Demography and conservation of the Tristan albatross Diomedea [exulans] dabbenena

The Tristan albatross Diomedea [exulans] dabbenena is the third rarest albatross species, with a breeding population of around 1500 pairs almost totally restricted to Gough Island in the Tristan da Cunha group, central South Atlantic. During January 2000, the entire breeding population of Gough was surveyed for the first time since 1956, and 2400 incubating pairs were counted. An analysis of the areas that are likely to have been surveyed most accurately in the past suggests that the population has decreased by around 28% over 46 years. The number of large chicks counted over three successive seasons (1999-2001) was highly variable (range 318-1129). The average count over this period (705 chicks) is less than counts made in 1979 (792) and 1982 (798). A total of 656 chicks were counted in September 2001, giving an island breeding success of just 27.3%. However, breeding success varied considerably in different areas of the island, ranging from 17.6 to 68.0%. During the 2001 season most breeding failures were of large chicks, and over 4 years where data were available, 75% of breeding failures occurred during the chick period. Predation by introduced house mice Mus musculus is the most likely cause of chick mortality. In a small study population, birds began breeding at an average age of 9.7 years and annual adult survival from 1985 to 2001 was 92.6% (SE=1.6%). Both breeding success and adult survival estimates are low in comparison with other Diomedea species and population modelling predicts a population decreasing at an annual rate of 2.9-5.3%. Further research is needed urgently to assess whether breeding success is typical, and to confirm that mouse predation is the cause of chick mortality. The low productivity of this species will compound the negative impacts of longline fishing mortality, which are likely to be reducing adult and juvenile survival.     

The impact of pelagic longline fishing on the flesh-footed shearwater Puffinus carneipes in Eastern Australia

The flesh-footed shearwater (Puffinus carneipes) is a medium-sized seabird (ca. 700 g) that is incidentally killed during longline fishing operations. We examined the levels of bycatch in Australia’s Eastern Tuna and Billfish Fishery and developed a model to examine the impact of this fishery on the eastern Australian population of flesh-footed shearwaters, which breeds at only one site, Lord Howe Island. Observed bycatch rates for flesh-footed shearwaters were 0.378 birds/1000 hooks for night sets, and 0.945 birds/1000 hooks for day sets. The mean number of birds killed from 1998 to 2002 was estimated to be 1794-4486 birds per year, with the estimated total killed over this period ranging from 8972 to 18,490 birds. Models incorporating both density-independent and density-dependent scenarios were applied to levels of bycatch representative of that observed in the fishery. Density-independent scenarios showed that fishing mortality levels caused declines in the majority of simulated populations. In contrast, density-dependent scenarios produced populations that were more resilient to fishing mortalities. Although some modelling scenarios led to population growth, under most stochastic simulations median population halving and quasi-extinction times were less than 55 and 120 years, respectively. We conclude that the level of bycatch observed in the fishery is most likely unsustainable and threatens the survival of the Lord Howe Island population. This situation can be improved only with the development and implementation of mitigation measures that will halt or greatly reduce the level of bycatch currently observed. Improved knowledge on a range of demographic parameters for the species, combined with a clearer idea of the at-sea distribution of breeding and non-breeding shearwaters, will greatly assist in improving understanding and the management of this population.     

At-sea distribution of waved albatrosses and the Galápagos Marine Reserve

Albatross populations worldwide are threatened by incidental takes in longline fishery operations. The recent establishment of the Galápagos Marine Reserve (GMR) is relevant to the longline bycatch issue, as it prohibits industrial longlining in the vicinity of the major nesting site of waved albatrosses (Phoebastria irrorata). However, the legality of the fishing protections is being challenged, highlighting a need for data on use of the GMR by albatrosses. We used satellite tracking over a total of four breeding seasons to determine the distribution of waved albatrosses inside and outside the GMR, and thereby assess the degree of protection that GMR provisions offer to this species. During the incubation period, breeding adults made commuting trips from the nesting island (Isla Española) to the Peruvian upwelling zone, traveling north, east, and south after leaving the nest. During the brooding period, the distribution contracted markedly, and most satellite fixes were within the GMR. During the rearing period, breeders performed both long trips outside the GMR and short trips within. The southeastern portion of the GMR is used throughout the incubation, brooding, and early rearing periods by breeding waved albatrosses. Indirect information from non-breeding adults indicates that they are likely to use the waters of the GMR extensively.     

Spatio-temporal trends of longline fishing effort in the Southern Ocean and implications for seabird bycatch

Longline fisheries have expanded throughout the world's oceans since major commercial distant-water pelagic fleets began fishing for tuna and tuna-like species in the early 1950s. Along with the more recent development and expansion of demersal longline fleets for species such as Patagonian toothfish, these vessels are a major source of mortality to several species of seabird. Vessels can set many thousands of baited hooks in a day across many kilometres of water. These waters are often used as foraging areas by wide-ranging seabirds. Attracted by baits and offal, the birds can be caught on the baited hooks and subsequently drown. To provide a greater understanding of the potential impact of the Southern Ocean's longline fleets on seabird populations, this paper describes the trends in longline effort of the major pelagic and demersal fisheries in southern waters. The total reported effort from all longline fleets south of 30°S has been well over 250 million hooks per year since the early 1990s. However the spatial and temporal distribution of this effort has not been constant. While effort from the Japanese pelagic distant-water longline fleet declined through the 1990s, the Taiwanese fleet expanded dramatically. Likewise demersal fishing for toothfish increased markedly during the mid-1990s. These fisheries, along with substantial illegal longline fisheries, may be placing the long-term viability of many Southern Ocean species of seabird in jeopardy.     

采用AIS计算中西太平洋延绳钓渔船捕捞努力量

对渔船捕捞行为和捕捞强度空间高分辨率的估计可以作为海洋资源管理和生态脆弱性评估的重要信息。为识别远洋延绳钓渔船作业状态,该文基于2017年10-11月中西太平洋延绳钓渔船卫星船舶自动识别系统(automatic identification system,AIS)数据和捕捞日志数据,采用支持向量机(support vector machine,SVM)学习方法,构建了中国中西太平洋延绳钓渔船捕捞作业状态(捕捞/非捕捞)分类模型。通过计算模型分类准确率、精确率、敏感度和特异度来评价模型对渔船作业状态分类能力。结果表明,模型训练数据的准确率为95.24%(Kappa系数为0.9),验证数据的准确率为93.85%(Kappa系数为0.87)。采用构建好的模型识别2017年10月和11月中西太平洋延绳钓渔船共计125624条AIS记录数据,模型准确率在83.3%(Kappa系数为0.67)。2017年10、11月所有数据分类精确率为82.33%,灵敏度为88.32%,特异度为77.27%。渔船主要作业空间在168°E^173°E,12°S^18°S,有3个明显的作业强度较高区域。基于SVM模型和日志记录的捕捞强度信息在空间上相关性很高(r>0.98),SVM模型识别的渔船捕捞努力量空间分布特征和实际吻合。捕捞努力量与单位捕捞努力量渔获量(catch per unit of effort,CPUE)、渔获尾数、渔获质量和投钩数的相关系数分别是0.68、0.93、0.93和0.94。基于AIS信息挖掘的渔船空间捕捞努力量可用于渔业资源分析。     

Estimating the odds of survival and identifying mitigation opportunities for common bycatch in pelagic longline fisheries

To evaluate how fishing practices affect bycatch survival and to identify opportunities to reduce bycatch mortality, we estimated the odds of hooking survival for common bycatch species in the Canadian longline fishery for swordfish (Xiphias gladius) and tunas (Thunnus spp.) fishing in the North Atlantic. Generalized linear models, with binomial response, were based on 859 sets observed between 2001 and 2004 and were tested using data from 2005 and 2006. Bycatch included targeted species in poor condition or below regulatory size limits. Odds of survival were two to five times higher for swordfish, yellowfin tuna (Thunnus albacares), pelagic stingray (Pteroplatytrygon violacea), porbeagle (Lamna nasus) and blue shark (Prionace glauca) caught on circle hooks compared to J-hooks during the 2001–2004 period. Further, odds of severe hooking injuries decreased for three shark species caught on circle hooks. We found no conservation benefit for loggerhead turtles (Caretta caretta) from circle hook use. Increased circle hook use coincided with increased targeting and higher landings of tunas. Hooking survival rates and, therefore opportunities to reduce bycatch mortalities differed among the 10 species commonly discarded or released. Where the odds of survival to the time of release are high (e.g., loggerhead turtles, pelagic stingray, blue shark), methods to reduce post-release mortality can be considered. Where the odds of hooking survival are low (e.g., swordfish and longnose lancetfish, Alepisaurus ferox), methods to reduce encounter rates would have greater conservation impact.     

Seabird and longline interactions: effects of a bird-scaring streamer line and line shooter on the incidental capture of northern fulmars Fulmarus glacialis

Interactions between seabirds and longline fishing can cause incidental bird mortality and reduced gear efficiency. The potential for solving these problems by using a bird-scaring streamer line and a line shooter was investigated in commercial longlining in the northern Atlantic off the coast of Norway. We compared the bycatch rate of northern fulmars Fulmarus glacialis, the loss rate of baits to fulmars and the catch rates of fish target species among lines set with either of these mitigation measures, a combination of both and no mitigation measure. A total of 58,420 hooks were set in each of the four treatments. No birds were caught using the bird-scaring line alone and a single fulmar was caught when the bird-scaring line was used in combination with the line shooter. In contrast, 32 fulmars were caught in sets with no mitigation device and thirteen in sets with the line shooter alone. Losses of mackerel bait were reduced when the bird-scaring line was used, but not by using the line shooter alone. Longlines set with the line shooter reached 3 m depth 15% faster then lines set without the line shooter; beyond this depth sinking rates were similar (about 15 cm s⁻¹). Fish catch did not vary significantly among setting methods. These results should also be applicable to the bycatch of Fulmarus spp. in demersal longline fisheries worldwide.     

On the present breeding status of the scarlet ibis Eudocimus ruber along the north-eastern coast of South America

During 1970–72 aerial surveys were made along the coasts of the Guianas, South America, and a reliable assessment of the present breeding status of the scarlet ibis (Eudocimus ruber (L.)) along these coasts was obtained. During this period seven scarlet ibis breeding colonies were active simultaneously, with a total number of about 20,000 breeding pairs, over half in Surinam.From correspondence with other ornithologists, it appears that little is known about the present breeding status in Columbia, in the Venezuelan llanos, and along the coast of eastern Brazil.It is argued that in the future adequate guarding of the breeding areas (and possibly also of the feeding areas) would be necessary to ensure the conservation of the species.     

A survey of natterjack toad Bufo calamita distribution and breeding success in the north merseyside sand-dune system,England

In spring 1978, adult natterjack toads Bufo calamita assembled at 101 out of 132 sites containing water in the north Merseyside sand-dunes. A total of 2001 spawn strings was counted in 95 sites, 95% of the spawn being deposited before 11 May. Metamorphosis was confirmed at 28 sites and probably occurred at a further 12 sites distributed throughout the dunes. Most spawning took place in shallow water in slacks or excavated scrapes. Deep ponds, ditches and bomb craters were little used. Unsuccessful breeding was mainly due to shallow water bodies drying up before metamorphosis could occur. Of sites where metamorphosis was confirmed, 82% were scrapes which had been excavated for conservation purposes.Water-table trends in the dune system and various methods of censusing the adult toad population are discussed.     

An integrated comparison of captive-bred and wild Atlantic salmon (Salmo salar): Implications for supportive breeding programs

Supportive breeding is a strategy consisting in maintaining a pool of locally-adapted wild genitors in captivity whose offspring are released in the wild at an early developmental stage. In this study, we tested the utility of this strategy in preventing phenotypic and genetic divergences between captive-bred and wild animals that could be detrimental for wild populations. Combining microsatellite analyses, morphological measurements and behavioural trials in the laboratory, we compared the progeny of Atlantic salmon (Salmo salar) born in captivity with individuals born in the wild. At all these levels, we found significant differences between the progeny of the two groups. Specifically, allelic frequencies significantly differed between groups, with captive-bred fish tending to be less variable with lower heterozygosity and allelic richness values. The shape of wild-born fish was also different from that of the captive-group, particularly in the depth of the head and the length of the pectoral fins. Finally, captive-bred individuals were, on average, more aggressive than wild-born fish. We demonstrated that this difference was strongly dependent upon the environment as captive-bred fish were more aggressive only when together with their wild conspecifics or with an exotic competitor, the rainbow trout (Oncorhynchus mykiss). Overall, our results showed that both phenotypic and genetic changes can arise even if genitors share a common brood-stock and after only a few months of rearing in a controlled environment. We conclude that the progeny produced in such supportive breeding programs does not meet the criteria necessary to ensure preserving the genetic and ecological integrity of wild populations.     

The potential contribution of ecotourism to African wild dog Lycaon pictus conservation in South Africa

African wild dogs are endangered, and in South Africa as elsewhere, they inhabit a fraction of their former range. In this study, we assessed the potential for economic benefits derived from ecotourism to offset the costs of three wild dog conservation options using a contingent valuation study of the willingness of visitors to four protected areas to pay to see wild dogs at the den - within a viable population in a large protected area (Kruger National Park), through reintroduction into nature reserves, and through the conservation of wild dogs occurring on ranchland in situ. Results indicated that tourism revenue from wild dogs in large protected areas is more than sufficient to offset the costs and could potentially be used to subsidise wild dog reintroductions or the conservation of wild dogs in situ on ranchland. On ranchland and for reintroductions, tourism revenue was generally predicted to offset most of the costs of conserving wild dogs where predation costs are low, and to exceed the costs where willingness to pay is high, and/or where the costs of predation by wild dogs are zero. Conservation efforts should facilitate the derivation of eco-tourism-related benefits from wild dogs on ranchland and in private reserves to create incentives for wild dog conservation. Ecotourism should be part of a multifaceted approach to wild dog conservation which also includes education and awareness campaigns, and efforts to encourage landowners to cooperate to form conservancies.     

Recent decline and potential distribution in the last remnant area of the microendemic Mexican axolotl (Ambystoma mexicanum)

Native populations of the axolotl (Ambystoma mexicanum), a microendemic salamander from Central Mexico, have seen alarming decline in the last decades owing to habitat loss caused by urban growth. The last remnant of its distribution is in a highly heterogeneous urban-rural water system in the Xochimilco region, at the southern edge of Mexico City. We developed a model of the species local distribution based on its ecological niche, using occurrence data and ad hoc limnetic variables via the Genetic Algorithm for Rule-set Production (GARP), to identify suitable areas for the species and prioritize conservation efforts. Results indicated that potential distribution of the axolotl in Xochimilco is limited to 11 sites in six reduced, isolated, and scattered areas, located mostly in zones where traditional agriculture (chinampas) is the primary land use. Recent surveys found only a single organism in the whole study region, in one of the predicted sites, suggesting a critical situation for the long-term survival of the axolotl in the wild, and demanding urgent actions toward habitat and population restoration. This study also illustrates the utility of niche modeling approaches for aquatic systems at a fine scale.     

The influence of food availability on breeding success of African penguins Spheniscus demersus at Robben Island, South Africa

From 1989 to 2004, the breeding success of African penguins Spheniscus demersus at Robben Island, South Africa was significantly related to estimates of the abundance of both their main prey species, anchovy Engraulis encrasicolus and sardine Sardinops sagax, and to the combined biomass of these species. When the combined spawner biomass of fish prey was less than 2 million ton, pairs fledged an average of 0.46 chicks annually. When it was above 2 million ton, annual breeding success had a mean value of 0.73 chicks per pair. Given previously estimated values of survival and age at first breeding, these levels of breeding success are inadequate to sustain the African penguin population. With the higher level of breeding success, an equilibrium situation might be attained if adult survival could be increased by 6-7% per annum. Attempts to reduce mortality of penguins have included the collection, cleaning and return to the wild of oiled birds, culling of Cape fur seals Arctocephalus pusillus pusillus seen preying on penguins around breeding localities and control of the spread of disease. Management of the purse-seine fishery should ensure adequate escapement of fish to maintain the combined biomass of anchovy and sardine above 2 million ton. The maintenance of suitable breeding habitat and removal of feral predators from breeding localities will also be important in improving breeding success.     

Influence of soil on the interactions between endomycorrhizae and Azospirillum in sorghum

Sorghum (S. bicolor L. Moench cv. Bok 8) plants were grown in soil or sand-perlite low in plant-available N and P. Plants were inoculated with a vesicular-arbuscular mycorrhizal (VAM) fungus, or a strain of Azospirillum brasilense or both endophytes together. Plants received a nutrient solution which did not contain N or P. Increases in plant dry weight, shoot-to-root ratios, and the N content of dually-infected plants could be accounted for by summing the VAM and Azospirillum effects. For sorghum inoculated with both endophytes, the presence of A. brasilense in the rhizosphere increased VAM colonization and biomass, while the N input due to Azospirillum decreased, possibly due to competition for carbohydrates.Comparisons between sorghum grown with or without VAM-fungal infection in four growth media showed that edaphic factors other than P availability determined the host response to VAM infection. The P-fixing capacity of the soil, rather than the amount of available (NaHCO₃-extractable) P, influenced the balance between mutualistic and parasitic VAM-fungal growth.     

Habitat moisture availability and the local distribution of the Antarctic Collembola Cryptopygus antarcticus and Friesea grisea

Population densities of the Collembola Cryptopygus antarcticus and Friesea grisea were compared in two maritime Antarctic habitats with different moisture availability. C. antarcticus was absent from the drier rock platform habitat, where F. grisea was the only collembolan collected. In contrast, the sand/pebble habitat on East Beach had greater moisture availability, and C. antarcticus dominated the arthropod community, with juveniles (individuals <1 mm length) representing 58% of the population. The hygropreference characteristics of F. grisea were determined in relative humidity (RH) gradients (12-98% RH) at 10 and 20 °C. F. grisea demonstrated a stronger preference for 98% RH conditions than C. antarcticus, suggesting that the former species is less likely to vacate moist refuges when available. The movement of both species was also monitored at 10 and 15 °C under conditions of 33, 75 and 100% RH. C. antarcticus was more active than F. grisea at both temperatures, and its movement increased at a greater rate as a consequence of reduced RH. The limited desiccation tolerance of C. antarcticus, combined with the increased water loss that would result from its continued movement under declining RH conditions, suggests this species is not well suited to drought-prone environments. In contrast, the reduced movement and ‘risk averse’ behavioural strategy of F. grisea, i.e. taking advantage of moist refuges when available, facilitates water conservation between precipitation/habitat rehydration events. This study provides the first evidence that moisture availability and habitat structure are potential habitat segregation mechanisms between these two Antarctic Collembola.     

Using monitoring data gathered by volunteers to predict the potential distribution of the invasive alien bumblebee Bombus terrestris

We explored the use of ecological niche-modeling from data compiled in a participatory program of thousands of volunteer observers to quantitatively evaluate the spatial risk of invasion by the alien species Bombus terrestris. B. terrestris has been commercially introduced to Japan for the pollination of greenhouse tomato crops since 1991. Recently, naturalized populations of this species have spread rapidly, particularly in Hokkaido, northern Japan. Two niche-based models were constructed from independent data sets (presence-absence and presence-only data sets) and were used to validate one another. Both models performed well and indicated that the data compiled by participatory programs were useful for generating predictive models of the potential distribution of this invasive species. The models also revealed that the potential distribution of B. terrestris is negatively related to the proportion of woodland area, which corresponds to the known biology of this species. In contrast, the effect of the number of colonies introduced for tomato pollination (represented by tomato production) did not significantly affect the distribution of B. terrestris, indicating that its spread is now entering a phase of dispersal from established feral populations and that primary dispersal from commercial colonies in greenhouses is no longer a limiting factor for the distribution of this invasive species.     

Spatial association as an indicator of the potential for future interactions between wind energy developments and golden eagles Aquila chrysaetos in Scotland

Despite their environmental benefits in generating electricity without emission of ‘greenhouse’ gases, wind farms have attracted controversy with regard to their impacts on birds, especially golden eagles Aquila chrysaetos. Evidence from USA studies suggest eagle fatalities through collision with turbines may be the main potential impact whereas for breeding eagles in Scotland, displacement from wind farm areas (indirect habitat loss) may be the primary impact. In this study, we examined the co-occurrence potential for golden eagles and wind farms in Scotland by documenting the spatial association between wind farm proposals and breeding eagle territories and areas potentially suitable for non-breeding eagles. Although there were records for over 500 wind farm proposals at various stages of development, relatively few coincided with eagle territories (ca. 4% of territories had a proposal within 3 km of territory centre). Similarly, only 2% of habitat predicted to be suitable for non-breeding eagles overlapped with proposed or installed wind farm areas. Moreover, estimates of the potential for electricity generation from all wind farm proposals, with respect to government targets for renewable energy supplies, suggested most proposals were unlikely to be constructed. We conclude that in comparison with other constraints on Scotland’s golden eagles, notably persecution, wind farms should not represent a serious concern if best practice in planning their location and minimising their impact are maintained. Potential future regional pressures on breeding eagles from wind farms are highlighted, however, and uncertainty of impact with respect to displacement or collision fatalities requires continued scrutiny.     

Post-breeding season distribution of black-footed and Laysan albatrosses satellite-tagged in Alaska: Inter-specific differences in spatial overlap with North Pacific fisheries

We integrated satellite-tracking data from black-footed albatrosses (Phoebastria nigripes; n = 7) and Laysan albatrosses captured in Alaska (Phoebastria immutabilis; n = 18) with data on fishing effort and distribution from commercial fisheries in the North Pacific in order to assess potential risk from bycatch. Albatrosses were satellite-tagged at-sea in the Central Aleutian Islands, Alaska, and tracked during the post-breeding season, July-October 2005 and 2006. In Alaskan waters, fishing effort occurred almost exclusively within continental shelf and slope waters. Potential fishery interaction for black-footed albatrosses, which most often frequented shelf-slope waters, was greatest with sablefish (Anoplopoma fimbria) longline and pot fisheries and with the Pacific halibut (Hippoglossus stenolepsis) longline fishery. In contrast, Laysan albatrosses spent as much time over oceanic waters beyond the continental shelf and slope, thereby overlapping less with fisheries in Alaska than black-footed albatrosses. Regionally, Laysan albatrosses had the greatest potential fishery interaction with the Atka mackerel (Pleurogrammus monopterygius) trawl fishery in the Western Aleutian Islands and the sablefish pot fishery in the Central Aleutian Islands. Black-footed albatrosses ranged further beyond Alaskan waters than Laysan albatrosses, overlapping west coast Canada fisheries and pelagic longline fisheries in the subarctic transition domain; Laysan albatrosses remained north of these pelagic fisheries. Due to inter-specific differences in oceanic distribution and habitat use, the overlap of fisheries with the post-breeding distribution of black-footed albatrosses is greater than that for Laysan albatrosses, highlighting inter-specific differences in potential vulnerability to bycatch and risk of population-level impacts from fisheries.     

Measurement, management and mitigation of operational interactions between the South Australian Sardine Fishery and short-beaked common dolphins (Delphinus delphis)

This study arose from recommendations given in response to a legislated ecological assessment of the South Australian Sardine Fishery in 2004, urging it to: (i) attempt to mitigate operational interactions with marine mammals if excessive levels were detected; and (ii) improve the accuracy of their reporting of these events.An initial observer program revealed high rates of encirclement and mortality (1.78 and 0.39 dolphins per net-set, respectively) of short-beaked common dolphins (Delphinus delphis). This equated to an estimate of 1728 encirclements and 377 mortalities across the entire fleet over the same period. The average time taken for fishers to respond to encirclements was 135.93 ± 3.72 min and 21.3% of encircled animals subsequently died. During that time, fishers only reported 3.6% of encirclements and 1.9% of mortalities recorded by observers.A code of practice (CoP) was subsequently introduced aimed at mitigating operational interactions. A second observer program revealed a significant reductions in the observed rates of dolphin encirclement (0.22; down 87.3%) and mortality (0.01; down 97.1%) with an estimate of 169 and eight, respectively. The average time taken for fishers to respond to dolphin encirclements also reduced to 16.33 ± 4.67 min (down 76.9%) and the proportion of encircled animals that subsequently died reduced to 5.0%. Agreement between industry reports and observer records improved, with the fishery reporting 57.9% and 58.9% of the rate of encirclements and mortalities, respectively, recorded by observers.A number of avoidance and release strategies in the CoP may have been responsible for these improvements. In particular, fishers were required to delay or relocate their activities if dolphins were observed prior to fishing and to release encircled dolphins immediately or abort the fishing event if release procedures were unsuccessful. Future improvements to the CoP include: (i) improved response times when an encircled dolphin is detected; (ii) better use of behavioural cues for deciding when to abort a net-set; (iii) ceasing fishing during rough weather; and (iv) continuing to increase reporting accuracy by fishers. It is also recommended that the abundance, movements and boundaries of the common dolphin population in the region be determined, so that the impact of fishing activities on their status can be established.