Jenn Lavers (Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia) and colleagues published in the journal Marine Ecology Progress Series last year on using feather analyses of from Flesh-footed Shearwaters Puffinus carneipes killed at sea to trace their breeding sites.

The paper’s abstract follows:

“An emerging issue in seabird conservation is the ability to link at-sea mortality with observed demographic changes at breeding colonies.  Applications of modelling and biochemical markers can be used to assign mortalities of unknown provenance to a colony of origin ensuring conservation actions are targeted at those colonies identified as the most affected.  We analysed feathers (n = 120) from flesh-footed shearwater Puffinus carneipes collected from 5 breeding colonies throughout their range.  Using stable isotopes (δ15N and δ13C) and trace element concentrations (Mn, Ni, Cu, Mo, Ag, Ba, Pb), we assigned birds recovered from fishing vessels off Australia, New Zealand, and the North Pacific to colony of origin, and investigated the rate of correct assignment at 3 spatial scales.  Using quadratic discriminant analysis, samples of known origin were correctly assigned to basin, region, and breeding colonies at similar rates (92.3, 81.3, and 88.1%, respectively).  Stable isotopes succeeded in assigning individuals among basins (72.8%), performing less well at the region and colony level (52.5 and 36.4%, respectively).  In contrast, correct assignment was consistent at all 3 scales using only trace elements (93.2, 95.7, and 96.6%, respectively).  Applying our final model based on trace elements to 116 flesh-footed shearwaters taken as bycatch in eastern Australia (n = 30), Western Australia (n = 32), New Zealand (n = 16), eastern North Pacific (n = 27) and western North Pacific (n = 11), we assigned individuals to colonies in New Zealand (35.3%), Western/South Australia (36.2%), Western Australia (27.6%), and Lord Howe Island (0.9%).  Bycatch in fisheries may help explain ongoing declines in flesh-footed shearwater populations across the species’ range, highlighting the utility of assignment tools to account for unobservable mortality of wildlife at-sea.”

Flesh-footed Shearwater at sea, photograph by Tim Reid

Reference:

Lavers, J.L., Bond, A.L., Van Wilgenburg, S.L. & Hobson, K.A. 2013.  Linking at-sea mortality of a pelagic shearwater to breeding colonies of origin using geochemical markers.  Marine Ecology Progress Series 491: 265-275.

John Cooper, ACAP Information Officer, 28 November 2014

Hannah Cousin and colleagues have written on ingestion of plastics by Short-tailed Shearwaters Puffinus tenuirostris, now in press with the journal Emu – Austral Ornithology.

The paper’s abstract follows:

“In recent years, there has been increased reporting of marine plastic debris ingestion in seabirds.  Our aim was to assess the frequency and impacts of ingested plastic debris in pre-fledging chicks of the Short-tailed Shearwater (Puffinus tenuirostris) in Tasmania.  We necropsied 171 chicks confiscated after illegal poaching to determine presence or absence of plastic debris in the proventriculus and ventriculus, and examined whether there was a correlation between body condition (as estimated based upon body mass and fat scores) and quantity of plastic ingested (by count and weight of items).  We found 1032 plastic particles were ingested, comprised of both industrial (31%) and user plastic (69%).  Most of the shearwaters (96%) contained plastic debris with an average of 148.1 mg (± s.e. 8.1 mg) per bird.  Most plastic was found in the ventriculus.  Light coloured plastic pieces dominated (63.76%), followed by medium and dark coloured (22.09% and 14.15%, respectively).  We found that total ingested plastic mass was not significantly related to body condition, fat scores or mass.  Our paper highlights the prevalence of plastic pollution in healthy shearwater chicks and underscores concern regarding the impacts of increasing marine pollution on a global scale.”

Short-tailed Shearwater at sea, photograph by Kirk Zufelt

Reference:

Cousin, H., Auman, H., Alderman, R. & Virtue, P. in press.  The frequency of ingested plastic debris and impacts on body condition in Short-tailed Shearwater (Puffinus tenuirostris) pre-fledging chicks in Tasmania, Australia.  Emu.

John Cooper, ACAP Information Officer, 27 November 2014

Johanna Pierre and colleagues (Dragonfly Data Science) have produced a draft report for the Conservation Services Programme of the New Zealand Department of Conservation on cryptic mortality of seabirds in New Zealand longline and trawl fisheries.

Painting of deployed bird-saving lines by Bruce Pearson

The report’s executive summary follows:

“Understanding the nature and extent of interactions between commercial fisheries and marine protected species is one component of best practice fisheries management.  These interactions can lead to mortalities of protected species, which may be detected (e.g., by fisheries observers on vessels), or not readily detectable, and undetected (also known as cryptic mortalities). For seabirds, cryptic mortalities may result, for example, when a bird carcass falls into the water after striking a trawl warp, or when a bird is landed alive on deck, removed from fishing gear and released, but later dies as a result of injuries sustained.  The assessment of the risk that New Zealand commercial fisheries represent to seabird populations, conducted by Richard & Abraham (2013), considers cryptic mortality using a set of multipliers applied across the various fishing methods.  These scalars are derived from sources including data collected in New Zealand and internationally.

Here, we draw on Richard & Abraham’s (2013) approach, updated in 2014, to identify seabird species and fisheries for which cryptic mortality contributes particularly strongly to the overall assessed risk.  We review assumptions and uncertainties inherent in Richard & Abraham’s (2014) methods, as well as relevant new information which may contribute to the development of more robust cryptic mortality scalars applicable to New Zealand fisheries.  Finally, we recommend options to improve the estimation of cryptic mortality for the seabird species groups and fisheries where this is particularly important.

From Richard & Abraham’s (2014) assessment, cryptic mortality was especially influential in determining overall assessed risk for both albatross and petrel species, including black petrel (Procellaria parkinsoni) interacting with small-vessel surface and bottom longline fisheries, and Salvin’s (Thalassarche salvini) and New Zealand white-capped (T. cauta steadi) albatross interacting with small inshore trawl vessels, and southern Buller’s albatross (T. bulleri bulleri) interacting with large trawl vessels with meal plants.  Key assumptions included that cryptic mortality scalars derived from fisheries outside New Zealand were appropriately applied to the New Zealand context despite differences in seabird assemblages, fishing operations and gear.  Further, scalars applied to cryptic mortality of seabirds due to aerial warp strikes and interactions with trawl nets were entirely assumption-based.

Relevant new information that may contribute to refining scalars describing cryptic mortality includes work conducted on cryptic mortality associated with a Falkland Islands demersal trawl fishery, and two new studies reporting the outcomes of seabird strikes on trawl warps.  Additional data sources that could prove valuable for the development of improved scalars include the database collected on seabird interactions with trawl fisheries in the Conservation of Antarctic Marine Living Resources Convention Area and from trawl fisheries off the Falkland Islands.  Given the seabirds and fisheries for which cryptic mortality is a particularly important determinant of overall risk, and the additional information that may be available, priority areas for improving estimates of cryptic mortalities in New Zealand fisheries include developing method-specific cryptic mortality scalars for bottom longline fisheries, exploring existing information to refine scalars applicable to inshore fisheries, and refining estimates of mortalities – both observed and cryptic - that result from aerial warp strikes.  Applying scalars for broad groupings of large (i.e., predominantly albatrosses) and small seabirds appears appropriate given current information. The immediate amendment of data collection protocols used by New Zealand fisheries observers is recommended to document cryptic seabird mortalities.  The implementation of new data collection protocols, potentially combined with experimental data collection, are also considered priorities in order to develop an understanding of cryptic mortality, especially in inshore fisheries.”

Reference:

Pierre, J.P., Richard, Y. & Abraham, E.R. 2014.  Assessment of Cryptic Seabird Mortality due to Trawl Warps and Longlines.  Draft Report prepared for the Department of Conservation: Conservation Services Programme Project INT2013-05.  Wellington: Dragonfly Data Science.  46 pp.

John Cooper, ACAP Information Officer, 26 November  2014

Barry Baker, Katrina Jensz and Ross Cunningham (Latitude 42 Environmental Consultants) have produced a draft final report for the Conservation Services Programme of the New Zealand Department of Conservation detailing population trends in Near Threatened White-capped Albatrosses Thalassarche steadi breeding on New Zealand’s Auckland Island Group, including on Adams and Disappointment Islands.

A White-capped Albatross guards its chick, photograph by David Thompson

The report’s executive summary follows:

“White-capped albatrosses Thalassarche steadi are endemic to New Zealand, breeding on Disappointment Island, Adams Island and Auckland Island in the Auckland Island group, and Bollons Island (50-100 pairs) in the Antipodes Island Group.  Population estimates suggest most (95%) of the global population breeds on Disappointment Island, an area where access is restricted to maintain environmental values at the site.  Virtually all aspects of the biology and ecology of white-capped albatrosses are poorly known and although approximate population sizes have developed there have been no well-documented population estimates for any of the colonies until this study.

Between 2006/07 and 2013/14 (hereinafter 2006 and 2013, respectively) we undertook repeated population censuses of the white-capped albatrosses breeding in the Auckland Islands using aerial photography. These population censuses were carried out in either December or January each year to estimate population size and track population trends.

In 2013 we estimated that there were 89,552 (95%CI 88,953 — 90,151), 5,542 (5,393 — 5,691) and 184 (157— 211) annual breeding pairs at Disappointment Island, South West Cape and Adams Island, respectively, based on the raw counts, giving a total for these sites of 95,278 (94,661 — 95,895) breeding pairs.

To assess population trend in total counts we used an appropriate Generalised Linear Model where the response was specified as an over dispersed Poisson distribution and the link was logarithmic.  To allow for possible non-linear trend effects we used regression splines with a single knot at 2010.  We also assessed trend using software program TRIM (TRends and Indices for Monitoring Data), the standard tool used by the Agreement for the Conservation of Albatrosses and Petrels (ACAP).

Evidence from a series of ‘close-up’ photographs taken each year (2007-2013) indicates that the number of non-breeding birds present in the colonies differed somewhat between December and January.  The proportion was very low in December counts (1-2% of birds present), but higher in the January counts (14% of birds present).  Estimated annual counts for all three breeding sites in the Auckland Islands were adjusted to account for the presence of non-breeding birds, giving adjusted estimates of annual breeding pairs of 116 025, 90 036, 96 118, 73 838, 76 119, 92 692, 102 273 and 74 031 for each year from 2006 to 2013 inclusive.  These adjusted figures were used as inputs into models used for assessment of population trend.

Trend analysis for all sites combined using regression splines showed no clear evidence for systematic monotonic decline over the 8 years of the study.  This is particularly so if the count for 2006 is excluded.  Given this we do not have sufficient evidence to reject the null hypothesis of no systematic trend in the total population.  The population size estimates computed from the TRIM model indicate an average growth rate of -3.16% per year (λ = 0.9684 ± 0.001; assessed by TRIM as moderate decline. We note, however, that a simple linear trend analysis, as performed by TRIM is not well suited to a data set with high inter-annual variability.  Trend analysis using regression splines is more appropriate to such data sets, and the TRIM analysis is only presented because it is currently used by ACAP to assess population trends in albatross populations.

In a global review of fisheries-related mortality of shy and white-capped albatrosses it was estimated that 8,000 white-capped albatrosses were killed each year as a result of interactions with trawl and longline fisheries in the Southern Ocean. This level of mortality highlights the need to continue to acquire accurate population estimates and trends for white-capped albatross populations to assess the impact of fisheries operations on this species. Although annual counts over the last eight years indicate the population is stable, ongoing population monitoring is recommended to clarify if current levels of fishing mortality remain sustainable.”

Reference:

Baker, G.B., Jensz, K. & Cunningham, R. 2014.  White-capped Albatross Aerial Survey 2014 Draft Final Report.  Report prepared for Department of Conservation Contract 4523/4524. [Kettering]:  Latitude 42 Environmental Consultants Pty Ltd.  19 pp.

John Cooper, ACAP Information Officer, 25 November 2014