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Response of Upper Mississippi River Channel Catfish Populations to Changes in Commercial Harvest Regulations
Author(s) -
Pitlo John
Publication year - 1997
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1997)017<0848:roumrc>2.3.co;2
Subject(s) - catfish , ictalurus , flathead , fishery , fish <actinopterygii> , channel (broadcasting) , biology , zoology , environmental science , electrical engineering , engineering
Channel catfish Ictalurus punctatus and flathead catfish Pylodictis olivaris provide important sport and commercial fisheries in the upper Mississippi River. These two species alone account for nearly one‐third of the monetary value of the annual commercial fish harvest and consistently rank among the top 10 species caught by sport anglers. Catfish harvested commercially from Pools 9–19 declined significantly from 1955 to 1984, and this decline was attributed to overharvest of fish over the legal length of 13 in. Overharvest resulted in (1) declines in yield, (2) increases in the proportion of small fish in the commercial harvest, (3) a narrow range of age‐groups represented in the fishery, (4) high dependence on single year‐classes, and (5) high mortality rates. It was projected that increasing the minimum length for commercially harvested catfish from 13 to 15 in would (1) improve recruitment and thus increase and stabilize year‐class abundance, (2) reduce fluctuations in the fishery caused by dependence on individual year‐classes, (3) increase the value of the commercial catfish harvest, and (4) increase the number of catfish available to sport anglers. The increase to a 15‐in minimum length limit for commercially harvested catfish became effective in 1985 for all pools of the upper Mississippi River. Following implementation of the new length limit, an upward trend in the commercial harvest from Pools 9–19 was observed, catch of age‐0 channel catfish increased significantly, and the average value of the commercial harvest increased. In addition, the numeric rank of channel catfish in the creel of sport anglers increased from sixth in 1963 to second in 1994.