the research block 88 in CCAMLR conversion area from December 2020 to January 2021. The diet composition and feeding strategy of D. mawsoni were studied using 548 specimens (54 to 183 cm in body length) in the research block 88, respectively. D. mawsoni is a carnivore and piscivorous fish that mainly consumed fishes. Macrourus caml, M. whitsoni, and M. spp. of Macrouridae was dominant taxa. Chionobathyscus dewitti of Channichthyidae were the second largest dietary component in the fish diet of D. mawsoni. Its diet also included small quantities of mollusks, crustaceans, stones, and cnidarians. In this study, fishes were the dominant prey item in all size classes (<100 cm, n=65; 100-120 cm, n=83; 120-140 cm, n=72; 140-160 cm, n=99; ≥160 cm, n=32). The graphical method for feeding strategy revealed that D. mawsoni is an opportunistic and specialized predator on fishes and showed narrow niche width.
Abstract:
This paper presents the results from a three-year longline fishing research survey (2017 - 2019), conducted to improve understanding of Dissostichus spp. population connectivity, biological characteristics and spatial structure across CCAMLR Subareas 48.2 and 48.4. The results provide evidence linking D. mawsoni with the Antarctic continental shelf and indicate a potential D. mawsoni spawning region in Subarea 48.2. The movements of recaptured tagged fish indicate potential connections with the Lazarev Sea (Subarea 48.6) as well as the southern South Sandwich Islands. The results contribute to the information available for further refinement of the D. mawsoni stock hypothesis.
Abstract:
En 2018 China presentó a la CCRVMA su primer documento (CCAMLR-XXXVII/32) sobre el desarrollo de planes de investigación y seguimiento (PISEG) para las AMP de la CCRVMA, que motivó numerosos comentarios y sugerencias. Con el fin de seguir contribuyendo a los debates sobre este tema, China revisó el documento desde una perspectiva científica, habiendo prestado suma atención a los comentarios recibidos el año pasado.
Abstract:
Los datos científicos son la base de la toma de decisiones en la CCRVMA. A lo largo de los años, los Miembros de la CCRVMA han realizado tareas continuas de investigación y de seguimiento de componentes clave de los recursos vivos marinos y de los ecosistemas antárticos. Los resultados de investigaciones de todo el mundo se publican en revistas académicas en todo tipo de lenguas. Para facilitar la tarea de una ordenación de la CCRVMA fundamentada científicamente, este documento hace un intento de obtener, resumir y actualizar los datos de referencia sobre los pingüinos emperador y adelia en la región del mar de Ross; como ejemplo, a través de la recolección y el análisis sistemático de datos de la bibliografía internacional de las últimas décadas, los planes de gestión de las Zonas Antárticas Especialmente Protegidas (ZAEP) pertinentes y el sitio web de la Aplicación Cartográfica para Poblaciones de Pingüinos y Dinámica Proyectada (MAPPPD), con el fin de determinar exhaustivamente los conocimientos sobre los pingüinos de esa región. Este documento explora, además, las posibles causas y tendencias de las fluctuaciones de las poblaciones de pingüinos para servir de guía a las investigaciones futuras.
Abstract:
Los fundamentos científicos en apoyo del Área Marina Protegida del Mar de Weddell (AMPMW) han sido objeto de debate en el seno de SC-CAMLR durante tres años. En SC-CAMLR se alcanzaron algunos consensos, mientras que aún quedan asuntos importantes por resolver. China ha participado activamente de dichas discusiones y ha aportado recomendaciones serias y constructivas al respecto.
Abstract:
La pesca de austromerluza negra (Dissostichus eleginoides) en la Subárea 48.3 se ha desarrollado de manera continua durante más de 40 años, con más de 25 de años bajo la ordenación de la CCRVMA.
En este documento se analiza la disminución observada a largo plazo en la composición por tallas de la captura de D. eleginoides, en la pesquería de palangre en la Subárea 48.3 (Atlántico Antártico, Área de la FAO 48.3). Cabe notar que, desde principios de la década del 2000, la pesquería de palangre en la Subárea 48.3 ha estado dirigida a peces juveniles con una talla menor de 100 cm. En el presente documento, se estudia la pesca no sostenible de los stocks de austromerluza negra en la Subárea 48.3
Abstract:
Se presenta información sobre un taller de capacitación dirigido a observadores científicos e inspectores de Rusia para su desempeño en pesquerías del Área de la Convención de la CRVMA. El taller se celebró en la Sección Atlántica del instituto VNIRO (AntlantNIRO), en Kaliningrado (16 a 20 de agosto de 2021).
El programa del taller incluyó una gran variedad de temas relacionados con la observación científica y las inspecciones en pesquerías de kril, austromerluza y centolla en el Área de la Convención de la CRVMA. El programa del taller se incluye a continuación.
Al final del taller se realizaron exámenes y se concedieron certificados tras la conclusión de las clases.