Temporal changes in harvesting dynamics of Canadian inshore fisheries for northern Atlantic cod, Gadus morhua

Abstract

We quantified temporal changes in catch rate, fishing effort, and catch misreporting for two sectors of the fixed-gear fishery for Newfoundland's northern Atlantic cod, Gadus morhua, from 1980 to 1991, the year preceding the stock's commercial fishing moratorium. Over the 12-year period, fishermen reported catch rate declines of 40 and 75% in the trap and gillnet fisheries, respectively, associated with significant increases in nominal fishing effort. Additional changes to effort included smaller gillnet and trap mesh sizes, larger traps, longer soak times, and modifications to trap design to increase catch retention probabilities. Compared with the early 1980s, unreported catches among inshore fishermen may have trebled by the late 1980s and early 1990s due to longer gillnet soak times, increased gear selectivity for small fish, and declining availability of fish of marketable size. These patterns in harvesting dynamics are consistent with the hypothesis that the decline of northern cod was gradual and that increased rates of catch misreporting contributed to increases in fishing mortality. The concomitants of declining fixed-gear catch rate, increasing quantitative and qualitative fishing effort, increased selectivity for smaller fish, and increasing levels of unreported catches may represent general correlates of imminent fish stock collapses.