High-Grading in a Quota-Regulated Fishery, with Empirical Evidence from the Icelandic Cod Fishery

Fishers in quota-regulated fisheries find it to their advantage to discard less valuable fish at sea to increase the value of their catch. A theoretical model describing the high-grading behavior of fishers is presented, and an empirical model is derived as well as a testing strategy to test for high-grading and to estimate the discarded amount of each grade. The model is applied to data for the Icelandic quota regulated cod fishery during the period September 1998 to June 2001. The results indicate that highgrading occurs in the Icelandic cod fishery for both long-line and net vessels. However, the discard rates are small, and the results clearly suggest that the ban on discards in Iceland has effectively dealt with high-grading. The estimated discard rates are consistent with existing estimates of high-grading for the same types of vessel in the same fishery. This suggests that the modeling of discarding decisions based purely on incentives is a useful alternative to classical biometric methods.