New technique for determining age of coastal skates (Chondrichthyes, Rajidae) from Argentinian sea by digital image processing analysis

PAULA A. CRISTINI; JUAN IGNACIO PASTORE; SANTIAGO BARBINI; JOSEFINA BALLARRE; DAVID SABADIN; AGUSTINA BOUCHET

Congreso; VIII Congreso Latinoamericano de Ingeniería Biomédica CLAIB 2016; 2016

To understand dynamic populations of cartilaginousfishes age and growth studies have essential importancein the demographic analysis application, especially to estimatevulnerability to mortality by fishing. However, knowledge ageof cartilaginous fishes have a serious inconvenient since inmany opportunities the calcified structures, as vertebrae, mustbe stained with different techniques to identify rings of growth,and the effectiveness of each technique varies according to thestudy species. This problem would be solved using methodsthat allow identifying rings of growth with an objective techniquesuch as digital image processing analysis. In the presentwork we performed a preliminary study using as model theSmallnose skate Sympterygia bonapartii (Rajidae). Corpuscalcareum from small specimen does not have growth bandswhile the medium one has four bands and the large, six. Thenumber of bands is related directly with the age of the specimensand is in good agreement with the visual counting madeby two readers. The use of the algorithm to determine thenumber of bands in skates allows to be independent of theoperator and to have a systematic method of measure.