Chapter

Unnatural Selection of Antarctic Toothfish in the Ross Sea, Antarctica

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  • HT Harvey & Associates
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Abstract

Springer 2012 3.1 Fishing Further and Deeper Historically, fishermen targeted fish in shallow, nearshore waters relatively close to port (Pauly et al. 2005). As these species became depleted, to meet growing demands, fishermen were forced to move offshore and into deeper waters (Hutchings and Reynolds 2004; Koslow et al. 2000; Morato et al. 2006; Hilborn et al. 2003; Pauly et al. 2002, 2005). Steady advances in fishing technology facilitated the exploitation of previously inaccessible fish stocks (Hutchings and Reynolds 2004; Koslow et al. 2000; Morato et al. 2006; Hilborn et al. 2003; Pauly et al. 2002, 2005), and by the mid-1980s fishermen began longline fishing in the northern Southern Ocean for the deep-living Patagonian toothfish Dissostichus eleginoides (Knecht 2006). Despite international efforts to regulate this fishery, extensive illegal, unregulated, and unre-ported (IUU) fishing compromised management and caused severe population declines, leading to localized depletions and stock closures within 10 years (Agnew et al. 2002). In search for other profitable toothfish stocks, fishermen soon moved into the southernmost marine regions of the Antarctic, to the freezing waters of the Ross Sea, this time in pursuit of the Antarctic toothfish, Dissostichus mawsoni. Reflecting market forces, both toothfish species are sold in industrialized countries under the market name "Chilean sea bass" and cost $25 or more a pound, a price that few can afford.

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... In the Anthropocene of the finite Earth, there are just a few large wilderness areas left, often occurring in remote areas difficult to access. The Ross Sea (Figure 1), a remote portion of the Southern Ocean, is one of those areas, which remained virtually pristine until the early 1900s when sealing and whaling started, as well as in 1996 when commercial fishery started the exploitation of Antarctic krill (Euphausia superba) and toothfish (Dissostichus mawsoni) [1]. The impact of these fisheries in the pristine waters is disputed, e.g., described as 'low' by FAO [2], with more relevant impacts described by Ainley [1]. ...
... The Ross Sea (Figure 1), a remote portion of the Southern Ocean, is one of those areas, which remained virtually pristine until the early 1900s when sealing and whaling started, as well as in 1996 when commercial fishery started the exploitation of Antarctic krill (Euphausia superba) and toothfish (Dissostichus mawsoni) [1]. The impact of these fisheries in the pristine waters is disputed, e.g., described as 'low' by FAO [2], with more relevant impacts described by Ainley [1]. Recent reports show a substantially triplicated effort since the late 1990s in Antarctic krill fishing (at least in the FAO areas 48, 58, and 88), while toothfish extraction remained stable over the years [2]. ...
... Moreover, some of the relevant existing data are not shared or available to the public (i.e., the Commission for the Conservation of Antarctic Marine Living Resources reports), may exist but are not digitally available or well-documented with metadata, and hence not truly accessible, or simply lack a robust research design for wider inference [6]. Paradoxically, this also applies to fishery target species such as the Antarctic toothfish Dissostichus for which ecological information is still incomplete [1,7,8], and specific spa-tial population models are constantly being developed and refined within the RSRMPA boundaries [9][10][11]. ...
Article
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Zooplankton is a fundamental group in aquatic ecosystems representing the base of the food chain. It forms a link between the lower trophic levels with secondary consumers and shows marked fluctuations in populations with environmental change, especially reacting to heating and water acidification. Marine copepods account for approx. 70% of the abundance of zooplankton and are a target of monitoring activities in key areas such as the Southern Ocean. In this study, we have used FAIR-inspired legacy data (dating back to the 1980s) collected in the Ross Sea by the Italian National Antarctic Program at GBIF.org. Together with other open-access GIS data sources and tools, it allows one to generate, for the first time, three-dimensional predictive distribution maps for twenty-six copepod species. These predictive maps were obtained by applying machine learning techniques to grey literature data, which were visualized in open-source GIS platforms. In a Species Distribution Modeling (SDM) framework, we used machine learning with three types of algorithms (TreeNet, RandomForest, and Ensemble) to analyze the presence and absence of copepods in different areas and depth classes as a function of environmental descriptors obtained from the Polar Macroscope Layers present in Quantartica. The models allow, for the first time, to map-predict the food chain per depth class in quantitative terms, showing the relative index of occurrence (RIO) in 3Dimensions and identifying the presence of each copepod species analyzed in the Ross Sea, a globally-relevant wilderness area of conservation concern. Our results show marked geographical preferences that vary with species and trophic strategy. This study demonstrates that machine learning is a successful method in accurately predicting the Antarctic copepod presence, also providing useful data to orient future sampling and the management of wildlife and conservation.
... Apart from Antarctica as a whole, the Ross Sea region has received much public and scientific attention (Smith et al., 2007;Ainley & Siniff, 2009;Pinkerton et al., 2010), as well as major critique of its management (e.g., Longhurst, 2010;see Blight et al., 2010;Ainley et al., 2012;Ainley & Pauly, 2013;Christian et al., 2013 for toothfish fishery by the Commission for the Conservation of Antarctic Marine Living Resources; CCAMLR). The abundance of many of the large marine mammals decreased in the Ross Sea under the ongoing management scheme of western nations. ...
... For instance, DDT residue was consistently found in penguin tissue (George & Frear, 1966;Lukowski, 1983;Kerry & Riddle, 2009 for a review) showing the direct connections of even one of the remotest areas with the industrialized production process. There is also increasing pressure on biological resources in the Ross Sea (e.g., fishing; see Ainley et al., 2012 for toothfish), which threatens its ecosystem. However, mining and oil and gas development essentially are still banned for the time being (Ainley, 2002). ...
... Considering that the Ross Sea characterizes most attributes that are on the forefront of nature protection (Halpern et al., 2008, it is surprising that it has not achieved full protection (see Table 6; Ainley et al., 2010Ainley et al., , 2012. For instance, climate change and ocean acidification are virtually left unmanaged for the Ross Sea (Turner et al., 2009). ...
Article
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It is now understood that the Ross Sea stands as one of the last relatively pristine (ocean) areas. Many decades of international research have been carried out under the Antarctic Treaty System stipulating that data acquired under this scheme must be shared with the global community. In line with Carlson (Nature 469:293, 2011, Polar Research 10.3402/polar.v32i0.20789, 2013), we find little evidence of enforcement towards making digital geographic information systems (GIS) project data available online for the wider Ross Sea ecosystem. While it is possible to find easily >40 digital datasets for most areas and pixels worldwide, despite many decades of research in the Ross Sea, only app. 100 digital datasets can be found for the study area. It simply shows that data from many studies in the region are not available. High-quality population and trend data explicit in space and time are mostly missing in the public realm, e.g., from the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR.org). This presents an ethical dilemma because it still appears that sufficient data exist for a pro-active and pre-cautionary management of this region. No coherent and efficient management scheme truly exists and is applied for this precious part of the world now heavily affected by global stressors and mismanagement of data and resources.
... These decreases corresponded to the initiation of an industrial fishery in 1996-1997 that targets the biggest fish. Fishing takes place within 20 to 50 km north and east of Ross Island as well as off Terra Nova Bay (Pinkerton et al., 2007;Ainley et al., 2012aAinley et al., , 2012b. ...
... Adults of both fish species have much higher fat content than smaller ones, and they are probably attractive to killer whales for that reason. Small (< 100 cm) subadult toothfish do not have high fat content and remain near the bottom owing to a lack of buoyancy (Near et al., 2003;Ainley et al., 2012aAinley et al., , 2012b. This lack of buoyancy means that small toothfish are generally out of reach of killer whales since bottom depths are ≥ 400 m in most of the study region. ...
... 785). The fishery exercises this strategy in the Ross Sea region by taking the largest fish, size having decreased in the fishery in recent years (Ainley et al., 2012a). Such a fishing strategy is necessitated in part by the economically expensive, 2,000 km distance to the nearest port. ...
Article
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Foraging events and related trends in numbers of Type-B and -C killer whales (Orcinus orca) are reported for the vicinity of Ross Island, Ross Sea, Antarctica between 2002 and 2010. Updating an earlier report, the frequency of sightings and the number of individuals per sighting of Ross Sea killer whales (Type-C; RSKWs), a fishing-eating ecotype, has continued to decrease in a pattern coincident with a decrease in the number and size of an important prey: Antarctic toothfish (Dissostichus mawsoni). Increasingly rare, large fish are much more energetically dense and may also be socially important to the whales, a rela-tionship with potential parallels to that known between well-studied fish-eating killer whales and large Chinook salmon (Oncorhynchus tshaw-ytscha) in the northeast Pacific. In contrast, the prevalence of the larger, mammal-eating Type-B killer whales has not changed in the southern Ross Sea study area. Predation events by Type-B killer whales involving Weddell seals (Leptonychotes weddellii), interest in large penguins, such as emperors (Aptenodytes forsteri), and lack of inter-est in small penguins, such as Adélies (Pygoscelis adeliae), are presented. In the case of both killer whale forms, the progressive seasonal breakup of fast ice in large bays bordering the Ross Sea likely provides reliable, enhanced foraging oppor-tunities as prey are exposed one area at a time during summer. Given the apparent relationship between RSKW prevalence and the availability of large toothfish, we speculate that the current management strategy of Antarctic toothfish in the Ross Sea region threatens current population levels of RSKWs.
... The approximate size of toothfish prey taken by killer whales was estimated from photographs by comparing the estimated body length of the whale (using data from Berzin &Vladimirov 1983 andPitman et al. 2007) with toothfish morphometrics based on images of adult toothfish in Calhaem & Christoffel (1969) and Ainley et al. (2012). ...
... Our estimate of toothfish prey size (n=1; Fig. 1) of 1.5 m coincides with the modal size classes (130 -159 cm) of toothfish caught in McMurdo Sound by scientists (Ainley et al. 2012). Based on estimated TCKW metabolic rates (Kriete 1995;Williams et al. 2004;Noren 2011) and differences in the energy content of potential fish prey (Lenky et al. 2012), toothfish is likely to be the only fish prey of sufficient size, energy density, and fat content in the Ross Sea region to support fish-eating killer whales, in particular during periods of increased energy requirements such as lactation. ...
Conference Paper
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Ecotype B and C (TBKW, TCKW) killer whales (Orcinus orca) were studied in McMurdo Sound, Antarctica, in late January and early February 2014. While the unusually extensive break-out of the sea ice in the 2013-14 season limited opportunities for the collection of dart biopsies, three whales were sampled. In the period from 20-28 January, a total of 307 whales were detected including 297 TCKW and 10 ecotype B killer whales (TBKW) along a 20-30 nautical mile stretch of fast ice at the western margin of McMurdo Sound. Feeding behaviour of TCKW was recorded during 5 of the 8 flights. TCKWs with prey items held in their jaws were seen on 5 occasions; in 3 cases, the prey was clearly identifiable as toothfish (Dissostichus mawsoni). A large number of images were collected for photo identification. Additional observations of hunting behaviour of Type B killer whales directed at seals and penguins were made from Scott Base between 30 Jan and 16 Feb 2014.
... Increases in the Ross Sea may also reflect competitive release for Adélie Penguins following an exploratory fishery for Antarctic toothfish (Dissostichus mawsoni) implemented in the late 1990s. Antarctic toothfish prey on Antarctic silverfish (Pleuragramma antarctica; Ainley et al. 2012), and their removal may benefit other predators of Pleuragramma spp., such as the Adélie Penguin (Ainley et al. 2012). Regional-scale changes in the Adélie Penguin population likely reflect both biotic and abiotic factors that deserve further study; our global census provides a baseline against which to assess future changes. ...
... Increases in the Ross Sea may also reflect competitive release for Adélie Penguins following an exploratory fishery for Antarctic toothfish (Dissostichus mawsoni) implemented in the late 1990s. Antarctic toothfish prey on Antarctic silverfish (Pleuragramma antarctica; Ainley et al. 2012), and their removal may benefit other predators of Pleuragramma spp., such as the Adélie Penguin (Ainley et al. 2012). Regional-scale changes in the Adélie Penguin population likely reflect both biotic and abiotic factors that deserve further study; our global census provides a baseline against which to assess future changes. ...
Article
Full-text available
We report on the first global census of the Adelie Penguin (Pygoscelis adeliae), achieved using a combination of ground counts and satellite imagery, and find a breeding population 53% larger (3.79 million breeding pairs) than the last estimate in 1993. We provide the first abundance estimates for 41 previously unsurveyed colonies, which collectively contain 420,000 breeding pairs, and report on 17 previously unknown colonies, 11 of which may be recent colonizations. These recent colonizations represent similar to 5% of the increase in known breeding population and provide insight into the ability of these highly philopatric seabirds to colonize new breeding territories. Additionally, we report on 13 colonies not found in the survey, including 8 that we conclude have gone extinct. We find that Adelie Penguin declines on the Antarctic Peninsula are more than offset by increases in East Antarctica. Our global population assessment provides a robust baseline for understanding future changes in abundance and distribution. These results are a critically needed contribution to ongoing negotiations regarding the design and implementation of Marine Protected Areas for the Southern Ocean.
... The organisation currently represents 36 states, including New Zealand, one of its 25 founding members. The threat of overfishing the Antarctic toothfish prompted CCAMLR to undertake stock assessment in the 1990s [16]. Its findings suggested that fishing might go ahead on a limited basis, and member states were tasked to ensure that vessels flying their flags did not overfish the region. ...
... In October 2014, at another Hobart meeting of CCAMLR, New Zealand and the USA made a fourth attempt to create the world's largest marine reserve in the Ross Sea [52]. Australia's delegation head reported positive informal talks with Russia, which was the second largest toothfish harvester from Area 88 after New Zealand [16] and a main objector to the initiative [53], but in the event neither Russia nor China acceded to the proposal [54]. ...
Article
Fishing firms sometimes give political support to marine conservation measures that seem contrary to their commercial interest. To explain this apparent paradox, an analysis is made of the stance taken by a New Zealand company in response to a proposed marine protected area in the Ross Sea. The firm defected from its industry’s opposition to the proposal, choosing to support the reserve. The analysis uses concepts from corporate political strategy to identify why such support might be forthcoming, and under what conditions. The article argues that a firm endorsing a conservation initiative in defiance of its industry intends to engineer a redistribution of profit and control within its global production network, regardless of any public benefit. While there was in this instance a public benefit in the form of potential environmental upgrading, the firm’s strategy risks compromising the effectiveness and impartiality of marine governance organizations.
... The CDS is a chain of custody system designed to track the landings and trade flows of toothfish throughout the trade cycle and requires all catch to be accompanied by a valid Dissostichus catch document [6,9]. All CCAMLR Contracting Parties that trade in toothfish are required to implement the CDS, while CCAMLR also provides mechanisms for non-Contracting Parties involved in the landing and/or trade of toothfish to participate in the scheme [9][10][11]. The CDS provides a means to monitor quantities of fish imported and exported, however it does not provide a method to monitor the economic value of toothfish within the international market. ...
... Publically available information indicated a wide range of prices for toothfish from US$10 /kg [16] to over US$50 /kg [10] for unspecified toothfish products, however the provenance and methods used to validate these prices are often unclear. Using a range of, typically internet based searches, publically available information was inconsistent and access to appropriate trade data varied greatly between trading entities. ...
... The spatial heterogeneity of the secular response of SST, OWDs, and NPP and the response of these variables to atmospheric forcing by SAM and ENSO apparent at the scale of our study provides an interesting context for understanding the impact of NPP variability on upper trophic levels and on the capacity of the Ross Sea region to act as a CO 2 sink. Phytoplankton are at the base of the foodweb in the Southern Ocean [Schofield et al., 2010] and their rates of production may have a significant influence on both toothfish and penguin populations in the Ross Sea [Ainley et al., 2012a[Ainley et al., , 2005. A significant decline in the toothfish fishery in the Ross Sea has been documented since the beginning of commercial fishing in the region [Ainley et al., 2012b] and it has been suggested that this may be due to a decrease in primary production on the Ross Sea shelf as a result of the increase in sea ice that has been reported for the region [Hanchet et al., 2010]. ...
Article
Recent studies have documented an increase in sea ice extent and the duration of the ice season in the Ross Sea, Antarctica. We conducted a satellite-based study to quantify changes in net primary production (NPP) and chlorophyll a (Chl a) in response to the observed changes in ice dynamics in the Ross Sea south of 60°S. Our study covers a 16 year time period (1997-2013) and incorporates both the shelf and off-shelf regions of the Ross Sea. We observed significant secular changes in NPP from 1997 to 2013 in the off-shelf region, with NPP increasing on the eastern side and decreasing on the western side of our study area. The changes we observed in NPP are consistent with the changes we observed in sea surface temperature (SST) and open water days (OWDs), decreasing (increasing) on the western (eastern) side of our study area. Finally, we examined the influence of the Southern Annular Mode (SAM) and the El Niño Southern Oscillation (ENSO), on SST, OWDs, Chl a, and NPP in the Ross Sea and observed a significant relationship between the state of the SAM and ENSO and SST, OWDs, and NPP across the study region. The response of OWDs, SST, and NPP to atmospheric forcing by SAM and ENSO was opposite for the shelf and off-shelf regions, such that during a positive phase of SAM or negative phase of ENSO (La Niña), SST, OWDs, and NPP increased on the shelf and decreased in the off-shelf region.
... The Ross Sea ( Figure 1) is a well-defined embayment of Antarctica about the size of southern Europe, bounded by Victoria Land to the west, King Edward VII Peninsula, Marie Byrd Land to the east, the Ross Ice Shelf to the south, and the Pacific Sector of the Southern Ocean to the north. The Ross Sea Ecosystem is of particular interest to scientists, as it has unique characteristics resulting from a long evolutionary history under extreme environmental conditions (Ainley, 2012). Anthropogenic contamination is negligible as is evidenced from the low concentrations of total mercury and methylmercury in the study area. ...
Experiment Findings
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... For reasons discussed herein, we think that an MPA can be considered "highly protective" even if it, as here, does not have unlimited duration or allows for limited research fishing in an otherwise no-take area. Noting the vulnerability of toothfish as a deep-dwelling, long-lived fish that is vulnerable to overfishing [54], we support research which further investigates its life history. However, the rigid process by which this fishing is approved is extremely important. ...
Article
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As the first large-scale (>150,000 km 2) marine protected area (MPA) on the high seas, the Ross Sea region MPA sets a precedent for other MPAs in areas beyond national jurisdiction. In the myriad of MPA guides and rankings (including the new "MPA Guide"), categorization and evaluation of the Ross Sea region MPA also sets precedent for categorizing and evaluating future protected areas on the high seas. Here, we provide clarity on the gover-nance of the Ross Sea region MPA, and evaluate the status of its General Protection Zone (comprising ~80% of the MPA) with respect to level of protection. We outline the extensive restrictions and science-based management in place within the Ross Sea region MPA General Protection Zone and support its status as highly protected. We further conclude that if an MPA as regulated as the Ross Sea region MPA, especially its General Protection Zone, cannot meet the threshold of a "highly protected" MPA, it may prove difficult for other high seas MPA to be categorized as such.
... Females do not accumulate enough stores over the winter to support lactation, a potential reason for the intermediate income-capital breeding strategy. The fact that Weddell seals are apparently unable to gain substantial amounts of mass over the winter may increase their vulnerability to changes in ecosystem structure, such as may occur in response to the Ross Sea toothfish fishery (Dissostichus mawsoni; DeVries, Ainley & Ballard 2008;Ainley & Siniff 2009;Ainley et al. 2012). That there was annual variation in physiological condition suggests some flexibility to cope with environmental changes such as sea-ice extent and large-scale oceanographic El-Niño Southern Oscillation events that influence primary productivity (Testa 1994 ...
Article
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Reproductive success can be influenced by maternal physiological condition at the time of embryo implantation and by foraging success during gestation. Polar marine mammals experience drastic fluctuations in body composition (lipid stores) as a result of life history events and large-scale changes in seasonal productivity and environmental conditions. These species provide the opportunity to explore physiological parameters important to reproductive success.There are conflicting physiological demands on Weddell seal (Leptonychotes weddellii) females during the moult period, when animals are at their leanest but still must generate an energetically-costly new pelage and begin active gestation.To investigate the impact of post-moult condition and hormonal mediators on the reproductive success of the southernmost breeding mammal, body composition was determined for post-moult (fall; 53 non-reproductive) and pre-breeding (spring; 31 non-reproductive, 17 reproductive) adult female Weddell seals. Animals were significantly larger and had greater lipid stores in spring, after the winter foraging period. There were no differences in the proportion of mass or condition gained overwinter between females that gave birth (n= 12) and those that did not (n= 8) the following year.Changes in body condition were correlated with endocrine factors that influence energy allocation, such as cortisol, growth hormone (GH), insulin-like growth factor (IGF)-1, and thyroid hormones (T3 and T4). Of these, GH and T4 were significantly higher during the post-moult period, likely to promote protein sparing and hair regeneration. In addition, females that had higher T4 concentrations in fall were significantly more likely to have a pup the following year, possibly due to the role of thyroid hormones in embryo attachment. This suggests that hormones influencing fuel use during the moult may also impact subsequent reproductive success.Unlike some other large pinnipeds, Weddell seals are not capital breeders. This work indicates that gestating Weddell seals do not gain as much mass or energy overwinter in preparation for lactation the following year as lower-latitude phocid species, which might explain why female Weddell seals rely on foraging to meet energetic demands during lactation.This article is protected by copyright. All rights reserved.
... The outlook for this continent is hardly a good one when considering alone the impacts brought by climate change, global growth of human population and consumption, and lack of an efficient sustainability governance scheme (Hilty et al. 2007, Friedman 2010. By now, Antarctica is not anymore a marginal place but it makes for an integral part of the global receipe of human well-being anywhere (Intergovernmental Panel on Climate Change IPCC 2007, Huettmann 2012; see Ainley et al. 2012 for toothfish harvest and global food supply) due to the free services this area provides. Its resources (marine, atmospheric, ecological services and slowly now also terrestrial) are at stake by global consumption, and also threatened due to related climate change (Thompson and Solomon 2002, Jenouvrier et al. 2009, McClintock et al. 2008, Turner et al. 2009). ...
Chapter
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The Antarctic Treaty is of global importance and it is very clear in its statement and spirit that science is to be shared with the global community. However, huge amounts of data still remain to be made freely available to the public. Available data is often in data formats that are not easily accessible or limited to just certain software platforms, and the associated metadata is often poorly done or non existent. There is tremendous progress brought by publicly available open access =presence only' (location only) data sets though, e.g. for scientific and conservation management questions. While this is fully in line with ongoing data initiatives such as the International Polar Year (IPY 2007), the International Council for Science (ww.icsu.org) and the Cyber-infrastructure with U.S. NSF and its relatives, such compiled and ready-to-use datasets in a good format do not exist or are still very difficult to come by. Here we make such data sets publicly available for free for 53 species and for further use by the global community. Secondly, we provide a first application of such datasets using free tools such as machine learning software in R, as well as open source geographic information systems (such as QGIS, R and SAGA GIS). While these resulting data can be used and improved further, here we present a first and robust meta-analysis and synthesis from these experiences and models.
... Peril for Antarctic fish long as 50 years-slow growing and developing, and probably low in fecundity; no eggs, larvae or small adults have been found in the Ross Sea (reviewed in [18]). Not surprisingly, intrinsic vulnerability indices reveal that D. mawsoni is at the top of the vulnerability list among deep-sea fishes worldwide [19]. ...
... These characteristics predispose D. mawsoni to accumulate mercury and persistent organic pollutants and suggest that the species is a potential indicator of mercury levels in the ecosystem (Corsolini et al., 2017;Sydeman et al., 2015). Current catches of D. mawsoni are~4000 tonnes per year (CCAMLR, 2018b), and its value varies between 25 and 50 US$ kg −1 , suggesting that the D. mawsoni fishery can generate revenues of more than 150 million US$ annually (Ainley et al., 2012;Baird, 2006;CCAMLR, 2016b;Grilly et al., 2015). This high value fishery is a potential source of mercury contamination for humans (Mason et al., 2012). ...
Article
Mercury is a bioaccumulating toxic pollutant which can reach humans through the consumption of contaminated food (e.g. marine fish). Although the Southern Ocean is often portrayed as a pristine ecosystem, its fishery products are not immune to mercury contamination. We analysed mercury concentration (organic and inorganic forms – T-Hg) in the muscle of Antarctic toothfish, Dissostichus mawsoni, a long-lived top predator which supports a highly profitable fishery. Our samples were collected in three fishing areas (one seamount and two on the continental slope) in the Southwest Pacific Sector of the Southern Ocean during the 2016/2017 fishing season. Mercury levels and the size range of fish varied between fishing areas, with the highest levels (0.68 ± 0.45 mg kg⁻¹ wwt) occurring on the Amundsen Sea seamount where catches were dominated by larger, older fish. The most parsimonious model of mercury concentration included both age and habitat (seamount versus continental slope) as explanatory variables. Mean mercury levels for each fishing area were higher than those in all previous studies of D. mawsoni, with mean values for the Amundsen Sea seamount exceeding the 0.5 mg kg⁻¹ food safety threshold for the first time. It might therefore be appropriate to add D. mawsoni to the list of taxa, such as swordfish and sharks, which are known to exceed this threshold. This apparent increase in mercury levels suggests a recent contamination event which affected much of the Southwest Pacific sector, including both the Amundsen and Dumont D’Urville seas.
... The toothfish fisheries managed by CCAMLR may be at risk as toothfish matures late, has low fecundity rate, and is slow growing (Collins et al., 2010); CCAMLR has no ITQ system in place; there also is no, or little, control of actual catches (the observers record some scientific data, not actual catches); there is low reporting of by-catch; and there is evidence of IUU (Ainley et al., 2012;Ainley and Pauly, 2014;Xiong et al., 2016). ...
Article
This article recognizes that the impacts and effects of fishing are key to marine ecosystem management and explores the relationship between fisheries exploitation and sustainable harvests, and the collapse and depletion of stocks. A survey of 21 fisheries from around the world assessed key biological, environmental, social, economic, industry, governance, and management variables and associated criteria that potentially affect stock abundance. We developed 51 criteria as potential contributing factors underpinning three main fishery management outcomes: a sustainable fishery, a depleted fishery, or a collapsed fishery. The criteria that scored highest for the 15 sustainable fisheries in the analysis were associated with the broad groupings of biology (characteristics of the species and stock), management (legal and policy frameworks, tools and decision systems), and industry (economic performance and value). This analysis showed that while a fishery might have a high score for management, sustainability is likely to be difficult to achieve without a medium or high score for biological knowledge.
Chapter
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Four broad categories of human activities that presently threaten Antarctic wildlife in the Antarctic were identified: (1) tourism and non-governmental activities, (2) scientific research, (3) commercial fisheries and (4) whaling. Two further broad categories of threats that originate from multiple forms of human activities are: (1) shipping-related impacts and (2) the introduction of non-native species or disease-causing agents. These threats are not mutually exclusive, and there are various interactions and synergies present amongst them. We have not incorporated climate change into the assessment of each of these, but briefly assess the hierarchical contribution of climate change to other threats. We confidently expect an expansion of virtually all anthropogenic activities in the Antarctic (primarily tourism, research and fisheries) in the next 50 years. The threats will also increase in their complex synergies and interactions, giving further increasing urgency to adopting a more precautionary approach to managing human activities in the Antarctic. We present predictions for 2060 and list suggested proactive management and conservation strategies to address the predicted threats to Antarctic wildlife and their environment.
Chapter
World fishery take peaked during the 1980s and has since declined as stocks have become fully or over exploited, forcing fishermen into ever deeper and more remote waters. Antarctic fishing has reflected this global trend. In 1996 a single, exploratory long-line vessel from New Zealand penetrated the icy waters of the Ross Sea, and in doing so, initiated the most remote fishery on Earth. Historically, the depletion of marine resources in other parts of the world had driven fishing vessels into the Southern Ocean, initially for seals, then whales, then fish and krill, in some areas a veritable ‘fishing down the food web’. Yet, some of the southernmost reaches of the Southern Ocean, including the Ross Sea, had remained protected by remoteness and daunting sea-ice conditions. These corners of the Southern Ocean contain some of the last healthy continental shelf ecosystems left on Earth, including the last remaining unexploited fish stocks. These competing realities have clashed in the Ross Sea, creating tension between ‘rational use’ and ecosystem conservation. While efforts to designate a Ross Sea marine protected area (MPA) have been underway for almost a decade, upwards of twenty vessels have continued to fish for toothfish which is marketed as ‘Chilean Sea Bass’, also known as ‘White Gold’ owing to the price it commands. The Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR), the arm of the Antarctic Treaty System (ATS) that governs biological resource extraction from the Southern Ocean, contains founding articles upon which these economically valuable resources can be regulated while protecting the integrity of the Antarctic marine ecosystem, all under conditions of rapid environmental change. This chapter reflects on the difficulties this has presented in practice, and the severe challenges posed for the maintenance of both ecosystem-based management, and (the crux of the issue) the maintenance of the Antarctic marine ecosystem itself. Given the centrality of resource management and environmental protection in the wider regime of the ATS – and the core purpose and functions of CCAMLR – this situation is one of political, ecological and economic significance. Indeed, one might argue that what we are seeing in relation to our management of the Southern Ocean is a test of the bona fides of the ATS. On the one hand, the Commission that oversees the Convention has been able to regulate the take of Antarctic krill (Euphausia superba) effectively and even implement ecosystem-based management (EBM). Success emanated from an early start initiated by SCAR (the Scientific Committee on Antarctic Research) through its BIOMASS program, which focused on Antarctic krill and its place in the ecosystem. The Commission’s success with krill may have been further facilitated by the dissolution of the Soviet Union in 1991. Until then, the Soviets had depleted many Antarctic fish stocks and were taking increasing amounts of krill in a heavily subsidized effort. However with the breakup of the USSR, krill fishing dramatically decreased, giving the Commission time to investigate further the ways of EBM, then a largely untried concept in fisheries management. Further, krill was not a high-value or quality fish product. Fish farming and fish oil pills (both of which use krill) were not in demand as they are today, and thus catch rates remained low relative to stock biomass and relative to CCAMLR catch limits.
Article
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Measurements of buoyancy on 11 species of notothenioid fishes from McMurdo Sound, Antarctica indicate that they range from neutrally buoyant to relatively heavy. Since these fishes lack a swim bladder, reduction in body weight is accomplished primarily through low levels of skeletal mineralization and lipid deposition. Neutrally buoyant species have ash contents of less than 1% of the body weight. There is no reduction in the percentage of body weight occupied by musculature. Lipid (triglyceride) deposits provide static lift in neutrally buoyant species; these deposits are contained in large connective tissue sacs or in typical adipose cells located subcutaneously as well as intermuscularly. As judged by low percentage weight and negative buoyancy, the liver is not an organ of buoyancy. Measurements of buoyancy and morphological studies allow recognition of species associated with pelagic, cryopelagic, benthopelagic and benthic habitats.
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By estimating probabilistic reaction norms for age and size at maturation, we show that maturation schedules of Atlantic cod (Gadus morhua) off Labrador and Newfoundland shifted toward earlier ages and smaller sizes during the late 1980s and early 1990s, when these populations underwent a severe collapse in biomass and subsequently were closed for directed commercial fishing. We also demonstrate that this trend towards maturation at younger ages and smaller sizes is halted and even shows signs of reversal during the closure of the fisheries. In addition, our analysis reveals that males tend to mature earlier and at a smaller size than females and that maturation age and size decrease with increasing latitude. Importantly, the maturation reaction norms presented here are robust to variation in survival and growth (through phenotypic plasticity) and are thus strongly indicative of rapid evolutionary changes in cod matu- ration as well as of spatial and sex-specific genetic variation. We therefore suggest that maturation reaction norms can provide helpful reference points for managing harvested populations with evolving life histories.
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The long-term monitoring program of demersal fi sh at inshore sites of the South Shetland Islands has continued at Potter Cove from 2000 to 2006, extending a continuous sampling period of 24 years which began in 1983, and at Harmony Cove in the summers of 2001 to 2003. The decline in trammel net catches of fjord Notothenia rossii and Gobionotothen gibberifrons in relation to the non-commercially fished Notothenia coriiceps is still evident. At Potter Cove, despite an overall increasing trend of N. rossii catches from 1991 to 2006, the actual levels are half of those found in the early 1980s, while those of G. gibberifrons have further declined and remain close to zero. At Harmony Cove, the relative abundance of N. rossii showed an increase in 2002 and 2003, whereas G. gibberifrons was absent in the catches. These trends are consistent with those observed in scientifi c cruises studying the offshore populations in a similar period. No recovery of the stocks of N. rossii and G. gibberifrons was observed, more than two decades after the end of the commercial fishery.
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Life-span estimates for orange roughy (Hoplostethus atlanticus) range from similar to 20 years to well over 100 years. In this study, an improved lead-radium dating technique provided independent age estimates from sagittal otoliths. This technique used the known properties of radioactivity for lead-210 and radium-226 to determine the validity of fish age estimates. An improvement to lead-radium dating using mass spectrometry allowed the use of smaller samples than previously possible; therefore, an application was made to otolith cores, the first few years of otolith growth. This approach circumvented the use of whole otoliths and alleviated many of the assumptions that were necessary in previous lead-radium dating applications. Hence, it was possible to critically evaluate lead-radium dating as a tool in fish age validation. The measurement of lead-radium ratios for a series of age groups that consisted of otolith cores, grouped based on growth-zone counts from thin sections, showed a high degree of correlation to the expected lead-radium ingrowth curve. This finding provided support for age estimation procedures using thin otolith sectioning. As independent estimates of age, the results indicated that fish in the oldest age group were at least 93 years old, providing robust support for a centenarian life span.
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We investigated temporal and spatial variability in the diet of chick-provisioning Adélie Penguins (Pygoscelis adeliae) breeding at all colonies within one isolated cluster in the southwestern Ross Sea, Antarctica, 1994-2000. We wished to determine if prey quality explained different population growth and emigration rates among colonies. Diet composition was described both by conventional means (stomach samples) and by analysis of stable isotopes in chick tissues (toenails of individuals killed by skuas [Stercorarius maccormicki]). Diets were similar among the four study colonies compared to the disparity apparent among 14 widely spaced sites around the continent. Calorimetry indicated that fish are more energetically valuable than krill, implying that if diet varied by colony, diet quality could attract recruits and help to explain differential rates of colony growth. However, a multiple-regression analysis indicated that diet varied as a function of year, time within the year, and percent of foraging area covered by sea ice, but not by colony location. Stable isotopes revealed similarity of diet at one colony where conventional sampling was not possible. We confirmed that sea ice importantly affects diet composition of this species in neritic waters, and found that (1) quality of summer diet cannot explain different population growth rates among colonies, and (2) stable isotope analysis of chick tissues (toenails) is a useful tool to synoptically describe diet in this species over a large area.
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From 1995 to 1998, we collected female black rockfish (Sebastes melanops) off Oregon in order to describe their basic reproductive life history and determine age-specific fecundity and temporal patterns in parturition. Female black rockfish had a 50% probability of being mature at 394 mm fork length and 7.5 years-of-age. The proportion of mature fish age 10 or older significantly decreased each year of this study, from 0.511 in 1996 to 0.145 in 1998. Parturition occurred between mid-January and mid-March, and peaked in February. We observed a trend of older females extruding larvae earlier in the spawning season and of younger fish primarily responsible for larval production during the later part of the season. There were differences in absolute fecundity at age between female black rockfish with prefertilization oocytes and female black rockfish with fertilized eggs; fertilized-egg fecundity estimates were considered superior. The likelihood of yolked oocytes reaching the developing embryo stage increased with maternal age. Absolute fecundity estimates (based on fertilized eggs) ranged from 299,302 embryos for a 6-year-old female to 948,152 embryos for a 16-year-old female. Relative fecundity (based on fertilized eggs) increased with age from 374 eggs/g for fish age 6 to 549 eggs/g for fish age 16.
Article
This paper summarises knowledge of the distribution and relative abundance of Antarctic toothfish (Dissostichus mawsoni) on the Ross Sea shelf (defined here as the continental shelf out to the edge of the shelf break at about 600-800 m depth). The focus is on D. mawsoni catches from the shelf, as this area is likely to have the greatest overlap between D. mawsoni and potential predators, and thus where any ecosystem effects would be most likely to occur. The shelf catch has been taken mainly in depths greater than 800 m from three localised fishing grounds of deep water off Terra Nova Bay, Ross Island, and in the south of small-scale research unit (SSRU) 881L (adjacent to the Ross Ice Shelf). The catch rates from the exploratory longline fishery typically show high temporal and spatial variability, even between consecutive sets within the main fishing grounds. Most toothfish caught in the southern Ross Sea were sub-adult and maturing fish, typically ranging from 60-130 cm in length, with some evidence for an ontogenetic migration from east to west as they grow. From the fisheries data available, there is no evidence for a northward contraction in the range of D. mawsoni over the course of the fishery. Nevertheless, it would seem prudent to have a monitoring system in place so that changes in relative abundance of these sub-adult fish could be detected. It is recommended that CCAMLR consider developing a sub-adult longline survey to monitor this part of the population.
Article
This study uses histological assessments to determine age- and length-at-spawning for female and male Antarctic toothfish (Dissostichus mawsoni) from fish sampled in the Ross Sea spanning the 2000-2009 fishing seasons. A characterisation of the oocyte developmental cycle of D. mawsoni shows that once development begins, oocytes grow and accumulate at the cortical alveoli stage for at least one year. Individual oocytes are then recruited into the vitellogenic phase over at least a 6-12 month period, resulting in a developed group of oocytes accumulating at the final maturation stage by approximately May each year. The age at 50% spawning for females on the Ross Sea slope region is 16.6 years (95% CI 16.0-17.3) or 133.2 cm (95% CI 130.9-135.7) by length. On average, males spawn at a younger age with an A50% of 12.8 years (95% CI 11.9-14.0) or 120.4 cm (95% CI 114.8-126.7) by length. Evidence of skip-spawning was observed for females only and results in a fatter, right-shifted ogive, increasing the functional difference between male and female ogives. The degree to which the overall population ogive is biased right (older) by applying the slope-derived ogive to the northern Ross Sea region depends on the proportion of the total population occurring in the northern Ross Sea region, which is currently unknown.
Article
Aspects of the reproduction, size distribution and movements of Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea region are reviewed. Based on the presumed location and timing of spawning and the probable early life-history characteristics of toothfish, the drift of eggs and larvae over a 6-24 month period were investigated using an oceanic circulation model linked to the high-resolution global environmental model (HiGEM). Model outputs indicated that the locations of toothfish larvae after an 18-24 month period were moderately consistent with the distribution of the smallest toothfish taken in the toothfish fishery. The hypothesis presented is that D. mawsoni in CCAMLR Subareas 88.1 and 88.2 spawn mainly on the ridges and banks of the Pacific-Antarctic ridge to the north and east of the Ross Sea. The spawning appears to take place during the austral winter and spring. Depending on the exact location of spawning, eggs and larvae become entrained by the Ross Sea gyres, and may move west, settling out around the Balleny Islands and adjacent Antarctic continental shelf; south onto the Ross Sea shelf; or eastwards with the eastern Ross Sea gyre, settling out along the continental slope and shelf to the east of the Ross Sea in Subarea 88.2. As the juveniles grow in size, they move west back towards the Ross Sea shelf and then move out into deeper water. As they mature, the fish gradually move deeper out onto the continental slope where they gain condition before undergoing a northwards spawning migration to the Pacific-Antarctic Ridge to start the cycle again. Toothfish probably remain in the northern area for 6-18 months before migrating back to the slope to regain condition.
Article
Longhurst examines the proposition, central to fisheries science, that a fishery creates its own natural resource by the compensatory growth it induces in the fish, and that this is sustainable. His novel analysis of the reproductive ecology of bony fish of cooler seas offers some support for this, but a review of fisheries past and present confirms that sustainability is rarely achieved. The relatively open structure and strong variability of marine ecosystems is discussed in relation to the reliability of resources used by the industrial-level fishing that became globalised during the 20th century. This was associated with an extraordinary lack of regulation in most seas, and a widespread avoidance of regulation where it did exist. Sustained fisheries can only be expected where social conditions permit strict regulation and where politicians have no personal interest in outcomes despite current enthusiasm for ecosystem-based approaches or for transferable property rights.
Article
Preface Part I. The Ecology of Antarctic Fish: 1. Introduction 2. The evolution of the fish fauna of the Southern Ocean 3. The composition of the fish fauna 4. Classification of the Notothenioidei 5. Geographical and bathymetric distribution of the fish fauna 6. Adaptations to the environment 7. Reproduction and early life history 8. Age, growth, mortality and biomass estimates 9. The significance of fish in the ecosystem 10. Parasites 11. Future research Part II. Antarctic Fisheries: 12. The commercially exploited species 13. The development of the fishery 14. Trends in the fishery 15. Fishing grounds and fishing conditions 16. Fish detection and catching methods 17. Fishery products 18. The development of fish stock assessment and fisheries management in the Southern Ocean 19. The effect of fishing on single stocks 20. Detrimental effect of krill fishing on recruitment 21. Effects of fishing and fishery-related activities on other components of the marine ecosystems of the Southern Ocean 22. Approaches to a more effective fisheries management in the Southern Ocean 23. Perspectives for a future fish harvest from the Southern Ocean.
Article
Size, condition, and age of female-Icelandic cod Gadus morhua were correlated to the size of their eggs and newly hatched larvae. A positive relationship was detected between egg size and some larval viability parameters, including the age at first feeding, successful development of a swimbladder. and specific growth rates during the first 15 days after hatching. These results reveal that the viability of cod larvae is related to attributes of the spawning females and that this information is important to our understanding of stock-recruitment relationships.
Article
Pogonophryne steward, new species, is described from collections made at 1700 m on the continental slope of the Indian Ocean Sector of the Southern Ocean, off Wilkes Land, Antarctica. The new species Is assigned to the unspotted P. albipinna species group and is related to P. immaculata. It Is distinguished from all other species of the P. albipinna species group by the following combination of characters: a long (about 15-20% SL) mental barbel without a terminal expansion, a shallow head and slender trunk with only slight taper to caudal peduncle, 8-13 middle lateral-line pores, and divergence In the mitochondrial ND2 gene. We discuss the composition and validity of the A albipinna group, which, up to this point, has been based on three holotype specimens. We provide meristic and morphometric data for seven recently collected adult specimens of P. immaculata. Bayesian analyses of mitochondrial gene sequences for I I of the now 19 recognized species of Pogonophryne, sampled from all five of the proposed species groups, resulted In reciprocal monophyly of the monotypic species groups. The P. albipinna and A mentella species groups were each monophyletic and resolved as sister lineages. We provide a revised key for the four species of Pogonophryne classified In the P. albipinna group.
Article
This article is a synthesis of the current literature on the potential of marine protected areas (MPAs) a useful management tool for limiting the ecosystem effects of fishing, including biological and socio-economic aspects. There is sufficient evidence that fishing may negatively affect ecosystems. Modelling and case studies show that the establishment of MPAs, especially for overexploited populations, can mitigate ecosystem effects of fishing. Although quantitative ecosystem modelling techniques incorporating MPAs are in their infancy, their role in exploring scenarios is considered crucial. Success in implementing MPAs will depend on how well the biological concerns and the socio-economic needs of the fishing community can be reconciled. Cet article fait la synthèse de la littérature sur la possibilité d'utiliser les zones marines protégées (MPAs) comme outils de gestion afin de limiter les effets de la pêche sur les écosystèmes, en incluant les aspects biologiques et socio-économiques. La littérature fournit suffisamment d'évidences à l'effet que la pêche peut avoir un effet négatif. Les MPAs établies dans divers habitats à travers le monde ainsi que les modélisations montrent que MPAs offrent une certaine protection contre ces effets négatifs. Les techniques quantitatives de modélisation des écosystèmes, bien que cruciales pour l'exploration de scénarios de gestion, n'en sont encore qu'à leurs débuts et mériteraient encore plus d'attention. Finalement, le succès des MPAs dépendra de la manière dont on réussira à allier les aspects biologiques et les intérêts socio-économiques.
Article
We aim to identify the important steps in the evolution of the ecosystem approach to management under the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR). The first section provides the background to CCAMLR, including the formulation of the convention and its objectives, its operation, and the historical trends in fisheries. Later sections describe (i) the reasons why a precautionary approach to setting catch limits evolved, (ii) how the precautionary approach takes account of ecosystem objectives and provides for the orderly development of new fisheries, and (iii) how the use of ecosystem indicators in the setting of catch limits and for monitoring the effects of fishing is being evaluated. The final section describes the general framework being used to develop a feedback-management system that incorporates objectives, target species assessments and ecosystem assessments. The CCAMLR experience provides two important lessons. First, conservation objectives can only be achieved by implementing management measures, even when very little is known. Second, methods were found for achieving scientific consensus despite the uncertainties surrounding estimates of parameters and the behaviour of the system. CCAMLR is yet to face the real test in its ecosystem approach, the development of the krill fishery. Before this occurs, appropriate management procedures have to be developed to avoid localized effects on the ecosystem and to provide effective feedbacks on the effects of fishing through its monitoring programme.
Article
At Terra Nova Bay, the scallop Adamussium colbecki (Smith, 1902) characterises the soft and hard bottoms from 20 to 80 m depth, constituting large beds and reaching high values of density (50–60 individuals/m2) and biomass (120 g/m2 DW soft tissues). To assess its role in the organic matter recycling in the coastal ecosystem, its filtering and biodeposition rates were evaluated in laboratory experiments during the austral summer 1993/94. Filtration rates, measured in a flow-through system, were calculated from the difference in particulate organic carbon (POC), nitrogen (PON) and chlorophyll-a (Chl-a) concentration in inflow and outflow water. Experiments were performed using natural sea water with POC, PON and Chl-a concentrations of about 450 μg/l, 90 μg/l and 2 μg/l, respectively. The biodeposition rate and the biochemical composition of the biodeposits were studied in order to detect how the organic matter is transformed through feeding activity of A. colbecki. At +1°C temperature, the average filtering rate was about 1 l h−1 g−1 (DW soft tissues) in specimens ranging in body mass from 2 to 3 g (DW soft tissues) and 6–7 cm long. The biodeposition rate in 3–8 cm long specimens, ranging from 0.4 to 5.7 g (DW soft tissues), was about 5.65 mg DW/g DW/day, leading to an estimate of Corg flux, through biodeposition by A. colbecki, of about 21 mg C m−2 day−1 at in situ conditions. Comparison between the biochemical composition of seston and biodeposits shows a decrease of the labile compounds, of the Chl-a/phaeopigments ratio in the biodeposits. The recorded C/N ratio decrease suggests a microbial colonisation in the biodeposits. This study suggests that Adamussium colbecki plays an important role in coupling the material fluxes from the water column to the sea bed, processing about 14% of total Carbon flux from the water column to the sediments, with an assimilation efficiency of 36%.
Article
Ages of orange roughy (Hoplostethus atlanticus) determined by two methods (counting annuli on the surface of whole and in longitudinally sectioned otoliths) were similar up to maturity. Beyond maturity, age estimates from sectioned otoliths exceeded those from whole otoliths. Maximum recorded age was 125 years for an individual 41 cm standard length (SL), and age at maturity was estimated to be 25 years (30–32 cm SL). These are consistent with ages estimated previously by radiometric methods. Results demonstrated a two-stage linear relationship between otolith weight and age that confirmed the two-stage otolith mass growth model previously used in radiometric ageing. However, in the radiometric analyses the reduction in otolith growth was arbitrarily estimated at 45% of the immature rate whereas annuli data demonstrated a reduction after maturity to 62% of the immature rate. The new estimates of otolith mass growth rate were incorporated into the radiometric data and ages recalculated, which reduced age estimates for 38–40 cm SL fish from 77–149 to 59–101 years. The radiometric data were also recalculated using only the percentage reduction in otolith growth after maturity, giving the radiometric age of 125 ± 9 years for the oldest fish.
Article
Satellite passive-microwave data have been used to calculate and map the length of the sea-ice season throughout the Southern Ocean for each year 1979-99. Mapping the slopes of the lines of linear least-squares fit through the 21 years of resulting season-length data reveals a detailed pattern of trends in the length of the sea-ice season around the Antarctic continent. Specifically, most of the Ross Sea ice cover has, on average over the 21 years, undergone a lengthening of the sea-ice season, whereas most of the Amundsen Sea ice cover and almost the entire Bellingshausen Sea ice cover have undergone a shortening of the sea-ice season. Results for the Weddell Sea are mixed, with the northwestern portion of the sea having experienced a shortening of the sea-ice season but a substantial area in the south-central portion of the sea having experienced a lengthening of the ice season. Overall, the area of the Southern Ocean experiencing a lengthening of the sea-ice season by at least 1 day per year over the period 1979-99 is 5.6 × 106 km2, whereas the area experiencing a shortening of the sea-ice season by at least 1 day per year is 46% less than that, at 3.0 × 106 km2.