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Topics Of Interest:

 

FDA Approval of New Otolith Marking System using Oxytetracycline

Experimental Treatment Used on Lake Trout Eggs

Aquaculture References from the World Wide Web

Blowers, Air Pumps or Compressors

Minnesota Fish Producers Report Losses to Cormorants and Other Birds

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FDA Approval of New Otolith Marking System
Submitted By:  Alpharma Animal Health

We are pleased to announce that on December 24, 2003, Alpharma Animal Health was granted FDA approval to market OxyMarine, a new soluble oxytetracycline product cleared for use in skeletal marking of finfish.  OxyMarine is the first and only soluble oxytetracycline product approved for such purposes.

Fish marking with Oxytetracycline (OTC) can now
be conducted without an INAD permit

OxyMarine is an entirely new aquaculture drug claim, and is the direct result of cooperative efforts between Alpharma, U.S. Geological Survey, U.S. Fish and Wildlife Service, International Association of Fish and Wildlife Agencies, National Coordinator for Aquiculture New Animal Drug Applications, National Research Support Project Number Seven, and the FDA.

This is a very exciting event for all of us who have been working diligently to bring new products to the U.S. aquaculture industry.  Fisheries managers with a need to mark fish should contact Mr. George Kohan for more in-depth information about OxyMarine.  You may contact George at:  Email: george.kohan@alpharma.com, Phone: 218-829-2858

 

Experimental Treatment Used on Lake Trout Eggs at Iron River National Fish Hatchery
By:  Steve Redman, U.S. Fish & Wildlife Service, Iron River NFH

 

Agencies and private aquaculturists need a safe,
effective therapeutant for lake trout culture that is environmentally friendly

Yearly, millions of lake trout eggs are collected and incubated at the Iron River National Fish Hatchery (NFH).  During the incubation process, fish eggs are exposed to fungi. Fungi are naturally occurring organisms that often attack dead fish eggs and can spread to adjacent live eggs, killing them. Formalin is currently used to control mortality associated with fungus on lake trout eggs; however, there are increasing concerns over user safety and environmental discharge following formalin use at hatcheries.

In a collaborative effort between the Iron River NFH and the U.S. Geological Surveys Upper Midwest Environmental Sciences Center, a study was generated to compare the effectiveness of formalin and hydrogen peroxide to control mortalities associated with fungal infections on lake trout eggs. Little information is available on the efficacy of hydrogen peroxide to control fungal infections on lake trout eggs.

 

Hatchery personnel would prefer to use hydrogen peroxide in their hatchery production facilities; however, they have concerns regarding its efficiency to control fungal infections under actual hatchery production conditions. A second concern of hatchery personnel is if there exists an egg developmental stage that is sensitive to hydrogen peroxide treatments. Results of this study will provide scientific data that will assist fish culturists in determining if hydrogen peroxide should be the therapeutant of choice in treating lake trout eggs. Recommendations will be formulated regarding hydrogen peroxide use in lake trout culture and identify if any sensitive egg development stages exist.

 

Aquaculture References from the World Wide Web

The Internet is an excellent source of information for aquaculture and related issues. 
The links listed below are for informational purposes and by no means represents all the sources available on the WWW

 

Blowers, Air Pumps or Compressors?
By: Aquatic Eco-Systems

Blowers are designed to provide large volumes of air at low pressure (less than 4 psi). They are commonly used in conjunction with air diffusers and airlifts. This combination adds oxygen and removes carbon dioxide with low power consumption.  Typical applications include re-circulating fish tank and aquarium systems, bait fish and lobster holding facilities, and shallow pond aeration.  Regenerative blowers are preferred in the aquaculture industry because they are the most reliable and economical in this pressure range.

Fractional horsepower Sweetwater Linear Piston Air Pumps fill the gap between aquarium air pumps and blowers.  These units supply up to 5 cfm at depths to 8 feet. Air pumps provide long service life, very quiet operation and very low energy use.  They are a perfect fit for bait shop tanks, classrooms and laboratories.

 

Sweetwater oil-less rotary vane and piston compressors are used in applications where water depths are greater, such as with lake aeration, algae culture and lobster pounds.  These compressors allow airlines to be run thousands of feet when electricity is not near the water.  A compressor as little as 3/4 hp can be used to aerate and de-stratify a 10-acre lake. 

>>  Compressors used for aquaculture should always be "oil-less."   <<

 

 

System Sizing

To size a system, first determine the pressure required.  Enough pressure is needed to overcome the water pressure at the diffuser's depth, the piping friction loss, and the diffuser's resistance to airflow.  Example: For a water depth of 36", a low restriction piping system of 4" of water and a low-resistance air diffuser of 10" of water (just prior to cleaning), will require an air pressure of at least 50" of water (36" + 4" + 10"). This is equal to about 2 psi.

The next consideration is the volume of air needed to accomplish the job.  If there is only one fish room, one linear air pump compressor with an additional one for emergency back up may be sufficient. In a larger facility, two or more primary blowers or compressors and one emergency back up may be required.  When using low-pressure air, it's important that the air piping system and diffusers offer little resistance to air flow (request our bulletin "Air Distribution Systems for Sweetwater Blowers").

Performance charts and tables are available for all of our blowers and compressors. Selecting the right system for your application is accomplished simply by comparing your pressure and airflow requirements with manufacturer's performance charts. If you need help, call an Aquatic Eco-Systems technician at 407-886-3939.

 

Back-Up Blower Setup

Anyone who has worked with fish for a while knows that, if you dont plan ahead, you wont be in business for long. When it comes to life support, a back-up blower could save your business.

The most crucial of life support requirements is maintaining an adequate oxygen level because it can be used up so quickly.

We always recommend having a second blower attached to the main air supply line, wired to come on if the primary blower fails for any reason. Both blowers must have check valves on them. A pressure switch is located between the primary blower and its check valve. When this pressure switch senses a loss of air pressure, it closes, causing an electric relay to start the backup blower (see diagram). The check valves keep air from being lost through the non-running unit. Check valves must be able to tolerate high temperatures.
 
Be sure the stand-by unit is on a different electrical circuit breaker.

 

 

Buying a Blower and Operating Tips

Compare blowers, not by horsepower ratings, but by watts. That's what you pay for!

Electricity cost should be a major concern when motors operate continuously. Don't get fooled by low horsepower ratings on electric equipment. Always compare work being done to power consumed in watts.

For instance, you may have seen air blowers and water pumps advertised with lower horsepower ratings than other equipment of the same size. The gimmick is to use an undersized, low-cost, high service factor motor to imply superior performance. But this smaller motor has to work harder to do the job. The small motor may get through a temporary overload condition, but is not reliable for continuous duty. It will actually use more electricity, operate at a higher temperature and have a shorter life than a larger 1.0 service factor motor doing the same work.

Sweetwater blowers run cooler because they use the correct 1.0 service factor motor for the continuous duty work being done.

Here are some blower operating tips:

• Bleed off as much excess air as you can while you still have as much air as you need. The blower will run cooler and use less power.
• If the ambient air is so dirty (feed dust, bird feathers, etc.) that the air filter requires frequent cleaning, pull a sock over the filter. Then change your socks frequently!
• In critical animal life support applications, after three years of continuous operation, purchase a new blower and have the original blower's motor bearings replaced. Operate the original unit for a month to be sure the work was done correctly, then switch back to the new blower, keeping the original one as a backup.

You can't measure watts without a watt meter - BUT you can estimate watt consumption with these formulas:

Single phase watts = volts x amps x power factor.

Three phase watts = volts x amps x 1.73 x power factor.

The power factor of a fully-loaded electric motor is about 0.9, but this goes down significantly as the load on the motor is reduced.

 

Minnesota Fish Producers Report Losses to Cormorants and Other Birds
By:  University of Minnesota, Sea Grant

The University of Minnesota Sea Grant Program recently funded researchers to look into conflicts over resource use by aquaculturalists and fish-eating birds in Minnesota. Linda Wires and Francie Cuthbert with the University of Minnesota surveyed 54 commercial fish producers with outdoor facilities to correlate bird-related fish losses with the distribution and abundance of double-crested cormorants, American white pelicans, and great blue herons.  The major results of Wires and Cuthberts report are available in a fact sheet, Minnesota Fish Producers Report on Losses to Birds. Highlights include:

• Fish losses to double-crested cormorants were generally considered more severe than losses to American white pelicans and great blue herons.

• Fish losses to great blue herons occurred most frequently but were generally not considered severe.

• 87 percent of fish producers experienced losses to fish-eating birds.

• 41 percent of fish producers defined their losses as severe.

• Concentrations of fish-eating birds were greatest at facilities during the birds migratory periods.

Mike Lint, co-president of the Minnesota Fish and Bait Farmers and fish farming business owner in West Central Minnesota, estimates that cormorants and pelicans can consume over $100,000 worth of marketable fish from his ponds in a year.  Populations of cormorants and pelicans have rebounded over the past 30 years in response to policy and improved environmental conditions. In Minnesota, there are an estimated 8,000-10,000 breeding pairs of each species. Wires and Cuthbert are poised to conduct a statewide census of Minnesotas breeding cormorants and pelicans during the 2004 nesting season.

Cormorants arent the only fish-eating birds that visit fish production ponds but they can be a fish producers biggest problem bird, said Wires. People seem to hold very polarized opinions about how cormorants should be handled. On one level, its miraculous that we have cormorants in the state at all given that environmental contaminants and persecution greatly reduced populations by the 1950s. From another perspective, the growing number of cormorants and pelicans arent making many friends among fish producers and anglers.

To order a free copy of the Minnesota Fish Producers Report on Losses to Birds fact sheet, contact Minnesota Sea Grant at seagr@d.umn.edu or call (218) 726-6191.  Minnesota Sea Grant is part of a network of 30 Sea Grant College Programs spanning coastal states throughout the United States and Puerto Rico.

 

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Product and company names mentioned in this publication are for informational purposes only. It does not imply endorsement by the MTAN or the U.S. Government.

 

 

 

Last updated: August 28, 2009

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