Research

Our group conducts research in ecology, focusing on fish. In particular, our research has two themes: Movement Ecology and Feeding Ecology.

Movement Ecology: Understanding the motivations and consequences of animal movements. To understand movement ecology, we use biotelemetry, geographic information systems, and simulation models.

Trophic Ecology: Understanding how predator and prey interact and influence one another, from the perspectives of movements, bioenergetics, and survival. To understand trophic ecology, we assess fish diet (stomach contents) and use bioenergetics models.

Animal migrations put predators on the move: migratory coupling in ecology

Animal migrations represent large pulses of energy that move across landscapes at predictable times. In response, predators can react to migrant prey to exploit these events to feed at high rates. In other words, animal migrations may result in predators moving - what we have termed as "migratory coupling." Such movements and feeding by predators may be really important to the annual energy .

We are currently researching how consumers may be affected by sockeye salmon life history in the Chilcotin region of British Columbia, Canada.

Nature Ecology and Evolution cover photo

Research Topics

Feast-or-famine life style: binge-feeding

In nature, feeding opportunities can be few or far between. In response, animals should have adaptations to maximize consumption of food when it is available. Fishes in particular often live in environments with strong fluctuations in food availability. When food is in great quantities (e.g. a resource pulse), fish can "binge-feed" on food, even if it takes several days or more to digest the meal.

We have identified one such system where binge-feeding occurs (bull trout feeding on sockeye salmon smolts), but we are further investigating other systems where such extreme feeding may occur (including the high Canadian Arctic).

Sockeye salmmon smolts collected from bull trout stomach in sieve

Understanding animal migrations

Animal migrations occur across taxa and act to connect ecosystems. Unfortunately, most migratory populations are in decline. We try to understand what influences the success of migrants during their journeys.

Current migratory taxa we research include Pacific salmon (sockeye), Atlantic salmon, Arctic char, and rainbow smelt.

Current Research Projects

Henry Bigelow Shallow Trawl Trial on 20170207 Photo by Ensign Lee Shoemaker

Nutritional ecology of climate change in the western Atlantic

The waters of the Gulf of Maine are warming faster than 99% of the world’s oceans, which can have important consequences for the occupants of the western Atlantic. As conditions change, fishes have sought new areas that might better resemble their preferred habitats; however, this relocation is neither universal nor equal in direction or magnitude. With these movements, previous trophic interactions have the potential to be lost with new ones forming. Using diet data collected by the National Marine Fisheries Service throughout the eastern seaboard since 1973, we can identify those changes and understand what the future holds for these communities. This research is funded by the National Science Foundation awarded in collaboration with the Gulf of Maine Research Institute.

Photo credit: NEFSC

Common tern movement and interaction with forage fishes

Common terns use islands along the Northeastern coast for nesting and raising their chicks during the summer. During this critical period of provisioning, terns are primarily foraging for pelagic juveniles that may recruit to valuable fisheries in future years. As a more effective sampler of these early years in fish life histories, the common tern may serve as an important indicator for fishery management. This work is done combining observations of tern provisioning to chicks on the Isles of Shoals since 1999, satellite telemetry to identify important foraging locations, targeting small fish at these locations, and using eDNA to fill in gaps in the diet and habitat. This research was funded by New Hampshire Sea Grant with further support coming from a Graduate Research Fellowship by the National Science Foundation.

Common Tern in flight, photo taken by Tim Briggs

Photo credit: Tim Briggs

Value of Great Bay to New Hampshire's Rainbow smelt

Rainbow smelt might be considered the forgotten diadromous fish. Although their upstream spawning migrations supported popular ice fisheries (and still do in Maine and Canada), populations of these fish have declined in recent decades, and surprisingly little is known regarding their use of estuaries throughout their life history. Funded by New Hampshire Sea Grant, this project will use complementary techniques of acoustic telemetry, otolith microchemistry, and experimental releases of larvae to quantify the importance of Great Bay, NH to regional rainbow smelt populations.

Photo credit: Tim Briggs

Invasive maneuvers: movements of green crabs in New England estuaries

Green crabs have invaded estuarine and coastal ecosystems along the Atlantic coast. In estuaries, green crabs can predate on important species (e.g. juvenile shellfish), destroy habitat, and destabilize salt marsh banks and substrates. The negative impacts of green crabs are likely affected by how much area each individual uses each day, and their ability to disperse to other habitats within and among estuaries. But we have little knowledge on how much green crabs move. We are tagging green crabs with acoustic telemetry transmitters in the Webhannet River estuary to characterize how much space they use and how far they travel throughout the year. This research is in collaboration with the Wells National Estuarine Research Reserve.

Green crabs equipped with acoustic transmitters in a trap

Jonah Crab equipped with acoustic transmitter in hand

Effects of claw removal on Jonah crab movements

Jonah crabs are commercially harvested along the Atlantic coast. Currently, fisheries are experimenting with a fishery where claws are removed from an individual that is then released back into the water. However, the effects of declawing crabs are unknown. We tagged crabs with acoustic telemetry tags and released in a telemetry array at the mouth of the Piscataqua River by UNH’s Judd Gregg Marine Research Complex. Half of the crabs were declawed to simulate the claw removal practice. We will compare the fine-scale movements of clawed and declawed crabs to understand the effects of claw removal on behavior and survival of this species of fisheries importance. This work is in collaboration with the Watson lab, New Hampshire Fish and Game, and the Wells National Estuarine Research Reserve.

Sockeye smolt outmigration survival effects

For juvenile fishes, leaving their nursery grounds is always a critical time in their life history fraught with dangers. This is especially true for anadromous migrants like the threatened Sockeye salmon that may have to venture thousands of kilometers to marine waters upon smolting. Using multiple forms of individual movement monitoring, we hope to monitor the levels of survival they experience at the onset of their journey. Adapted mark-recapture models, such as the Cormack-Jolly-Seber model, are being used to evaluate the risks these sensitive fish face, including those risks imposed by the research process itself. This research was conducted in the Chilko Lake system in collaboration with the University of British Columbia and Fisheries and Oceans Canada

Impacts of Invasive Japanese Knotweed on Brook Trout

An invasive riparian plant species, Japanese Knotweed (Fallopia japonica), has grown abundant throughout much of New England and the White Mountains are no exception. This invasive plant is known to choke out other riparian plants and degrade stream banks, but the impacts that it can have on stream occupants is less understood. In this project, a combination of intensive habitat mapping and invertebrate sampling with monitoring populations of Brook Trout in Garland Brook seeks to understand how a large stream resident might be affected. Habitat suitability models are used to estimate growth under observed.

Photo credit: Tim Briggs

Movement and trophic ecology of Arctic fishes

The Arctic is currently the fastest warming region on the planet. Rising temperatures affect sea ice phenology. Ice-off in the spring is followed by a bloom of productivity that provides feeding opportunities throughout the food web. We use Arctic char and sculpin species in Tremblay Sound, near Pond Inlet (Nunavut, Canada) as models to understand how consumers respond to this extreme seasonal variability in productivity. We use acoustic telemetry to track the movements of these fish as they enter, move throughout, and potentially exit the system. Additionally, we examine stomach contents and use bomb calorimetry to characterize the diet of sculpin and Arctic char. Our work in this system is only a small piece of a highly collaborative effort that includes the University of Windsor, Fisheries and Oceans Canada, local communities, and non-government organizations.