Economic Evaluation of the Northern hake Long Term Management Alternatives: An Example Using FLR

Introduction

In this exercise we are trying to evaluate the Northern hake long term management alternatives presented in (SEC (2007)). It implies that is not a pure economic evaluation of the situation of the fleet, given that we are restricting the evaluation to the effort drivers presented in it. With this in mind we present an evaluation using FLR (Kell et al., 2007) and its economic module FLecon for pursuing advances in the economic evaluation of management strategies.

With this in mind we have focused our work in two trawl fleets, that capture around the 30% of the total northern hake stock, with the characteristic that one (pair trawlers) face almost a single target fishery (hake is in average the 88% of the total landings) while the other is facing a multispecies fishery (where hake accounts for the 64% of their landings), even if they first face hake as the target species. This last characteristic is extremely important since the evaluation of the management strategy is based on several assumptions that are based on a single species framework. The most important one and the driver of the whole system is that Hake’s TAC is defining the effort applied, that is, the other species will be subrogated to this effort (even if in some alternative cases this assumption can be relaxed).

In terms of conditioning we have read this assumption as dividing species types of production function in three categories (explained in the conditioning section). Firstly hake is considered management driven in terms that all TAC is always caught, and that the corresponding effort is calculated assuming a fixed catchability per age. Given that effort, and through the estimation, when availability of data makes it possible, of a production function for each fleet and species (anglerfish, and megrim), catches of the rest of the species are calculated. Finally a third group of species is explicitly considered but catches are calculated based on an ad hoc calibration. The overall captures are also calibrated using what we have called (probably, in not a very fortunate way), “ghost species”.

In any case inclusion of new species and fleets has been left as open, but they have to be conditioned.

Contents of the work

A complete description of the Northern Hake Fishery, the Operating Model (OM), Fleets Considered, how the model was conditioned, main species, Prices, Effort, Catches, Variable and Fix Costs, Number of vessels, Limitations, Indicators of the Management Strategies and the different Mangement Strategies approached:

Base case: F Target is set to a Precautionary Approach level Base case: F Target is set to a FMSY(proxy) with an annual reduction of F of 5% Base case: F Target is set to a FMSY(proxy) with an annual reduction of F of 10% Base case: F target is set to a FMSY(proxy) with an annual reduction of F of 15% Base case: F target is set to a 120% of FMSY(proxy) with an annual reduction of F of 5% Base case: F is set to a 80% of FMSY (proxy) with an annual reduction of F of 15% Base case: Comparison between management alternatives

are presented and analysed in this work.

The compleate study is presented in the followwing draft document:

Economic evaluation of the Northern Hake Long Term Management Alternatives using FLR

 
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