Relationship between weight and linear dimensions of Bluefin tuna (Thunnus thynnus) following fattening on western Mediterranean farms

Abstract

This study presents various models based on formulae relating weight and dimensions (length, height and width) of Bluefin tuna, Thunnus thynnus (L.), fattened in captivity. The main aim of establishing these expressions is to design tools for indirectly predicting the weight of a Bluefin tuna from measurements of one or more dimensions obtained using non-invasive methods such as stereoscopic cameras. Measurements of maximum length, height and width following slaughter were taken of fish fattened in captivity (n = 2078). Different relationships drawn from the dimensions of the tuna against their weight are fitted with part of the data collection and later checked against a reserved sample set. The resulting formulae are compared with the formulae most commonly used in the case of wild tuna. The results of this study confirm that, for tuna fattened in cages, the availability of more than one dimension to estimate weight improves the predictive power of the model and reduces error in the estimate.

Automatic Bluefin Tuna Sizing with a Combined Acoustic and Optical Sensor

“…Fish length information is an important indicator of the health of wild fish stocks and for predicting biomass using length–weight relationships [ 9 , 45 ], although recent studies have attempted to show that biomass can be estimated more accurately if fish measurements in dimensions other than length (such as width and height) are available [ 19 , 44 , 46 ]. The total biomass of a fish stock is commonly determined by obtaining the mean length of a statistically representative number of fish [ 8 , 47 ].…”

“…It is important to note that our sensor and automatic processing of acoustic and optical information provides not only length measurements (SFL) of tunas, but also width measurements (W), which requires an additional computational time cost. Fish length information is an important indicator of the health of wild fish stocks and for predicting biomass using length-weight relationships [9,45], although recent studies have attempted to show that biomass can be estimated more accurately if fish measurements in dimensions other than length (such as width and height) are available [19,44,46]. The total biomass of a fish stock is commonly determined by obtaining the mean length of a statistically representative number of fish [8,47].…”

Automated Monitoring of Bluefin Tuna Growth in Cages Using a Cohort-Based Approach

“…However, in [11,12], relationships between weight and linear dimensions of BFT were analysed using data from Grup Balfegó harvests. One of the conclusions drawn was that weight could be more accurately estimated by considering various dimensions apart from length.…”

“…Considering that the automatic system can provide both length and width measurements, the weight of each sample can be estimated using Equation (2). The accuracy of each equation was previously examined in [11,12], yielding a mean relative error of 25.68% for Equation (1) and 4.88% for Equation (2).…”

“…In these solutions, fish weight may be deduced from fish length, as established in [10]. However, recent works [11,12] have attempted to find better approximations for their weight by using both fish length and width measurements. They work on the hypothesis that a better estimation of the biomass can be achieved by using more dimensions of the tuna than only length.…”