COASTAL 



TIDINGS 



Around the Sea Grant Network: 



Aerators Minimize Marina Fish Kills 



In the thick of a hot Texas summer, 

 Sea Grant researchers discovered that 

 aerators could add enough oxygen to 

 marina basins to improve water quality 

 and decrease the potential for fish kills. 



"The aerators provided marina 

 operators with a simple solution to an 

 often smelly and expensive problem," 

 says Dewayne Hollin, Texas Sea Grant 

 marine business management specialist. 



Texas Sea Grant sponsored the 

 project in 1997 with the help of several 

 marinas in the Clear Lake/Galveston Bay 

 area. Marina personnel were briefed on 

 why fish kills occur and were trained to 

 use a dissolved oxygen (DO) meter. 

 Marina operators took several DO 

 readings per week at various times and 

 locations, using the aerators when DO 

 levels dropped or they saw fish on the 

 water's surface. 



While many marina operators 

 reported conditions conducive to fish 



kills, the aerators alleviated the problem 

 and no fish kills were reported. Fishing 

 also improved in the marina basin while 

 the aerators operated. 



"The use of aerators gives marinas 

 an 'insurance policy' and an effective 

 tool to deal with low DO levels in these 

 circulation-restricted areas of their 

 basins," Hollin says. "It is not the final 

 solution to the water quality problem, 

 but it is an excellent preventative 

 measure for fish kills and maintenance 

 of better water quality." 



Summertime conditions in Texas 

 this year favored oxygen depletion and 

 fish kills as temperatures soared and 

 winds diminished. As of mid- August, 

 marinas using the aeration devices 

 covered in the demonstration project 

 reported no fish kills, even in basins 

 with poor circulation. The weather had 

 caused several fish kills along the coast 

 at other marinas, Hollin says. E 



The Dirt on Sediment 



Water pollution is not just 

 toxins and trash. Sediment, tiny 

 particles of soil introduced into 

 water, is considered a pollutant if it: 



• remains suspended in water 

 and prevents light penetration, thus 

 reducing the photosynthesis of 

 bottom-dwelling plants; 



• clogs the gills of filter-feedin 

 animals such as oysters and clams; 



• buries fish eggs, plants and 

 bottom-dwelling animals; 



• stores pollutants 

 such as metals or 



nutrients and releases them into the 

 water when the sediments are stirred 

 up. 



Sediment can enter aquatic 

 habitats through runoff from 

 activities on land, including farming, 

 road construction and other develop- 

 ment. □ —D.D. 



Fishing Video 



Fishers and others who want to 

 learn more about bycatch reduction 

 devices can get a free, private lesson in 

 their homes. 



The video Commercial Fishing Gear 

 and Bycatch Reduction Devices highlights 

 various commercial gear used in our 

 coastal waters and the bycatch reduc- 

 tion devices associated with each type of 

 gear. 



"This video literally takes you 

 onboard with the fishers who work our 

 waters," says Bill Hitchcock, the video's 

 producer. "We went out with the fishers 

 and scientists and let them show, tell 

 and demonstrate on location. The intent 

 is to educate the public about the gear 

 and how it works." 



The video, which was funded by a 

 Fishery Resource Grant, includes 

 extensive underwater and aerial 

 videography. 



A limited number of the videos is 

 available. To get a copy, send $5 for 

 shipping and handling to Hitchcock 

 Broadcasting, P.O. Box 1 136, Newport, 

 NC 28570. 



Hitchcock plans to post the video 

 on his World Wide Web site soon. 

 Check it out at http://www. 

 ncsaltwater.com. □ — D.D. 



COASTWATCH 5 



