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Integration of Auxiliary Information in Statistical Catch‐at‐Age (SCA) Analysis of the Saginaw Bay Stock of Walleye in Lake Huron
Author(s) -
Fielder David G.,
Bence James R.
Publication year - 2014
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 - 10.1080/02755947.2014.938141
Subject(s) - fishery , bay , stock (firearms) , fishing , recreational fishing , recreation , stock assessment , environmental science , population , catch per unit effort , geography , oceanography , ecology , demography , biology , geology , archaeology , sociology
Estimates of mortality rates and abundance for the Saginaw Bay stock of Walleye Sander vitreus has traditionally been performed with an analysis of tag returns using a Brownie‐style analysis. An estimation approach that more fully accounted for sources of exploitation in addition to the recreational fishery in Saginaw Bay and inclusive of the rest of Lake Huron was needed. We developed a statistical catch‐at‐age model to accomplish this and evaluated four versions including three different treatments of natural mortality ( M ): a constant value, age‐based M values, and time‐varying M values. Deviance information criterion model selection procedures indicated that an age‐based M model version was optimal. We also evaluated an integrated version that incorporated tag returns as auxiliary information for the recreational component. In this case, model selection was based on conformity between observed and predicted data and model convergence. The integrated version was ruled out due to poor agreement of the observed and predicted values and predictions of abundance that were not reflected by the fisheries. We concluded that the component of the population used for tagging may exhibit dynamics that differ from the rest of the stock. Total annual mortality of Walleyes was greatest for older ages in all fisheries and ranged from 32% for age‐2 fish to 39% for fish of ages 10 and older. The recreational fishery accounted for the majority of fishing mortality, but the commercial trap‐net fishery in the main basin of Lake Huron and bykill from other trap nets in the bay accounted for proportionally greater fishing mortality of younger ages of fish. Abundance peaked in 2007 at 4 million Walleyes age2 and older, but estimates indicated a previous period of high abundance in the late 1980s, forcing the reconsideration of the past stock as depressed and dependent on stocking. Received January 8, 2014; accepted June 11, 2014