Alex Bond (Department of Biology, University of Saskatchewan, Saskatoon, Canada) and Jennifer Lavers write in the journal Global Change Biology on evidence that the Flesh-footed Shearwaters Puffinus carneipes has changed its diet historically from 1936.

The paper’s abstract follows:

“Changes in the world's oceans have altered nutrient flow, and affected the viability of predator populations when prey species become unavailable.  These changes are integrated into the tissues of apex predators over space and time and can be quantified using stable isotopes in the inert feathers of historical and contemporary avian specimens.  We measuredδ¹³C andδ¹⁵N values in Flesh-footed Shearwaters (Puffinus carneipes) from Western and South Australia from 1936-2011.  The Flesh-footed Shearwaters more than doubled their trophic niche (from 3.91 ± 1.37 ‰²to 10.00 ± 1.79 ‰²), and dropped an entire trophic level in 75 years (predictedδ¹⁵N decreased from +16.9 ‰ to +13.5 ‰, andδ¹³C from –16.9 ‰ to –17.9 ‰) – the largest change inδ¹⁵N yet reported in any marine bird, suggesting a relatively rapid shift in the composition of the Indian Ocean food web, or changes in baselineδ¹³C andδ¹⁵N values.  A stronger El Niño-Southern Oscillation results in a weaker Leeuwin Current in Western Australia, and decreased Flesh-footed Shearwaterδ¹³C andδ¹⁵N.  Current climate forecasts predict this trend to continue, leading to increased oceanic ‘tropicalisation’ and potentially competition between Flesh-footed Shearwaters and more tropical sympatric species with expanding ranges.  Flesh-footed Shearwater populations are declining, and current conservation measures aimed primarily at bycatch mitigation are not restoring populations.  Widespread shifts in foraging, as shown here, may explain some of the reported decline.  An improved understanding and ability to mitigate the impacts of global climactic changes is therefore critical to the long-term sustainability of this declining species.”

Flesh-footed Shearwater, photograph by Tim Reid

With thanks to Jenn Lavers for information.

Reference:

Bond, A.L. & Lavers, J.L. 2014.  Climate change alters the trophic niche of a declining apex marine predator.  Global Change Biology DOI: 10.1111/gcb.12554.

John Cooper, ACAP Information Officer, 27 March 2014

The fishery for Patagonian Toothfish Dissostichus eleginoides around the Falkland Islands (Islas Malvinas)* has received Marine Stewardship Council (MSC) certification this month.  The toothfish are caught by longlines set from a single vessel.

This certification brings to six the number of toothfish fisheries utilizing longlines or trawls in the Southern Ocean that have been approved as considered to be environmentally (and seabird) friendly by the Marine Stewardship Council (click here).

“The fishery entered assessment in August 2012 and was evaluated by independent MSC certifier Intertek Fisheries Certification (formerly Intertek Moody Marine) against the MSC Standard for well-managed and sustainable fisheries in three principle areas: the sustainability of the fish stock, the environmental impacts of fishing activity and the administration system in place for managing the fishery.

The fishery scored well against all the individual performance indicators within each principle achieving a minimum of 80 points on all, bar three performance indicators, giving rise to 3 conditions being placed on the client to be met within the certification period of 5 years.  A further condition was voluntarily agreed by CFL - to conduct further research into the identity of the stock in Falkland’s waters -- following objection to the certification by an Argentine NGO, the Fundación Vida Silvestre Argentina.” (click here and here).

Management measures used by the now-certified fishery to reduce bycatch of albatrosses and petrels include deployment of bird scaring lines, night-setting of lines, line weighting, use of only thawed bait, careful management of offal discharge, removal of hooks from offal and bycatch, and use of the ‘Brickle curtain’ to deter birds from bait during hauling.  The use of the Chilean ‘umbrella’ hook system also significantly discourages interactions with seabirds and marine mammals.

John Cooper, ACAP Information Officer, 26 March 2014

*A dispute exists between the Governments of Argentina and the United Kingdom of Great Britain and Northern Ireland concerning sovereignty over the Falkland Islands (Islas Malvinas), South Georgia and the South Sandwich Islands (Islas Georgias del Sur y Islas Sandwich del Sur) and the surrounding maritime areas.

Takashi Yamamoto (Department of Polar Science, Graduate University for Advanced Studies, Tokyo, Japan) and colleagues have published in the journal Behaviour on the migratory behaviour of the Streaked Shearwater Calonectris leucomelas.

The paper’s abstract follows:

“Many animals migrate between breeding and wintering areas; however, whether each animal behaves consistently in space and time between consecutive years is less well understood.  Furthermore, previous breeding state (successful or failed) is often not considered when attempting to understand consistent individual differences in behaviour that are likely to impact upon the subsequent behaviour.  Between 2006 and 2010, we used geolocators to track the migratory movements of a pelagic seabird, the streaked shearwater Calonectris leucomelas, with individuals (N=46) being followed for two years or more, including 23 birds that had chicks in two seasons and 23 birds in just one season.  All individuals, except for one bird, migrated to the same broad wintering areas, and their migratory route as well as the centre of wintering distribution did not change in relation to the previous breeding outcomes.  Migration schedules (dates of departure from the breeding colony, southward and northward migrations, and first return to the colony) did not differ significantly between years for individuals that had chicks during both years, while failed individuals left the breeding colony and appeared to start the southward migration at an earlier date than the previous successful year.  Nonetheless, the timing of the southward migration was consistent within individuals, including both males and females, over successive years regardless of the previous breeding outcome, and also the timing of first return back to the colony for females that had chicks in the both previous years and eggs in the both following season.  This may imply the existence of individual-specific broad time schedules, possibly a circannual rhythm, though ecological conditions might affect the exact timing of the actual departure event.  Our results present evidence for high levels of individually consistent behaviour for this pelagic seabird outside the breeding season.”

Reference:

Yamamoto, T., Takahashi, A., Sato, K., Oka, N., Yamamoto, M. & Trathan, P.N. 2014.  Individual consistency in migratory behaviour of a pelagic seabird.  Behaviour DOI:10.1163/1568539X-00003163.

John Cooper, ACAP Information Officer, 25 March 2014

David Hyrenbach (Oceanic Institute, Hawai’i Pacific University, Waimanalo, Hawaii, USA) and colleagues report in ‘Elepaio (Journal of the Hawai‘i Audubon Society) on depths achieved by four diving Wedge-tailed Shearwaters Puffinus pacificus (WTSH) in Hawaii carrying tail/mounted time-depth-recorders (TDRs).  Maximum dive depth attained was 21.8 m.  Both single and multiple (bout) dives were recorded.

“[T]he mean maximum dive depths we recorded for WTSH are shallower than those of related sub-arctic, subtropical and tropical species [of shearwaters].  This result is consistent with anatomical evidence suggesting that WTSH are not deep divers, due to having significantly less laterally compressed tarsi than other diving species, like the Short-tailed Shearwater and the Sooty Shearwater.”

The paper concludes: “[f]uture research could further investigate the ecological context of night-time foraging and dive bouts.  To this end, we hypothesize that single dives and dive bouts indicate solitary foraging events and multi-species feeding flocks involving subsurface predators, respectively."

Wedge-tailed Shearwater, photograph by Alan Burger

Reference:

Hyrenbach, K.D., Gleichman, J.S. & Karnovsky, N.J. 2014.  Diving behavior of Wedge-tailed Shearwaters rearing chicks on Lehua Islet.  ‘Elepaio 74(4): 1-4.

John Cooper, ACAP Information Officer, 24 March 2014