Population Trend of the World’s Monitored Seabirds, 1950-2010

Seabird population changes are good indicators of long-term and large-scale change in marine ecosystems, and important because of their many impacts on marine ecosystems. We assessed the population trend of the world’s monitored seabirds (1950–2010) by compiling a global database of seabird population size records and applying multivariate autoregressive state-space (MARSS) modeling to estimate the overall population trend of the portion of the population with sufficient data (i.e., at least five records). This monitored population represented approximately 19% of the global seabird population. We found the monitored portion of the global seabird population to have declined overall by 69.7% between 1950 and 2010. This declining trend may reflect the global seabird population trend, given the large and apparently representative sample. Furthermore, the largest declines were observed in families containing wide-ranging pelagic species, suggesting that pan-global populations may be more at risk than shorter-ranging coastal populations

An analysis of temporal and spatial patterns in global seabird abundance during the modern industrial era, 1950-2010, and the relationship between global seabird decline and marine fisheries catch

Seabird populations worldwide are threatened by anthropogenic activities including hunting, introduced predators, habitat destruction, pollution, and fisheries, yet the cumulative effects of these threats on seabird populations is difficult to assess because seabird population studies are mainly limited to small temporal and spatial scales. The present study used global databases of seabird abundance, seabird distribution, and fisheries catch, to estimate global annual seabird population size, overall and by seabird family, 1950-2010; map observed global seabird population change within the same timeframe; and compare temporal and spatial patterns in seabird decline with fisheries, a major threat for which global temporally and spatially explicit data is available throughout the modern industrial era. The global seabird population was estimated to decline by 25% during the modern industrial era, from 1.023 billion individuals in 1950 to 0.768 billion individuals in 2010, and overall decline was observed in eleven of the fourteen seabird families. Maps of observed seabird population change indicated decline covering 90% of the world’s marine surface area, and most severe in the southern temperate and tropical oceans. There was a significant positive relationship between annual seabird decline and annual forage fish catch (a metric of forage fish depletion), as well as between observed seabird decline per spatial cell and year of maximum primary production to support fisheries per marine spatial cell (a metric of the timing of peak ecological footprint of fisheries), both indicating that fisheries presence may play a role in shaping spatial and temporal patterns in global seabird population change. The present study identifies the temporally, taxonomically and spatially pervasive nature of global seabird decline during the modern industrial era and a potentially globally important role of fisheries in this global seabird decline, thus indicating the need for a large-scale and precautionary approach to seabird and marine ecosystem management.Science, Faculty ofZoology, Department ofGraduat

Values of the fixed parameters of the model (<i>u</i> and <i>a</i>), as well as the process (<i>Q</i>) and non-process errors expressed as a proportion of the fixed effects.

<p>For each population, process and non-process errors differed for each year of the sampling period. Within each population, we therefore used the mean of the process errors across years to produce the data in the table.</p><p>Values of the fixed parameters of the model (<i>u</i> and <i>a</i>), as well as the process (<i>Q</i>) and non-process errors expressed as a proportion of the fixed effects.</p

Number of records (annual and cumulative) in the global seabird population database, 1950–2010.

<p>Number of records (annual and cumulative) in the global seabird population database, 1950–2010.</p

Percent of breeding individuals monitored, per marine region.

<p>Percent of breeding individuals monitored, per marine region.</p

Population size per seabird family, monitored (i.e., ≥ 5 records) versus unmonitored (i.e., 1–4 records).

<p>Population size was estimated per population as the median between earliest and latest available records, then summed per family.</p

Persisting Worldwide Seabird-Fishery Competition Despite Seabird Community Decline

International audienc

Global seabird response to forage fish depletion - one-third for the birds

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 productivity. This response was common to all seven ecosystems and 14 bird species examined within the Atlantic, Pacific, and Southern Oceans. The threshold approximated one-third of the maximum prey biomass observed in long-term studies. This provides an indicator of the minimal forage fish biomass needed to sustain seabird productivity over the long term