Total of 1072 Asian seabass or barramundi (Lates calcarifer) were harvested at two different locations in Queensland, Australia. Each fish was digitally photographed and weighed. A subsample of 200 images (100 from ea...Total of 1072 Asian seabass or barramundi (Lates calcarifer) were harvested at two different locations in Queensland, Australia. Each fish was digitally photographed and weighed. A subsample of 200 images (100 from each location) were manually segmented to extract the fish-body area (S in cm2), excluding all fins. After scaling the segmented images to 1mm per pixel, the fish mass values (M in grams) were fitted by a single-factor model (M=aS1.5, a=0.1695 )achieving the coefficient of determination (R2) and the Mean Absolute Relative Error (MARE) of R2=0.9819 and MARE=5.1%, respectively. A segmentation Convolutional Neural Network (CNN) was trained on the 200 hand-segmented images, and then applied to the rest of the available images. The CNN predicted fish-body areas were used to fit the mass-area estimation models: the single-factor model, M=aS1.5, a=0.170, R2=0.9819, MARE=5.1%;and the two-factor model, M= aSb, a=0.124, b=0.155, R2=0.9834, MARE=4.5%.展开更多
Dogtooth tuna,Gymnosarda unicolor were sampled off the east coast of Australia(southwest Pacific Ocean)from 2007 to 2012.Ages were determined by examining thin transverse sections of their sagittal otoliths and were b...Dogtooth tuna,Gymnosarda unicolor were sampled off the east coast of Australia(southwest Pacific Ocean)from 2007 to 2012.Ages were determined by examining thin transverse sections of their sagittal otoliths and were based on counts of alternating opaque and translucent zones(annual growth increments).Growth was rapid during the first year of life,after which growth in length was much reduced.Parameters of the constrained von Bertalanffy growth function(fork length-at-age)were L∞=1164.77(mm,FL)and K=0.44 year^(-1).Preliminary estimates of longevity indicate a maximum observed age of at least 20 years.There was a high degree of variation in the observed length and age of sexual maturity for G.unicolor.Despite this variation,the size at 50%maturity for female G.unicolor estimated in this study was 713 mm FL(<2 years of age).The diet of G.unicolor is very broad and covers a range of fish species.The life history characteristics of G.unicolor overall,indicate that this species may be somewhat resilient to fishing.However,reports of localised depletions,in association with heavy targeting by sports fishers,low effective population sizes and patchy recruitment indicate that this species is particularly vulnerable to overfishing.展开更多
文摘Total of 1072 Asian seabass or barramundi (Lates calcarifer) were harvested at two different locations in Queensland, Australia. Each fish was digitally photographed and weighed. A subsample of 200 images (100 from each location) were manually segmented to extract the fish-body area (S in cm2), excluding all fins. After scaling the segmented images to 1mm per pixel, the fish mass values (M in grams) were fitted by a single-factor model (M=aS1.5, a=0.1695 )achieving the coefficient of determination (R2) and the Mean Absolute Relative Error (MARE) of R2=0.9819 and MARE=5.1%, respectively. A segmentation Convolutional Neural Network (CNN) was trained on the 200 hand-segmented images, and then applied to the rest of the available images. The CNN predicted fish-body areas were used to fit the mass-area estimation models: the single-factor model, M=aS1.5, a=0.170, R2=0.9819, MARE=5.1%;and the two-factor model, M= aSb, a=0.124, b=0.155, R2=0.9834, MARE=4.5%.
文摘Dogtooth tuna,Gymnosarda unicolor were sampled off the east coast of Australia(southwest Pacific Ocean)from 2007 to 2012.Ages were determined by examining thin transverse sections of their sagittal otoliths and were based on counts of alternating opaque and translucent zones(annual growth increments).Growth was rapid during the first year of life,after which growth in length was much reduced.Parameters of the constrained von Bertalanffy growth function(fork length-at-age)were L∞=1164.77(mm,FL)and K=0.44 year^(-1).Preliminary estimates of longevity indicate a maximum observed age of at least 20 years.There was a high degree of variation in the observed length and age of sexual maturity for G.unicolor.Despite this variation,the size at 50%maturity for female G.unicolor estimated in this study was 713 mm FL(<2 years of age).The diet of G.unicolor is very broad and covers a range of fish species.The life history characteristics of G.unicolor overall,indicate that this species may be somewhat resilient to fishing.However,reports of localised depletions,in association with heavy targeting by sports fishers,low effective population sizes and patchy recruitment indicate that this species is particularly vulnerable to overfishing.
