Determination of Fish Gender Using Fractal Analysis of Ultrasound Images

Abstract

The gender of cod Gadus morhua can be determined by considering the complexity in their gonadal ultrasonographic appearance. The fractal dimension (D(B)) can be used to describe this feature in images. B-mode gonadal ultrasound images in 32 cod, where gender was known, were collected. Fractal analysis was performed on these images and D(B) was determined using the box counting method. A receiver-operating curve (ROC) was drawn for D(B) as a test for male fish. Using a range of D(B) values, the maximum accuracy for this test was calculated and compared with the accuracy for identifying male fish by subjective analysis alone. The mean (and standard deviation) of the fractal dimension D(B) for male fish was 1.554 (0.073) while for female fish it was 1.468 (0.061); the difference was statistically significant (P = 0.001). The area under the ROC curve was 0.84 indicating the value of fractal analysis in gender determination in cod. Maximum accuracy (0.84) for D(B) as a test for male fish was obtained using the threshold value D(B) = 1.5058 compared with an accuracy of 0.78 for subjective image evaluation. The use of two thresholds, D(B) < 1.4475 (females) and D(B) > 1.5054 (males) gives an 80% certainty in the classification result. Fractal analysis is useful for gender determination in cod. This or a similar form of analysis may have wide application in veterinary imaging as a tool for quantification of complexity in images.

Effectiveness of Ultrasonic Imaging for Evaluating Presence and Maturity of Eggs in Fishes in Remote Field Locations

“…), and 78% of adult Atlantic Cod Gadus morhua (McEvoy et al. ). However, for species like the Red Hind Epinephelus guttatus , gonads can be identified only immediately prior to spawning (Whiteman et al.…”

Sexual Dimorphism and Discrimination of Barbel Steed (Hemibarbus labeo) in the Jinhe River, China: An Indicator of Habitat Status

“…Sexual dimorphism is a phenomenon in which fish exhibit distinct external characteristics between males and females [4][5][6]. Sex identification is a fundamental study in fish biology and aquaculture, and its results provide a theoretical basis for precious fish conservation and artificial reproduction [7]. Studies have found that many species of female and male fish show more pronounced differences in body size, minority body structure, and body surface color [8][9][10][11].…”

Sex identification in immature Eurasian perch ( Perca fluviatilis ) using ultrasonography

“…In the same way, since early 1980s, ultrasonography has been mainly used to determine the sex of numerous fish species, for conservation, research or aquaculture purposes. Among them, we can list coho salmon Oncorhynchus kisutch (Martin et al, 1983), Pacific herring Clupea pallasii (Bonar et al, 1989), Atlantic salmon Salmo salar (Mattson, 1991;Naeve et al, 2018), rainbow trout Oncorhynchus mykiss (Reimers et al, 1987), Atlantic halibut Hippoglossus hippoglossus (Martin-Robichaud & Rommens, 2001;Shields et al, 1993), striped bass Morone saxatilis (Blythe et al, 1994), Atlantic cod Gadus morhua (Karlsen & Holm, 1994;McEvoy et al, 2009), stellate sturgeon Acipenser stellatus (Moghim et al, 2002), shovelnose sturgeon Scaphirhynchus platorynchus (Colombo et al, 2004;Wildhaber et al, 2005), Murray cod Maccullochella peelii peelii (Newman et al, 2008), hapuku Polyprion oxygeneois (Kohn et al, 2013), European eel Anguilla Anguilla (Kucharczyk et al, 2016) or Chinese sturgeon Acipenser sinensis (Du et al, 2016).…”