This is the reference case scenario for Albacore Tuna for the 2015 Stock Assessment.

Stock assessment for south Pacific albacore tuna. Rev 1 (4 August 2015), Harley, S. J[1], N. Davies[2], L Tremblay-Boyer[1], John Hampton[1] , and S McKechnie[1], Affiliations: [1] Oceanic Fisheries Programme, Pacific Community, [2] Te Takina Ltd.

Introduction

This paper presents the 2015 stock assessment of south Pacic albacore tuna (Thunnus alalunga) covering the southern hemisphere component of the Western and Central Pacic Fisheries Commission (WCPFC) convention area and sheries for the period 1960{2013.  Since 1999, the stock has been assessed regularly and the most recent assessments are documented in Hoyle et al. (2008b); Hoyle and Davies (2009); Hoyle(2011), and Hoyle et al. (2012).

The overall objectives of the assessment are to estimate population parameters, such as time series of recruitment, biomass and shing mortality, which indicate the stock status and shing impacts. We  summarize  the  stock  status  in  terms  of  reference  points  adopted  or  under  consideration  by the WCPFC. The methodology used for the assessment is commonly known as MULTIFAN-CL 3(Fournier  et  al., 1998; Hampton  and  Fournier, 2001; Kleiber  et  al., 2014).   MULTIFAN-CL  is  a software program that implements a size-based,  age- and spatially-structured population model. Model parameters are estimated by maximizing an objective function, consisting of both likelihood (data) and prior information components.

This assessment report should not be seen as a standalone document and should be read in conjunction with several supporting papers, specically this assessment is supported by an analysis of operational longline data to construct both CPUE time series (Tremblay-Boyer et al., 2015b) and regional weights (Tremblay-Boyer et al., 2015a) and the analysis of longline size data (Scott and McKechnie, 2015).  The assessment also includes results from a wide-scale study of the biological parameters of albacore (Williams et al., 2012; Farley et al., 2013b) { in particular results from the age and growth study aimed to address uncertainty around growth which has troubled previous assessments.  This is the rst MULTIFAN-CL stock assessment that includes conditional age-length observations with the aim of improving growth estimates.