Lisa T. Ballance

Parkinson's Petrel Distribution and Foraging Ecology in the Eastern Pacific: Aspects of an Exclusive Feeding Relationship with Dolphins

During 28 research vessel cruises in the eastern tropical Pacific Ocean from 1976 through 1990, Parkinsons Petrels (Procellaria parkinsoni) were observed near shore from southern Mexico (ca. 15?N) to northern Peru (ca. 5?S), and along a broad seaward extension that continued west of the Galapagos Islands to 110?W. Parkinsons Petrels regularly associated with dolphins: of the 618 petrels observed, 469 (76%) were associated with 10 species of dolphins, on 55 occasions, with I to 300 petrels present. They occurred mostly with two rare dolphin species: the melon-headed whale (Peponocephala electra) and the false killer whale (Pseudorca crassidens). This appeared to be a largely obligatory foraging relationship for Parkinsons Petrels. Associations with other dolphin species occurred primarily when those species also associated with melon-headed and false killer whales. Parkinsons Petrels avoided a common and widespread, multi-species feeding assemblage which consisted of a diverse, fast-moving group of seabirds, spotted and spinner dolphins (Stenella attenuata and S. longirostris), and tuna, all of which feed on live prey forced to the surface. The lumbering Parkinsons Petrels appeared ill-equipped to take such prey. In contrast, melon-headed and false killer whales apparently fed by dismembering large prey below the surface and so, provided feeding opportunities for a scavenging bird with diving capabilities. Among eastern tropical Pacific (ETP) seabirds, Parkinsons Petrels alone are adapted for recovering food scraps well below the surface. Parkinsons Petrels appear to be more dependent on marine mammals for foraging than any other species of seabird studied and feed diurnally more than was previously thought.

Wing ecomorphology of seabirds from Johnston atoll

Wing morphology of nine species of seabirds from Johnston Atoll in the central tropical Pacific was analyzed to determine how wing size and shape correlated with observed foraging behavior and, in some species, the energetic cost of flight. Red-tailed Tropicbirds (Phaethon rubricauda) and Christmas Shearwaters (Puffinus nativitatis) had lower wing areas, shorter wing spans, and higher relative wing loading than would be predicted from mass alone. Brown Noddies (Anous stolidus) and Red-footed Boobies (Sula sula) had lower wing loading, Brown Boobics (Sula leucogaster) and Sooty Terns (Sterna fuscata) had higher aspect ratios, and Brown Noddies had lower aspect ratio than would be predicted from mass alone. Aspect ratio showed greater intraspecific variation than the other variables. In most cases, predicted differences in wing morphology correlated well with observed foraging differences among species, and species that did not differ significantly in body mass differed with respect to wing size and shape; these morphological differences reflected varying flight and foraging behaviors. Sooty Terns had a higher aspect ratio and higher wing loading than Brown Noddies reflecting their more pelagic lifestyle, and Christmas Shearwaters had a lower aspect ratio and higher wing loading than Wedge-tailed Shear-waters (Puffinus pacificus) reflecting their pursuit plunging behavior.

Range Expansion of the Jumbo Squid in the NE Pacific: δ15N Decrypts Multiple Origins, Migration and Habitat Use

Coincident with climate shifts and anthropogenic perturbations, the highly voracious jumbo squid Dosidicus gigas reached unprecedented northern latitudes along the NE Pacific margin post 1997–98. The physical or biological drivers of this expansion, as well as its ecological consequences remain unknown. Here, novel analysis from both bulk tissues and individual amino acids (Phenylalanine; Phe and Glutamic acid; Glu) in both gladii and muscle of D. gigas captured in the Northern California Current System (NCCS) documents for the first time multiple geographic origins and migration. Phe δ15N values, a proxy for habitat baseline δ15N values, confirm at least three different geographic origins that were initially detected by highly variable bulk δ15N values in gladii for squid at small sizes (<30 cm gladii length). In contrast, bulk δ15N values from gladii of large squid (>60 cm) converged, indicating feeding in a common ecosystem. The strong latitudinal gradient in Phe δ15N values from composite muscle samples further confirmed residency at a point in time for large squid in the NCCS. These results contrast with previous ideas, and indicate that small squid are highly migratory, move into the NCCS from two or more distinct geographic origins, and use this ecosystem mainly for feeding. These results represent the first direct information on the origins, immigration and habitat use of this key “invasive” predator in the NCCS, with wide implications for understanding both the mechanisms of periodic D. gigas population range expansions, and effects on ecosystem trophic structure.

THE CHANGING STATUS OF MARINE BIRDS BREEDING AT SAN BENEDICTO ISLAND, MEXICO

Abstract We reviewed the status of the breeding marine birds on San Benedicto Island, Mexico, based on >100 years of published observations and seven of our own surveys conducted between 1978 and 2000. We found that there have been marked changes in the island avifauna with two main trends evident. First, a volcanic eruption destroyed much of the island in 1952. The Wedge-tailed Shearwater (Puffinus pacificus; estimated breeding population 1,000 pairs), Townsends Shearwater (Puffinus auricularis; probable breeder, small numbers), and Red-footed Booby (Sula sula; 60 pairs) historically had much larger populations, but they apparently never fully recovered from the eruption. The Masked Booby (Sula dactylatra; 2,185 pairs), however, has become much more abundant perhaps due to changes in the vegetation. The second trend is that within the last three decades at least two, and possibly four, species from the central Pacific have colonized the island. The Laysan Albatross (Phoebastria immutabilis; 12 pairs) started breeding in the late 1980s; Black-footed Albatross (Phoebastria nigripes; 1 pair) in 2000. Red-tailed Tropicbirds (Phaethon rubricauda; probable breeder, 10 pairs) may have started breeding in the 1980s, and at least some of the breeding Brown Boobies (Sula leucogaster; 300 pairs) are from central Pacific populations. The reason(s) for this influx of central Pacific species is unknown, but likely involves changes in the marine environment. Other breeding species include the Red-billed Tropicbird (Phaethon aethereus; 200 pairs), Nazca Booby (Sula granti; 50 pairs), Great Frigatebird (Fregata minor; 165 pairs), and Magnificent Frigatebird (Fregata magnificens; 5 pairs).

An Ecosystem Services Perspective for the Oceanic Eastern Tropical Pacific: Commercial Fisheries, Carbon Storage, Recreational Fishing, and Biodiversity

The ocean provides ecosystem services (ES) that support humanity. Traditional single-issue management largely failed to protect the full suite of ES. Ecosystem-based management (EBM) promotes resilient social-ecological systems that provide ES. To implement EBM, an ES approach is useful: 1) characterize major ES provided (magnitude, geographic extent, monetary value, trends, and stakeholders), 2) identify trade-offs, 3) determine desired outcomes, and 4) manage anthropogenic activities accordingly. Here we apply the ES approach (steps 1-2) to an open ocean ecosystem, the eastern tropical Pacific (ETP), an area of 21 million km2 that includes waters of 12 nations and the oceanic commons, using 35 years (1975-2010) of fisheries and economic data, and 20 years (1986-2006) of ship-based survey data. We examined commercial fisheries, carbon storage, biodiversity, and recreational fishing as the major provisioning, regulating, supporting, and cultural ES, respectively. Average catch value (using U.S. import prices for fish) for the 10 most commercially fished species was

Pelagic distribution of Gould’s Petrel (Pterodroma leucoptera): linking shipboard and onshore observations with remote-tracking data

2.7 billion yr-1. The value of carbon export to the deep ocean was

Massive Mortality of a Planktivorous Seabird in Response to a Marine Heatwave

12.9 billion yr-1 (using average European carbon market prices). For two fisheries-depleted dolphin populations, the potential value of rebuilding carbon stores was

Incidence of Wing Deformities (‘Angel Wing’) Among Masked Boobies at Clipperton Island: Life History Consequences and Insight into Etiology

1.6 million (cumulative); for exploited fish stocks it was also

Temporal variation in pelagic food chain length in response to environmental change

1.6 million (an estimated reduction of 544,000 mt). Sport fishing expenditures totaled

Limited trophic partitioning among sympatric delphinids off a tropical oceanic atoll

1.2 billion yr-1, from studies of three popular destinations. These initial, conservative estimates do not represent a complete summary of ETP ES values. We produced species richness maps for cetaceans, seabirds, and ichthyoplankton, and a sightings density map for marine turtles. Over 1/3 of cetacean, seabird, and marine turtle species occur in the ETP, and diversity (or density) hotspots are widespread. This study fills several gaps in the assessment of marine and coastal ES by focusing on an oceanic habitat, utilizing long-term datasets, mapping the spatial distribution of ecological components, and concentrating on an area beyond Europe and the USA. Our results improve our understanding of ETP ES, highlight their variety, and offer a new perspective for a fisheries-dominated system. This study sets the stage for further analyses of trade-offs, which can inform decisions about resource management and biodiversity conservation.