Comparative use of vendace by humans and Saimaa ringed seal in Lake Pihlajavesi, Finland

The Saimaa ringed seal, Phoca hispida saimensis, is one of the most endangered ringed seals in the world. Its total population consisted of 240 adult seals in the Saimaa lake complex in 2000. We estimated the amount of vendace, Coregonus albula, consumed by the seals and compared it with fishermen’s vendace catches and our vendace stock estimates in Lake Pihlajavesi, Finland. Our study area was the habitat of 43 mature seals and 17 immature seals as well as 12 pups in 2001. Five commercial two-boat trawlers fished in the area. Vendace stock size was estimated at 660 tonnes i.e., 12 kg ha⁻¹ in the study area in August-September 2001. The vendace catch by fishermen was approximately 250 tonnes, and the vendace consumption by the Saimaa ringed seal was estimated at 68 tonnes in 2001. We estimated that during the whole year seals ate approximately 8% of the vendace spawning stock biomass in the area while fishermen caught 30% of it. The seals and the fishermen together used less than 10% of the available vendace biomass in each month. Fishing pressure on the vendace stock was highest in August-October. The amount of vendace eaten by the seals exceeded the vendace catch in fisheries only in December-April. In periods of low vendace density, the seals can consume a higher proportion of the stock and reduce the catch per unit of effort in fisheries. However, our assumption that seals fed only on vendace should be considered as an extreme scenario when considering the conflict between fisheries and the seal.     

Phocine distemper virus in the North and European Seas - Data and models, nature and nurture

Two outbreaks of phocine distemper have severely affected harbour seal (Phoca vitulina) populations in European and UK waters. The first occurred in 1988 when the causative virus was identified as a new member of the genus morbillivirus. The second outbreak in 2002 was first detected on the same Danish Island of Anholt and involved similar populations and geographical locations. However, despite the obvious similarities between the epidemics, differences in viral transmission and case mortality were found. Harbour seals are highly susceptible to infection while sympatric grey seals (Halichoerus grypus) are resistant but could be important asymptomatic carriers of the disease. Arctic phocid seals remain the most likely source of the virus and grey seals could be the link between these primary hosts and the harbour seal populations further south. Future epidemiological models should therefore consider including multiple host species. The future conservation and management of harbour seal populations vulnerable to PDV relies on the ability to accurately predict the long-term impact on population abundance and distribution. Although knowledge about the behaviour and pathogenesis of the virus has increased substantially and data on host movements and contact rates are accumulating, studies into the determinants of the host range have lagged behind. The development of more realistic epidemiological models should be combined with studies into the factors controlling species and individual susceptibility. Assessing the risk of infection to endangered but currently unexposed potential host species (such as the Hawaiian monk seal, Monachus schauinslandi) is essential for guiding potential conservation management options, such as vaccination     

Status and conservation of the grey seal, Halichœrus grypus, in France

We investigated the status of the grey seal in the Molène archipelago, western Brittany, where a Marine National Park is planned. We combined regular censuses, photo-identification and satellite telemetry to investigate trends in grey seal abundance, site fidelity, individual movements and haulout site use. Individual movements and seasonal variations in abundance suggest that the seals used the Molène archipelago alternatively with other haulout sites of the South-west British Isles during their annual cycle. Nine out of 16 seals fitted with Satellite Relay Data Loggers (SRDLs) moved to the Isles of Scilly, English Cornwall, Wales or the Channel islands. On average the seals spent 85% of their time Near Haulout, 56.8% of which in the Molène archipelago. Overall the seals spent 66% of their tracking time within the boundaries of the Marine National Park. From 1997 to 2000 in the Molène archipelago, we observed a peak in number during the moulting season (mean = 49.8 seals) and a lower abundance during the breeding season (mean = 38.3 seals). The sex ratio was strongly skewed towards males during the moult (between 3.1 and 5.3-1), and was close to 1:1 during the summer. Inter-annual site fidelity outside the breeding season was very high, varying from 70% to 95% of identified seals, suggesting that the observed movements constitute rotations rather than random dispersion. From 1991/1994 to 1997/2000, the mean number of seals counted at haulout sites increased by 7%, close to the rates of increase observed in the core population of the British Isles at the same period. The Marine National Park may be too restricted for the overall conservation of the population but management plans should be aimed at preserving the characteristics of the habitat for the grey seal.     

Assessing conservation priorities in the Benguela ecosystem, South Africa: analysing predation by seals on threatened seabirds

Cape fur seals (Arctocephalus pusillus pusillus), a protected species, have become abundant in the Benguela ecosystem off the west coast of southern Africa (present population size about 1.5-2 million animals), and are killing substantial numbers of red data book species of seabirds (African penguin Spheniscus demersus, Cape gannet Morus capensis, Cape cormorant Phalacrocorax capensis, bank cormorant P. neglectus and crowned cormorant P. coronatus). The decision has been taken to reduce the impact of seal predation by selectively culling seals which are witnessed killing seabirds. Between 1993 and 2001 a total of 153 seals, which were killing fledgling gannet chicks, were culled.     

Sex-specific roost movements and population dynamics of the vulnerable long-fingered bat, Myotis capaccinii

The roosts of many IUCN-listed cave-roosting bat species are under threat from tourist development in SE Europe and other regions of the world. Much-needed conservation strategies require, among other information, an understanding of their roost movements and population dynamics, which can now be obtained relatively quickly using advanced models. We have studied the long-fingered bat, Myotis capaccinii, an obligate cave-dweller, in Dadia National Park, Greece. The species formed colonies of up to a few thousand individuals and was highly mobile, frequently switching summer roosts up to 39 km apart, even during late pregnancy. The bats migrated to distant hibernacula including a cave in Bulgaria 140 km NW of the Park. Adult recapture probabilities varied with season and sex: low female recapture rates in autumn, relative to spring and summer, indicated non-random temporary emigration following nursery colony dispersal. The opposite pattern was seen in males: increasing recapture rates in the autumn suggest that males gather in these roosts to mate with females in transit. Adult survival (0.86-0.94) was similar in females and males, similar in winter and summer, and comparable to recent estimates for other bats based on similar modelling techniques. Sex-based differences in juvenile recapture suggest female philopatry and male-biased dispersal. Our work shows that protection of M. capaccinii roosts must extend beyond the Park’s and indeed the country’s boundaries: its conservation requires large-scale, trans-national integrated conservation plans. Our results will apply to many other warm-temperate species with similar life history cycles.     

Habitat use and preliminary demographic evaluation of the critically endangered Mediterranean monk seal (Monachus monachus) in the Cilician Basin (Eastern Mediterranean)

Over the last few decades a dramatic decline in the number of Mediterranean monk seals (Monachus monachus) limited scientific studies on the biology, behaviour, and ecology of the species. This lack of information impaired the effectiveness of conservation strategies. Thus, any further information gathered on the monk seal has utmost value in the work to halt and reverse the plight of the species. A hitherto unknown Cilician Basin colony of the Mediterranean monk seal has been investigated during a 6-year period between 1995 and 2001. Results of direct in-cave surveys and land based seal-watch observations enabled the evaluation of habitat use and preliminary demographic information. A total of 39 caves were discovered among which only three were used for breeding. Scarcity of the breeding caves emphasised the importance of breeding habitat in the survival of the colony. Common features of the breeding caves are found as an entrance with a protective barrier against strong waves; a chamber with a wide beach; and a well-sheltered shallow pool. Supplementary data obtained from infrared monitors installed in three actively used caves were used to assess the number of individuals. Throughout the study period, 25 individuals were identified and 11 newborn pups were found. Evaluation of the results suggests the presence of sub-regions inhabited by an individually identified sub-group of monk seals. Recommendations for conservation guided by this information is a Marine Protected Area consisting of two zones; a restricted core zone prohibiting any human activity securing breeding habitat and a restricted fishery zone securing sustainability of the food source.     

History and present status of populations of harp and hooded seals

The biology of harp (Pagophilus groenlandicus Erxleben) and hooded (Cystophora cristata Erxleben) seals is described. These abundant species inhabit the seasonally-shifting pack ice of the North Atlantic. Intensive hunting over 150 years depleted but did not exterminate three harp seal populations, which initially may have totalled some 9 million animals and may now total some 3 millions. All are now hunted under quotas and other restrictions. One population is rising and the other two, while probably still declining slowly, are probably close to stability. Knowledge of hooded seals is less advanced; one of three major sub-populations has only recently been rediscovered after 150 years. These populations are more closely interconnected than populations of harp seals, and management of hooded seals seems likely to need a wider framework than exists at present.     

Translocation as a tool for conservation of the Hawaiian monk seal

The deteriorating demographic status of the endangered Hawaiian monk seal has motivated renewed and expanded proposals for conservation action, including translocation of seals to improve survival. Over the past three decades, numerous monk seal translocations have been conducted with a variety of objectives, including mitigating shark predation and conspecific male aggression, reducing human–seal interactions, and taking advantage of favorable foraging habitats to improve survival. Here, we analyze our cumulative experience with translocation of Hawaiian monk seals. We found a strong correlation between the time seals remained in the vicinity of the release site and their age. Recently weaned pups (with little or no at-sea foraging experience) exhibited high fidelity to release sites commensurate with that shown by untranslocated pups to their birth location. In contrast, juvenile and adult seals tended to stray from their release locations farther and sooner. Nevertheless, when 21 adult male seals were moved more than 1000 km from Laysan Island in the Northwestern Hawaiian Islands (NWHI), to the main Hawaiian Islands (MHI), they subsequently dispersed among the MHI; however, only one was observed to return to the NWHI. Translocated seals appeared to survive at rates comparable to seals native to the release site. Outcomes suggest that in most cases the intended objectives of translocations were achieved. Except for one notable case, translocations within the MHI to arrest human–seal interactions were mostly unsuccessful. These findings will be essential for informing successful large-scale translocation plans in the future.     

An assessment of the status of the common seal Phoca vitulina vitulina in Ireland

Common seals Phoca vitulina vitulina Linnaeus 1758 were surveyed throughout Ireland during the 1978 breeding season. Compared with the abundance of the species in Great Britain, the Irish stock is small. The results are discussed in relation to the activities of man, particularly bounty hunting to protect fisheries, and the availability of suitable breeding localities. Problems relating to stock management, not least of which is that the species is subject to legislation in the south but not in the north, are discussed.     

The grey seal (Halichoerus grypus) in Cornwall and the Isles of Scilly

Cornwall and the Isles of Scilly were explored for grey seal (Halichoerus grypus) breeding localities during the 1973 breeding season. The work invelved investigating many sea caves on the north coast of Cornwall, in addition to open beach and skerry sites. Pup production was determined by relating the number of pups produced in a sample period to the number produced in the same period (in another year) at Ramsey Island, Pembrokeshire. The all-age populations derived from these pup production estimates suggest that the number of grey seals in Cornish waters is about 250 and in Scilly about 120. Haulouts of several hundred animals seen in Scilly outside the breeding season almost certainly breed elsewhere.     

Conservation and management of Britain's reptiles based on their ecological and behavioural requirements: A progress report

Britain's native reptile fauna consists of three lizard species and three snake species, some of which may be unique physiological races (evidence is so far based only on their Critical Minimum Temperatures). Three species (Anguis fragilis, Lacerta vivipara, Vipera berus) are widely distributed although the populations are fragmented. The other three (Coronella austriaca, Lacerta agilis, Natrix natrix) are more or less limited in distribution to southern England (although N. natrix does reach Latitude 56°N) and most of the populations are small, scattered and geographically isolated from each other. Pressures such as land development, collecting and habitat destruction by fire are great. The snake Coronella austriaca and the lizard Lacerta agilis are now rare and several colonies and/or habitats of these two species are destroyed each year. As the survival of Britain's rarer reptiles may depend on well managed nature reserves and on the relocation of endangered colonies it is imperative that much more basic herpetological research be completed during the next few years. Fundamental eco-physiological requirements (e.g. food, heat, water) and behavioural requirements (e.g. space) of these animals are being examined in order to maintain or develop optimum habitats on nature reserves and in the hope of establishing viable reptile colonies. One example of this procedure is discussed with particular reference to the construction of an island habitat for Lacerta agilis, and suggestions for future management are outlined.     

Status of the Pelecanidae

The recent history, current status and prospects in the immediate future of the seven species of the Pelecanidae are reviewed. As a consequence of pesticide poisoning, Pelecanus occidentalis suffered severe population declines in the 1950s and 1960s in portions of its range in the United States. However, since the ban on use of DDT in 1972 the species is again laying eggs of near normal thickness, reproductive success appears to be normal and populations are stable or increasing. Similarly, available data indicate that the world populations of P. rufescens, P. conspicillatus, and P. erythrorynchos remain stable, although local population fluctuations do occur. Data for P. onocrotalus show a stable population in Africa but a decline in Asia and Europe, both in numbers of birds and breeding colonies. More seriously, only very small populations of P. crispus and P. philippensis exist. Fewer than 1000 pairs of P. crispus next in 19 colonies in eastern Europe and Asia. Fewer than 1200 pairs of P. philippensis nest in four colonies in eastern/southern India and 23 colonies in Sri Lanka. The populations of both species have declined considerably in the past few decades. The causes for the declines are not documented but are thought to result from a combination of human disturbance in nesting colonies; destruction of nesting and roosting-loafing areas; declines in fish availability; and pesticide contamination. Only immediate action and concerted efforts at stabilizing the populations in the wild, in conjunction with the establishment of captive breeding populations, will preserve these two species from extinction.     

Depositional seals in polyacrylamide-amended soils of varying clay mineralogy and texture

Purpose  

Depositional seals, formed when turbid waters infiltrate into soils, lead to a reduction in soil hydraulic conductivity (HC) and enhance runoff and soil erosion. Since clay size particles constitute a dominant proportion of depositional seals, soil texture and clay mineralogy play a significant role in determining the seal’s hydraulic characteristics. Presence of high molecular weight anionic polyacrylamide (PAM) in suspension flocculates fine sediments, and therefore, its application to the soil surface may modify the characteristics of the depositional seal. The impact of PAM on the latter is expected to be influenced by soil properties. The aim of this study was to elucidate the effects of PAM application on clay flocculation and the HC of depositional seals formed in four soils varying in texture (ranging from loamy sand to clay loam), and diverse proportions of clay mineral constituents (kaolinite, smectite, and vermiculite).     

Seal–fishery operational interactions: Identifying the environmental and operational aspects of a trawl fishery that contribute to by-catch and mortality of Australian fur seals (Arctocephalus pusillus doriferus)

Australian fur seals are known to interact directly (i.e. operational interactions) with trawlers fishing in the winter blue grenadier trawl fishery of western Tasmania, Australia. The purpose of this study was to identify the environmental and operational aspects of the fishery that were associated with increased numbers of seals observed at the surface. The incidence of net entry was determined in order to establish the effectiveness of the currently used Seal Exclusion Device (SED) at reducing by-catch and mortalities. In addition, the stage and depth at which seals were at greatest risk of entering the net at depth and becoming by-catch were also identified.

An increase in seal numbers observed at the surface is assumed to be proportional to the increased risk of by-catch and mortality incidences at trawlers. The most important subset of environmental and operational factors for predicting the number of seals observed at the surface both in the fishing ground in general and during fishing operations were identified using Generalised Linear Modelling. The final model yielded a significant result (R² = 0.63, P < 0.01, n = 149) and indicated that the number of seals observed increased when weather conditions deteriorated, particularly when barometric pressure decreased and when swell height and visibility increased. Vessel operations also influenced the number of seals observed; seal numbers increased when the number of nearby vessels and trawl frequency increased, but decreased when vessel speed increased. Seal numbers also increased as the distance from the nearest breeding colony and haul-out site decreased.

Seal numbers at the surface generally increased steadily during trawling operations (n = 475), although brief declines were noted during shooting and hauling phases. Sub-surface net interactions were also examined using a submersible video camera unit. Seal activity at depth was converse to that observed at the surface, with increased seal numbers noted during shooting and hauling, suggesting that seals dived to forage on fish in the submerged net.

All seal by-catch occurred during the day and almost half occurred during shooting. Mortalities were significantly higher during shooting compared with hauling (Fishers exact test: coef. = 0.65, P < 0.05). However, mortality rates were similar between tows with the Seal Exclusion Device (SED) attached and those without (Fishers exact test: coef. = 0.07, P < 0.99). Only one seal was detected entering and exiting the net mouth during monitored tows, suggesting that the recently observed reduction in by-catch levels (and mortalities) may not necessarily be attributed to the introduction of the Seal Exclusion Device. Seal by-catch recorded during hauling typically occurred when haul speeds exceeded minimum average swimming speeds for fur seals.

Recommendations based on these findings have been made to assist with the future management of fur seal populations that interact with trawl fisheries.     

An endangered population of Wattled Cranes (Grus carunculatus)

The Kafue Flats, a river floodplain in southern Zambia, supports the largest known population of Wattled Cranes. In a normal year fewer than 1,000 are present at high flood; but as the water subsides the population increases, and in the latter half of the dry season it numbers some 3,000 birds. Following widespread flooding in 1972, at least 300 pairs nested as the water fell. However, in 1973 there was little flooding and few pairs bred. Many full-grown birds moult their remiges between January and April, and are then flightless. The diet is largely of rhizomes dug from soft mud. Suitable feeding grounds in the dry season are created by a falling water-level. The population is threatened by a hydro-electric scheme that is scheduled to be completed in 1978. The scheme will reduce fluctuations in the water level on the floodplain and, in so doing, reduce the area of suitable habitat.     

Abundance of the Hawaiian monk seal in the main Hawaiian Islands

Most of the extant circa 1400 Hawaiian monk seals Monachus schauinslandi live in the Northwestern Hawaiian Islands (NWHI). However, an increasing number of sightings and births have recently occurred in the main Hawaiian Islands (MHI), where no systematic surveys of monk seals were conducted prior to 2000. We estimate that there were at least 45 seals in the MHI in 2000 and at least 52 in 2001, based on aerial surveys of all MHI coastlines, supplemented by sightings of seals from the ground. Moreover, annual births in the MHI have evidently increased since the mid-1990s. Weaned pups in the MHI are longer and have greater girth than those in the NWHI, perhaps reflecting greater per-capita abundance of prey resources. We think that Hawaiian monk seals have recently re-colonized the MHI, which were a very likely part of their historic range. Regardless, the MHI habitat appears to be favorable for continued increases of this endangered species.     

Entanglement of monofilament fishing lines and coral death

This study examined the extent of damage by monofilament fishing lines on the cauliflower coral (Pocillopora meandrina) colonies at a popular cast fishing site in Oahu, Hawaii in March 1998. Sixty-five percent of coral colonies had fishing lines on their surface, and 80% of colonies were either entirely or partially dead. The percentage of entirely and partially dead colonies was positively correlated with the percentage of colonies entangled with fishing lines. Percent dead coral surface area was larger for colonies with fishing lines than colonies without fishing lines. In colonies with fishing lines, percent dead coral surface area was positively correlated with percent area with fishing lines. The high incidence of coral colonies with fishing lines and the three sets of significant results indicated destructive effects of monofilament fishing lines to P. meandrina corals. There is thus a clear case that reefs should be protected not only from the effects of excessive removal of fishes, but also from the effects of unsuccessful fishing that results in fishing-line entanglement on corals.     

The behaviour and habitat requirements of Maculinea nausithous (the dusky large blue butterfly) and M. teleius (the scarce large blue) in France

Maculinea nausithous and M. teleius are among the world's rarest butterflies. Both oviposit on the flowerheads of Sanguisorba officinalis, but spend most of their immature lives inside Myrmica spp. ant nests, where their larvae feed on ant brood. Very few colonies of these butterflies survive, and leading conservation bodies have called for urgent research into their habitat requirements: at present, too little is known for successful conservation programmes to be devised.This paper described observations made on three small bogs in France, which each supported colonies of both Maculinea in 1981. The main content is a detailed habitat analysis of each site. Studies were also made of the behaviour of both butterflies, and of the size of the population of each species on every site. From these, it was possible to identify some of the factors that make these sites suitable habitats for M. nausithous and M. teleius. It eas concluded that the abundance, and perhaps the species, of Myrmica ant was the crucial factor on each site.     

Application of Cost Criteria for Selection of Municipal Wastewater Treatment Systems

Analysis of economic data pertinent to the existing municipal wastewater treatment plants (MWTP) in Greece is presented. Thisinformation is important when budgeting for future plants. Thedata include land usage and the costs for construction, operationand maintenance of the form y = ax ^b, where a and b are calculated coefficients. Equations for cost and landuse were produced for specific systems. Personnel and energy aspects are analysed as they are major contributors to operationalcost. A life cycle analysis (LCA) of plants is undertaken. The results of such an analysis should suggest the most preferabletechnology under given circumstances. Thus, under high energy costs and low level of automation and operation, at low F/M ratios, conventional activated sludge systems are relatively notcost effective. In addition, for cost of land less than US$30 per m², waste stabilisation ponds are cost effective subjected to minor earthworks.     

Effects of slope length on erosion of some alfisols in Western Nigeria

Erosion was monitored for erosive rainstorms received during 1977 and 1978 from an Alfisol at Ibadan in western Nigeria on bare plowed soil using field runoff plots on natural slopes of 1, 5, 10 and 15% and with 5, 10, 15 and 20 m slope lengths. Equations of the type A = αL^b were computed relating soil erosion (A) to slope length (L).Erosion was affected more by slope gradient than by slope length and was in the order of 1, 17.6, 31.3 and 22.8 for 1977 and 1, 25.5, 53.0 and 62.4 for 1978 for 5, 10 and 15% slope gradients, respectively. For gentle slope gradients of 1 and 5%, slope length had little effect on erosion. During 1978, erosion for 10% slopes was in the order of 1, 1.05, and 1.08 for 5, 10 and 15 m slope lengths, respectively. For 15% slope, however, the soil erosion was in the order of 1, 1.11, 1.51 and 1.60 for 5, 10, 15 and 20 m slope lengths. The mean sediment concentration (averaged over all slope gradients), was 1, 1.27, 1.50, 1.99 for 1977 and 1, 1.61, 2.71, 2.73 for 1978 for 5, 10, 15 and 20 m slope lengths, respectively.