Red Snapper: Ecology and Fisheries in the U.S. Gulf of Mexico

2007 ◽  
Keyword(s):  
Visual Analysis ◽  
Reproductive Potential ◽  
Red Snapper ◽  
Marine Fisheries ◽  
Lutjanus Campechanus ◽  
Explanatory Variables ◽  
Life History Pattern ◽  
Simple Power Function ◽  
Effect Of Age ◽  
Combined Data

<em>Abstract.</em>—The red snapper <em>Lutjanus campechanus </em>exhibits rapid growth early in life, yet is a relatively long-lived species with an indeterminate spawning pattern. Batch fecundity (<EM>BF</EM>), a principal determinant of the reproductive potential of indeterminate spawners, appears to increase geometrically with length and asymptotically with age based upon combined data from National Marine Fisheries Service (NMFS) and Marine Fisheries Initiative (MARFIN) reproductive sampling programs. As the life history pattern sets up a potential disconnection between size and age, we modeled their interaction as explanatory variables of <EM>BF</EM>. Visual analysis suggests a dome-shaped relationship between <EM>BF </EM>and age within a given size-class. To test this, a general log-linear model and a new “standardized-age” model (where the effect of age depends explicitly on the size of the fish) were fitted to data. These analyses suggest that the effect of age, while statistically significant, was relatively small (the models with age and length terms explaining only slightly more of the variation in <EM>BF </EM>than a simple power function of length). The age effect seems to be most pronounced for fish that are exceptionally small or exceptionally large given their age, which constitute a small fraction of the sample and presumably also a small fraction of the population at large. Hence, it seems unlikely that including this interaction would have any important ramifications for stock assessments of red snapper. Nevertheless, the effect of age on <EM>BF </EM>remains open to the degree that old fish (i.e., greater than age 13) were rare in the combined data set and tended to exhibit lower <EM>BF </EM>values than predicted. Age effects of other reproductive determinants remain to be evaluated but we found hydrated females to be of greater size-at-age than nonhydrated red snapper suggesting an age-length interaction on batch frequency.

Spawning of Red Snapper (Lutjanus campechanus) in Response to Hormonal Induction or Environmental Control in a Hatchery Setting

2009 ◽  
Vol 17 (2) ◽  
pp. 149-155 ◽  
Author(s):  
R. P. Phelps ◽  
N. Papanikos ◽  
B. D. Bourque ◽  
F. T. Bueno ◽  
R. P. Hastey ◽  
...  
Keyword(s):  
Environmental Control ◽  
Red Snapper ◽  
Lutjanus Campechanus ◽  
Hormonal Induction

Red Snapper: Ecology and Fisheries in the U.S. Gulf of Mexico

2007 ◽  
Keyword(s):  
Gulf Of Mexico ◽  
Fork Length ◽  
Red Snapper ◽  
Minimum Size ◽  
Minimum Length ◽  
Commercial Fishing ◽  
Lutjanus Campechanus ◽  
Commercial Harvest ◽  
Length Regulation ◽  
The U.S

<em>Abstract.</em>—Red snapper <em>Lutjanus campechanus </em>were sampled from commercial landings from the Gulf of Mexico (GOM) off Louisiana from October 2001 to May 2004. Fork length (FL), eviscerated weight, otoliths (both sagittae), and sex determinations were taken from 2,900 specimens; FL was subsequently converted to total length (TL) with the equation TL = 1.073 (FL) + 3.56. Red snapper ages (<EM>N </EM>= 2,867) estimated from counts of opaque annuli in otoliths ranged from 1 to 14 years; however, the vast majority (97.7%) of these were ages 2 to 6 years and the modal age was 3 years. Total lengths among 2,897 specimens ranged from 278 to 940 mm, modal TL was 400 mm, and 98% of all specimens were less than 600 mm TL. We also investigated the fate of red snapper regulatory discards (individuals <381 mm [15 in] TL) during 16 trips on working commercial vessels; over two-thirds of 4,839 red snapper assigned among four discard fate categories (ranging from alive and vigorous to dead) were returned to the water either in moribund or dead condition. Among 399 potential discards retained for age and length analyses, 86% were between 12 and 15 in (305–381 mm) TL and 85% were 2 years of age. The minimum size regulation appears to do little to protect juvenile red snapper from commercial fishing mortality. Heavy red snapper mortality, which begins as bycatch mortality in shrimp trawls, continues as discard mortality at sub-legal lengths when they first recruit to the offshore fishing grounds, and persists as harvest mortality among the youngest legal year- and size-classes. If the minimum size limit is intended to provide a respite from such mortality, a reconsideration of the utility of the minimum length regulation in the commercial harvest of red snapper may be warranted.

Red Snapper: Ecology and Fisheries in the U.S. Gulf of Mexico

2007 ◽  
Keyword(s):  
Gulf Of Mexico ◽  
Red Snapper ◽  
Lutjanus Campechanus ◽  
Nursery Areas ◽  
Side Scan Sonar ◽  
Bathymetric Data ◽  
Habitat Effect ◽  
Inner Continental Shelf ◽  
The U.S ◽  
Trawl Surveys

<em>Abstract.</em>—Trawl surveys were conducted to measure patterns of habitat use by newly settled red snapper <em>Lutjanus campechanus </em>at three natural banks on the inner continental shelf of Texas. Digital side-scan sonar and multibeam bathymetric data were used to define inshore (mud), ridge (shell), and offshore (mud) habitats for Freeport Rocks, Heald Bank, and Sabine Bank. Otter trawls were conducted July through September in 2003 (Heald Bank, Sabine Bank) and in 2004 (Freeport Rocks) during the settlement period of red snapper. Freeport Rocks had markedly higher densities of red snapper (91 ha<sup>⁻1</sup>) in 2004 than Heald Bank (6 ha<sup>⁻1</sup>) or Sabine Bank (<1 ha<sup>⁻1</sup>) in 2003. A significant habitat effect was observed at Heald Bank and densities were higher at offshore mud habitats; no habitat effect was detected for Freeport Rocks or Sabine Bank. Growth rates varied from 0.86 mm‧d<sup>⁻1</sup> at Sabine Bank up to 1.12 mm‧d<sup>⁻1</sup> at Freeport Rocks, and rates were higher on inshore and offshore mud than ridge habitats. Otolith-based estimates of age indicated that settlers were first detected at 22–28 d and the majority of individuals were 30–60 d. Hatch dates peaked from early June to early July in both 2003 and 2004. Results from this study indicate that both shell and inshore and offshore mud habitats associated with these natural banks serve as settlement habitat of red snapper, and all three habitats have the potential to function as nursery areas of this species.

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