Predicting The Spawning Area & Survival Of Bluefin

The Fish Site
by The Fish Site
5 July 2011, at 1:00am

SPAIN - For seven days, scientists at IEO, SOCIB and IMEDEA and technicians at Balfeg Group, on board the fishing vessel Tio Gel, collected data to parameterise a model to predict the location of spawning areas and larval survival of bluefin tuna in the Balearic Sea, a tool to implement management systems to optimise the exploitation of this threatened species and promote the good state and its populations.

A team of researchers at the Oceanographic Center of the Balearic Islands of the Spanish Institute of Oceanography (IEO), Coastal Observing System in the Balearic Islands (SOCIB) and the Department of Marine Technologies, Operational Oceanography and Sustainability (TMOOS) at IMEDEA (UIB-CSIC ), embarked the Tio Gel fishing vessel on Sunday 19 June, owned by Balfeg Group.

The researchers led the second oceanographic survey in a series, which aim is to obtain the necessary data for parameterisation and validation of models to predict the location of spawning areas and larval survival rate of bluefin tuna (Thunnus thynnus) in the Balearic Sea.

The specific objectives of the last oceanographic survey were gauge and analyse oceanographic drift and dispersion of patches of high density of larvae of bluefin tuna populations, both wild and kept in captivity, to determine the vertical distribution of tuna larvae along the daily cycle to determine daily mortality rates in the early stages of development of larvae of tunas and define the beginning of piscivorous activity in larvae of bluefin tuna.

In order to characterise the environmental scenarios in the spawning areas, researchers have sampled a number of stations in two areas between Ibiza, Formentera and Cabrera, defined and programmed previously by analysis of satellite images.

The work involved making hydrographic data and biological samples in areas of confluence of Mediterranean surface waters and other recent Atlantic origin in which, taking into account the results of previous studies, are more likely to find tuna larvae.

This is part of oceanographic research project on sustainable use of marine living resources: the impact of the variability of the Mediterranean on reproduction and population dynamics of bluefin tuna (the acronym BlueFin).

This is the result of a specific collaboration agreement between the IEO and the Coastal Observing System in the Balearic Islands (SOCIB), a Singular Scientific and Technological Infrastructure (ICTS) located in the Islands.

The project, which will take place until 2014 and which also involved researchers from the Department of Marine Technologies, Operational Oceanography and Sustainability (TMOOS) of IMEDEA (UIB-CSIC), has as main objective the development of operational models for predicting the location of the breeding of tuna and estimates the level of bluefin tuna recruitment taking into account variations in larval survival rates resulting from changes in environmental conditions.