• Energy Research

Southern Ocean ecosystems are globally important and vulnerable to global drivers of change, yet they remain challenging to study. Fish and squid make up a significant portion of the biomass within the Southern Ocean, filling key roles in food webs from forage to mid-trophic species and top predators. They comprise a diverse array of species uniquely adapted to the extreme habitats of the region. Adaptations such as antifreeze glycoproteins, lipid-retention, extended larval phases, delayed senescence, and energy-conserving life strategies equip Antarctic fish and squid to withstand the dark winters and yearlong subzero temperatures experienced in much of the Southern Ocean. In addition to krill exploitation, the comparatively high commercial value of Antarctic fish, particularly the lucrative toothfish, drives fisheries interests, which has included illegal fishing. Uncertainty about the population dynamics of target species and ecosystem structure and function more broadly has necessitated a precautionary, ecosystem approach to managing these stocks and enabling the recovery of depleted species. Fisheries currently remain the major local driver of change in Southern Ocean fish productivity, but global climate change presents an even greater challenge to assessing future changes. Parts of the Southern Ocean are experiencing ocean-warming, such as the West Antarctic Peninsula, while other areas, such as the Ross Sea shelf, have undergone cooling in recent years. These trends are expected to result in a redistribution of species based on their tolerances to different temperature regimes. Climate variability may impair the migratory response of these species to environmental change, while imposing increased pressures on recruitment. Fisheries and climate change, coupled with related local and global drivers such as pollution and sea ice change, have the potential to produce synergistic impacts that compound the risks to Antarctic fish and squid species. The uncertainty surrounding how different species will respond to these challenges, given their varying life histories, environmental dependencies, and resiliencies, necessitates regular assessment to inform conservation and management decisions. Urgent attention is needed to determine whether the current management strategies are suitably precautionary to achieve conservation objectives in light of the impending changes to the ecosystem.

{"references": ["Collins, M. A., Xavier, J. C., Johnston, N. M., North, A. W., Enderlein, P., Tarling, G. A., Waluda, C. M., Hawker, E. J., & Cunningham, N. J. (2008). Patterns in the distribution of myctophid fish in the northern Scotia Sea ecosystem. Polar Biology, 31(7), 837-851. doi:10.1007/s00300-008-0423-2", "Collins, M. A., Stowasser, G., Fielding, S., Shreeve, R., Xavier, J. C., Venables, H. J., Enderlein, P., Cherel, Y., & Van de Putte, A. (2012). Latitudinal and bathymetric patterns in the distribution and abundance of mesopelagic fish in the Scotia Sea. Deep-Sea Research Part II-Topical Studies in Oceanography, 59, 189-198. doi:10.1016/j.dsr2.2011.07.003", "Collins, M., Piatkowski, U., & Saunders, R. A. (2021). Distribution of mesopelagic fish in the Scotia Sea from RMT25 and pelagic trawls deployed from RRS James Clark Ross and RRS John Biscoe. 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(2017). Overwinter habitat selection by Antarctic krill under varying sea-ice conditions: implications for top predators and fishery management. Marine Ecology Progress Series, 568, 1-16. doi:10.3354/meps12099", "Sutton, C. A., Kloser, R. J., & Gershwin, L. A. (2018). Micronekton in southeastern Australian and the Southern Ocean; A collation of the biomass, abundance, biodiversity and distribution data from CSIRO's historical mesopelagic depth stratified new samples. CSIRO, Australia. doi:http://hdl.handle.net/102.100.100/365479?index=1", "Trebilco, R., Walters, A., Melbourne-Thomas, J., Bestley, S., Cox, M., Gastauer, S., & Constable, A. (2019). Mesopelagic community struture on the southern Kerguelen Axis. In The Kerguelen Plateau: Marine Ecosystem and Fisheries (pp. 49-54).", "Van de Putte, Anton (2006). Fish catches from Rectangular Midwater Trawl - data collected from the BROKE-West voyage of the Aurora Australis, 2006. Australian Antarctic Data Centre. dataset. 10.4225/15/598d453109182", "Van de Putte, A. P., Jackson, G. D., Pakhomov, E., Flores, H., & Volckaert, F. A. M. (2010). Distribution of squid and fish in the pelagic zone of the Cosmonaut Sea and Prydz Bay region during the BROKE-West campaign. Deep-Sea Research Part II-Topical Studies in Oceanography, 57(9-10), 956-967. doi:10.1016/j.dsr2.2008.02.015"]} The global importance of mesopelagic fish is increasingly recognised, but they remain poorly studied. This is particularly true in the Southern Ocean, where mesopelagic fishes are both key predators and prey, but where the remote environment makes sampling them challenging. Despite this, multiple national Antarctic research programs have undertaken regional sampling of mesopelagic fish over several decades. However, data are dispersed, and sampling methodologies often differ precluding comparisons and limiting synthetic analyses. Here, we have collated and standardised existing survey data of mesopelagic fishes into a circumpolar dataset called Myctobase. To date, Myctobase holds 17,491 occurrence and 11,190 abundance records from 4780 net hauls from 72 different research cruises. Data include trait-based information of individuals including standard length, weight and life-stage. Data span across 37 years from 1991 to 2019. Detailed metadata has also been provided for each sampling event including the date, time, position (latitude, longitude, and depth), sampling protocol, net type, net mesh size, tow speed, volume filtered and haul type (routine, target, random). The dataset is comprised of three comma-separated files. The first file (event.csv) describes the survey methodology. The second file (groupOccurrence.csv) contains the catch data linked to the survey methodology by an event ID. The final file (individualOccurrence.csv) contains measurements of individuals. Each row contains the event and occurrence ID, which links each measurement to the first and second file. See associated metadata record for definitions and units for each variable in 'definitions.xlsx'. The final dataset was subject to quality control and validation processes. Entries with ambiguous or incomplete records were identified with a '0' in the column labelled 'validation' (event.csv) and a description of the missing data can be found in the proceeding column labelled 'validationDescription'. The taxonomic name for each individual was verified against the World Register of Marine Species (http://www.marinespecies.org/). This work is licensed under CC BY 4.0. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

The global importance of mesopelagic fish is increasingly recognised, but they remain relatively poorly studied. This is particularly true in the Southern Ocean, where mesopelagic fishes are both key predators and prey, but where the remote environment makes sampling challenging. Despite this, multiple national Antarctic research programs have undertaken regional sampling of mesopelagic fish over several decades. However, data are dispersed, and sampling methodologies often differ precluding comparisons and limiting synthetic analyses. We identified potential data holders by compiling a metadata catalogue of existing survey data for Southern Ocean mesopelagic fishes. Data holders contributed 17,491 occurrence and 11,190 abundance records from 4780 net hauls from 72 different research cruises. Data span across 37 years from 1991 to 2019 and include trait-based information (length, weight, maturity). The final dataset underwent quality control processes and detailed metadata was provided for each sampling event. This dataset can be accessed through the Antarctic Biodiversity Portal. Myctobase will enhance research capacity by providing the broadscale baseline data necessary for observing and modelling mesopelagic fishes. The paper which this dataset refers to is available at https://doi.org/10.1038/s41597-022-01496-y. The original dataset as submitted for the paper is also available on Zenodo at https://doi.org/10.5281/zenodo.6131579. This dataset is published by SCAR-AntOBIS under the license CC-BY 4.0. We would appreciate it if you could follow the guidelines from the SCAR and IPY Data Policies (https://www.scar.org/excom-meetings/xxxi-scar-delegates-2010-buenos-aires-argentina/4563-scar-xxxi-ip04b-scar-data-policy/file/) when using the data. If you have any questions regarding this dataset, please do not hesitate to contact us via the contact information provided in the metadata or via data-biodiversity-aq@naturalsciences.be. Issues with dataset can be reported at https://github.com/biodiversity-aq/data-publication/ This dataset is part of the Belgian contribution to the EU-Lifewatch project funded by the Belgian Science Policy Office (BELSPO, contract n°FR/36/AN1/AntaBIS) .