Publikationsdatum:
2022-05-25
Beschreibung:
Submitted in partial fulfillment of the requirements for the degree of
Doctor of Philosophy at the Massachusetts Institute of Technology
and the Woods Hole Oceanographic Institution February 2017
Beschreibung:
Animal movement is motivated in part by energetic constraints, where fitness is maximized
by minimizing energy consumption. The energetic cost of movement depends on
the resistive forces acting on an animal; changes in this force balance can occur naturally
or unnaturally. Fishing gear that entangles large whales adds drag, often altering energy
balance to the point of terminal emaciation. An analog to this is drag from tags attached
to cetaceans for research and monitoring. This thesis quantifies the effects of drag loading
from these two scenarios on fine-scale movements, behaviors and energy consumption.
I measured drag forces on fishing gear that entangled endangered North Atlantic right
whales and combined these measurements with theoretical estimates of drag on whales’
bodies. Entanglement in fishing gear increased drag forces by up to 3 fold. Bio-logging
tags deployed on two entangled right whales recorded changes in the diving and fine-scale
movement patterns of these whales in response to relative changes in drag and buoyancy
from fishing gear and through disentanglement: some swimming patterns were consistently
modulated in response. Disentanglement significantly altered dive behavior, and can affect
thrust production. Changes in the force balance and swimming behaviors have implications
for the survival of chronically entangled whales. I developed two bioenergetics approaches to
estimate that chronic, lethal entanglements cost approximately the same amount as the cost
of pregnancy and supporting a calf to near-weaning. I then developed a method to estimate
drag, energy burden and survival of an entangled whale at detection. This application is
essential for disentanglement response and protected species management.
Experiments with tagged bottlenose dolphins suggest similar responses to added drag:
I determined that instrumented animals slow down to avoid additional energetic costs associated
with drag from small bio-logging tags, and incrementally decrease swim speed as
drag increases. Metabolic impacts are measurable when speed is constrained. I measured
the drag forces on these tags and developed guidelines depending on the relative size of
instruments to study-species.
Together, these studies quantify the magnitude of added drag in complementary systems,
and demonstrate how animals alter their movement to navigate changes in their energy
landscape associated with increased drag.
Beschreibung:
Throughout graduate school, my research has been funded by the M. S. Worthington Foundation,
the North Pond Foundation, Sloan and Hardwick Simmons, the Herrington-Fitch
Family Foundation, the National Oceanographic Partnership Program [National Science
Foundation via the Office of Naval Research N00014-11-1-0113], the Cooperative Institute
for the North Atlantic Region [CINAR; NA14OAR4320158], and NOAA Cooperative Agreements
POEA133F09SE4792 and NA09OAR4320129. A Postgraduate Scholarship from the
Natural Sciences and Engineering Research Council of Canada, and the MIT Martin Family
for Sustainability and WHOI-Duke Fellowships gave me flexibility in pursuing my academic
interests.
Schlagwort(e):
Whales
;
Dolphins
;
Drag
Repository-Name:
Woods Hole Open Access Server
Materialart:
Thesis
Permalink
