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Issue Aquat. Living Resour. Volume 22, Number 2, April-June 2009 Fish Stock Assessments Using Surveys and Indicators Page(s) 233 - 241 DOI 10.1051/alr/2009024 Published online 17 June 2009

Aquat. Living Resour. 22 (2009) 233-241
DOI: 10.1051/alr/2009024

ALADYM: an age and length-based single species simulator for exploring alternative management strategies

Giuseppe Lembo¹, Alvaro Abella², Fabio Fiorentino³, Sergio Martino¹ and Maria-Teresa Spedicato<sup>1

1</sup>  COISPA Tecnologia & Ricerca, Via dei trulli 18-20, 70126 Bari, Italy
²  ARPAT-AREA MARE, Via Marradi 114, Livorno, Italy
³  IAMC-CNR, Via L. Vaccara 61, Mazara del Vallo (TP), Italy

Received 29 August 2008; Accepted 29 January 2009; Published online 17 June 2009.

Abstract - ALADYM (age-length based dynamic model) is an age-length based simulation model designed to predict the consequences of management scenarios on a single population, in terms of different metrics and indicators. Removals are simulated as total mortality modulated using a selectivity pattern and a fishing activity coefficient. ALADYM uses the classical equations of population dynamics to create a tool that uses fishery-independent information (e.g. from trawl surveys) as the primary source. The formulation of population dynamics at a small time scale (month) allows to model the effects of harvest controls that evolve through the year, which is particularly useful for fast growing species. The possibility of specifying a vector of natural mortality by age/length makes the model more suitable for situations where stocks are exploited at an early life stage, as in many Mediterranean fisheries, while introducing variations along the time of the harvesting pattern accounts for non-equilibrium situations. Stochastic effects can be added to some key life-history traits to incorporate uncertainty in input parameters and in their relationships. ALADYM can be used for a range of applications such as comparing management strategies, evaluating indicator changes or searching for reference points.

Key words: Fish population dynamics / Simulation model / Fishery-independent approach / Fishery management

Corresponding author: lembo@coispa.it

© EDP Sciences, IFREMER, IRD 2009

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