Comparing Observed and Unobserved Fishing Characteristics in the Drift Gillnet Fishery for Swordfish

This publication examines the assumption that observed fishing behaviors are representative of unobserved fishing behaviors. We used a suite of trip- and set-level fishing characteristics from an integrated data set of locations from the vessel monitoring system (VMS), observer, and logbook data with depth, SST, and landings information to facilitate quantitative comparisons between observed and unobserved behaviors in the U.S. West Coast drift gillnet fishery.

We present a methodical workflow for data integration and feature engineering and a simple approach for assessing differences across fleet behaviors in space and time that could be applied to many fisheries with limited observer coverage. We then quantified potential differences by coupling trip- and set-level catches and revenues with spatial, environmental, and operational characteristics of observed and unobserved trips. For the DGN fishery, we observed little statistical evidence of differences between observed and unobserved trips, neither for vessels that periodically carried observers nor for vessels that were never observed.

Suter JM, Ames RT, Holycross B, Watson JT. 2022. Comparing observed and unobserved fishing characteristics in the drift gillnet fishery for swordfish. Fisheries Research. Volume 256:106456.  https://doi.org/10.1016/j.fishres.2022.106456.