Figure 1.
The white line outlines the Great Barrier Reef Environment (GBRE); a region of barrier reef and adjacent habitats considered important for black marlin spawning.
Orange triangles are inshore gonad sampling sites (north to south: Dunk Island, Cape Bowling Green, Cape Moreton). Orange circles are larval sampling sites (inset north to south: Yonge Reef, First Corner, Second Corner). Red line is region of adult gonad sampling and PSAT tagging. Data SIO, NOAA, U.S. Navy, NGA, GEBCO; Image ©2011 TerraMetrics; Image © 2011 DigitalGlobe; © 2011 Cnes/Spot IMage.
Figure 2.
Histology of Spawning Black Marlin Ovary.
A) Perinucleolar oocytes (PN), previtellogenic oocytes (PV) and vitellogenic oocytes (VT) displaying incremental development within these stages. B) Vitellogenic oocyte displaying a prominent nucleus with numerous peripheral nucleoli surrounded by yolk granules. C) early stage hydrated oocytes (HY) with large yolk globules and the 3 axes used to measure distorted oocytes. D) Post ovulatory follicles (POF) alongside advanced vitellogenic oocytes. Scale bar 200 µm.
Figure 3.
Size and relative frequency of black marlin oocyte stages.
A - Mean sizes of oocyte development stages (+ 1SD) pooled from 19 black marlin taken from the Ribbon Reefs. The numbers above the bars indicate the number of oocytes measured. B – The mean proportional distribution of the various oocyte development stages in a fish (+ 1SD) compiled from 9312 egg counts. The numbers above the bars indicate the percentage of fish with each of the development stages. Stage designations are translated in Figure 2.
Figure 4.
Gonad weights as a proportion of fish weight for black marlin taken from the inshore coastal waters (Fin – females, Min - males) and the Ribbon Reefs (Foff – females, Moff - males).
Figure 5.
Age and growth of istiophorid larvae captured by towed plankton nets off the Ribbon Reefs.
A - Size classes (midpoints) for istiophorid larvae captured by towed plankton nets off the Ribbon Reefs. B - Calculated ages for the larvae based on instantaneous growth rates for blue marlin of 0.0976 (lower curve after [16]) and 0.1280 (upper curve after [17]). Dotted lines indicate the median size and corresponding calculated ages.
Figure 6.
Movement of PSAT tagged black marlin within the GBRE, demonstrating an affinity for SST of approximately 26–27°C.
A) October-November (n = 26 tagged fish); B) Dec-Jan (n = 27); C) February-March (n = 15); and D) April-May (n = 4). Sea Surface Representative monthly SST data from 2004–2005 MODIS (Moderate Resolution Imaging Spectroradiometer).
Figure 7.
Catchment area of the GBR black marlin spawning aggregation, as determined by popup satellite tagging.
Data SIO, NOAA, U.S. Navy, NGA, GEBCO; Image ©2011 TerraMetrics; Data © 2011 MIRC/JHA; © 2011 Cnes/Spot IMage.
Figure 8.
Range (km) of Black Marlin Dispersal from the GBR Spawning Aggregation.
Figure 9.
Conventional Tagging Results for Black Marlin Tagged off Eastern Australia.
Recapture locations for black marlin tagged on the GBR (A) closely agree with popup tagging results; results of black marlin tagged throughout Australia (B) show some ocean basin crossings. Red tracks are those fish known to be mature (100+ kg).