Walleye fishery threatened; Puerto Rico aquaculture, calling ALVIN on ocean bottom

October 24, 2002

ENVIRONMENTAL ESTROGENS MAY THREATEN MINNESOTA WALLEYE FISHERY
Some male fish that dwell in Minnesota waters are developing female characteristics, according to a study by Sea Grant researchers. Smaller sex organs, female proteins and sterility were some of the characteristics found among populations of walleye, fathead minnow and carp. The mix-up is caused when chemicals get into waterways and then interferes with the fishes' development and reproductive systems. The chemicals, known as environmental estrogens, act the same as natural estrogen, a female hormone. Trace amounts of the chemicals are enough to change the male fish. If too many fish lose their male traits, a drop in the fish population could lead to major ecological problems and impact the economically important recreational walleye fishing industry.

University of Minnesota Sea Grant researcher Deb Swackhamer and her team are studying two Minnesota waterways (Duluth-Superior Harbor and the Mississippi River near St. Paul) to learn more about the source of the environmental estrogens, as well as their effects on fish. Considered endocrine disruptors, the chemicals can reach the environment through sewage systems, paper mills, feed lots or industrial waste. Environmental estrogens can come from the natural hormone estrogen (found in animals, including humans), or from synthetic hormones like those found in birth control pills and industrial products such as detergents, packaging plastics and insecticides.

Many questions still remain. So far, researchers have been unable to pinpoint a specific chemical as the cause of the sexual changes. The team has found that some wild male walleye taken from waters near a sewage outflow of the Mississippi River had high levels of the female egg protein vitellogenin, decreased gonad size and no sperm. But laboratory goldfish exposed to the same water experienced much lesser effects. "Even these subtle effects may have an impact on wild fish," says Swackhamer, "where reproductive opportunities are limited and competition is severe." Further study of fish in Duluth, and eventually the entire Great Lakes, should give her team a better idea of what causes the fish to develop female characteristics.
CONTACT: Deb Swackhamer, Minnesota Sea Grant Researcher and University of Minnesota Professor, School of Public Health 612-626-0435, Email: dswack@umn.edu

PUERTO RICO AQUACULTURE PROJECTS AIM TO BE ENVIRONMENTALLY, ECONOMICALLY FRIENDLY
Off the Puerto Rican Island of Culebra, researchers are testing new aquaculture technology that could reduce the environmental impact of such fish farming operations. By using offshore aquaculture cages, Snapperfarm, Inc, and Dr. Daniel Benetti, Director of the Aquaculture Program at the Rosenstiel School of Marine and Atmospheric Science, at the University of Miami, hope to grow fish in offshore waters with minimal environmental impact. A group of Puerto Rico Sea Grant scientists will conduct a study to monitor the environmental impact of this innovative technology as well as its social impact.

Two cages were stocked in August, one with 12,000 cobia (the first time this has ever been done for this species) and the other with 4,000 mutton snapper. So far the fish are doing well-- they grew to three times their original size in just two weeks.

Currently, only five percent of Puerto Rico's seafood supply comes from aquaculture fisheries. Inshore aquaculture projects are subject to domestic and industrial runoff, and its own wastes can impact the local environment. Offshore, limited technology previously prevented deployments from being harmed by ocean elements. The new cage technology, developed by Ocean Spar, can resist the elements and is cleaner for the environment. In addition to monitoring the caged fish and their development, future studies will include environmental monitoring and determining the cage's social impact on the area. If successful, the aquaculture project should pave the way for clean, economical fisheries operations in the Caribbean.
CONTACT: Alexis Cabarcas, Puerto Rico Sea Grant, University of Puerto Rico Marine Sciences Department, Email: aacabarcasn@hotmail.com; 787-832-4040 ext. 5491
Dallas Alston, Puerto Rico Sea Grant, University of Puerto Rico Marine Sciences Department, Email: d_alston@rumac.uprm.edu; 787-832-4040 ext. 5491.

Sea Grant Web Spotlight: "Extreme 2002: Mission to the Abyss" -www.ocean.udel.edu/extreme2002/
Beginning October 21 nearly 42,000 middle and high school students in 525 schools in 49 states and five foreign countries will begin a virtual journey to the depths of the Pacific Ocean through Delaware Sea Grant's "Mission to the Abyss" education program. Students and teachers will follow the action as University of Delaware scientist Craig Cary explores hydrothermal vents in the Pacific Ocean. Cary and his team will study the vents and the creatures that inhabit them, including the Pompeii worm, the "hottest" animals on the planet, as it can withstand temperatures of up to 176 degrees F. Scientists will use the submersible ALVIN and research vessel ATLANTIS to perform their work. As part of the National Science Foundation research, Delaware Sea Grant is helping to sponsor classroom materials that will allow students and teachers to participate in the action. While the research team explores, students can tune in to an interactive website that will be updated daily throughout the 24-day voyage. More than 450 schools from across the U.S. and several other countries will use the provided resource guides, curricula and video about the deep sea to guide them through Cary's expedition. A select group of 48 classrooms will have the opportunity to participate in one of four live conference calls, over the next month, with the scientists as they conduct research in ALVIN on the seafloor.
CONTACT: Tracey Bryant, University of Delaware Sea Grant, Marine Public Education Office, 302-831-8185, Email: tbryant@udel.edu; Craig Cary, Delaware Sea Grant Researcher, Associate Professor of Marine Biology-Biochemistry, University of Delaware, Email: caryc@udel.edu

Sea Grant Calendar Spotlight: 2nd International Seafood Byproduct Conference, Nov. 10-13, 2002, Anchorage, Alaska
The Alaska seafood industry harvests over 60% of the food fish caught in United States waters. The amount of fish processing wastes generated from human food processing wastes generates in excess of 1.1 million metric tons annually. Since the first such gathering in 1990 a wide range of new advances in medical sciences, and the development of new secondary products for human, animal, and industrial uses from seafood processing byproducts have been developed. This conference looks at issues of fish byproduct utilization and environmentally sound fish waste disposal.
Contact: Donald Kramer, Alaska Sea Grant Marine Advisory Program, 907-274-9691 ext. 5, Email: afdek@uaa.alaska.edu ; Website: www.uaf.edu/seagrant/Conferences/byproduct.html
-end-
Sea Grant is a nationwide network of 30 university-based programs that works with coastal communities and is supported by NOAA. Sea Grant research and outreach programs promote better understanding, conservation, and use of America's coastal resources. For more information about Sea Grant visit the Sea Grant Media Center Website at: www.seagrantnews.org , which includes on-line keyword searchable database of academic experts in over 30 topical areas.

National Sea Grant College Program

Related Fish Articles from Brightsurf:

Fish banks
Society will require more food in the coming years to feed a growing population, and seafood will likely make up a significant portion of it.

More than 'just a fish' story
For recreational fishing enthusiasts, the thrill of snagging their next catch comes with discovering what's hooked on the end of the line.

Fish evolution in action: Land fish forced to adapt after leap out of water
Many blennies - a remarkable family of fishes - evolved from an aquatic 'jack of all trades' to a 'master of one' upon the invasion of land, a new study led by UNSW scientists has shown.

How fish got onto land, and stayed there
Research on blennies, a family of fish that have repeatedly left the sea for land, suggests that being a 'jack of all trades' allows species to make the dramatic transition onto land but adapting into a 'master of one' allows them to stay there.

Fish feed foresight
As the world increasingly turns to aqua farming to feed its growing population, there's no better time than now to design an aquaculture system that is sustainable and efficient.

Robo-turtles in fish farms reduce fish stress
Robotic turtles used for salmon farm surveillance could help prevent fish escapes.

Heatwaves risky for fish
A world-first study using sophisticated genetic analysis techniques have found that some fish are better than others at coping with heatwaves.

A new use for museum fish specimens
This paper suggests using museum specimens to estimate the length-weight relationships of fish that are hard to find alive in their natural environment.

Reef fish caring for their young are taken advantage of by other fish
Among birds, the practice of laying eggs in other birds' nests is surprisingly common.

Anemones are friends to fish
Any port in a storm, any anemone for a small fish trying to avoid being a predator's dinner.

Read More: Fish News and Fish Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.