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Bits & Pieces
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Bits & Pieces (cont.)
CONSERVATION SCIENCE -- DO LANDING NETS HARM FISH?
In-Fisherman has long recommended the use of thick rubber or knotless-mesh nets to land fish, rather than nets with knotted thin nylon or rayon open meshes that more readily scrape away fish slime and injure fish.
Researchers from the University of Illinois and Canada's Queen's University* recently compared the injuries and mortalities of bluegills caught by anglers and landed with four types of nets--rubber, knotless nylon, fine-knotted nylon, and course-knotted nylon nets--to fish caught and held out of water an equal time but not netted. Fish were caught in an Ontario lake when surface temperatures were 79F. Anglers used circle hooks and only fish hooked in the upper jaw or lip were studied. Dorsal spine clips identified the landing method used for each fish.
No hand-landed fish died during a 7-day holding period, but mortality rates ranged from 4 to 14 percent for fish landed with nets. Mortalities occurred between 2 and 5 days after capture.
Retention in a landing net for 30 seconds caused more fin and skin damage than in hand-landed fish. Dying fish exhibited impaired swimming ability, severe tail fin erosion, and expanding fungal lesions near their tails, starting approximately 24 hours prior to death.
Bluegills landed without nets had fewer obvious injuries. Knotted-mesh nets caused more fin and skin damage than knotless or rubber-mesh nets. Knotless-mesh nets and hand-landing caused the fewest tears in tail fins.
Larger fish are likely to thrash more and sustain greater injuries in landing nets. The authors recommend further study using larger fish, but we suggest that the evidence is already adequate to guide most anglers. If you plan to release healthy fish, hand-land your catch whenever possible, minimizing contact with fins and body slime, and use a thick-rubber or knotless-small-mesh net if net landing is necessary.
When anglers swing-land bass and other fish and let them hit the floor of their boats or the ground, the contact is likely more harmful than using the worst net type. Post-release mortality will be higher even if fish appear healthy at the time of release.
Ralph Manns
IN THE NEWS -- MUSKIE SYMPOSIUM PLANNED
In 1984, Muskies, Inc. co-sponsored the International Symposium on Muskellunge in North America, held in LaCrosse, Wisconsin. That conference was the source for the book, Managing Muskies--A Treatise on the Biology and Propagation of Muskellunge in North America, published by the American Fisheries Society in 1986.
Many of the techniques described in that book have furthered the study and management of muskies. Meanwhile, much has been learned in the ensuing 18 years, encouraging fishery scientists in the United States and Canada to plan another symposium.
Hosted by the Hoosier Muskie Hunters Chapter of Muskies, Inc., "Building For the Future" is scheduled for September 17-19, 2004, in Indianapolis. It will provide a forum for biologists, fishing industry leaders, and muskie enthusiasts to share technical information and fishing insights in an effort to promote and guide muskie management and conservation over the next decades. For further information, contact Jim Bagnoli, 317-844-0299, jimbagnoli@aol.com.
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