Estimating discard excess catch in the industrial purse seine fisheries of the North-Center stock of the Peruvian anchoveta (Engraulis ringens) from an on-board observer program

Abstract

This paper presents estimates of the discard excess catch in the industrial purse seine fisheries of the North-Center stock of the Peruvian anchoveta (Engraulis ringens). Discard excess catch is defined as the portion of the catch that is thrown into the sea when has captured more than the hold capacity can store. The analysis is based on the “On-board observer of the purse seine vessels program” led by the Instituto del Mar del Peru (IMARPE), and in the period 2005 – 2014, 5837 trips were sampled, corresponding to 1.6% of the total trips. The methodologies used in the discard excess catch estimation were: Generalized Linear Model (GLM) and Delta Model. The estimations showed difference in magnitudes but similar trends, although the delta model appears to be a better alternative procedure for estimating the discard excess catch. The Delta Model estimated the purse seine fisheries discarded a range from 2954 to 199 164 tons, an average estimated 121 312 tons, which represent 2.6% of the landings in the period 2005 - 2014. Spatial variables (e.g. distance from the shore, latitude, longitude), physical (SST), and school behavior (e.g. fish aggregation) should be included to improve the analysis and a better understanding of the discard excess catch behavior.