June 25, 2013
By Dr. Rob Neumann
Length and creel limits are important tools for regulating harvest of sportfish populations, and implementation of harvest regulations is based on accurate harvest rates. In cases where fish release is frequent and post-release mortality may be substantial, catch-and-release mortality should also be accounted for in addition to harvest. This prompted Minnesota DNR researchers to evaluate winter catch-and-release hooking mortality of saugers below Lock and Dam 3 of the Mississippi River, a popular winter sportfishery.*
Saugers were caught on rod and reel by volunteers and DNR biologists using jigs baited with minnows and plastic grubs over two consecutive winters. Anglers fished vertically near the edge of or within deep scour holes, and baits were set at depths within 3 feet of the bottom. Water temperature ranged from about 33°F to 40°F and air temperature ranged from about 19°F to 46°F. Caught fish were transported to vertical net pens for observation of mortality for a 72-hour period.
Sauger hooking mortality averaged 26.2 and 26.7 percent for the two consecutive winters. Depths of catches ranged from 20 to 76 feet. Hooking mortality increased with water depth but was not related fish length. Saugers caught from shallow water were larger than those caught from deep water. Anglers caught an estimated 28,923 and 35,910 saugers during the two winters, and harvested 9,114 and 8,728 fish based on creel data. Estimated winter sauger loss from hooking mortality during each winter was 5,229 and 7,176 fish.
About 70 percent of saugers caught in this winter fishery annually are released due to small size or voluntary release. Between 5,500 and 6,300 pounds of saugers were lost to catch-and-release mortality. The researchers report, however, that this represents less that 9 percent of the total annual harvest of saugers in Pool 4 of the Mississippi River, and that hooking mortality doesn't substantially influence the population. The researchers suggest that anglers can reduce hooking mortality by limiting fishing time in water depths exceeding 30 feet.
*Meerbeek, J. R., and R. J. H. Hoxmeier. 2011. Winter catch-and-release hooking mortality of saugers below Lock and Dam 3 of the Mississippi River. N. Am. J. Fish. Mgmt. 31:197-202.