The effect of the lunar phase on the catch per unit effort (CPUE) of the Turkish swordfish longline fishery in the eastern Mediterranean Sea

Tevfik Ceyhan,Okan Akyol,Panagiota Peristeraki,George Tserpes

doi:10.3750/aiep/02431

Abstract

The effect of the lunar phase on the catch per unit effort (CPUE) of the Turkish swordfish longline fishery in the eastern Mediterranean Sea

Highlights

The swordfish, Xiphias gladius Linnaeus, 1758, is a pelagic and highly migratory species distributed in the Atlantic, Indian, and Pacific oceans as well as in the Mediterranean Sea
Information is available on the influence of the lunar phases on the catch per unit effort (CPUE) of the swordfish longline fishery in the Atlantic (Draganik and Cholyst 1987, Moreno et al 1991, Neves dos Santos and Garcia 2005, Orbesen et al 2017) and the Pacific oceans
The analysis of deviance table indicated that only the effect of year was significant (Table 2) and from the yeareffect plot, it appears that CPUE is decreasing up to 2012 remaining rather stable afterwards (Fig. 5)

Summary

Introduction

The swordfish, Xiphias gladius Linnaeus, 1758, is a pelagic and highly migratory species distributed in the Atlantic, Indian, and Pacific oceans as well as in the Mediterranean Sea. Information is available on the influence of the lunar phase on the catch per unit effort (CPUE) for the swordfish longline fishery in the Atlantic and Pacific oceans, the data concerning the Mediterranean is rather limited. The aim of this study was to examine the relation between the lunar phase and the swordfish CPUE, based on data from Turkish longline fisheries, targeting swordfish in the eastern Mediterranean during the 2008–2016 fishing seasons. A total of 86 surveying operations were carried out, including 79 in the area between Fethiye and Alanya, the remaining ones were in Özdere in the southern Aegean coasts along the eastern Mediterranean Sea. The effect of the lunar phase on the swordfish catch rates, expressed in terms of kg · 1000 hooks–1, was examined by means of the Generalized Additive Modelling (GAMs) techniques. Further studies are needed to better clarify the impact of the lunar phase on the longline gear, considering additional parameters, such as light transition, prey abundance, physico-chemical characteristics of the marine environment, and the soak time of the gear

Objectives

Results

Conclusion