Three low-relief banks (Heald Bank, Sabine Bank, Freeport Rocks) in the
northwestern Gulf of Mexico were evaluated as lane snapper (Lutjanus synagris
Linnaeus, 1758) nursery habitat. Trawl surveys were conducted in three habitat types
(inshore mud, shell ridge, offshore mud), designated by side-scan sonar surveys, to
determine patterns of distribution and abundance. Heald Bank and Sabine Bank were
trawled in 2003 while Freeport Rocks was trawled in 2000 (Freeport A) and 2004
(Freeport B). Density of lane snapper was higher on Sabine Bank (20.8 ± 2.8 ind ha-1)
than on Heald Bank (1.1 ± 0.4 ind ha-1), Freeport A (12.7 ± 2.3 ind ha-1) or Freeport B
(3.0 ± 1.0 ind ha-1). Habitat-specific differences in density were observed, although
patterns were not consistent among banks. Highest densities of lane snapper were found
on Heald Bank’s offshore habitat (1.7 ± 1.0 ind ha-1), Sabine Bank’s ridge habitat (26.5
± 6.9 ind ha-1), and on the inshore habitat of Freeport A and B (17.6 ± 4.9 ind ha-1 and
4.8 ± 3.6, respectively). Otolith microstructure analysis was performed on lane snapper
collected in trawl surveys to determine age, hatch-date distribution, growth and mortality
of new recruits. Hatch dates ranged from May 1 to August 31, peaking in June for
Freeport (A and B) and in July for Heald Bank and Sabine Bank. Growth rates varied from 0.90 mm d-1 at Heald Bank to 1.27 mm d-1 at Sabine Bank, and rates were highest
on the ridge habitat of Sabine Bank (1.31 mm d-1). Mortality of post-settlement lane
snapper was higher on Sabine Bank (15.2% d-1; Z = 0.165), than on Freeport A (9.2% d-
1; Z = 0.097), and was greatest on the ridge habitat of Sabine Bank (24 % d-1; Z = 0.275).
Recruitment potential (G : Z), evaluated on habitats at Sabine Bank, was highest on the
offshore habitat, with a value greater than 1.0, indicating higher potential contribution to
the adult population. Results indicate Heald Bank, Sabine Bank, and Freeport Rocks all
serve as settlement habitat of lane snapper, which appear to be capable of successful
settlement across a variety of habitats and banks.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1391 |
| Date | 15 May 2009 |
| Creators | Mikulas, Joseph John |
| Contributors | Rooker, Jay R. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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