OREGON STATE UNIVERSITY

Saving Nemo: Researchers Hope to Reduce Mortality in Marine Ornamental Fish

03/29/2007

CORVALLIS, Ore. – Oregon State University researchers are working to help more aquarium fish survive the often hazardous journey from where they’re collected until they arrive in pet shops and home aquaria.

The result may not only be healthier fish and happier pet owners, but significant environmental and economic benefits.

Jerry Heidel, director of OSU’s Veterinary Diagnostic Laboratory, and Tim Miller-Morgan, an OSU veterinarian with the Oregon Sea Grant Extension, have partnered with Hollywood Aquariums in Lake Oswego and Sea Dwelling Creatures, Inc., a Los Angeles-based fish importer and distributor, in the project funded by Oregon Sea Grant.

The collaboration allows the researchers to examine causes of mortality at all stages of the supply chain, from the fish capture on tropical coral reefs to purchase by hobbyists. SDC, Inc. provides fish to retailers and aquaria throughout the United States and internationally, including Monterey Bay Aquarium, SeaWorld and the National Aquarium in Baltimore.

The marine fish aquarium hobby is growing by approximately 1 percent a year, Miller-Morgan says, faster than any other pet ownership sector. And nearly 99 percent of the fish are caught in the wild, not raised in captivity. Typical mortality rates for the more commonly shipped species range from about 5 percent to 12 percent, according to previous studies conducted by Heidel and Miller-Morgan.

The OSU researchers conducted broad mortality surveys of all fish species imported by SDC, Inc., and in their newest study will focus on a few key species, including the popular green chromis and the false percula clownfish, of “Finding Nemo” fame. The most expensive fish they will study is the Imperator angelfish, which can retail for $200 or more.

Preliminary observations suggest that water quality and handling, rather than parasitic or bacterial infections, are the biggest problems faced by marine fish shipped to the U.S. for the pet trade.

“These animals are hit with multiple stressors throughout the chain of custody, and water quality may be the thing that pushes them over the edge,” said Miller-Morgan.

In particular, Heidel and Miller-Morgan have noted that water in which marine ornamental fish have been shipped typically has low pH – the water is more acidic than normal – and high ammonia levels, both of which can cause stress to the animals.

They also suspect that high carbon dioxide in the water is responsible for some fish deaths. In high concentrations, CO2 can cause acidosis – a condition that limits the amount of oxygen the fish can carry in their blood.

Miller-Morgan traveled with partners from SDC, Inc. to Indonesia in 2005, where they examined exporters’ animal husbandry practices and storage and shipping facilities. He noted that once the fish are collected from a reef, they commonly sit on a boat in water-filled plastic bags for as long as three weeks. The longer a fish is held on the boat, he theorizes, the more likely it is to be stressed if it is eventually shipped.

The first step of the new project is to collect baseline data on fishes’ blood chemistry, comparing fish shipped from the South Pacific to SDC Inc.’s Los Angeles facility with cinnamon clownfish at OSU’s Hatfield Marine Science Center in Newport that will serve as control fish. Carl Schreck of OSU’s Department of Fisheries and Wildlife, an expert in stress response in fishes, will assist with the blood work.

The investigators will also measure water quality and analyze stress during shipping. They expect to recommend measures that exporters can take to reduce shipping stress, most likely through improving water quality and changing fish handling prior to shipping.

Heidel and Miller-Morgan will share the study’s results as widely as possible to the industry.

“We’d like to focus on ‘train the trainer’ efforts by which we can achieve an exponential dissemination of this information,” said Heidel.

The benefits of their findings should be both economic and environmental. Shipping mortality significantly decreases the profit margin of all involved in the process.

“In general, ornamental fish importers’ two biggest business costs are labor, which is fairly fixed, and fish mortalities,” Miller-Morgan pointed out.

In addition, Heidel said “if fewer fish die in transit, the industry won’t have to go back to the reef quite as often to collect more,” thereby lessening the industry’s impact on tropical reef systems.

“Our goal with all of this work is conservation through quality health management,” said Miller-Morgan.