Saving Seafood

Study finds some sport fish are caught repeatedly – which could throw off population estimates

November 18, 2020 — A new study reports that, for several species of oceanic sport fish, individual fish that are caught, released and recaught are more likely to be caught again than scientists anticipated. The findings raise some interesting questions for policy makers tasked with preserving sustainable fisheries.

The study makes use of data from tagging programs, in which researchers tag  and release them into the wild. When those fish are caught, and the tag information is returned to the researchers, it can give scientists information that informs fishery policies.

“Fisheries researchers who work in tagging programs have long noticed that certain fish seem to get caught repeatedly, and we set out to determine the implications of this phenomenon,” says Jeff Buckel, co-author of the study and a professor of applied ecology at North Carolina State University.

To that end, researchers examined decades’ worth of Atlantic coast tagging datasets on four : black sea bass (Centropristis striata), gray triggerfish (Balistes capriscus), red grouper (Epinephelus morio), and Warsaw grouper (Hyporthodus nigritus). Using a computational model, the researchers determined that—for the black sea bass and both types of grouper—survival was significantly higher after the second, third, and fourth release as compared to the first release.

“Think of it this way,” says Brendan Runde, first author of the study and a Ph.D. student at NC State. “Let’s say you tagged 1,000 fish and recaptured 100 of them for a first time. After re-releasing those 100 fish, you would only expect to recapture 10 of them a second time. But that’s not what we’re seeing. We’re seeing much higher numbers of fish getting recaptured after the second time.

Read the full story at PHYS.org

What can researchers learn by eavesdropping on fish?

July 17, 2019 — Oyster reef restoration provides important benefits, such as stabilizing shorelines, filtering water, and providing habitat for estuarine fish. However, quantifying fish use of restored oyster reefs can be difficult. Traditional sampling methods do not record all fish species and are often conducted only intermittently. As a result, fish diversity and resulting conservation and restoration decisions often rely on incomplete “snapshots” in time.

Luckily, many  and invertebrates make sounds to communicate, navigate, and feed, providing the opportunity to “listen in” to learn about what species are present, when they are present, and what behaviors they exhibit on restored reefs.

Passive acoustic recording offers a non-destructive method to gather data on species of ecological and economic importance that traditional sampling misses. This information is vital for understanding fish behavior, including when and where certain species are spawning—a key to conservation and for establishing targets for habitat restoration.

Researchers at NC State University monitored oyster cultch reefs for two years following restoration, using a combination of traditional net and trap fish sampling and underwater acoustic surveys. In North Carolina, oyster cultch reefs are constructed primarily to provide oysters for harvest, and the NC State team wanted to determine their value as fish habitat, which is currently unknown.

Read the full story at PHYS.org

N.C. Study: Warmer Water Linked to Higher Proportion of Male Flounder

April 30, 2019 — If southern flounder live in warmer water during a critical window of early development, a higher percentage become male – more than 90 percent in some cases – research from North Carolina State University found. Having a high proportion of adult males over the long term could threaten both wild populations and the valuable commercial fishing industry, which depends on larger female flounder.

Field research and lab experiments showed that a four-degree Celsius difference in average water temperature during juvenile development shifted the male-female ratio from about 50-50 to as much as 94-6, says Jamie Honeycutt, an NC State postdoctoral researcher and lead author of an article about the research in Scientific Reports. That difference is within the range of expected ocean temperature increases under climate change models.

Environmental factors such as water temperature influence sex determination in southern flounder, as well as in other fish and reptiles, Honeycutt explains. Flounder stick to shallow waters that serve as nurseries until after they become male or a female, hanging around estuaries until reaching maturity before returning to the ocean to spawn at about age 2.

“We think that southern flounder have a genetic sex-determining system similar to humans, who have two X chromosomes for a female and an X and a Y for a male. In flounder, if an individual is a genetic male, it is destined to be male,” Honeycutt says. “However, if a genetic female is exposed to temperature extremes, then it can develop as a functioning male.”

Read the full story at North Carolina State University

Aquaculture does little to conserve wild fisheries, according to study

February 11, 2019 — New research finds that aquaculture, or fish farming, does not help conserve wild fisheries.

“Our fundamental question with this study was: does  conserve wild fish?” says Stefano Longo, an associate professor of sociology at North Carolina State University and first author of a paper on the work. “The answer is: not really.”

To determine the impact of  efforts on traditional, or “capture” fisheries, Longo and his collaborators looked at data from the World Bank and the Food and Agriculture Organization of the United Nations, from 1970 to 2014. Specifically, the researchers evaluated data that shed light on changes in aquaculture and traditional fisheries, such as aquaculture production numbers and the number of fish harvested by wild fisheries.

“We found that aquaculture has expanded production, but does not appear to be advancing fishery conservation,” Longo says. “In fact, aquaculture may contribute to greater demand for seafood as a result of the social processes that shape production and consumption.

“In other words, aquaculture is not taking the place of traditional fishing efforts, or even necessarily reducing them,” Longo says.

Read the full story at PHYS.org

Future offshore drilling could wreak havoc on deep sea ecosystems

April 27, 2018 —   In early January, U.S. Secretary of the Interior Ryan Zinke announced that more than 90 percent of the outer continental shelf in federal offshore areas is now available for offshore drilling exploration and development. In the official release, Zinke noted that the plan for this new exploration would strike a balance between protecting the coasts and achieving “energy dominance” in America. But marine scientists say that scale is really tipped. Opening up more areas to drilling, they say, means far more disruption for marine ecosystems and an even greater increased risk for oil spills.

Offshore drilling is way more than sucking up oil through pipes.

Mohammed Gabr, professor of civil engineering at North Carolina State University, says that offshore drilling requires three steps: investigating the site, boring exploratory wells, and laying the pipe, and each one can affect the ecosystems that surround the area.

To find potential oil deposits, engineers can use seismic techniques like generating sound waves, Gabr says. The waves bounce along the sea bed and reflect and identify the kind of stone underneath. If sound waves indicate the possibility of oil beneath the ocean bottom, the oil company then builds an exploratory well. This initial drilling is not necessarily to look for oil Gabr says, but to understand the structure and composition of the soil sediments. He likens the process to sticking a straw into a piece of cake: when removed, the straw will contain every layer of that cake.

Once they understand the soil’s makeup, Gabr says the company starts the search for oil. With the hole in place, workers pump mud in to prevent it from caving in. Then they place a casing in to house the pipe that will pull the oil out. As the hole gets closer to hitting oil, workers use cement to secure the casing. This hole exists under pressure, which must be controlled to make sure that the oil doesn’t come rushing up too quickly, he says. An oil spill can happen at any point along the oil production process, including drilling and the set up that goes along with it.

Read the full story at Popular Science

 

Making a better “hot dog of the sea”

April 24, 2018 — When people think of Alaska seafood, salmon and halibut come to mind. But the state also produces a lesser-known fish product sought after all around the world: surimi, the base for imitation crab.

Now the guy who helped establish surimi in America — more than 30 years ago — is on a mission to improve how it’s made.

Tyre Lanier is a food scientist at at North Carolina State University, where he’s been since the 1970s. He has a background in the science of hot dogs.

So, working on seafood initially was a bit of a stretch for him.

“I started off trying to make hot dogs out of fish believe it or not,” Lanier said. “Then I heard about surimi.”

Or as Lanier refers to it, “the hot dog of sea.”

For thousands of years, surimi seafood has been part of Japanese cuisine. Sometimes referred to as kamaboko, it comes in a variety of flavors and shapes.

Read the full story at Alaska Public Radio

 

Male Fish in North Carolina Rivers Found to Have Female Parts

August 30, 2015 –Male black bass and some sunfish in North Carolina rivers and streams are developing eggs in their testes, which can cause reproductive problems and potentially threaten populations, according to unpublished research.

The research adds to growing evidence that exposure to estrogen compounds is feminizing male fish across the U.S. and suggests that North Carolina fish might be particularly at risk.

“It’s a very interesting study and certainly adds to our understanding of what’s potentially going on in our rivers and with the intersex fish,” said Vicki Blazer, a U.S. Geological Survey fish biologist who was not involved in the study.

North Carolina State University researchers tested 20 streams and rivers throughout North Carolina during the 2012 spawning season for contaminants known to disrupt endocrine systems, such as industrial chemicals and pesticides. They also tested black bass – largemouth and smallmouth bass – and sunfish in the rivers for “intersex” characteristics, looking for eggs in the testes of males.

Read the full story from Truthout