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Bibliographic record number: 71779

Journal

Authors: Tičina, Vjekoslav
Title: Biometry of northern bluefin tuna (Thunnus thynnus, Linnaeus, 1758) from the Mediterranean (Adriatic) Sea
Source: Abstracts of the 36th European Marine Biology Symposium "A Marine Science Odyssey into the 21st Century"
Meeting: European Marine Biology Symposium (36 ; 2001)
Location and date: Mao, Španjolska, 17.-22.09. 2001.
Keywords: biometry; Thunnus thynnus; Mediterranean (Adriatic) Sea
Abstract:
The very impotrant question, concerning to management of northern bluefin tuna in the Atlantic, is: "Are there only one stock or two separated stocks of bluefin tuna?" Current two-stock hypothesis was based on some assumptions that are inconsistent with available data collected. Furthermore, it is known that variability in morphological characteristics is considered to be a result of the degree of isolation and localisation of fish populations. For this reason, biometric studies have been widely used as a tool for stock differentiation. In the last more than 40 years, there were no paper published concerning to biometry of northern bluefin tuna from Mediterranean Sea area. So, the aim of this paper was to gain a recent knowledge about some particular morphometric and meristic characteristics of the northern bluefin tuna from Mediterranean Sea. The random sampling of bluefin tunas (LF = 50.0 - 127.0 cm) was performed during commercial catches in the Adriatic Sea. In total, 150 fishes from 11 different catches were sampled and analysed. All specimens were caught with purse seine, in the summer period from 1992-1994. In this biometric study, 14 different characteristics of the bluefin tuna were analised. Based on the results obtained, the following relationships were found: Head length enters 3.27 - 3.69 times ; preanal length enters 1.53 - 1.74 times ; body depth enters 3.40 - 4.26 times ; second dorsal fin height enters 7.03 - 11.67 times, and caudal fin width enters 3.00 - 4.50 times in the fork length. Eye diameter enters 5.92 - 9.72 times, and preorbital length enters 2.78 - 3.64 times in the head length. Changes of these relationships (i.e. relative growth), during first five years of tuna's life, are described also. Gillrakers (branchiospinae) on the first gill arch numbered from 28 - 38. The first dorsal fin consisted of 13 - 14 spines, and pectoral fin consisted of 29 - 38 soft rays connected by a membrane. Number of dorsal finlets ranged from 9 - 11, while the number of ventral finlets ranged from 8 to 10. Comparison of these results with the results of the similar biometric studies concerning to northern bluefin tuna from the western Atlantic will provide additional arguments for or against the current two-stock hypothesis.
Type of meeting: Poster
Type of presentation in a journal: Abstract
Type of peer-review: International peer-review
Project / theme: 00010301
Original language: ENG
Category: Znanstveni
Research fields:
Biology



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