PhD Dissertation: Elucidating Drivers of Data-Limited Marine Predator Distribution

Chapter 1: Can prey predict predator in a North Carolina estuarine system?

In North Carolina, blue crab has been one of the most important fisheries for decades, but has declined in recent years. There are many theories to why this is the case: overfishing, water quality, hurricanes, or predation. This chapter investigated the predation idea by seeing if predator distribution was linked to blue crab distribution. To further understand the relationship between blue crabs, their predators, alternate prey items, and the environment, I used species distribution models (SDMs). We asked 1) Does total prey or blue crab abundance help explain predator distribution and abundance in addition to the environment; 2) Does a joint modeling approach enhance our understanding of these explanatory variables; and 3) Does scale and data resolution impact joint SDM predictive ability?

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Chapter 2: What drives humpback whale density in the Gulf of Maine?

As marine megafauna, humpback whales are integral to the ecotourism industry in the Northeast U.S. and consume large amounts of forage species that other species likewise rely on. In a rapidly warming region of the world, the Gulf of Maine, this research investigates what drives humpback whale density. I am using a spatiotemporal species distribution model to 1) Determine if the distribution for humpback whales should be modeled with general oceanography data, prey abundance, or prey proxies; 2) Quantify spatio-temporal overlap between predators and prey based on surveys; and 3) Examine if the abundance of forage impacts the density of humpback whales annually.

3) When and where are sharks captured through land-based recreational shark fishing? What is the behavior, effort, and management opinions from participants in the fishery?

My last dissertation project relies on field interviews with land-based shark fishers (LBSFs) to learn about the distribution of large coastal sharks and the fishery itself in North Carolina. I aim to 1) Define the perceptions of seasonal distribution of large coastal shark catch in North Carolina and what drives it; 2) Collect individual angler behavior and effort information to increase our understanding of the land-based recreational shark fishery (LBSF) in the state; 3) Gather anglers’ opinions on and recommendations to local fisheries management; and 4) Identify how anglers learn to fish, how they share information in the community, and what resources would help others learn.

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