Evidence of blue marlin, Makaira nigricans, spawning in the vicinity of Exuma Sound, Bahamas

Abstract

Exuma Sound is a semi-enclosed body of water bounded by islands of the Bahamas. During July 2000, sampling for larval billfish was carried out throughout the Sound's surface waters as well as in adjacent open waters of the Atlantic Ocean. A total of 99 larval billfish (Istiophoridae) was collected. Ninety of the larvae were identifiable as blue marlin (Makaira nigricans) and three as sailfish (Istiophorus platypterus). The remaining larvae were also istiophorids, unidentified to species owing to damage; no larval Xiphias gladius were collected. Larval blue marlin densities ranged from 0 to 3.4 larvae/1000 m2; their sizes ranged from 3.1 mm notochord length to 22.6 mm standard length. Densities tended to be highest north-east of the Sound's central axis, especially within the two regions where exchange with the Atlantic is greatest. Mean densities tended to decrease in the direction of mean flow; mean lengths increased from 8.08 mm at the Sound's mouth to 14.7 mm standard length at its upper reaches. Length-based estimates of larval age ranged from 2.2 to 17.2 days. Given these age estimates and assuming passive surface transport, the blue marlin larvae collected were likely the result of recent spawning in waters that include Exuma Sound and may extend some 200 km south-east of its mouth. This study suggests that Exuma Sound functions as a nursery area for blue marlin, and possibly other billfish species, at least during the summer. Limited sampling just outside Exuma Sound, in the Atlantic Ocean proper, also yielded blue marlin larvae.

Distribution and Habitat Associations of Billfish and Swordfish Larvae across Mesoscale Features in the Gulf of Mexico

“…Direct comparisons of abundance with other studies are problematic due to differences in sampling designs and gear types; nevertheless, our estimates of mean and maximum densities as well as percent frequency of occurrence of sailfish and blue marlin larvae were comparable or at times higher than reported values from other putative spawning and nursery areas in the western Atlantic, including the Straits of Florida and the Bahamas [23], [42], [43]. Over the three-year sampling period, nearly 40% of our net tows contained sailfish larvae with blue marlin present in approximately 25% of the samples.…”

Growth variation in larval Makaira nigricans

“…The value of G L calculated for Exuma Sound blue marlin larvae in this study was higher than that estimated for larvae <6·22 mm by Serafy et al . (2003).…”

“…To date the only published data on ageing is a study based on 18 larval blue marlin collected off Florida over a 2 day period (Prince et al ., 1991). Later efforts re‐examined these age‐length data to estimate the ages of additional larvae collected from Exuma Sound, Bahamas (Serafy et al ., 2003). Because so little empirical data on the age and growth of billfish larvae are available, the scope of variation, and possible factors contributing to it, have not been examined.…”

Sex ratios, spawning seasonality, sexual maturity, and fecundity of white marlin (Tetrapturus albidus) from the western central Atlantic

“…Due to this program, regional awareness grew, which resulted in an increase in funding for studies to provide answers of habitat utilization and life history of Atlantic marlins (e.g. Prince et al, 2005;Horodysky et al, 2007;Serafy et al, 2003;Drew et al, 2006). In 1991, ICCATs ERPB expanded its coverage to include Venezuela as part of the Program.…”