Showing papers by "Claire B. Paris published in 2003"

The Role of Long Distance Dispersal Versus Local Retention in Replenishing Marine Populations

Abstract: Early models and evidence from genetics suggested that long distance dispersal of larvae is likely a common event leading to considerable population connectivity among distant populations. However, recent evidence strongly suggests that local retention is more the rule, and that long distance transport is likely insufficient to sustain marine populations over demographic timescales. We build on earlier model results to examine the probability of larval dispersal to downstream islands within different regions of the Caribbean at varying distances from source populations. Through repeated runs of an ocean circulation model (MICOM), coupled with a random flight model estimating larval sub-grid turbulent motion, we estimate the likelihood of particular circulation events transporting large numbers of larvae to within 9km radii of downstream populations, as well as account for total accumulations of larvae over each year. Further, we incorporate realistic larval behavior and mortality estimates and production variability into our models. Our results are consistent with the hypothesis that marine populations must rely on mechanisms enhancing self-recruitment rather than depend on distant 'source' populations.

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 m 2 ; 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.