Figure 2 from the paper: Habitat suitability estimates for (a) Antarctic krill (E. superba) and (b) Ice krill (E. crystallorophias). (c) Comparison of estimated habitat based on species-specific HSMs using 0.40 and 0.46 as binary cut-off maximizing the area under the receiver operating characteristic curve (AUC) for Antarctic krill and Ice krill, respectively. The PF, SACCF, and >10 d with sea ice coverage each year (ICE) are illustrated in (a–c) as stippled, solid black, and dotted lines, respectively (Park et al., 2019). (d) Observational data distribution (presences and absences) for the two species used to model species-specific HSM, including CCAMLR MPA Planning Domains 1–9.

Research on the distribution of Antarctic krill and Ice krill in the Southern Ocean has shown distinct habitats between the two species. The study, “Quantifying circumpolar summer habitat for Antarctic krill and Ice krill, two key species of the Antarctic marine ecosystem”, published in the journal ICES Journal of Marine Science, was conducted by Benjamin Merkel (Akvaplan-niva As, Fram Centre, Tromsø, Norway) and colleagues.

The abstract follows:

“Antarctic krill (Euphausia superba) and Ice krill (Euphausia crystallorophias) are key species within Southern Ocean marine ecosystems. Given their importance in regional food webs, coupled with the uncertain impacts of climate change, the on-going recovery of krill-eating marine mammals, and the expanding commercial fishery for Antarctic krill, there is an increasing need to improve current estimates of their circumpolar habitat distribution. Here, we provide an estimate of the austral summer circumpolar habitat distribution of both species using an ensemble of habitat models and updated environmental covariates. Our models were able to resolve the segregated habitats of both species. We find that extensive potential habitat for Antarctic krill is mainly situated in the open ocean and concentrated in the Atlantic sector of the Southern Ocean, while Ice krill habitat was concentrated more evenly around the continent, largely over the continental shelf. Ice krill habitat was mainly predicted by surface oxygen concentration and water column temperature, while Antarctic krill was additionally characterized by mixed layer depth, distance to the continental shelf edge, and surface salinity. Our results further improve understanding about these key species, helping inform sustainable circumpolar management practices.” 

Reference:

Merkel, B., Trathan, P., Thorpe, S., Murphy, E.J., Pehlke, H., Teschke, K. and Griffith, G.P. Quantifying circumpolar summer habitat for Antarctic krill and Ice krill, two key species of the Antarctic marine ecosystem, ICES Journal of Marine Science, Volume 80, Issue 6, August 2023, Pages 1773–1786, https://doi.org/10.1093/icesjms/fsad110

23 October 2023

Figure 2. from the study: Predicted impacts on top predator habitat within (columns, e.g., 2014) and among (rows, e.g., White shark) marine heatwave events measured using four metrics.
"A Displacement distance (kilometers), B displacement direction (degrees, where 0/360 is north (N), 90 is east (E), 180 is south (S), and 270 is west (W)), Crange compression or expansion (percent change relative to baseline conditions), D habitat area gain or loss (percent change relative to baseline conditions). All metrics were calculated from August–October in each MHW year relative to baseline conditions (August–October 2000–2020), see Supplementary Table 5 for an analysis of metric uncertainty. Northern, Coastal, and Southern regional groupings indicate the geographies where the majority of the species telemetry data occurs. Source data are provided as a Source Data file."

Heather Welch (NOAA, Southwest Fisheries Science Center, Environmental Research Division, USA) and colleagues have published in the journal Nature Communications on the responses of top predators to marine heatwaves in the Northeastern Pacific.

The abstract follows:

“Marine heatwaves cause widespread environmental, biological, and socio-economic impacts, placing them at the forefront of 21st-century management challenges. However, heatwaves vary in intensity and evolution, and a paucity of information on how this variability impacts marine species limits our ability to proactively manage for these extreme events. Here, we model the effects of four recent heatwaves (2014, 2015, 2019, 2020) in the Northeastern Pacific on the distributions of 14 top predator species of ecological, cultural, and commercial importance. Predicted responses were highly variable across species and heatwaves, ranging from near total loss of habitat to a two-fold increase. Heatwaves rapidly altered political bio-geographies, with up to 10% of predicted habitat across all species shifting jurisdictions during individual heatwaves. The variability in predicted responses across species and heatwaves portends the need for novel management solutions that can rapidly respond to extreme climate events. As proof-of-concept, we developed an operational dynamic ocean management tool that predicts predator distributions and responses to extreme conditions in near real-time.”

Reference:

Welch, H., Savoca, M.S., Brodie, S. et al. Impacts of marine heatwaves on top predator distributions are variable but predictable. Nat Commun 14, 5188 (2023). https://doi.org/10.1038/s41467-023-40849-y

20 October 2023

The Mouse-Free Marion (MFM) Project is working to eradicate the introduced House Mice Mus musculus that have taken to attacking and killing albatrosses and petrels on South Africa’s sub-Antarctic Marion Island. Last week, the MFM Project released the 7th issue of its Quarterly Newsletter.

Leaping into spring on Marion Island. From left “birders” (ornithological researchers) Chris Jones, Mpumelelo Mabutyana, Michelle Risi and Kyle Maurer get airborne; photograph from Michelle Risi

In this latest issue you can read:

A Welcome Editorial by MFM Project Manager Anton Wolfaardt on the reasons why the eradication exercise is now set to take place in the austral winter of 2026 (read more on the postponemement here).

Announcement of three new International Patrons to join His Royal Highness the Duke of Edinburgh and seabird author and illustrator Peter Harrison MBE. They are well-known Antarctic scientist and conservationist Professor Steven Loudon Chown FAA, South African businesswoman Gloria Tomatoe Serobe and Christel Takigawa, anchorwoman based in Japan.

Two overwintering researchers currently on the island write about their work. Camilla Smyth, MFM’s current field worker, describes her role in planning for the mouse eradication, and Michelle Risi writes about the welcome seasonal changes on Marion Island heading into austral spring.

Scalped by Marion’s mice. This Light-mantled Albatross Phoebetria palpebrata chick is certain to have died as a result, photograph by Peter Ryan

Access all MFM’s Quarterly Newsletters here. More information can be found in weekly posts to MFM News on the project’s website and on social media via Facebook and Instagram.  And you can become part of the project by sponsoring a hectare (or more), joining 1650 concerned conservationists who have already done so.

John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses and Petrels, 19 October 2023

An image from ACAP's Night-setting Factsheet - available to download at the ACAP website under Resources. According to the research undertaken by The Navigators, fishers agreed that setting at night was an effective seabird bycatch mitigation measure

New Zealand social research agency, The Navigators, have prepared a report for the Department of Conservation’s Conservation Services Program. The research analyses the barriers and drivers for fishers to implement seabird bycatch mitigation measures in New Zealand’s small vessel bottom longline fisheries.

The report’s Executive Summary follows:

“Commercial fishers are expected to meet the seabird mitigation standards under the New Zealand Government’s National Plan of Action — Seabirds 2020 (NPOA 2020). Objective one of the NPOA 2020 is to “ensure all New Zealand commercial fishers are using practices that best avoid the risk of seabird bycatch, enabled by appropriate regulations”. These practices referred to are outlined in the 2021 legislative requirements as well as the 2019 mitigation standards, and are supported via collaborative industry approaches including the Department of Conservation’s (DOC) liaison programme.

In the past, DOC has mostly focused on technical solutions and support to help fishers mitigate seabird bycatch. To help supplement their work, DOC identified the need for a deeper understanding of fishers’ drivers and barriers to seabird bycatch mitigation uptake using a social science research approach.

To undertake the research, The Navigators (an independent social research agency) were commissioned to seek feedback from fishers in New Zealand’s inshore small vessel bottom longline commercial fleet. The Navigators conducted 18 in-depth interviews with skippers, owner-operators and owners, representing two-thirds of the fishing effort across the fleet. The research found that fishers are driven to avoid seabird captures, with the key drivers being their respect for seabirds, government interventions (e.g. outreach support, industry education, and compliance monitoring and enforcement), protection of themselves, their crew and industry, and productivity and commercial demand interests.

The research also found fishers have a broad range of motivational and capability barriers to implementing the mitigation standards. Two of the core motivational barriers were:

• fishers were not personally catching any or very few seabirds per year; and
• fishers didn’t understand why it’s necessary to mitigate against seabird captures at times when seabirds are not present.

In addition to the above motivational barriers, bluenose and hāpuka fishers had significant capability barriers in being able to meet the tori line and line weighting regulations. There are also a broad range of other barriers specific to the each of the mitigation standards. The recommendations from this research list a broad range of opportunities to improve seabird mitigation in the fishery and/or to get fishers to consistently follow the mitigation standards. The recommendations are grouped under four topic areas to address each of the following:

1. achievability and safety barriers: These barriers are in most need of attention from a fishers’ point of view and ideally need to be addressed before cameras come onboard. They mostly relate to bluenose and hāpuka fishing, solo fishing, as well as the use of tori lines and hauling mitigation. 
2. motivational barriers: These barriers must be resolved if fishers are going to willingly do more than they are currently. They mostly relate to fishers’ experience in regard to not catching seabirds, their low versus high risk scenarios, and technical issues regarding tangles, weighting, and sink rate tests.
3. information, clarity and direction: The recommendations in this section relate to suggested areas of improvement to help fishers better understand what is expected of them as well as to help increase their knowledge (e.g. through knowledge sharing).
4. sense of fairness and robustness: These recommendations in this section relate to fishers’ understanding and the measurement of seabird capture statistics, as well as how fishers are perceived by the public and NGOs.

Reference: 

Turner, P. 2023. Understanding drivers and barriers to seabird bycatch mitigation uptake in small vessel bottom longline fisheries. MIT2022-02 final report prepared by The Navigators Ltd for the Department of Conservation. 123 p.

18 October 2023