Randall, Landes Lee (2014-08). The Distribution and Abundance of Bluntnose Flyingfish (Prognichthys occidentalis) Across the Gulf of Mexico. Master's Thesis. Thesis uri icon

abstract

  • Flyingfishes are an essential component of pelagic food webs, serving as both predator and prey. Many pelagic fishes (billfishes, dolphinfishes, and tunas) consume large quantities of flyingfish, and several studies have documented their importance as prey for apex predators residing in coastal and offshore environments. Six summer ichthyoplankton cruises were conducted from 2009 to 2011 to investigate ocean influences on the distribution and abundance of flyingfish larvae in the northern Gulf of Mexico (NGoM). Over the three-year sampling period, a total 9,533 bluntnose flyingfish (Prognichthys occidentalis) larvae were collected and this species alone accounted for 77% of the total flyingfish catch. The remainder of the flyingfish assemblage was comprised of 8 species from 4 different genera (Cheilopogon, Hirundichthys, Exocoetus, and Parexocoetus), but given the dominance of bluntnose flyingfish our assessment of distribution, abundance, and habitat associations focused on this species. Interannual variation was detected with densities of bluntnose flyingfish larvae higher in 2009 and 2010 (11.3 and 7.9 larvae 1000m^(-2), respectively) than 2011 (1.9 larvae 1000m^(-2)). Bluntnose flyingfish larvae were present in each month and year sampled, and percent frequency of occurrence ranged from 40% in July 2011 to 100% in June 2010, suggesting that this species is a common and important component of the ichthyoplankton assemblage in this region. Generalized additive models were used to evaluate the effect of oceanographic conditions on the abundance of bluntnose flyingfish, and several environmental variables (sea surface height anomaly, distance to Loop Current, and salinity) were found to be influential in explaining patterns of abundance. Habitat suitability was linked to physicochemical properties of the seawater, and higher larval abundances were found at higher salinities and negative sea surface heights. In addition, a positive relationship with distance to the dominant mesoscale oceanographic feature in the NGoM (Loop Current) was detected, suggesting that the abundance of bluntnose flyingfish larvae increases away from this frontal feature. This study emphasizes the importance of NGoM as a spawning/nursery area of bluntnose flyingfish, and suggests that oceanographic conditions play an important role in determining their distribution and abundance in this region.
  • Flyingfishes are an essential component of pelagic food webs, serving as both predator and prey. Many pelagic fishes (billfishes, dolphinfishes, and tunas) consume large quantities of flyingfish, and several studies have documented their importance as prey for apex predators residing in coastal and offshore environments. Six summer ichthyoplankton cruises were conducted from 2009 to 2011 to investigate ocean influences on the distribution and abundance of flyingfish larvae in the northern Gulf of Mexico (NGoM). Over the three-year sampling period, a total 9,533 bluntnose flyingfish (Prognichthys occidentalis) larvae were collected and this species alone accounted for 77% of the total flyingfish catch. The remainder of the flyingfish assemblage was comprised of 8 species from 4 different genera (Cheilopogon, Hirundichthys, Exocoetus, and Parexocoetus), but given the dominance of bluntnose flyingfish our assessment of distribution, abundance, and habitat associations focused on this species. Interannual variation was detected with densities of bluntnose flyingfish larvae higher in 2009 and 2010 (11.3 and 7.9 larvae 1000m^(-2), respectively) than 2011
    (1.9 larvae 1000m^(-2)). Bluntnose flyingfish larvae were present in each month and year sampled, and percent frequency of occurrence ranged from 40% in July 2011 to 100% in June 2010, suggesting that this species is a common and important component of the ichthyoplankton assemblage in this region. Generalized additive models were used to evaluate the effect of oceanographic conditions on the abundance of bluntnose flyingfish, and several environmental variables (sea surface height anomaly, distance to Loop Current, and salinity) were found to be influential in explaining patterns of abundance. Habitat suitability was linked to physicochemical properties of the seawater, and higher larval abundances were found at higher salinities and negative sea surface heights. In addition, a positive relationship with distance to the dominant mesoscale oceanographic feature in the NGoM (Loop Current) was detected, suggesting that the abundance of bluntnose flyingfish larvae increases away from this frontal feature. This study emphasizes the importance of NGoM as a spawning/nursery area of bluntnose flyingfish, and suggests that oceanographic conditions play an important role in determining their distribution and abundance in this region.

publication date

  • August 2014