Winter flounder – sold in markets as flounder or lemon sole – in the Gulf of Maine went into serious decline in the 1980s, taking with it a major commercial and recreational fishery. Despite stringent fishing regulations, it’s estimated that it could take more than a decade for winter flounder to regain its once-robust place in New England coastal waters.
Now, researchers at the University of New Hampshire are setting the winter flounder (Pseudopleuronectes americanus) fishery on the fast track to recovery. New research indicates that winter flounder is a good candidate for stock enhancement, in which juvenile fish hatched from wild brood stock are raised in captivity and released into the wild.
“We’re studying winter flounder because we think they are an excellent local candidate for stock enhancement,” says Elizabeth Fairchild, a post-doctoral researcher in zoology at the University of New Hampshire who has worked with professor of zoology W. Huntting Howell on winter flounder stock enhancement for a decade. “We know how to raise them, and we’ve learned how to release them in a way that maximizes their survival.”
Raising the juvenile flounder is, in many ways, the easy part. The process begins in what Fairchild calls the “honeymoon tank” in UNH’s Coastal Marine Laboratory in New Castle. Commercial fishermen provide the wild brood stock; Fairchild and colleagues expertly gauge their readiness for releasing sperm and eggs then give the males and females their privacy: “We let the fish spawn on their own,” she says, noting that stock enhancement is most effective when the raised fish are as similar as possible to the wild fish they’ll ultimately breed with.
The work gets tricky – and makes for fascinating research -- when the juveniles reach the size of a potato chip and are ready to join their wild brethren in the shallow coastal waters where winter flounder naturally spawn. “Hatchery-bred fish are different than wild fish,” says Fairchild. They haven’t been exposed to predators, for instance; nor have they had to forage for food. “For stock enhancement to work, the raised fish must be as fit as the wild fish.” Much of her research turns on the challenge of making the cultured fish more wild.
In a study published in the “Journal of Fish Biology,” Fairchild examined several factors that she hypothesized made hatchery flounder more vulnerable to predators: the amount of time it took them to conceal themselves by changing skin color and pattern and burying themselves in sediment, the rate at which gulls preyed on white versus dark-colored flounder on sediment, and the fish’s behavioral reactions to predators. Her findings led her to test the effectiveness of acclimatization cages, marine halfway houses that give hatchery-raised fish a protected introduction to the wild blue sea.
Fairchild’s current studies build on explorations of optimal release strategies. Earlier this month, she released 1,000 one-year-old juveniles in the Hampton-Seabrook Estuary several months ahead of their usual summertime launch; she’s hoping that earlier release will mitigate the juvenile flounders’ vulnerability to green crabs, which are less prevalent in the spring than the summertime. Unlike in previous releases, when divers submerged crab-proof acclimatization cages of flounder into 20 feet of water prior to release, Fairchild and a team of researchers released the flounder directly into the Hampton River. “The cages were like snack cages for the green crabs,” says Fairchild, noting that the predators clustered around the cages hungrily awaiting the juveniles’ release. “It was like ringing the dinner bell.”
Fairchild tags the juveniles so she can track their survival over time. She’s also starting to explore pre-release conditioning for hatchery-raised fish, to see if they can be “trained” to have the same reactions to predators and predation as the wild flounder. And she’s starting to explore the hatchery-raised flounders’ impact on the wild population. “We want to be sure we’re not displacing or otherwise harming the wild fish,” she says.
“Targeted at the restoration of commercial and recreational fish and shellfish, enhancement is becoming a very important tool in NOAA’s fishery management tool box,” says Michael Rubino, aquaculture program manager for the National Oceanographic and Atmospheric Administration (NOAA).
Fairchild’s work is part of SCORE, the Science Consortium for Ocean Replenishment, which is a national research group dedicated to developing scientifically-based marine stock enhancement technology. SCORE is funded through NOAA and is part of UNH’s Atlantic Marine Aquaculture Center, a center for aquaculture research and technology development. For more information, go to www.amac.unh.edu/stock_enhancement/stock_about.html or http://zoology.unh.edu/faculty/howell/grad/efairchild/fairchild.html.
Beth Potier | EurekAlert!
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy