Fine-scale knowledge of spatiotemporal dynamics in cetacean presence and abundance throughout the Antarctic Peninsula (AP) is lacking yet essential for effective ecosystem-based management (EBM). We used cruise vessels as platforms of opportunity to investigate an important area both for migratory humpback whales (Megaptera novaeangliae) and Antarctic krill (Euphausia superba) fisheries to assess potential spatiotemporal interactions, for future use in EBM. Whale observations were collected using tourist cruise ships as platforms of opportunity during the austral summer of 2019/2020. Data were analyzed using both traditional design-based line transect methodology and spatial density surface hurdle models to estimate the abundance and distribution of whales in the area, and to describe their temporal dynamics. The latter were fitted using a set of physical environmental covariates (sea surface temperature, ocean filaments, bathymetry and their derivatives). Our results indicate that few humpback whales are present in the Bransfield and Gerlache Straits in early December, however, their abundance increase rapidly to late December in the northern Gerlache Strait, reaching a stable abundance by mid-January. The distribution of humpback whales appeared to change from a patchier distribution in the Gerlache Strait to a significantly concentrated presence in the northern Gerlache and southern Bransfield Straits, followed by a subsequent dispersion throughout the area. Depending on the modelled abundance, estimates agreed well with previous literature, increasing from approximately 7000 individuals in 2000 to a peak of 19 107 in 2020. Based on these estimates, we project a total krill consumption of between 2.0 and 5.2 million tons based on traditional and contemporary literature, respectively. Based on our results and catch data in the study area, we conclude that there is minimal spatiotemporal overlap between humpback whales and krill fishery activity during our study period of November – January. However, there is potential for significant interaction between the two later in the feeding season, but cetacean survey efforts need to be extended into late season in order to fully characterize this potential overlap.
Abstract:
We present here a summary of the euphausiid larvae collected during the summer seasons in waters off the West Antarctic Peninsula: Gerlache Strait and surroundings of South Shetland Islands in 2017-2018; Mar de la Flota (Bransfield Strait) and Elephant Island surroundings during 2019 and 2020. Euphausia superba larvaeshowed a very low abundance in 2017. In general terms the stations situated at the southern entrance of the Gerlache Strait presented higher densities. In 2018 E. superba was present in half of the stations sampled. The abundance of Thysanoessa macrura remained stableinboth years, with higher numbers in 2018. During 2019 in Mar de la Flota (Bransfield Strait) area E. superba abundance was very high, while during 2020 all euphausiid larvae had very low densities, as the whole area was full of salps.
Abstract:
This paper responds to a request from the Scientific Committee for the Secretariat to review the data that has been submitted for estimating the green-weight of krill, for each of the methods specified in CM 21-03, Annex 21-03/B (SC-CAMLR-38, paragraph 3.4). Results from the analysis demonstrate a good relationship between reported green-weights and the calculated krill green-weights using the estimation parameters, with exception of two vessels’ data reported in seasons 2014 and 2015. Conversion Factors were also investigated, and results show that considerable variation exists for reported figures associated with particular processing type and direct green-weight estimation combinations. A number of recommendations are provided to potentially address these issues.
Abstract:
With the goal of collating, synthesizing, and working towards coordination of U.S. research and monitoring in the RSRMPA, the U.S. Ross Sea science community convened a virtual workshop on 26-27 April 2021. The workshop included 51 participants (see Appendix A) representing active U.S. Ross Sea scientists as well as representatives of major U.S. science funding institutions (National Science Foundation - Office of Polar Programs, OPP, NASA, NOAA, Pew Charitable Trusts, and Schmidt Ocean Institute). The array of participants was multi-disciplinary, with Ross Sea expertise spanning biophysical (weather, sea ice, physical oceanography, polynyas, primary productivity, climate effects and variability), forage species (silverfish, krill), mesopredators (toothfish, seals, penguins, whales), benthos, pollution and wildlife health (see Appendix A). The workshop goals were to identify, collate, assess, and synthesize research conducted by U.S. researchers in the Ross Sea since 2010, and seen to be relevant to the goals of the MPA (defined in CCAMLR Conservation Measure 91-05). This was done via participants’ summary presentations of research in their areas of expertise (see Appendix A) and gathering all published U.S. Ross Sea region research since 2010 (see Appendix C), as well as currently funded research (see Appendix D). Further goals were to discuss and identify gaps in RSRMPA research and monitoring, determine ways to fill those gaps, elucidate critical uncertainties regarding the Ross Sea ecosystem structure and dynamics (see Appendix B), and develop ideas for coordination between ongoing and future research in the RSRMPA. Below we provide a summary of ongoing and, since 2010, peer-reviewed U.S. Ross Sea research of relevance to meeting the objectives and possible future updates of the RSRMPA and RMP. We also note critical uncertainties, data gaps and actions the workshop participants consider necessary to address them.
Abstract:
This document summarizes several papers submitted to the Grym e-group and other working groups during 2020 and 2021 on proportional recruitment (R.mean, R.var inputs to the Grym: the square of SD of proportional recruitment is the 'R.var' input) from research surveys and the fishery; and biomass variability (B0logsd input to Grym) from research surveys in Subarea 48. Two different length ranges, <36 mm and <40 mm, are used to define 'recruits' in the proportional recruitment comparisons. Proportional recruitments calculated from the fishery samples were generally lower (mean range 0.083 to 0.405, SD range 0.109 to 0.213) than the means and standard deviations from the survey data (mean range 0.174 to 0.579, SD range 0.274 to 0.412) for the two length values used to define recruits. This may be the result of the fishery targeting specific size ranges instead of random sampling of the annual size distributions for krill. Using the AMLR data aggregated over all areas and years, proportional recruitment mean and standard deviation were 0.219 and 0.320, respectively, if krill < 36 mm are defined as recruits, and 0.303 and 0.358, respectively, if krill < 40mm are defined as recruits. The mean of the annual CVs for Subarea 48.1 was 0.399, for a mean B0logsd of 0.384. The mean annual CV for Subarea 48.3 was 0.373, for a mean B0logsd of 0.361. Biomass CVs for Subareas 48.1 and 48.3 combined ranged from 0.086 to 1.15. B0logsd values for the combined Subareas ranged from 0.086 to 0.918 with a midpoint of 0.502.
Abstract:
Information on marine predator at-sea distributions is a key component of spatial management frameworks that aim to identify regions important for conservation. Tracking data from seabirds have been widely used to define priority areas for conservation, but such data are often restricted to the breeding population. This also applies to penguins in Antarctica, where identification of important habitat for nonbreeders has received limited attention. The foraging ranges of breeding penguins are constrained to near-shore areas by the high energy needs of chicks at the colony. Conversely, nonbreeding adults are expected to have larger foraging distributions, which may increase their conspecific interactions with birds from neighboring colonies and their vulnerability to threats distant from the breeding colony. Here, we study the movement behavior of nonbreeding Adélie penguins tracked during the 2016/17 breeding season at King George Island (Isla 25 de Mayo) in the South Shetland Islands, Antarctica. We quantify how nonbreeding penguins’ moment behavior varies in relation to environmental conditions and assess the extent of spatial overlap in the foraging ranges of nonbreeders and breeders, which were tracked over several years. The utilization distributions of breeders and nonbreeders overlapped in the central Bransfield Strait. Habitat segregation was greater during the crèche stage of the breeding season compared to incubation and brood, because chick provisioning still constrained the foraging range of breeders while nonbreeders commenced pre-molt foraging trips into the Weddell Sea. Nonbreeders increased their prey search and area-restricted foraging behavior in areas where sea surface temperatures were lower, sea-ice concentration were higher, and over shallower bathymetry nearer the coastline of the Antarctic Peninsula. Differences in the at-sea spatial distribution of nonbreeding and breeding penguins highlight the need to account for different life-history stages when characterizing habitat use of marine predator populations. This is particularly important for “sentinel” species monitored as part of marine conservation and ecosystem-based fisheries management strategies.
Abstract:
The timing of breeding is an important aspect of a species’ realised niche, a method of avoiding competition and a key determinant of breeding success. The flexibility of these strategies may structure community assemblages, particularly in highly seasonal environments such as the Polar Regions. Flexibility in timing likely determines the adaptability of species to rapid, anthropogenic ecological change. Variance in a species’ phenology over time and across locations is an important source of information, but phenology is only rarely recorded at appropriate spatial scales due to the difficulty of monitoring. Using a network of time-lapse photographic cameras to monitor a large number of colonies of three Pygoscelid species of penguins, we show that two species (Adélie and Chinstrap) breed earlier in warmer years, both at the individual colony and species levels. Both temperature-sensitive species have shown a population decline over the roughly 10 years of our study in the Antarctic Peninsula, while Gentoo penguins (temperature insensitive) have stable or increasing populations, particularly at the Southern edge of their range. Latitude was an important determinant of the start of breeding across the same region and temperature-related breeding in Adélie and Gentoo, but not Chinstrap penguins (which have a narrower range than the other two). The sensitivity to temperature in Adélie and Chinstrap penguins is greater than previously reported. The phenological responses to temperature differed according to latitude, showing greater sensitivity to temperature at warmer, lower latitudes. Our results demonstrate that the flexibility of reproductive strategies within as well as between closely related species needs to be considered as a landscape of outcomes with some adaptation to local conditions. This study offers a starting point to understanding whether polar animals can adapt to rapid change or whether elasticity is indicative of increasing stress given the two species showing the most adaptation to changing temperatures are declining in the study area.
Abstract:
In this paper, we report recent changes in the spatial extent of the Pine Island Glacier. The 22% reduction in areal extent means that the newly exposed marine area has been classified as a Stage 1 Special Area for Scientific Study (SASS) in accordance with Conservation Measure 24-04.
This paper provides additional information to that included in COMM CIRC 21/76, allowing WG-EMM opportunity to comment.
Abstract:
As the most abundant penguin species, the diet of Adélie penguin, Pygoscelis adeliae, would be one of the most important indicators for the ecosystem conditions where they inhabit. The diet of seven Adélie penguin populations in the Ross Sea was studied using both metabarcoding and quantitative PCR (qPCR) analyses. 18Sv9 and miniFish primers provided the overall diet compositions and accurate fish species names, respectively. Based on the metabarcoding analysis, main prey items for Adélie penguin were notothenioid fish, Euphausia superba, and Euphausia crystallorophias varies from small fishes. Among the notothenioid fish, three species, including Pleuragramma antarctica, Pagothenia borchgrevinki, and Trematomus spp. were most abundant. qPCR analysis showed a significant geographical difference in the ratio between krill and notothenioids. Populations inhabiting inbound parts of Ross Sea (Edmonson Point and Inexpressible island) showed higher proportions of fish taxa without E. superba, while the other five populations exhibited a higher krill ratio to fish taxa with two krill. The ratio of krill to fish taxa was highly variable for three-year of study and showed annual synchronous patterns in observed populations, suggesting the long-term study for the penguin’s diet should be conducted to understand the relationship between the populations of Adélie penguin and their marine ecosystem in the Ross Sea.
Abstract:
To identify the dietary composition and characteristics of both Adélie (Pygoscelis adeliae) and emperor penguin (Aptenodytes forsteri) at four breeding sites, we performed stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of down of penguin chicks. Adélie penguin chicks at Cape Hallett mostly fed on Antarctic krill (Eupausia superba; 65.5±3.5%) reflecting the prevalence of that species near Cape Hallett, and no significant differences were noted between 2017 and 2018. However Adélie penguin chicks at Inexpressible Island located near Terra Nova Bay fed on both Antarctic silverfish (Pleuragramma antarctica; 42.5%) and ice krill (Euphausia crystallorophias; 47%) reflecting the high biomass observed in Terra Nova Bay. On the other hand, no significant difference was noted between at both breeding sites of the emperor penguin. Emperor penguin chicks predominantly fed on Antarctic silverfish (74.5±2.1%) at the breeding sites (Cape Washington and Coulman Island), suggesting that diet preference represents the main factor for emperor penguin foraging. In contrast, the diet of Adélie penguin reflected presumed regional differences in prey prevalence as inferred from available survey data.