Defining value per unit effort in mixed métier fisheries

Abstract

Value achieved from time spent at sea is a central driver of fishing decisions and fishing behaviors. Value per unit effort (VPUE) is an important indicator of economic performance in itself and a useful metric within integrated mixed fisheries models. A time series of Irish first sale prices and total per trip landings values (VPT) highlight heterogeneity in fish prices and VPTs achieved by the Irish fleet spatially and temporally, as well as variability with species targeting. This investigation compared models to standardize fishing trip VPUE accounting for species targeting (métier groupings), engine power (a kW proxy for vessel size), seasonal and annual variability, fishing effort, and individual vessels (encompassing variability in vessel characteristics and skipper effects). Linear mixed effects models incorporating random vessel effects and within-group variance between métier groupings performed best at describing the variability in the dataset. All investigated factors were important in explaining variability, and thus important in standardizing VPUE. Models incorporating fishing days (days with reported fishing activity) and engine power as separate 2 variables resulted in improved AIC values. Therefore, fishing days were considered to be the most appropriate effort measure to generate VPUE. The effort unit traditionally applied in measures of per unit effort, fishing hours, performed comparatively poorly in relation to VPT.

Disaggregating species unit costs in mixed fisheries: the case of the Irish whitefish fleet

“…Sandberg (2006) empirically examines how variable unit costs in Norwegian demersal and pelagic fisheries depend on output and the fish stock. Davie et al (2014) define value per unit of effort in Irish mixed metier fisheries.…”

Αλιευτική Δραστηριότητα Και Στρατηγικές Διαχείρισης Της Μικρής Παράκτιας Αλιείας Στα Δωδεκάνησα

“…Γενικά, οι αλιείς στόχευαν είδη υψηλής αξίας, όπως τα P. pagrus, S. aurata, P. erythrinus, D. vulgaris και X. gladius και επιλεγμένα άτομα μεγάλου μεγέθους, τα οποία έχουν υψηλότερες τιμές στην αγορά. Η παραπάνω τακτική που ακολουθούσαν οι αλιείς υποδηλώνει ότι η τιμή της αγοράς επηρεάζει την επιλογή των ψαράδων (Sumaila et al, 2006;Davie et al, 2015 (Llorent & Font, 2013). Ωστόσο, αρκετές έρευνες «προειδοποιούν» για σοβαρή συρρίκνωση αυτού του τύπου αλιείας σε πολλές περιοχές (Colloca et al, 2004;Maynou et al, 2011;Lloret & Font, 2013), συμπεριλαμβανομένων των ελληνικών θαλασσών (Tsikliras et al, 2013), προκαλώντας έτσι ανησυχία για τη μελλοντική βιωσιμότητα.…”