MLML Ornithology & Mammalogy Lab

Elizabeth Phillips

Beth earned a BS in Biology with Honors from Western Washington University in Bellingham, WA in 1995, and a MS in Marine Science from Moss Landing Marine Laboratories in 2005. For her Master's thesis research, she investigated biases associated with scat analysis in the Pacific harbor seal. She conducted captive feeding experiments at California Department of Fish and Game’s Marine Wildlife Veterinary Care and Research Center in Santa Cruz throughout 2003 with seals held at the facility. Much of her work focused on improving estimates of salmon consumption by pinnipeds, because salmon are threatened and/or endangered in many parts of the West coast of the US. Salmonid otoliths (ear bones) are so small that they are rarely found in scat samples, thus estimates of pinniped impacts on these important fish are hard to make. She also worked on improving consumption models for the entire harbor seal population, which fisheries managers can now incorporate into their estimates.

Beth’s current role is with the Central California Marine Bird Health Study (CCMBHS). Marine birds are important indicators of marine ecosystem health, and this study provides a quantitative demographic assessment of disease and other mortality factors affecting Common Murres and other seabird populations in California. She works with the Monterey Bay National Marine Sanctuary's BeachCOMBERS program, in cooperation with local rehab facilities to collect and necropsy local seabirds. CCMBHS is based out of California Department of Fish and Game - Marine Wildlife and Veterinary Care and Research Center in Santa Cruz and provides a regional information center for federal, state, and local resource managers.

See the project’s photo gallery:
http://shutterbug.ucsc.edu/gallery/albums.php

Beth has worked as a wildlife biologist on a variety of projects in places such as the Channel Islands, Baja California Sur, Australia, and aboard research vessels in the North Atlantic/Gulf Stream, offshore California, and the Northern Marianas Islands, Micronesia.

Research interests: Seabird population and demographic characteristics, population modeling, seabird and marine mammal diet, human impacts to seabirds, marine mammals, and sea turtles including oil and plastic pollution, fishery by-catch, and habitat destruction, and marine conservation.

 

Captive feeding study of Pacific harbor seal (Phoca vitulina richardii) improves species-specific consumption estimates

Phillips, Elizabeth M.

Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA

To properly evaluate potential impacts of increasing pinniped populations on commercially valuable and threatened fish stocks, accurate diet estimates are necessary. Scat analysis is a tool to determine diet using undigested hard parts to calculate frequency of occurrence or biomass of prey consumed. However, discrepancies between methods can result in inaccurate consumption estimates. I conducted captive feeding experiments (n=177) with Pacific harbor seals to quantify scat analysis biases. Seals were fed Pacific sanddab, Pacific sardine, market squid, shortbelly rockfish, pink salmon, steelhead smolt, and Pacific hake (ntotal>2,700). I found hard parts 4.0 to 161.0 hours after ingestion, and 73.2% of hard parts passed within 48 hours of ingestion. Hard parts from a single meal were recovered in 1 to 10 scats (mean=3.8), confirming that a single scat does not represent a single meal, but rather a series of foraging events throughout the previous 24-48 hours. A mean of 58% of otoliths and 89% of cephalopod beaks were recovered. Recovery of all prey except pink salmon was improved by 31.7% when all diagnostic skeletal structures were used, indicating that the all-structure technique will improve recovery biases due to complete otolith erosion. However, recovery of pink salmon was 9.5 times that fed to seals when the all-structure technique was used, highlighting the issue of fragmentation of a single meal across a series of scats. Species-specific length correction factors improved estimates of all ingested prey length except sardines (P<0.05) and furthermore, prey with highly eroded otoliths (shortbelly rockfish, hake) benefited from grade-specific correction factors that account for varying erosion levels. I found that, when compared to known consumption rates of seals in this study, diet estimates based solely on frequency of occurrence (e.g. split sample frequency of occurrence) are flawed, whereas estimates based on biomass calculations (e.g. reconstructed biomass) are likely accurate.

Examples of otoliths and cephalopod beak.

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