Relationship Of Interval Between Lifts And The Catch Of Ten-Foot Wisconsintype Trap Nets

A study to determine the relationship of the interval of time between lifts and the catch of ten-foot Wisconsin-type trap nets was included as a segment of an investigation designed to determine the potential of utilizing trap nets as a commercial fishing device in warmwater reservoirs. Data obtained from the catch of 170 trap net lifts, which varied in interval of time between lifts from one to seven days, indicate that with an increase in the interval of time between lifts, the total catch increased while the catch per net day decreased. A logarithmic curve Y = 73.866 + 235.229 log X, where Yequals total catch in pounds and X equals the interval of time between lifts in days, appears to best describe this relationship. The species composition ofthe catch also changed significantly as the interval of time between lifts increased. This change was the result of a decreasing percentage of gizzard and threadfin shad in the catch as the interval increased. It has been shown that stationary gear such as gill or trammel nets are most efficient when tended daily. Operating in this manner requires less time to tend the gear due to the smaller catch. In addition, mortality of the catch increases substantially with an increase in the interval of time between lifts. Trap net catches differ in that the time required to tend this gear varies only slightly with an increase in the size of catch and the mortality of fish in the crib does not appear to increase significantly with an increase in the interval of time between lifts. It is therefore possible to increase the total catch of a commercial fishing operation by increasing the number of trap nets and tending each one less frequently. The most efficient operation, considering the conditions under which this study was conducted, would have been to set 30 nets and lift each net every 3 days.

Starting page
532
Ending page
545
ID
53071