In 2003, haddock on Georges Bank experienced the largest baby boom ever documented for the stock, with an estimated 800 million new young fish entering the population. With typical annual averages of 50 to 100 million new fish in the last few decades, fisheries biologists have been puzzled by the huge increase and its ramifications for stock management. They have been looking for answers and may have found one - healthy adults.
In a study to be published in the June issue of the Canadian Journal of Fisheries and Aquatic Sciences, Dr. Kevin Friedland and colleagues from NOAA’s National Marine Fisheries Service and the University of Massachusetts suggest that the successful 2003 recruitment year is related to the fall phytoplankton bloom the year before spawning, and to the condition of the adult haddock. Phytoplankton, microscopic marine plants, form the basis of the ocean food web, and are the main source of food for many fish and other animals in the ocean. The fall 2002 bloom was significant, providing a larger than usual source of food for the ecosystem.
“Simply put, having more food to eat gives adult haddock a chance to get into better physical shape to reproduce healthy offspring with a higher chance of survival,” says Friedland, a research scientist at NOAA Fisheries’ Northeast Fisheries Science Center. “We reviewed the commonly applied factors that control recruitment, and found that the fall phytoplankton bloom the year before seems to link parental condition with a good recruitment. We call this new approach the parental condition hypothesis.”
The researchers analyzed various factors that control recruitment, from egg and larval retention, feeding conditions for larvae, size of juveniles in the fall and their estimated hatch dates, prey and time of spawning to circulation patterns and the timing and size of spring and fall phytoplankton blooms. They found that the fall phytoplankton bloom the year prior to spawning and its affect on the condition of adults to be the best supported hypothesis.
Their study suggests that the condition of the adult haddock not only leads to an improved chance to reproduce, but that the adults will produce more eggs of higher quality with higher fertilization rates. Those factors in turn will produce more abundant, larger and potentially better-conditioned offspring with a higher probability of survival to adulthood, which can significantly affect haddock stocks.
Georges Bank haddock have been heavily fished by domestic and foreign fleets over the past 50 years, with shifting patterns of fishery yieldsthat are largely dependent on successful recruitment events. The paradigm that processes affecting mortality during the early life stages determine recruitment has guided research on Georges Bank for decades, with many recent studies suggesting that the formation of each incoming year class of new fish is driven by differing sets of external environmental factors ranging from climate change patterns like the North Atlantic Oscillation to timing of spawning and the feeding environment.
Friedland and colleagues suggest a new paradigm, that the condition of parents affects egg size and fertilization success through the most difficult growth-mortality period early in the haddock life cycle. The bottom line: the number and quality of offspring is more important than the external environmental factors that occur after spawning.
“We need to be able to explain extreme recruitment events for species like haddock, where recruitment is typified by highly unusual circumstances like that in 2003,” Friedland says. “Factors that may be responsible for these large recruitments will help dictate how the haddock resource on Georges Bank is utilized and conserved. This new hypothesis needs to be tested, but it seems to be the only one that explains the 2003 record year class. If it proves true, the implications could be significant.”
NOAA Fisheries Service is dedicated to protecting and preserving our nation's living marine resources and their habitat through scientific research, management and enforcement. NOAA Fisheries Service provides effective stewardship of these resources for the benefit of the nation, supporting coastal communities that depend upon them, and helping to provide safe and healthy seafood to consumers and recreational opportunities for the American public.
The National Oceanic and Atmospheric Administration, an agency of the U.S. Commerce Department, is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects.
Shelley Dawicki | EurekAlert!
Scientists team up on study to save endangered African penguins
16.11.2017 | Florida Atlantic University
Climate change: Urban trees are growing faster worldwide
13.11.2017 | Technische Universität München
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses