Warming waters: A Rhode Island story
Funded by a grant from the National Science Foundation (NSF), the Rhode Island Experimental Program to Stimulate Competitive Research (EPSCoR) supports research at nine institutions of higher education in the Ocean State.
Working together to understand the response of marine life to climate variability, teams of Rhode Island scientists study three specific research questions about adaptation, food webs, and pathogens:
• What are the stress responses and evolutionary potentials of marine organisms in response to climate change?
• How are the structure and function of coastal marine food webs and biogeochemical cycling being directed in response to climate change?
• How will global climate change affect the ecology of marine pathogens and parasites?
RI EPSCoR research tracks impact of shifting species
In 2008, David Taylor was collecting specimens in the Taunton and Seekonk Rivers for his NIH INBRE research on mercury contamination in local fisheries.
Sifting through the catch in his seine net, he noticed something he hadn’t seen before in his trips through the upper reaches of Narragansett Bay — a small, left-eyed flounder that he identified as a juvenile summer flounder.
“I paused and thought to myself, ‘This area is not recognized as nursery habitat for summer flounder,’” recalled Taylor, associate professor of marine biology at Roger Williams University.
Adult summer flounder, or fluke, are a common catch in Rhode Island coastal waters. The arrival of juveniles, however, as small as 25 millimeters in the early days of summer, using Narragansett Bay and surrounding waters for early stage habitat, was new and grabbed Taylor’s attention.
The traditional pattern for this mid-Atlantic species is to spawn on the inner continental shelf, its larvae then migrating into coastal estuaries, with New Jersey having been the northern most range of the juvenile life stage.
Starting in 2009, intrigued by the little, seemingly out-of-place fish high up in the Bay’s estuary, Taylor began studying the potential interactions between summer flounder and another native flatfish, the winter flounder. Then, in 2010, as he was conducting juvenile flounder surveys in the Taunton and Seekonk Rivers, as far north as Dighton and Pawtucket, respectively, his nets filled with blue crabs, also a more southerly-located species.
“Blue crabs have always been in these waters, but historically they occurred in much lower numbers,” explained Taylor, a fisheries ecologist who focuses on the early life stages of fish and the factors that impact their recruitment into adult populations. “In recent years, I observed earlier life stages of blue crabs in these waters than what had occurred in the past.
“Today, they’re here in higher abundance and in a broader range of life stages. They appear to be using Narragansett Bay as nursery habitat and feeding grounds.”
With the changes he witnessed in his fieldwork, Taylor launched a new investigation in 2011, followed by RI NSF EPSCoR supported research in 2012, to study the affect of climate change on the range expansion of more southern species and the impact on fish native to the Ocean State.
In 2013, he and University of Rhode Island Professor Jeremy Collie, Graduate School of Oceanography (GSO), landed a Rhode Island Science and Technology Advisory Council (STAC) collaborative research grant to study the population dynamics of winter flounder, summer flounder and blue crab. The interaction posed questions given the dramatic increase of summer flounder and blue crab, both of which may negatively affect winter flounder populations.
Sitting in his office in the RWU Marine & Natural Sciences building, the shelves lined with books, rods and reels, Taylor detailed the shift in the Bay’s habitats and surrounding watershed from what he has observed since his time as a graduate student at URI GSO:
“The Bay that I knew when I first started studying it in 1999 versus the Bay that I know today has changed quite a bit. From an ecological perspective, projecting forward, the Bay when I retire may be more similar to Delaware Bay.”
Today, he said, the summer flounder offshore spawning stock has shifted northward. Carried by open ocean currents and coastal tides, navigating a complex series of turns through Narragansett Bay and floating their way up to inland Rhode Island waters, the summer flounder larvae and juveniles are settling in new territory.
Spawned in the fall, the early life stages of summer flounder face a critical survival test their first winter. However, the recent warming of local waters improves their over-wintering survival. Taylor’s research investigates whether the greater numbers negatively impact species like winter flounder, first with increased competition for food and then in a predator/prey relationship with the growth of summer flounder hugely outpacing that of the winter flounder.
From dominance to decline
The marine fisheries division of the Rhode Island Department of Environmental Management sits at the southeastern tip of Jamestown, on Conanicut Island, overlooking the mouth of Narragansett Bay. That vantage point, along with decades of surveys, gives Jason McNamee, DEM chief of marine resource management, unique insight into the life of the Bay.
“We are becoming in Narragansett Bay less like New England and more like a mid-Atlantic estuary with the decline of indigenous, northern cold water species,” McNamee said. “Now we’re getting huge recruitment events of scup and black sea bass that we equate more to Chesapeake Bay animals.”
Meanwhile, the winter flounder stock dwindles, a stark contrast to the late 1970s and early 1980s, when the benthic species could be found in abundance in southern New England. In the 35 or so years since, the winter flounder population continues to decline and has yet to rebound despite occasional, promising surges of juveniles.
The survey McNamee operates has been going since 1988. Each month from June through October, he said, he surveys 18 spots in the Bay, specifically looking for juvenile finfish, or babies, that can be tracked into the population and inform an assessment of the stock dynamics of the earliest age classes.
At the same time, a trawl survey in the Bay has been keeping records since 1979; a URI GSO survey that visits two stations dates back to 1952. Both trawl surveys track seasonal abundance of finfish and invertebrates with larger nets that sample deeper water (in contrast to Taylor’s and McNamee’s seine surveys, which sample shallower water closer to shore), collecting bigger, older individuals.
When talking about the case of winter flounder, the scientists see strong recruitment events, but then the young fail to survive the season, according to McNamee. It could be a dissolved oxygen problem made worse by warmer water. Or, lack of ice cover during warmer winters eliminates protection from predators during spawning.
It’s not so much a single cause, but rather multiple factors at play, he said: “It’s never an easy story. There’s this cascade of warmer temperatures, all the problems with that, new predators, increased numbers of existing predators — it’s compounding the problem. It’s not necessarily just an overfishing story, but also a climate change story. The decline is a symptom of all of these factors.”
Ultimately, the juvenile summer flounder exacerbate an already troubled winter flounder population, growing at such a fast pace in their first winter that they become big enough to prey on the winter flounder by the following season.
What was once a key fishery in this area, winter flounder populations have now collapsed completely in inshore areas. The consequences weave trouble throughout the fabric of Rhode Island life, from recreational fishing to the party and charter boat trade, the commercial catch, tackle and bait shops, and hotel, restaurant and other tourism-related industries.
People don’t realize it, McNamee said, but fishing represents a huge part of the state’s economy, contributing hundreds of millions of dollars. In that light, he added, Taylor’s weekly surveys of the estuaries coupled with regular DEM data collection in the Bay and coastal salt ponds lay the groundwork not only to understand what is taking place but also to help craft and shape fishery management policy.
The loss of an icon
The idea of a Rhode Island without winter flounder weighs heavily on 80-year-old George Allen, who has lived in Newport with his wife since retiring in 1987 from the Navy.
“There is a whole generation of young people now who have never caught a winter flounder,” said Allen, sitting back in his 24-foot Grady White at the Navy marina in Newport, the Claiborne Pell Newport Bridge stretching across the Bay’s waters in the distance. “Does it make a difference that there’s no winter flounder? It’s huge – they’re part of our culture.”
Allen, formerly commander of a ship out of the Newport base and twice a student at the War College, has been fishing nearly his entire life. He said he learned from his father, an avid fly fisherman, at about age five during his childhood in Syracuse, N.Y.
He is a member of the Rhode Island Saltwater Anglers Association, serving on the board of directors for about six years, including a stint as second vice president. Deeply involved in the state’s winter flounder management for more than two decades, he also chaired the winter flounder advisory panel to inform the Marine Fisheries Council on regulatory recommendations.
Allen saw firsthand the late 1970s heyday of winter flounder and then witnessed the precipitous drop of the early 1980s: “Winter flounder used to be the most important fish in Narragansett Bay. It wasn’t one season, but rather over a period of five years; the population crashed and essentially has been in a collapsed condition since. There’ve not been enough adults to overcome natural- and human-caused mortality.”
Echoing Taylor and McNamee, Allen pointed to multiple reasons and cited, from his perspective, liberal regulations that led to overfishing and warming water temperatures wrought by climate change. Overall, though, Allen said, the state was doing a reasonably good job to manage the fishery and ensure a spawning stock sufficient enough to overcome the challenges.
He championed the idea of spawning sanctuaries; a proposal he said was approved during his involvement with the advisory council. No fishing by any ground tending gear, no bottom draggers, no recreational fishing for anything.
Beyond the economic argument, bringing back the winter flounder means preserving a longstanding tradition of Rhody life, according to Allen. From his description, winter flounder sounds like an equal opportunity fish — relatively easy fish to catch from both shore and boat, by kid and adult alike, for people with or without waterfront access. It’s also one of the first fish of the spring; bluefish and fluke don’t arrive until May or June.
Allen said striped bass now face trouble and the limit has been dropped to one per year. A recent summer flounder stock assessment indicates fluke numbers are down, and a coast wide catch reduction will be necessary in 2016. Bluefish is not for eating, he added, grinning, unless you catch the little ones, smoke them and drink beer to wash them down.
Keepers of the Bay
Chris Brown’s life and livelihood have been tied to the health of Rhode Island’s fisheries since he built his first boat at age 20 in 1978. He has captained a boat every day since and today runs two bottom trawlers out of Point Judith, catching scup, squid, fluke and winter flounder, and operates the Narragansett-based Brown Family Seafood.
Brown is active in the fishing industry, serving as president of the Rhode Island Commercial Fishermen’s Association. He is the founder, executive director, and a participating member of the Rhode Island Fluke Conservation Cooperative, and a founding member of the Commercial Fisheries Research Trust Foundation.
“The handprint of man has taken its toll,” Brown said. “And, it’s not just fishing pressure. It’s the excesses of life. We haven’t been very good keepers of our Bay. It remains to be seen how we’re going to do going forward.”
Land development, sewage, parking lots and paved roadways, power plant discharge — Brown ticked off a list borne from our creature comforts. On the one hand, we make efforts at inshore habitat restoration. On the other, we create thermal pollution.
“Take a parking lot that’s 10 acres,” Brown said. “Today (a hot summer day), the tar is 130 or 140 degrees. It’s insanely hot. Then, the sky opens up and we get an inch or half an inch of rain in 20 minutes. The water super heats and runs into the Bay.”
Each solitary factor — even the medications we take that wind up in our waste flushed down the toilet — enacts a toll on Rhode Island’s fisheries, Brown noted.
By virtue of our dependence on the ocean, we will either thrive or fail based on our willingness to invest in and manage our natural resources.
Consequently, he said, the conversation about the absence or abundance of fish is a large and complicated one, with more components thrown into the mix every year. The question Brown raises is whether the state’s citizens and its Legislature are willing to invest in an industry that provides a healthy, accessible, protein rich food capable of feeding the population.
“We are the Ocean State by name,” Brown said. “And, the oceans are at the leading edge of climate change. By virtue of our dependence on the ocean, we will either thrive or fail based on our willingness to invest in and manage our natural resources.”
If he was in charge of the world, Brown said, he would tear down every house within three miles of the ocean and plant white pines: “But, we can’t do that. We make choices as a society that leads us to conclusions that may or may not be pleasant. But, we do make choices.”
Cues from early findings
With data from five years of research, Taylor said he could report that at this time the influx of juvenile summer flounder is not yet affecting the mortality rate of winter flounder, whether through competition or predation. He is still analyzing the blue crab data.
“We’re finding plenty of food in the winter flounder stomachs and their growth rates are relatively high in the tidal rivers, Taylor noted. “But, what is happening today may not be the case in 10 years.”
It remains to be seen how different species will adapt to climate change. Some, like the summer flounder, will expand their range. Others may either shrink in population or move to a more suitable habitat. Species such as winter flounder with distinct habitat needs may be unable to shift their populations northward with the warming of water temperatures.
Taylor said the repercussions often depend on reproductive strategies. For example, summer flounder do not rely on specific habitat structure for spawning. They spawn offshore and the buoyant eggs and larvae transfer to inshore locations by virtue of local ocean circulation patterns.
In contrast, winter flounder migrate to estuaries to spawn their eggs, which sink to the bottom where the males fertilize them. Blue crabs also spawn offshore, less dependent on specific habitat needs.
“Winter flounder intentionally spawn their eggs in discrete locations,” Taylor said. “They have distinct habitat needs for reproduction, and they return to natal areas to spawn.”
Together, Taylor’s upper estuary and the DEM bay and salt pond surveys document the patterns. Winter flounder spawn throughout the estuary while the summer flounder seek out the rivers for early stage habitat. It may be, Taylor said, that species with fewer distinct habitat needs are more capable of adapting to environmental changes than those with more specific needs, like the winter flounder.
Citing Taylor’s observations and research work, McNamee said Rhode Island could be undergoing a shift in species with changes in climate and the predator suite. If the state can put proper protections in place along with nutrient reduction in the upper Bay, it may be possible to secure a big enough cohort of juvenile winter flounder that will turn into a significant population and rekindle a more productive phase.
These are the critical details both the scientists and the fishermen said need to be studied and tracked to inform policy, allocate resources and best manage Rhode Island’s fisheries for generations to come. The catching, counting, sizing, estimating, and comparing growth rates across different habitats will indicate not only what is taking place, but also the location of significant nurseries that support the vital fisheries.
The role of research
Out in the water, Brown sees a role for the fishermen, particularly given the inconsistency of support.
“The science is only as dependable as the funding,” he said. “The industry needs to step up and help pay for research.”
Taylor said the work supported by RI NSF EPSCoR to understand foraging ecology and diet of organisms sheds light on their role in the Bay’s ecosystem. For example, he pointed to the lobster fishery and the substantial population decline in the Bay’s inshore areas. The population has shifted northward and, despite the Bay’s decline, is doing well offshore, in deeper water, and to the north.
Said McNamee: “I think that’s the key — adaptation. It’s happening right now, so it’s not a question of whether we need to change, but making sure we are able to change and allow the fishermen flexibility.
“Our groundfish fleet turned into a squid fleet as cod, winter flounder and yellowtail flounder declined. Our guys switched and were able to make a profit. Rhode Island is now one of the biggest harvesters of squid on the East Coast. The ability of fishermen to do that is an adaptation to what the environment is providing.”
McNamee also noted another potential project focused on winter flounder with URI’s Collie, a grant proposal that would identify remaining spawning habitats of the winter flounder in Narragansett Bay as well as looking at key factors affecting winter flounder survival. Based on the research from such projects, he said, the scientists could offer specific recommendations for good management changes that could help rebuild winter flounder stocks.
Meanwhile, DEM monitoring efforts continue to assess the stock in the Bay and can help determine whether a recovery is occurring, McNamee said: “It’s important to do the science and make sure that when we’re making policy decisions, we’re doing so in an informed manner.”
For Allen, we have no other options; the fishery is as much the Ocean State as the tides and the seasons. Every year in the late fall, when the water cools, the adult winter flounder swim in from offshore and move into the traditional spawning areas of the upper Bay.
As the water reaches its coldest temperature sometime after the New Year, in January or February, the winter flounder spawn. Then, in the spring, when the water warms to about 52 degrees, the adults move out of the Bay and head south and east of here, toward Nantucket.
The juveniles remain in the native spawning areas for about two years. Those that survive, join the adult population. It is a cycle that supports the fish, the ecosystem of the Bay and the Rhode Island way of life.
Said Allen: “Winter flounder is an historic fish that lives, spawns and dies in Narragansett Bay. We have a moral responsibility to try to restore the fishery.”
Story and photos by Amy Dunkle