Seasonal movements and diving behaviour of black marlin (Istiompax indica) in the northwestern Pacific Ocean

The global biology, ecology and phylogenetic status of black marlin (Istiompax indica)

“…Evidence of gravid females and the presence of young-of-the-year (<10 kg) in the waters surrounding the island of Ko Samui indicate that this population is likely to extend into the Gulf of Thailand (Takahashi et al, 1983). shown movements restricted to west of the Philippine Sea, and year-long tracks indicate behaviour consistent with reproductive philopatry (Chiang et al, 2015).…”

“…gladius in the Mediterranean Sea still occurs in the current day ( Figure 1.1), with other notable billfish harpoon fisheries operating off Taiwan, Newfoundland (Canada) and the Ryukyu Islands of Japan (Nakamura, 1942;Chiang et al, 2015;Battaglia et al, 2017). Since the industrialisation of distant water fishing during the last century, the pressure from commercial exploitation of fish stocks has expanded throughout all of the major ocean basins.…”

“…Australia suggest that successful fertilisation and recruitment are likely to be highly influenced by environmental conditions (Pepperell, 1990). While some effort has been made to investigate which environmental factors influence the movement of I. indica (Domeier and Speare, 2012;Chiang et al, 2015;Hill et al, 2016), more work is required to understand how the physical environment impacts the behavioural ecology and physiology.…”

“…In addition, the suggestion of body mass influencing depth utilisation also does not consider the large ecological differences between billfish species or actual mass of individuals tagged in studies (Hoolihan et al, 2011;Braun et al, 2015). Despite the black marlin (Istiompax indica) being one of the largest billfishes, tagging of I. indica have shown the deepest dives to be less than 250 m (minimum ambient temperate of 14.5 o C) (Pepperell and Davis, 1999;Gunn et al, 2003;Chiang et al, 2015), which are equivalent to the maximum depths reported for I. platypterus (8.7 o C) and K. albida (12 o C) which maintain a much smaller average mass (Horodysky et al, 2007;Hoolihan et al, 2011). In addition, I.…”

“…indica have been observed to primarily occupy the upper 50 -100 m of the water column and no indications of diel diving behaviour have been reported (Pepperell and Davis, 1999;Gunn et al, 2003;Chiang et al, 2015). To effectively evaluate the relationship between body mass and vertical habitat use, an intraspecific comparison is required to reduce the potentially large effect of variation due to differing species' ecologies.…”