Scientia Marina, Vol 69, No 4 (2005)

Stock assessment of sardine (Sardina pilchardus, Walb.) in the Adriatic Sea with an estimate of discards


https://doi.org/10.3989/scimar.2005.69n4603

Alberto Santojanni
ISMAR - CNR, Sezione Pesca Marittima, Largo Fiera della Pesca, Italy

Nando Cingolani
ISMAR - CNR, Sezione Pesca Marittima, Largo Fiera della Pesca, Italy

Enrico Arneri
ISMAR - CNR, Sezione Pesca Marittima, Largo Fiera della Pesca, Italy

Geoff Kirkwood
Renewable Resources Assessment Group (RRAG), Department of Environmental Science and Technology, Italy

Andrea Belardinelli
ISMAR - CNR, Sezione Pesca Marittima, Largo Fiera della Pesca, Italy

Gianfranco Giannetti
ISMAR - CNR, Sezione Pesca Marittima, Largo Fiera della Pesca, Italy

Sabrina Colella
ISMAR - CNR, Sezione Pesca Marittima, Largo Fiera della Pesca, Italy

Fortunata Donato
ISMAR - CNR, Sezione Pesca Marittima, Largo Fiera della Pesca, Italy

Catherine Barry
Marine Resources Assessment Group (MRAG), Italy

Abstract


Analytical stock assessment of sardine (Sardina pilchardus, Walb.) in the Adriatic Sea from 1975 to 1999 was performed taking into account the occurrence of discarding at sea of sardine caught by the Italian fleet. We have attempted to model the fishermen’s behaviour using data collected by an observer on board fishing vessels. This enabled us to estimate the amounts of discards, which were added to the catches landed, collected by ISMAR-CNR Ancona. Discards were calculated for the period 1987-1999, as their values were negligible before 1987. Stock assessment on the entire data series from 1975-1999 was carried out by means of Virtual Population Analysis (VPA). Discarding behaviour differs among ports due to different local customs and market conditions. The quantity added to the annual total catch ranged from 900 tonnes to 4000 tonnes, corresponding to between 2% and 15% of the total corrected catch. VPAs indicated that mid-year sardine stock biomass rose steadily from 400,000 tonnes in 1975 to a peak of 950,000 tonnes in 1984. Subsequently, biomass declined steadily to the more recent values, around 300,000 tonnes. Although discarded quantities were relatively high, their influence on stock assessment was not strong because of the high level of both catch and, in particular, estimated biomass at sea.

Keywords


sardine; Adriatic Sea; discards; observer data; regression tree models; stock assessment; population dynamics methods; Virtual Population Analysis (VPA)

Full Text:


PDF


Copyright (c) 2005 Consejo Superior de Investigaciones Científicas (CSIC)

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.


Contact us scimar@icm.csic.es

Technical support soporte.tecnico.revistas@csic.es