Walt is a post doctoral research associate that holds a joint appointment with the University of Maine's School of Marine Sciences and the Gulf of Maine Research Institute. Walt came to UMaine and GMRI after completing his Ph.D. at the University of New Hampshire in May 2010. During the past five years, Walt has been studying the energetic condition, spatial distribution, foraging ecology, age and growth of bluefin tuna and broadbill swordfish in the Atlantic. A key finding from Walt's dissertation was that tuna in the Gulf of Maine were skinnier during the 1990's.
Walt's current research builds on this initial finding of declining tuna weights as part of a joint venture NSF/NOAA CAMEO grant using inter-decadal comparisons to understand tradeoffs between abundance and condition in fishery ecosystems. The project is investigating how changes in physical conditions such as temperature, primary productivity, and fishing affect the abundance and condition of key species (bluefin tuna, herring) in the Gulf of Maine. We are using data from the 1980's (low herring, low stratification) with the 1990's (high herring, high stratification) and 2000's (moderate herring, intermediate stratification) to fit models with and without the condition variables. By comparing the models for each period, we are evaluating the role of bottom up processes (changes in physical conditions and productivity) relative to top down forces (e.g. fishing) in shaping large scale ecosystem changes. This work has immediate relevance to the management of ecosystems dominated by a few small pelagic fish (i.e. herring or anchovies) and will help us predict how the Gulf of Maine will respond to changes in climate and fishing pressures.
Primary Research Interests
My broad research interests involve the ecology of large pelagic species (tunas, swordfish, sharks), especially how changes in environmental conditions impact their energetic condition, growth patterns, reproduction and spatial distribution.
Ph.D. College of Biological Sciences, University of New Hampshire
M.S. College of Biological Sciences, University of New Hampshire
B.S. College of Natural Resources, University of Maine, Orono