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Verifying Residuals from Catch Curves to Detect Recruitment Variation in Largemouth Bass and Crappies
Author(s) -
Maceina Michael J.
Publication year - 2004
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/m02-162
Subject(s) - electrofishing , micropterus , bass (fish) , juvenile , fishery , biology , mathematics , zoology , fish <actinopterygii> , ecology
Abstract Residuals associated with catch‐curve regressions can represent variable recruitment in fish populations, but the use of this method to quantify recruitment variation has not been verified. I computed age‐0 and age‐1 catch rates of crappies Pomoxis spp. collected with trap nets set in the fall in three Alabama reservoirs and the age‐1 catch rate of largemouth bass Micropterus salmoides captured with electrofishing during spring over a 13‐year period in a single Georgia reservoir. These indices of juvenile abundance were correlated ( r = 0.52–0.81, P < 0.01) to residuals generated from catch‐curve regressions for electrofishing data collected when these same year‐classes recruited to the fishery at age 3 and older. At higher age‐0 crappie and age‐1 largemouth bass catch rates, these relations became curvilinear, and improved fit was computed with data transformation and nonlinear fits to the data. An asymptotic relation was observed between age‐0 and age‐1 catch rates for the same crappie year‐classes, and an inverse relation was evident between mean length at age 1 and juvenile crappie catch rates. This result suggested that density‐dependent growth suppression and mortality occurred, as age‐0 fish did not proportionally recruit to the age‐3+ fishery. However, the age‐1 crappie (about 18 months old) catch rate was linearly related ( r 2 = 0.48–0.55; P < 0.01) to residuals when data were compared separately for each reservoir, which suggested that full recruitment to the population occurred at this age. For largemouth bass, mean length at age 1 was positively related to age‐1 catch rate, and recruitment of strong year‐classes to the fishery appeared proportionally greater than for abundant age‐0 crappies. Residuals generated from catch‐curve regressions can serve as a useful quantitative index of juvenile crappie and largemouth bass abundance that can be used in subsequent analyses to explain recruitment variation. However, in some instances, initial strong year‐class abundance may not be fully expressed in the fishery later in life.