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Effects of blue crab range expansion on New England shellfishWith warming waters, the blue crab, a native of the Chesapeake Bay, is expanding its range north (Figure 1). Oyster farmers at the historical range limit for blue crab on the south of Cape Cod have been seeing record numbers of blue crabs on their lease areas. At the same time, blue crabs have been observed for the first time in the Gulf of Maine. Our research is examining (1) overlap between shellfish habitat and areas suitable for blue crab, (2) vulnerability of New England bivalves to blue crab predation, and (3) how temperature and pH affect bivalve shell growth in ways that affect shell strength. We use a combination of laboratory experiments, field observations, and analyses of historical species distributions to answer these questions.
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Adaptive capacity of fishing communities
To understand how fishing communities may or may not adapt to climate-driven changes in availability of their target species, we examined the capacity for Northeast US fishing communities to have changed what they catch and where they fish in dealing with past variability.
Small fishing vessels in Plymouth, MA. Image credit: Eva Papaioannou
We developed indicators of catch flexibility and fishing ground mobility for 266 "Communities at Sea"-- communities defined by fishing gear and port of landing. We found that different gear types differed in the ways that they might adapt to change. Scallop fleets were well equipped to change where they fish and keep targeting scallop. Small groundfish trawlers were more likely to stay in traditional fishing grounds and change what they catch. Communities using one type of gear had distinct strategies: lobster traps had low mobility and catch flexibility while communities using other types of trap gear we able to shift what they fish and where they fish. Differences in the range of fleets present in a port drove wide variation in adaptive capacity among ports in the same geographic region. This highlights the value of taking a community-centric approach to inform resilience and vulnerability. Our work was published in ICES JMS and was featured on the Wellesley News, on the news page of WeAreAquaculture
In addition to the broad scale analysis of communities along the entire Atlantic Seaboard, we combined quantitative analyses of fishing patterns with qualitative interviews in 12 focal trawl communities to understand how fishing communities are perceiving and responding directly to changes in the abundance of their target species. Our research revealed that following the fish as waters warm was rare. An owner/operator of a large trawler from New Jersey said it best: "It's very temperature sensitive, changing the. migratory patterns, it's left us with no squid to catch unless we travel 100 miles and we are not those types of wanderers". Instead, most trawl communities were more likely to switch what they catch, but this strategy is limited by permits and regulations. Understanding what strategies communities would prefer and why can help guide the ways that we consider making our fisheries management more "climate-ready." Our work was published in Frontiers in Marine Science and featured by Hakai Magazine
In addition to the broad scale analysis of communities along the entire Atlantic Seaboard, we combined quantitative analyses of fishing patterns with qualitative interviews in 12 focal trawl communities to understand how fishing communities are perceiving and responding directly to changes in the abundance of their target species. Our research revealed that following the fish as waters warm was rare. An owner/operator of a large trawler from New Jersey said it best: "It's very temperature sensitive, changing the. migratory patterns, it's left us with no squid to catch unless we travel 100 miles and we are not those types of wanderers". Instead, most trawl communities were more likely to switch what they catch, but this strategy is limited by permits and regulations. Understanding what strategies communities would prefer and why can help guide the ways that we consider making our fisheries management more "climate-ready." Our work was published in Frontiers in Marine Science and featured by Hakai Magazine
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Climate change impacts on fisheriesAs species shift poleward to keep pace with climate change, they move away from those fishing communities that have relied upon them for generations, and become newly available to others. Fisheries are on the frontlines of climate impacts and their livelihoods are at stake. I testified to the House Subcommittee on Water Oceans and Wildlife on May 1, 2019 on the effects of climate change on fisheries and the need to design our management to be proactive.
Our paper in ICES Journal of Marine Science describes how changes in overall stock biomass interact with shifts in species distributions to result in dramatic differences in availability to fishing ports along the West Coast.
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Warming effects on marine ecosystems |
As suitable thermal habitat moves poleward, marine species are shifting their spatial distributions. However, asymmetries in thermal responses among species may lead to mismatches in their response to warming and disruptions in key species interactions. My post-doctoral research at Rutgers University revealed that warming is driving range contraction among cold-water predators like cod in the Northeast US LME (a hot-spot of warming over the last ten years as shown in the map) and this is creating spatial refugia for its prey. In contrast, range expansion by predators with warmer-water affinity like spiny dogfish is leading to increases in spatial overlap with prey that may compensate for the loss of cod's functional role.
See paper in Global Change Biology
See paper in Global Change Biology
Image Credit: http://www.seascapemodeling.org/
Fishing alters marine food webs
Image Credit: Ray Troll
While seafood can be one of the most sustainable forms of human protein, human harvest of large amounts of fish biomass has the potential to alter marine food webs, especially if predators are selectively targeted. Recent research has shown that over-exploitation of predators can drive trophic cascades in coastal and pelagic marine ecosystems. My PhD research examined whether fishing-induced reductions in predator size structure might drive similar ecosystem consequences even without dramatic reductions in predator abundance.
Size truncation alters potential for top-down control of sheephead on urchins Proc Roy Soc B
Diet changes with size drive impacts of fishing on predator-prey interactions Fisheries Research
Observe our predation experiments in action at Catalina Island
