Predation on adult Puffins<i>Fratercula arctica</i>by Great Black‐backed Gulls<i>Larus marinus</i>at a Newfoundland colony

Russell, Janet; Montevecchi, William A.

doi:10.1111/j.1474-919x.1996.tb08839.x

Cited by 25 publications

(10 citation statements)

References 13 publications

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“…In recent years reductions in discarding by these fisheries (Reeves and Furness, 2002) appear to be having serious impacts on entire seabird communities rather than just on the scavenging species themselves. Large scavenging seabirds unable to find sufficient discards have been turning to predation on smaller seabirds to supply their food needs (Regehr and Montevecchi,1996;Russell and Montevecchi, 1996;Furness, 1999b;Phillips et al, 1999). A 50% drop in numbers of kittiwakes in Shetland in the last 10 years can be attributed partly to increased killing by great skuas (Heubeck et al, , 1999Oro and Furness, 2002), which had previously been able to feed on sandeels and discards without needing to kill many other seabirds.…”

Section: Discharge Of Offal and Discardsmentioning

confidence: 99%

Impacts of fisheries on seabird communities

Furness¹

2003

Sci. Mar.

192

156

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SUMMARY: 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.Key words: conservation, discards, ecosystem, fisheries management, industrial fisheries, predator-prey, sandeel. RESUMEN: EL IMPACTO DE LAS PESQUERIAS EN LAS COMUNIDADES DE AVESMARINAS. -Las capturas accidentales de los albatros y petreles en palangres pueden llevar pronto a algunas especies a la extinción. La captura en redes de trasmallo ha causado también grandes reducciones en ciertas poblaciones de aves marinas. Ciertas pesquerías pueden provocar la disminución en el número de aves marinas al reducir la abundancia de los peces presa. Otras pesquerías pueden hacer crecer el número de aves marinas, al incrementar la abundancia de los peces presa mediante la disminución de las efectivos de los peces depredadores, o mediante el suministro de despojos y descartes. Estos últimos impactos de las pesquerías en las aves marinas son con frecuencia difíciles de medir por el efecto de numerosas y variadas influencias ambientales y humanas. La disminución de efectivos de pescado azul de pequeño tamaño ha reducido el número de aves marinas en Perú, el Mar de Noruega y el Mar de Barents. Sin embargo, en el Mar del Norte, la reducción del lanzón (A. marinus) como consecuencia de su pesca específica se ha visto ampliamente compensada por una reducción en los efectivos de peces predadores. Mientras los efectivos de peces piscívoros se mantengan bajos, la pesca del lanzón y las aves marinas parecen ser capaces de coexistir. No obstante, si los efectivos de peces piscívoros se recuperan en el Mar del Norte, reduciendo la disponibilidad de lanzones para las aves marinas, esto afectaría a ciertas especies. El aprovisionamiento de descartes y despojos pudiera estimular grandes increme...

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Section: Discharge Of Offal and Discardsmentioning

confidence: 99%

Impacts of fisheries on seabird communities

Furness¹

2003

Sci. Mar.

192

156

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“…data) compared to 42 ' X, on Gull Island in 1984 (Roy 1986). The relatively greater success of great black-backed gulls may be related to their dietary flexibility and larger size, making them better foraging competitors (Furness et al 1992) and more effective predators of other seabjrds (Mylne 1960, Threl.fal1 1968, Harrls 1980, Buckley 1990, Russell & Montevecchi 1996, which would help to buffer them when other prey 1s scarce.…”

Section: Food-stressed Predatory Gullsmentioning

confidence: 99%

“…These are often overlooked in single-species investigations of environmental and prey interactions (see Montevecchi 1996). Food supply, fisheries and seabird interactions …”

Section: Food-stressed Predatory Gullsmentioning

confidence: 99%

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Interactive effects of food shortage and predation on breeding failure of black-legged kittiwakes:indirect effects of fisheries activities and implications for indicator species

Regehr¹,

Montevecchi²

1997

Mar. Ecol. Prog. Ser.

131

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ABSTRACT. We investigated the roles of food shortage and predation in anticipated breeding failure of black-legged kittiwakes Rlssa trldactyla at Great Island, Kr~tless Bay, Newfoundland, Canada In 1992 and 1993, following widespread failure in 1991 Reduced and delayed availability of capelin Mallotus villosus, plus elimination of previously plentiful fish offal and discards following an eastern Canadian groundfish moratorium in 1992, induced food-stress on kitt~wakes and on large predatory Larus gulls. Breeding was late, a low proportion of pairs laid eggs, and egg and clutch sizes were small, indicating that feeding condlt~ons for kittiwakes were poor early in the season. Extreme food-stress resulted in low b r e e d~n g success of Larns gulls that turned to kittiwake eggs as an alternate food source. Forced egg predation by great black-backed gulls Larus marinus was the primary cause of low hatching success (10 to 11 %) in both years. Durations of incubation and chick-rearing shifts decreased following the inshore arrival of capelin, and chicks that hatched after capelin arrival survived longer than earlier hatched chicks. Unattended nests were uncommon, probably in response to predation. In 1992, earlier hatching, later capelin arrival, and apparent lack of alternate prey resulted in many chicks starving and poor fledging success (7%). In 1993, food appeared to be more available both before and after capelin arrival, parents were able to provision chicks, and fledging success was normal (68%) The interactive effects of food shortage and predation have important linplications for the use of kittiwakes as indicator species and for the indirect effects of fishery activities on seabird interactions. Kittiwake productivity also reflects the resource base of t h e~r predators and caution is required when llnking kittiwake breeding success to prey abundance. Moreover, fishery activities, such as the eastern Canadian groundfish morator~um that eliminated fish discards and offal for large scavenging gulls, can have profound second-order effects on other seabird species that are preyed on by scavengers.

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“…The ground fishery closure intensified the effects of changes in capelin biology for some seabirds by removing massive tonnages of discards and offal from offshore and inshore waters. This food limitation of surface-feeding and scavenging Larus gulls resulted in intense predation pressure on other smaller seabirds, primarily black-legged kittiwakes (Regehr & Montevecchi 1997), Atlantic puffins (Russell & Montevecchi 1996) and Leach's storm petrels (Stenhouse & Montevecchi 1999).…”

Section: Introductionmentioning

confidence: 99%

Signals from seabirds indicate changing biology of capelin stocks

Davoren¹,

Montevecchi²

2003

Mar. Ecol. Prog. Ser.

124

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Key forage species lie at the core of complex marine food webs, providing essential linkages among trophic levels. We examined the interactions of an important forage and commercial fish, capelin Mallotus villosus, and its primary avian predator, the common murre Uria aalge, in the NW Atlantic. Murres are capelin specialists and robust samplers of capelin biology. During the 1990s, the coldest surface-water event in the past 50 to 100 yr occurred in the NW Atlantic (1991), and the eastern Canadian ground-fishery was closed (1992). Concordantly, the biology and behaviour of capelin has undergone very substantial changes. We examined parental food deliveries and production at the world's largest common murre colony on Funk Island off the northeast coast of Newfoundland throughout the 1990s. Murres delayed breeding and delivered smaller and lower quality capelin to their chicks. These changes, corroborated with independent fisheries data, resulted in poor condition of murre chicks, indicating significant effects of changing capelin demographics at higher trophic levels. The diets of the murre chicks indicate that the composition of the capelin population has shifted from high size diversity to mainly smaller capelin. We hypothesize that this change resulted from the elimination of the larger-sized and earlier-spawning genotype and that the NW Atlantic capelin population is exhibiting signs of reduced reproductive potential that likely reflects lower spawning biomass.

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Predation on adult PuffinsFratercula arcticaby Great Black‐backed GullsLarus marinusat a Newfoundland colony

Cited by 25 publications

References 13 publications

Impacts of fisheries on seabird communities

Impacts of fisheries on seabird communities

Interactive effects of food shortage and predation on breeding failure of black-legged kittiwakes:indirect effects of fisheries activities and implications for indicator species

Signals from seabirds indicate changing biology of capelin stocks

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