Global Seabird Response to Forage Fish Depletion—One-Third for the Birds

  title={Global Seabird Response to Forage Fish Depletion—One-Third for the Birds},
  author={Philippe M. Cury and Ian L. Boyd and Sylvain Bonhommeau and Tycho Anker‐Nilssen and Robert J. M. Crawford and Robert W. Furness and James A. Mills and Eugene J. Murphy and Henrik {\"O}sterblom and Michelle Paleczny and John F. Piatt and Jean-paul Roux and Lynne J. Shannon and William J. Sydeman},
  pages={1703 - 1706}
One-third of maximum fish biomass must be available for seabirds to sustain high breeding success. Determining the form of key predator-prey relationships is critical for understanding marine ecosystem dynamics. Using a comprehensive global database, we quantified the effect of fluctuations in food abundance on seabird breeding success. We identified a threshold in prey (fish and krill, termed “forage fish”) abundance below which seabirds experience consistently reduced and more variable… 

Evaluating impacts of forage fish abundance on marine predators

It is suggested that additional limitation of forage fish harvest to levels well below sustainable yields would rarely result in detectable increases in marine predator populations.

Seabirds maintain offspring provisioning rate despite fluctuations in prey abundance: a multi-species functional response for guillemots in the North Sea

Guillemots appeared able to adjust their foraging tactics over a wide range of prey abundances to maintain a consistent energetic intake rate for chicks, conferring some resilience in the face of environmental variation.

Forage fish, their fisheries, and their predators: who drives whom?

Size-based foodweb modelling suggests that reducing fishing mortality may not necessarily lead to larger stocks of piscivorous fish, especially if their early life stages compete with forage fish for zooplankton resources.

The global contribution of forage fish to marine fisheries and ecosystems

Forage fish play a pivotal role in marine ecosystems and economies worldwide by sustaining many predators and fisheries directly and indirectly. We estimate global forage fish contributions to marine

Impacts of depleting forage species in the California Current

Two well-developed ecosystem models for the California Current on the West Coast of the USA were used to test the impacts on other parts of the ecosystem of harvesting euphausiids, forage fish, mackerel and mesopelagic fish such as myctophids.

Breeding failure of seabirds in relation to fish depletion: Is there one universal threshold of food abundance?

It is found that breeding success of gannets started to decline at about 8% of MPA, in contrast to the general CT previously proposed and when corrected for the sizes of prey available that may be eaten by the birds and the removal of fish by the fishing industry, the observed threshold was reduced, indicating that such effects should be included in the context of ecosystem based management.

Varied breeding responses of seabirds to a regime shift in prey base in the Gulf of Maine

It is concluded that razorbills and murres need higher-quality diets than puffins, which more frequently exploited lower-lipid food during food shortages, however, puffin reproductive output was much more vulnerable to ocean warming owing to their longer breeding season and more varied diet.

A structured seabird population model reveals how alternative forage fish control rules benefit seabirds and fisheries.

An age-stage structured Seabird model is developed that incorporates seabird diet specialization, foraging behavior, and reproductive strategy, as well as different functional responses between prey availability and adult survival, juvenile survival, reproductive success, and breeder propensity, to explore how different forage fish harvest policies affect seabirds.


A requisite for reliable food web models and ecosystem-based management in regions such as the California Current is the availability of diet information on key predators. In upwelling ecosystems,



Responses of seabirds to depletion of food fish stocks

  • R. Furness
  • Environmental Science
    Journal of Ornithology
  • 2007
The sensitivity of seabird adult survival rates may be a feature of the detailed ecology of particular species and may be affected by ecological conditions such as the possibilities for prey switching, and Fishery managers may set a lower limit biomass to protect fish stock recruitment, but it is unclear whether this threshold would also protect the needs ofSeabirds dependent on the fish stock.

Seabirds as Indicators of Marine Food Supplies

An integrated approach to the use of seabirds as indicators of marine food supplies is developed, based on proposed relations between food availability and seabird population and behavior parameters, which may be particularly useful for the many species and areas for which conventional fisheries data are sparse or absent.

Impacts of Fishing Low–Trophic Level Species on Marine Ecosystems

It is found that fishing low–trophic level species at conventional maximum sustainable yield (MSY) levels can have large impacts on other parts of the ecosystem, particularly when they constitute a high proportion of the biomass in the ecosystem or are highly connected in the food web.

Estimating the impacts of fishing on dependent predators: a case study in the California Current.

The results are consistent with the premise that the impacts of local rockfish fisheries on seabird productivity are less than impacts that have occurred to the prey resources themselves due to ocean climate and the ability of seabirds to buffer against changes in prey availability through prey-switching and other behavioral mechanisms.

Forage fish of the Pacific Rim as revealed by diet of a piscivorous seabird: synchrony and relationships with sea surface temperature

Predator diet sampling offers a fishery-independent, large-scale perspective on forage fish dynamics that may be difficult to obtain using conventional means of study and factors other than local SST or interannual variability may more strongly influence forage fishes.

Integrated environment–prey–predator interactions off South Georgia: implications for management of fisheries

1. The oceanography of the South Georgia region is principally that of the Southern Ocean rather than the South Atlantic. A combination of factors, including advection, local bathymetry and high

Diets of top predators indicate pelagic juvenile rockfish (Sebastes spp.) abundance in the California Current System

Diets of top predators may be useful indicators to the availability of forage fish in marine ecosystems. Juvenile rockfish (young-of-the-year Sebastes spp.) compose a significant part of the diet for

Changes in fisheries discard rates and seabird communities

Reduced rates of discarding, particularly when coupled with reduced availability of small shoaling pelagic fish such as sandeel, result in an increase in predation by great skuas on other birds.

Monitoring of seabirds in the Benguela upwelling system: can seabirds be used as indicators and predictors of change in the marine environment?

Cyclic variations in the annual yields of seabird products evident at decadal long time-scales may reflect fluctuations in prey populations at similar periods, but no such relationship has been demonstrated and consequently the value of such annual yields as indicators is not proved.


The value of the marine bird monitoring program is enhanced by having sufficiently long time-series to describe patterns for these long-lived species.