Numbers Of Seabirds Research Articles

Status of black-legged kittiwakes (Rissa tridactyla), commonguillemots (Uria aalge) and Brünnich's guillemots (U. lomvia) in Murman, north-west Russia, and Varanger, north-east Norway

Recent published estimates of the numbers of seabirds breeding along the coast of Murman have been partly based on data collected in the 1960s. Counts made in some of the largest colonies in 1999–2005 show that the present populations of black-legged kittiwakes ( Rissa tridactyla ), common guillemots ( Uria aalge ) and Brünnich’s guillemot ( U. lomvia ) in Murman are approximately 110 000 pairs, 10 000–12 000 pairs and 2000–3000 pairs, respectively. In Varanger the numbers are ca. 32 000 pairs, 6000–7000 pairs and 400–500 pairs, respectively. Although there has been a large decline in black-legged kittiwake numbers in the Varanger region since 1980, there is no evidence of a similar decline in Murman at least until 1999. With the exception of one colony in Murman, numbers of common guillemots breeding throughout the region seem to have recovered after suffering a huge decline in 1986/87.

Stable isotopes document seasonal changes in trophic niches and winter foraging individual specialization in diving predators from the Southern Ocean

1. Climatic variation outside the breeding season affects fluctuations in population numbers of seabirds and marine mammals. A challenge in identifying the underlying biological mechanisms is the lack of information on their foraging strategies during winter, when individuals migrate far from their breeding grounds. 2. We investigated the temporal variability in resource partitioning within the guild of five sympatric Subantarctic penguins and fur seals from Crozet Islands. The stable isotopic ratios of carbon (delta(13)C) and nitrogen (delta(15)N) for whole blood were measured for penguins and fur seals, as were the isotopic ratios for penguin nails and food. Animals were sampled at two periods, during breeding in summer and at their arrival in the colonies in spring (hereafter winter, since the temporal integration of blood amounting to several months). 3. In summer, delta(13)C and delta(15)N for blood samples defined three foraging areas and two trophic levels, respectively, characterizing four nonoverlapping trophic niches. King penguins and female Antarctic and Subantarctic fur seals are myctophid eaters foraging in distinct water masses, while both macaroni and rockhopper penguins had identical isotopic signatures indicating feeding on crustaceans near the archipelago. 4. Isotopic ratios were almost identical in summer and winter suggesting no major changes in the species niches, and hence, in the trophic structure of the guild during the nonbreeding period. A seasonal difference, however, was the larger variances in delta(13)C (and also to a lesser extent in delta(15)N) values in winter, thus verifying our hypothesis that trophic niches widen when individuals are no longer central place foragers. 5. Winter isotopic ratios of macaroni penguins and male Antarctic fur seals had large variances, indicating individual foraging specializations. The range of delta(13)C and delta(15)N values of male fur seals showed, respectively, that they dispersed over a wide latitudinal gradient (from Antarctica to north of the archipelago) and fed on different prey (crustaceans and fish). 6. By comparing summer and winter isotopic ratios and examining the summer diet, we highlight the feeding habits of marine predators that were not previously addressed. The findings have a number of implications for understanding the functioning of the pelagic ecosystem and on the demography of these species.

Waterbirds of the Xisha Archipelago, South China Sea

The Xisha Archipelago, South China Sea, was surveyed for waterbirds in March-April 2003 and April-August 2004. Forty-five waterbird species were recorded, making a grand total of 53 species for the Archipelago when earlier published records are included. The Archipelago is of great importance for the Red-footed Booby (Sula sula), with an estimated 10% of the world population breeding on Dong Island. Other breeding seabird species were Great Frigatebird (Fregata minor), Great Crested Tern (Sterna bergii) and Sooty Tern (S. fuscata), and it is believed that Black-naped Tern (S. sumatrana) and Roseate Tern (S. dougallii) also breed there. Compared to 1926, the number of seabirds, and the islands on which they breed, has declined greatly. The data for Ardeidae and shorebirds provide information on migration and, possibly, wintering strategies of these species. Despite habitat degradation and human disturbance, the Xisha Archipelago is still important for breeding seabirds and there is an urgent need to improve the conservation status of this bird group.

Exploiting sensory ecology to reduce seabird by-catch

In a previous study, we reported that deploying small amounts of biogenic oil derived from the livers of school sharks (Galeorhinus galeus) was effective in reducing the numbers of seabirds attending fishing vessels and seabird diving activity in the Hauraki Gulf, New Zealand. This seabird assemblage was numerically dominated by Flesh-footed Shearwaters (Puffinus carneipes) and the globally vulnerable Black Petrel (Procellariaparkinsoni). The results suggested that the oil deterrent operated via an olfactory or chemesthetic mechanism. Here we compare the deterrent effects of shark- liver oil with three other fish oils, in the Flesh-footed Shearwater-Black Petrel assemblage. We also report on trials assessing the deterrent efficacy of shark-liver oil and one other fish oil in an assemblage including four species of albatrosses (Diomedea spp., Thalasarcche spp.), Southern and Northern Giant-Petrels (Macronectes giganteus and M. halli), and Cape Petrels (Daption capense). Shark-liver oil was the most effective deterrent of the four fish oils tested in the Flesh-footed Shearwater—Black Petrel assemblage, but it did not deter albatrosses, giant-petrels or Cape Petrels from attending vessels. Thus, the deterrent was effective only on burrow-nesting seabird species. These results may provide further support for our speculation that the deterrent operates via an olfactory mechanism, while corroborating other work linking life-history characteristics of seabirds to their sensory ecology. We recommend research to investigate the mechanism and active ingredients by which shark-liver oil deters some species of seabirds. We also suggest testing fish oils on White-chinned (Procellaria aequinoctialis) and Grey (Procellaria cinerea) Petrels, and Sooty Shearwaters (Puffinus griseus), as well as in other areas occupied by Flesh-footed Shearwaters, to assess further potential for this natural oil or its ingredients to reduce by-catch of seabird species globally.

Seabird predation by great skuas Stercorarius skua– intra‐specific competition for food?

Competition for food is widely cited as an important cost of coloniality among birds and much of the evidence in support of this hypothesis comes from studies of colonial piscivorous seabirds. However, for generalist seabirds able to switch between different prey types, the role of food availability in relation to colony size is unclear. Here we investigate patterns of the consumption of seabird prey in relation to colony size in a generalist seabird, the great skua Stercorarius skua, in Shetland, UK. At the population level skuas feed mainly on sandeels Ammodytes marinus and fishery discards, but respond to declines in fish availability to facultatively prey on other seabirds. By comparing the consumption of seabirds among seven different sized colonies, including one colony with artificially reduced numbers of skuas (Fair Isle), we investigate whether consumption of seabird prey is influenced by skua population size, while simultaneously measuring seabird prey availability. Data from five years also enables us to investigate the influence of annual variation in environmental conditions on seabird consumption. Using measures of body condition and reproductive performance we investigate the consequences of living in different sized colonies, which may provide insight into ultimate costs of nesting at high population density. Skua diets varied among colonies and the proportion of seabird prey in the diet was inversely related to skua colony size, despite similar per capita numbers of seabirds across colonies. At the colony where their numbers were artificially suppressed, skuas consumed a greater proportion of seabirds per capita. Highly significant year effects in seabird predation were observed but the pattern among colonies remained consistent over time. Two measures of adult body condition (pectoral muscle index and mean corpuscular volume) revealed that adult great skuas were in poorer condition at the largest colony (Foula), but reproductive performance did not alter significantly among colonies. This study provides evidence that intra‐specific competition among skuas may limit opportunities for obtaining seabird prey, which may be particularly important during periods of poor availability of sandeels and fishery discards, and has implications for assessing the impact of skuas on seabird populations.

Comparing an estimate of seabirds at risk to a mortality estimate from the November 2004 Terra Nova FPSO oil spill

On 21 November 2004, about 1000 barrels of crude oil were accidentally released from the Terra Nova FPSO (floating production, storage and offloading) onto the Grand Banks, approximately 340 km east-southeast of St. John’s, Newfoundland. We estimated the number of vulnerable seabirds (murres ( Uria spp.) and dovekies ( Alle alle)) at risk from this incident by multiplying observed densities of seabirds with the total area covered by the slick, estimated at 793 km 2. A mean density of 3.46 murres/km 2 and 1.07 dovekies/km 2 on the sea surface was recorded during vessel-based surveys on 28 and 29 November 2004, with a mean density of 6.90 murres/km 2 and 13.43 dovekies/km 2 combining those on the sea and in flight. We calculated a mean of 9858 murres and dovekies were at risk of being oiled, with estimates ranging from 3593 to 16,122 depending on what portion of birds in flight were assumed to be at risk. A mortality model based on spill volume was derived independently of the risk model, and estimated that 4688 (CI 95%: 1905–12,480) birds were killed during this incident. A low mortality estimate based strictly on spill volume would be expected for this incident, which occurred in an area of relatively high seabird densities. Given that the risk and mortality estimates are statistically indistinguishable, we estimate that on the order of 10,000 birds were killed by the Terra Nova spill.

Status of black-legged kittiwakes (Rissa tridactyla), common guillemots (Uria aalge) and Brünnich’s guillemots (U. lomvia) in Murman, north-west Russia, and Varanger, north-east Norw

Recent published estimates of the numbers of seabirds breeding along the coast of Murman have been partly based on data collected in the 1960s. Counts made in some of the largest colonies in 1999–2005 show that the present populations of black-legged kittiwakes ( Rissa tridactyla ), common guillemots ( Uria aalge ) and Brunnich’s guillemot ( U. lomvia ) in Murman are approximately 110 000 pairs, 10 000–12 000 pairs and 2000–3000 pairs, respectively. In Varanger the numbers are ca. 32 000 pairs, 6000–7000 pairs and 400–500 pairs, respectively. Although there has been a large decline in black-legged kittiwake numbers in the Varanger region since 1980, there is no evidence of a similar decline in Murman at least until 1999. With the exception of one colony in Murman, numbers of common guillemots breeding throughout the region seem to have recovered after suffering a huge decline in 1986/87.

Coastal connections, local fishing, and sustainable egg harvesting: patterns of Viking Age inland wild resource use in Mývatn district, Northern Iceland

The 'Landscapes of Settlement Project' has carried out archaeological and paleoenvironmental research in the Lake Mývatn region of N. Iceland since 1996. Animal bone collections dating from the late 9th century to the early 13th century AD have been recovered from five sites in different ecological zones around the lake, and three of these sites provide multiple phases datable through radiocarbon, artefacts, and volcanic tephra. Modern systematic biological and geological investigations in the Mývatn district date to the 19th century and a detailed picture of the recent ecology can be combined with both archaeological and historical evidence for long term resource exploitation by humans in this inland region. Analysis of bird bones and bird eggshell suggests that the locally managed sustainable harvest of migratory waterfowl eggs carried out over the last 150 years extends back to the 9th century. These inland archaeofauna also include significant numbers of marine fish and sea birds, marine mollusca, and a few seal and porpoise bones. Marine fish remains recovered indicate specialised transport of partial skeletons missing most cranial and some thoracic vertebrae, suggesting that a cured fish product was being regularly brought to inland farms during the early years of the settlement. Inter-regional exchange and a pre-Hanseatic artisanal fish trade prior to AD 1000 suggests the importance of preserved marine fish in early Scandinavian economies, and may shed light on the source of the 11th century 'fish event horizon' recently documented in southern Britain.

Reducing seabird bycatch in longline fisheries using a natural olfactory deterrent

Longline fisheries throughout the world have frequent and often fatal interactions with seabirds. We experimentally tested one possible solution to seabird–fisheries interactions that was proposed by a New Zealand longline fisherman. This involved dripping school shark Galeorhinus galeus liver oil on the ocean surface behind fishing vessels. We tested the efficacy of shark liver oil in reducing the numbers of seabirds attending fishing vessels and the number of dives seabirds executed in pursuit of pilchard Sardinops neopilchardus baits. We conducted trials in northern New Zealand where seabird assemblages include the globally vulnerable black petrel Procellaria parkinsoni. Shark liver oil was effective in reducing both seabird numbers and dives on baits, compared to canola oil and seawater control treatments. Comparisons of seabird responses to shark liver oil and vegetable oil suggest that shark liver oil acts as an olfactory or chemesthetic deterrent for seabirds. Further work should include testing the oil with additional seabird species and investigating active ingredients and habituation of seabirds to the oil in order to assess wider opportunities for long-term use of shark liver oil to reduce seabird bycatch.

Seabird numbers and prey consumption in the North Atlantic

Abstract We compared seasonal composition, abundance, and biomass of seabirds between the Northeast (ICES region) and Northwest (NAFO region) Atlantic fisheries regions to identify differences in community assemblage and prey consumption. Seabirds were more abundant in the Northwest Atlantic, but biomass was greater in the Northeast. This disparity resulted from enormous numbers of little auks Alle alle breeding in West Greenland and of Leach's storm-petrels Oceanodroma leucorhoa breeding in Newfoundland, plus large numbers of non-breeding shearwaters Puffinus spp. entering southern NAFO areas in summer. The Northeast Atlantic communities were dominated numerically by northern fulmars Fulmarus glacialis, large auks Uria spp., and the Atlantic puffin Fratercula arctica. Seabirds occupying the North Atlantic consume approximately 11 × 106 t of food annually. Overall consumption rates peak during summer as a result of increased breeding activity and seasonal movements of birds into the North Atlantic. Because of the greater biomass of birds in the northeast, consumption (mainly by piscivores) in ICES areas was approximately 20% higher than that in NAFO areas, where planktivores dominate. NAFO areas had, however, a much greater consumption rate per unit area than ICES areas. Comparative studies such as these could prove informative in assessing large predator responses to the influence of fishing and ocean-scale climate change.

Interannual changes in distribution of age-0 walleye pollock near the Pribilof Islands, Alaska, with reference to the prediction of pollock year-class strength

Abstract Walleye pollock (Theragra chalcogramma) is a key species and a major commercial fishery target in the eastern Bering Sea (EBS). Recruitment of juveniles to the adult stock is largely determined by first-year survival in favourable nursery areas, and the waters around the Pribilof Islands are an important nursery area. Based on a six-year acoustic survey programme (September 1994–1999) to investigate abundance and distribution variations of age-0 pollock, we developed a set of predictive indices relating the age-0 Pribilof population to the EBS pollock stock at recruitment (age-3). EBS year-class strength at recruitment correlates with age-0 density, the spatial relationship between juveniles and euphausiids, and the degree of centricity of the age-0 distributions around the Pribilof Islands, i.e. neither too far inshore nor offshore. Seabird numbers and density ratios of predatory groundfish also influenced age-0 pollock distribution, but did not provide consistent discrimination among year classes. We hypothesize that age-0 pollock must transition from a copepod diet to a euphausiid diet by September to maximize their survival potential and to estab ish a strong adult cohort.

The summer seabird community of the Flemish Cap in 2002

We describe the seabird community and the distribution of seabirds in the Flemish Cap in the summer of 2002. Data were collected by means of sixty-six 300 m wide boat transects of varied length in the first half of July. A total of 802 seabirds and 8 species were counted within census transects. Over 70% of seabirds were Great Shearwaters (Puffinus gravis), followed by Northern Fulmars (Fulmarus glacialis) with 17.1% of the seabirds recorded. The number of seabirds recorded per census transect was, on average, very low (mean = 10.68, SD = 19.54) and no seabirds were observed in 20 transects. Overall seabird abundance was 8.78 birds km-1 (n = 66, SD = 16.98). Seabird abundance and seabird species richness were not evenly distributed across the Flemish Cap but seemed to concentrate at the edges of the southern half of the study area. This pattern suggests that seabirds were mostly distributed in the area of confluence of the North Atlantic Current with the Labrador Current. We also call attention on the possibility that the Flemish Cap may be an important area for wintering Great Shearwaters.

Occurrence of dolphins and seabirds and their consumption of by-catch during prawn trawling in Spencer Gulf, South Australia

In the Spencer Gulf prawn fishery prawns are caught at night by trawling. Groups of dolphins, the short-beaked common dolphin ( Delphinus delphis) and the bottlenose dolphin ( Tursiops truncatus), and seabirds, the silver gull and the pacific gull ( Larus novaehollandiae, Larus pacificus), feed on discarded by-catch. The dolphins follow the cod ends as they appear close to or on the surface. Here they pick or bite fish protruding through the cod end mesh or forage on discards. Seabirds pick floating objects. In order to quantify the importance of dolphins and seabirds as consumers of discarded by-catch, four series of surveys were undertaken using prawn trawlers engaged in commercial fishing thereby obtaining a large number of observations simultaneously over a large area and at different seasons. On three successive nights, each night on three occasions, after the first trawl shot, at midnight and after the last shot of the night, the trawler skippers recorded the numbers of seabirds and dolphins feeding on discarded by-catch. The mean number of dolphins per boat and observation varied between seasons with 0.5–1.3 dolphins/boat/observation. At the northerly Site 1, 3.4 dolphins were recorded per boat and observation while at the more southerly sites (Sites 2–5), 0.5–0.8 dolphins were observed per boat and observation. No significant difference between observations at night was observed. The occurrence of seabirds varied between sites but not between season and time of night. The largest numbers of seabirds was observed at Sites 1 and 4 with a mean of 2.2 and 2.8 seabirds per observation. It was concluded that an estimated 18–183 t of discards are consumed per year by dolphins constituting 0.3–2.6% of the discarded by-catch. Seabirds potentially consume 1647–165 kg discards per year from the Spencer Gulf prawn fishery, which constitute less than 0.03% of the discarded by-catch.

Diel changes in numbers of seabirds occupying Cays on the Swain Reefs, Great Barrier Reef, Australia

Diel changes in numbers of seabirds occupying Cays on the Swain Reefs, Great Barrier Reef, Australia

Seabirds as potential vectors of penaeid shrimp viruses and the development of a surrogate laboratory model utilizing domestic chickens

White spot syndrome virus (WSSV), Taura syndrome virus (TSV), Yellow head virus (YHV), and Infectious hypodermal and hematopoietic necrosis virus (IHHNV) have caused significant economic losses of farmed penaeid shrimp worldwide. Because the presence of large numbers of seabirds at shrimp grow-out ponds may be related to disease transmission, we hypothesized that these birds may be capable of carrying infectious viral particles in their feces from affected ponds to nearby unaffected ponds, and perhaps even to nearby farms. Because of the difficulties posed by working with wild fowl in a laboratory setting, a surrogate model, employing domestic white leghorn chickens ( Gallus domesticus), was developed to compare with the detection and infectivity results from captive laughing gulls ( Larus atricilla). Using standard histology, PCR/RT-PCR and infectivity challenges, this study demonstrated that IHHNV and TSV remained infectious for up to 1 day following passage through both chickens and seagulls, while no viable WSSV or YHV were found following passage through the gut of either bird species. This study demonstrated that wild seabirds may serve as mechanical vectors of TSV and IHHNV by passing infectious particles to aquatic environments in their feces, and that chickens may be used as a surrogate laboratory model for seabirds in such viral infectivity tests.

Walpole, a "Mystery Island" in southeast New Caledonia? In A Pacific Odyssey: Archaeology and Anthropology in the Western Pacific. Papers in Honour of Jim Specht

Walpole Island, the southernmost island of Melanesia, is a spectacular raised limestone formation 135 km south of the Loyalty Islands within the New Caledonian archipelago. Occupied by enormous numbers of seabirds when the first westerners landed, this rocky spot was mined for guano. Workers frequently reported archaeological finds that indicated prehistoric occupation and an early collection of artefacts was sent to the Australian Museum in Sydney. Over the last 30 years, research on the archaeological heritage of the island has been carried out through the study of museum collections and excavations. This paper reports the results of recent stratigraphic excavations, and synthesizes current archaeological knowledge about the human occupation of Walpole spanning at least 2,500 years. SAND, CHRISTOPHE, 2004. Walpole, a “Mystery Island” in southeast New Caledonia? In A Pacific Odyssey: Archaeology and Anthropology in the Western Pacific. Papers in Honour of Jim Specht, ed. Val Attenbrow and Richard Fullagar, pp. 109–122. Records of the Australian Museum, Supplement 29. Sydney: Australian Museum. Records of the Australian Museum, Supplement 29 (2004): 109–122 ISBN 0-9750476-3-9 www.amonline.net.au/pdf/publications/1407_complete.pdf During the last two decades, Melanesian and Polynesian prehistory has come of age (Kirch, 2000). Jim Specht was a pioneer with an insatiable drive to explore new directions in Pacific prehistory. Amongst numerous other projects, he initiated modern archaeological studies of the pre-European settlement on Norfolk Island (Specht, 1984). Before discovering Norfolk on the 5th October 1774, James Cook put a new archipelago on the European map—New Caledonia (Beaglehole, 1961). One week previously he had passed just out of sight of a small uplifted coral island, at the southeastern tip of the Grande Terre. Its name, given a few decades later, is Walpole. Very few people know of this island at the southernmost point of Melanesia. Although Walpole appeared as a “mystery” early in the literature (see Sand 2002: 14 for a review), it is not normally listed in studies of the Pacific “mystery islands”, which focus only on Polynesia and eastern Micronesia (Bellwood, 1978: 352–353; Kirch, 1988; but see Di Piazza & Pearthree, 2001: 165). A historical connection links Walpole to the Australian Museum in Sydney, where the oldest archaeological collection from the island is stored. In this paper I summarize the historical and archaeological data of Walpole and propose a tentative chronology. “Mystery Islands”: a short review When European navigators started to systematically explore the Pacific, they visited uninhabited islands with signs of former human occupation, like Pitcairn in East Polynesia, and Norfolk off eastern Australia. These abandoned islands were mostly in Polynesia (Kirch, 1984: table 9), although some east Micronesian islands were also identified (Terrell, 1986: fig. 28). The “mystery” of their pre-historic settlement and abandonment led to early research (e.g., Emory, 1928, 1934). As Kirch (1984: 89–92, 1988) pointed out, although all these “mystery islands” were grouped on the basis of isolation, resource scarcity and absence of occupation at

Trends in carbon flux to seabirds in the Peruvian upwelling system: effects of wind and fisheries on population regulation

AbstractWe hypothesized that change in the annual population size of guano‐producing seabirds (cormorant, Phalacrocorax bougainvillii; booby, Sula variegata; pelican, Pelecanus thagus) is a response to changes in primary and secondary production of the Peruvian upwelling system. We tested this hypothesis by modeling nitrate input through upwelling to the upper layers of the ocean off Peru between 6° and 14°S using data on wind stress and sea surface temperature. The model predicted the amount of carbon fixed by primary production each year from 1925 to 2000, which was then apportioned to the Peruvian anchovy (Engraulis ringens) biomass and ultimately to the seabird population and the anchovy fishery, the largest single‐species fishery on Earth. The model predicted a marked increase in primary production as a consequence of increasing wind stress. It overestimated the anchovy biomass after the collapse of the fishery in 1972, but closely predicted the growth of seabird populations from 1925 to the mid‐1960s, and their decline thereafter, explaining about 94% of the variation in seabird numbers from 1925 to 2000. The model indicates the seabirds consumed 14.4% of the available anchovies and, thus, that seabirds consumed 2.3% of the new production, before the development of the anchovy fishery, and only 2.2% of the available anchovies and 0.3% of the new production after the development of the fishery. The model results clarify the roles that environmental and anthropogenic factors may have had in regulating the guano‐producing seabird populations. It indicates that the growth of seabird populations from 1925 to 1955 was likely a response to increased productivity of the Peruvian upwelling system and that the subsequent drastic decline in seabird abundance was likely due to competition for food with the fishery, which caught ∼85% of the anchovies, which otherwise would have been available for the seabirds. This model also shows that an increase in oceanic primary production promotes reproductive success and population growth in higher trophic level organisms.

Impacts of fisheries on seabird communities

Long-line by-catch of albatrosses and petrels may soon lead to species extinctions. Set-net bycatch has caused major reductions in certain seabird populations. Some fisheries may decrease numbers of seabirds by reducing abundance of prey-fish. Other fisheries may increase seabird numbers, by increasing prey-fish abundance through depletion of predatory fish stocks, or by provision of offal and discards. These latter impacts of fisheries on seabirds are often difficult to measure against a background of many and varied environmental and human influences. Depletion of stocks of small lipid-rich fish have reduced numbers of seabirds, in Peru, the Norwegian Sea, and the Barents Sea. However, reductions of predatory fish stocks in the North Sea have more than compensated for quantities of sandeels removed by the sandeel fishery. While piscivorous fish stocks remain low, sandeel fishery and seabirds appear to be able to coexist. However, if piscivorous fish stocks recover in the North Sea, reduced availability of sandeels to seabirds may affect certain species. Provision of discards and offal can stimulate large increases in scavenging seabird numbers. Desirable reductions in discard rates may have an unfortunate side-effect of forcing some scavenging seabirds to turn to killing smaller seabirds, with drastic consequences for community structure.

Attendance of scavenging seabirds at trawler discards off Galicia, Spain

The occurrence of scavenger seabirds at fishing trawlers was studied off Galicia, Spain. A total of 9,368 seabirds of 23 species were recorded during 92 fishing operations in 1998 and 1999. The most common species were the yellow-legged and lesser black-backed gull ( Larus cachinnans and L. fuscus ), Sabine´s gull ( L. sabini ), the northern gannet ( Morus bassanus ), the great shearwater ( Puffinus gravis ), sooty shearwater (P. griseus), the Manx and Balearic shearwater ( P. puffinus and P. mauretanicus ), the great skua ( Catharacta skua ) and terns (mainly Sterna hirundo and S. paradisaea ). Other species occurred in small numbers: Leach´s petrel ( Oceanodroma leucorhoa ), the storm petrel ( Hydrobates pelagicus ), the little shearwater ( Puffinus assimilis ), Cory´s shearwater ( Calonectris diomedea ), the parasitic skua ( Stercorarius parasiticus ), the pomarine skua ( S. pomarinus ), the black-headed gull ( Larus ridibundus ), the glaucous gull ( L. hyperboreus ), the kittiwake ( Rissa tridactyla ), the sandwich tern (Sterna sandvicensis), the black tern (Chlidonias niger), the guillemot ( Uria aalge ) and the little auk ( Alle alle ). The maximum number of seabirds recorded at a haul was 320. The maximum number of a particular species ranged from 120 great shearwaters to 250 yellow-legged/lesser black-backed gulls during a single haul. The differences in ship-follower species abundance are related to migratory movements but fisheries could also have a strong influence at a smaller scale on the distribution of seabirds off Galicia. The degree to which seabirds rely on fishery discards as food was not quantified, but may be important for several species.

Conserving Surface-nesting Seabirds at the Prince Edward Islands: The Roles of Research, Monitoring and Legislation

South Africa's subantarctic Prince Edward Islands support substantial proportions of the global populations of a number of surface-nesting seabirds. Populations of most of these have decreased at the islands since the 1980s and 12 of 16 species are regarded as Threatened or Near Threatened regionally or internationally. The main causes of population decreases are thought to be by-catch mortality of albatrosses and giant petrels in longline fisheries, and environmental change influencing availability of prey to penguins and the Crozet shag Phalacrocorax [atriceps] melanogenis. It is proposed that the Prince Edward Islands Special Nature Reserve be expanded to include surrounding territorial waters so as to afford additional protection for seabirds breeding there, especially those species feeding near to the islands. Consideration needs also to be given to listing species as threatened or protected in terms of planned new legislation in South Africa and then developing management plans for them, preferably linked closely with the Agreement on the Conservation of Albatrosses and Petrels and the National Plan of Action (NPOA) – Seabirds. The islands should also be nominated as a Ramsar Wetland of International Importance in recognition of their importance to seabirds, with 13 of the 16 species exceeding the 1% of the global population criterion. A combination of research, monitoring and legislation will help conserve the surface-nesting seabirds of the Prince Edward Islands into the 21st century, but only providing the effects of climate change can somehow be addressed.