Progress 10/01/04 to 09/30/10
Outputs
OUTPUTS: Project activities carried out from 2004 to 2010 included 6 laboratory experiments and 9 experiments in offshore waters concerning reef fish ecology in the northern Gulf of Mexico. These experiments included 6 manipulative studies, 8 surveys, 2 tagging studies, and 1 assessment of coastal marine fishes. All of the research in this project involved graduate students that have completed 4 MS and 2 PhD degrees through Auburn University. Project events included 28 conference presentations, extensive graduate training, and more than 400 offshore field days. Products included the design and study of a standard artificial reef that is used for early-life-history ecological studies, set up and establishment of an experimental telemetry system for fish mortality and movement studies, the setup and establishment of a standard fishery independent stock assessment protocol, and an important and new method of aging young fishes through computer counting and shape analyses. Product results were disseminated to large audiences through web site publications, newspaper articles (two front page stories in Mobile Press Register), seminars at fisher meetings, and various civic groups (e.g., Sertoma and Kiwanis clubs). PARTICIPANTS: Partner organizations that provided financial support: NOAA, NMFS, MARFIN program. NOAA, Sea Grant program Alabama Department of Conservation and Natural Resources, Marine Resources Division Graduate Students that received training and advanced degrees: Darin Topping (PhD), Carrie Simmons (PhD) Sabrina Beyer (MS), Dianna Miller (MS), Rebecca Redman (MS), Allison Chapin (MS) TARGET AUDIENCES: Target audiences include the entire coastal community that has interest in the wellbeing of coastal marine resources, especially fishery exploitation, ecology of marine systems, life history and biology of important marine resources, and the general care and understanding of human impacts on marine systems. These audiences cross all economic and social barriers, racial differences, age differences, educational backgrounds, and geographic locations. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Movement and survival studies of hatchery reared red snapper showed that fish stayed and survived on artificial habitats for extended periods (more than 1 year), and showed that stocking of hatchery reared fish could be successful. A significant finding was that survival was related to habitat provided to newly stocked fish. A critical question concerning reef habitat is the contribution of food from the structured habitat versus that derived from open habitats. To examine this aspect we deployed reefs that were coated with a copper based paint to prevent epifaunal growth and compared them to non-painted reefs. There were significantly more fishes and invertebrates on non-painted compared to painted reefs. Most important marine fishes are open water spawners that provide no parental care. In this project we discovered an exception in gray triggerfish, which showed unique spawning behavior, elaborate courtships, territoriality, and parental care of the eggs. These unique patterns need to be considered in management, e.g., if you remove a single dominant male, this may affect the spawning of several females. Also, competitive interactions were shown between gray triggerfish and red snapper, where aggressive gray triggerfish reduced red snapper abundance. Fish age is one of the most important parameters that biologist measure. However early life stages of red snapper are difficult to age. We developed new methods of otolith shape analyses to age young red snapper. This new method could provide help in the aging this important species. Mortality estimates of red snapper are extremely important in stock assessments, but most estimates are based on many assumptions, and mortality estimates have received substantial criticisms. In this project we applied a new approach of mortality estimations with ultrasonic telemetry. The newly developed methods provided a substantial increase in the accuracy of mortality estimates, which will benefit management and stock assessments for this species. The early life history stages of marine fishes are important in determination of later year class strengths, but difficult to study because of their cryptic nature. We developed a new artificial "sampling" reef specifically designed to examine early life stages of reef fishes. These studies have shown high mortality rates in the first months of life, which in turn have significantly affected stock assessments. The question of production or attraction of artificial reefs remains. One aspect that has not been studied is the affect of reef age on fish age. If reef age is correlated with fish age it would provide support for new production at artificial reefs. In this project, a significant correlation of reef age to red snapper age was shown and provides support that artificial reef construction was providing new habitat where fish stayed and grew older as the reef aged.
Publications
- Simmons, C.M., and Szedlmayer S.T. 2011. Recruitment of Age-0 Gray Triggerfish to Benthic Structured Habitat in the Northern Gulf of Mexico. Transactions of the American Fisheries Society (in press).
- Szedlmayer, S.T. 2011. The use of artificial habitats for estimating juvenile reef fish abundance. In S.A. Bortone (ed.). The use of artificial reefs in fishery management. Taylor and Francis, Boca Raton, FL, (in press).
- Szedlmayer, S.T., and Beyer, S.G. 2011. Validation of annual periodicity in otoliths of red snapper, Lutjanus campechanus. Environmental Biology of Fishes (in press).
- Beyer, S.G., and Szedlmayer, S.T. 2010. Otolith shape analysis and age determination of juvenile red snapper, Lutjanus campechanus. Environmental Biology of Fishes. 89: 333-340.
- Gallaway, B.J., Szedlmayer, S.T., and Gazey, W.J. 2009. A life history review for red snapper in the Gulf of Mexico with an evaluation of the importance of offshore petroleum platforms and other artificial reefs. Reviews in Fisheries Science. 17: 48-67.
- Chapin, A.M., Szedlmayer, S.T., and Phelps, R.P. 2009. Survival and movement of hatchery-reared red snapper on artificial habitats in the northern Gulf of Mexico. Fisheries Management and Ecology. 16: 28-36.
- Redman R.A., & S.T. Szedlmayer. 2009. The effects of epibenthic communities on reef fishes in the northern Gulf of Mexico. Fisheries Management and Ecology. 16:360-367.
- Szedlmayer, S.T. 2007. An evaluation of the benefits of artificial habitats for red snapper, Lutjanus campechanus, in the northeast Gulf of Mexico. Proceedings of the Gulf and Caribbean Fisheries Institute. 59: 223-230.
- MacKichan, C.A., and Szedlmayer, S.T. 2007. Reproductive behavior of the gray triggerfish, Balistes capriscus, in the northeastern Gulf of Mexico. Proceedings of the Gulf and Caribbean Fisheries Institute. 59: 231-236.
- Piko, A.A., and Szedlmayer, S.T. 2007. Effects of habitat complexity and predator exclusion on the abundance of juvenile red snapper. Journal of Fish Biology. 70: 758-769.
- Lingo, M.E., and Szedlmayer, S.T. 2006. The influence of habitat complexity on reef fish communities in the northeastern Gulf of Mexico. Environmental Biology of Fishes. 76: 71-80.
- Schroepfer, R.L., and Szedlmayer, S.T. 2006. Estimates of residence and site fidelity for red snapper on artificial reefs in the northeastern Gulf of Mexico. Bulletin of Marine Science. 78(1): 93-101.
- Szedlmayer, S.T., and Schroepfer, R.L. 2005. Long-term residence of red snapper on artificial reefs in the northeastern Gulf of Mexico. Transactions of the American Fisheries Society. 134: 315-325.
- Szedlmayer, S.T., and Lee, J.D. 2004. Diet shifts of red snapper, Lutjanus campechanus, with changes in habitat and fish size. Fishery Bulletin. 102: 366-375.
- Simmons, C.M. 2008. Gray triggerfish, Balistes capriscus, reproductive behavior, early life history, and competitive interactions between red snapper, Lutjanus campechanus, in the northern Gulf of Mexico. Ph.D., Dissertation. Auburn University. 105 p.
- Miller, D.R. 2008. A comparison of fish and epibenthic assemblages on artificial reefs with and without copper-based anti-fouling paint. M.S., Thesis, Auburn University. 82 p.
- Beyer, S.G. 2008. Age determination through shape analysis and validation of otolith annular increments in red snapper, Lutjanus campechanus. M.S., Thesis, Auburn University. 53 p.
- Sutterer, R.A. 2005. A comparison of the fish communities between artificial reefs with and without epibenthic communities. M.S., Thesis, Auburn University. 46 p.
- Hruskoci, A. M. 2004. Survival and movement of hatchery-reared red snapper on artificial habitats in the northern Gulf of Mexico. M.S., Thesis, Auburn University. 59 p.
- Topping, D.T., and Szedlmayer. S.T. 2010. The use of ultrasonic telemetry to estimate natural and fishing mortality of red snapper, Lutjanus campechanus. MARFIN conference, Tampa, FL, April 2010.
- Mudrak, P.A., and Szedlmayer, S.T. 2010. Predator avoidance by age-0 red snapper Lutjanus campechanus, on artificial reefs in the northern Gulf of Mexico. Alabama Fisheries Association, Huntsville, AL, February 2010.
- Topping, D.T. and S.T. Szedlmayer. 2009. Use of telemetry methods to estimate mortality rates, residency, and movement patterns of red snapper, Lutjanus campechanus. American Society of Ichthyologists and Herpetologists, Portland, OR, July 2009.
- Szedlmayer, S.T. and S.G. Beyer. 2009. Validation of annual periodicity in otoliths of red snapper, Lutjanus campechanus. International Otolith Symposium, Monterey, CA, August 2009.
- Beyer, S.G. and S.T. Szedlmayer. 2009. Otolith shape analysis and age determination of juvenile red snapper (Lutjanus campechanus). International Otolith Symposium, Monterey, CA, August 2009.
- Topping, D.T. and S.T. Szedlmayer. 2009. Estimation of mortality rates, residency, and movement patterns of red snapper, Lutjanus campechanus using long-term ultrasonic telemetry data. American Fisheries Society, Nashville, TN, Sept 2009.
- Szedlmayer, S.T. 2009. The use of artificial habitats for estimating juvenile reef fish abundance. Conference on Artificial Reefs and Habitats, Curitiba, BR November 2009.
- Miller, D.R. and S.T. Szedlmayer. 2008. A comparison of fish and epibenthic assemblages on artificial reefs with and without copper-based antifouling paint. Conference on Artificial Reefs and Habitats, Curitiba, BR November 2009.
- Beyer, S.G. and S.T. Szedlmayer. 2008. Validation of annual periodicity and age estimation from shape analysis of otoliths from red snapper, Lutjanus campechanus. Gulf and Caribbean Fisheries Institute Meeting, Gosier, Guadeloupe, November 2008.
- Simmons, C.M. and S.T. Szedlmayer. 2008. Gray triggerfish, Balistes capriscus, reproductive behavior, early life history, and competitive interactions with red snapper, Lutjanus campechanus, in the northern Gulf of Mexico. Mississippi - Alabama Sea Grant Bays and Bayous Symposium Biloxi, MS, October 2008.
- MacKichan, C.A., and S.T. Szedlmayer. 2005. Preliminary observations of reproductive behavior in gray triggerfish, Balistes capriscus. Alabama Fisheries Association, Auburn University Jan. 2005.
- Sutterer, R.A., and S.T. Szedlmayer. 2005. A comparison of the fish communities between artificial reefs with and without epibenthic communities. Alabama Fisheries Association, Auburn University Jan. 2005.
- Szedlmayer, S.T., and D. Moss, M. Maceina. 2005. A fishery independent survey of red snapper, Lutjanus campechanus in the Gulf of Mexico. Alabama Fisheries Association, Auburn University Jan. 2005.
- Sutterer, R.A., and S.T. Szedlmayer. 2005.Comparisons of fish communities on artificial reefs with and without epibenthic communities. Conference on artificial reefs and artificial habitats, April 2005, Biloxi.
- MacKichan, C.A., and Szedlmayer, S.T. 2007. Reproductive behavior of the gray triggerfish, Balistes capriscus, in the northeast Gulf of Mexico. 87th Annual Meeting of the American Society of Ichthyologist and Herpetologists, July 2007, Saint Louis, Missouri.
- MacKichan, C.A., and Szedlmayer, S.T. 2006. Interactions between red snapper Lutjanus campechanus, and gray triggerfish Balistes capriscus, a laboratory and field study in the northeast Gulf of Mexico. Alabama Fisheries Association, Gulf Shores, February 2006.
- Schroepfer, R.L., and S.T. Szedlmayer. 2005. Long-term residence of red snapper on artificial reefs in the northeastern Gulf of Mexico. Conference on artificial reefs and artificial habitats, April 2005, Biloxi.
- Szedlmayer, S.T. 2005. Associations of red snapper Lutjanus campechanus, with artificial habitats and the evidence for production. Conference on artificial reefs and artificial habitats, April 2005, Biloxi.
- Szedlmayer, S.T. 2005. Evidence for production of red snapper Lutjanus campechanus, from artificial habitats. ASIH meeting, Tampa July 2005.
- Beyer, S.G. and S.T. Szedlmayer. 2008. Age determination through shape analysis and validation of otolith annular increments in red snapper, Lutjanus campechanus. Alabama Fisheries Association, Gulf Shores, February 2008. Miller, D.R. and S.T. Szedlmayer. 2008. A comparison of fish and epibenthic communities on artificial reefs with and without copper-based anti-fouling paint. Alabama Fisheries Association, Gulf Shores, February 2008.
- Simmons, C.M. and S.T. Szedlmayer. 2008. Gray triggerfish, Balistes capriscus, recruitment to artificial reefs in the northeastern Gulf of Mexico and gray triggerfish competitive interactions with red snapper, Lutjanus campechanus, in laboratory studies. Alabama Fisheries Association, Gulf Shores, February 2008.
- MacKichan, C.A., and Szedlmayer, S.T. 2007. Reproductive behavior of the gray triggerfish, Balistes capriscus, and interactions with red snapper, Lutjanus campechanus, in the northeast Gulf of Mexico. Alabama Fisheries Association, Gulf Shores, February 2007.
- Szedlmayer, S.T., and MacKichan, C.A. 2007. Interaction between gray triggerfish, Balistes capriscus, and red snapper, Lutjanus campechanus, in the northeast Gulf of Mexico. 87th Annual Meeting of the American Society of Ichthyologist and Herpetologists, July 2007, Saint Louis, Missouri.
- Redman, R.A., and S.T. Szedlmayer. 2006. A comparison of red snapper abundance between artificial reefs with and without epibenthic communities. Amer. Fish. Soc., South. Div. San Antonio TX. February 2006.
- MacKichan, C.A., and Szedlmayer, S.T. 2006. Reproductive Behavior of the Gray Triggerfish, Balistes capriscus, in the Northeastern Gulf of Mexico. November 2006.
- Szedlmayer, S.T. 2006. An evaluation of the benefits of artificial habitats for red snapper, Lutjanus campechanus, in the northeast Gulf of Mexico. November 2006.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Mortality rates for large (500 - 860 mm TL) red snapper Lutjanus campechanus (N = 87) were estimated with telemetry methods from December 2005 to October 2009 in the northeastern Gulf of Mexico. We released 87 fish, of these 70 remained at the site past a 7-d post-release recovery period, 19 were caught, 10 died naturally, and 28 emigrated from the 12.6 km2 study site. Estimates of total mortality (Z) ranged from 0.43 to 0.50, fishing mortality (F) from 0.30 to 0.38, and natural mortality (M) from 0.12 to 0.22. Annual fishing mortality reflected changes in fishing regulations (i.e. F decreased with lower total allowable catch). In 2006, F = 0.80; in 2007, F = 0.25; in 2008, F = 0.14; and in 2009, F = 0.14. Red snapper showed a median residence time of 588 d, ranging from 1 to 1020 d, with 76% of fish staying at least one year at the site. Several fish (N = 9) that emigrated showed directed movements to other sites (up to 8 km away), then returned to original sites after periods of time up to 7 months. Red snapper (N = 9) were also manually tracked over continuous 24-h periods. These red snapper stayed near (< 80 m) the artificial reef over the diel period (80% of locations within 30 m of the structure), but were significantly further from the reef at night (mean = 26.0 m) than day (mean = 16.1 m). In 2009 we compared fish recruitment to small "recruitment" reefs (n=10) that were 15 m from large cage reefs (n=10), to small reefs (n=10) that were 500 m from the large cage reefs. There were significantly (p < 0.05) higher abundances of age-0 red snapper on the small reefs placed 500 m (46.1/ m2 + 8.3) from the larger reefs compared to small reefs placed 15 m away (3.4/ m2 + 1.8) on all three surveys. We suggest that the typically larger fish (> 300 mm TL) of several species that occupied the larger reefs resulted in a predator avoidance response by the age-0 red snapper. The periodicity of otolith growth increments (opaque and translucent zones) from red snapper was examined through a mark and recapture study (2005-2009), and laboratory holding of hatchery reared red snapper over a two year period (2002-2004). Wild red snapper (n=295) were caught hook-and-line, marked with anchor tags, injected with oxytetracycline dihydrate (OTC), and released in the Gulf of Mexico 15-40 km south of Dauphin Island, Alabama. Marked fish were recaptured up to 2.8 years after release (n=33). The number of opaque growth zones past the OTC mark was compared to time at liberty for each fish and supported an annual periodicity of growth increment formation. Also, most (87%) of the hatchery reared fish showed two opaque zones that supported an annual increment formation rate. However, an unusual timing of opaque zone formation was shown for mark-recaptured fish. Based on known timing of OTC marking, otoliths from mark-recapture fish showed opaque zone formation from late summer (August) to early winter (December). This fall formation of opaque zones is in contrast to previous studies and its timing may relate to the end of spawning for this species. PARTICIPANTS: D. Topping Ph.D. Fisheries & Allied Aquacltrs Major Professor M. Piraino Master Fisheries & Allied Aquacltrs Major Professor T. S. Syc Master Fisheries & Allied Aquacltrs Major Professor G. Lipkey Master Fisheries & Allied Aquacltrs Major Professor P. A. Mudrak Master Fisheries & Allied Aquacltrs Major Professor TARGET AUDIENCES: This past year (2009) has been difficult for both commercial and sport coastal fishers (private & charter fleet). In this past year (2009), federal regulations on red snapper seasons and bag limits the NMFS restricted the season to just 2 months (June and July), based on NMFS model stock assessments. As stated in the past, our data and assessment don't agree with that model and we have consistently supported the contention that the red snapper fishery off coastal Alabama is a sustainable viable fishery. In that context, I have served the Gulf of Mexico Fishery Management Council on their Scientific and Statistical Committee (SSC). This committee meets about 3 or 4 times a year, and evaluates and makes recommendations to the Gulf Council on various fishery management plans that affect coastal fishers and communities. Under the new Magnuson-Stevens Fishery Conservation and Management Act, the Gulf Council is now required by law to follow their recommendations within certain limits. This past year I was able to get acceptance of higher mortality rates for age-0 red snapper from our studies at Auburn University. These new mortality rates have provided a more optimistic estimate of the red snapper stock and allowed an increase in total allowable catch for 2010. However, restrictions will still only provide modest increases in TAC and fishers will continue to suffer. In this context, I have published a review in "Reviews in Fisheries Science" that has provided a valid argument for the production of red snapper at artificial reef sites in the Gulf of Mexico. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The results for this project have been disseminated to communities of interest by presentations at five professional meeting in 2009: The annual meetings of the Alabama Fisheries Association, American Society of Ichthyologists and Herpetologists, American Fisheries Society, International Otolith Symposium, and Conference on Artificial reefs and Habitats. Information has also been disseminated through final grant report requirements of the MARFIN program of the National Marine Fisheries Service, NOAA. Reports have also been provided to the Marine Resources Division, Alabama Department of Conservation and Natural Resources, and findings have been presented to the general public through presentations at the Mobile Boat Show, and The Saltwater Sportsmans Association, Mobile, Alabama.
Publications
- Redman, R.A., and S.T. Szedlmayer. 2009. The effects of epibenthic communities on reef fishes in the northern Gulf of Mexico. Fisheries Management and Ecology. 16:360-367.
- Topping, D.T. 2009. The use of ultrasonic telemetry to estimate residency, movement patterns, and mortality of red snapper, Lutjanus campechanus. Ph.D., Dissertation, Auburn University, Auburn AL. 53 pp.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: The results for this project have been disseminated to communities of interest by presentations at three professional meeting in 2008: The annual meetings of the Alabama Fisheries Association, the Gulf and Caribbean Fisheries Institute, and the Sea Grant Bays and Bayous Symposium. Information has also been disseminated through 6-month and 12-month grant report requirements of the MARFIN program of the National Marine Fisheries Service, NOAA, and a final report to the Mississippi Alabama Sea Grant program, NOAA. Reports have also been provided to the Marine Resources Division, Alabama Department of Conservation and Natural Resources, and findings have been presented to the general public through presentations at the Mobile Boat Show, and The Saltwater Sportsmans Association, Mobile, Alabama. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We examined recruitment periodicity for gray triggerfish, Balistes capriscus, through fish counts on experimental habitats in the northern Gulf of Mexico. Peak recruitment of age 0 gray triggerfish occurred from Sep to Dec. Significantly more age 0 gray triggerfish versus age 1 fish were found on reefs in the Fall. We tested for competition between gray triggerfish and red snapper, Lutjanus campechanus in the laboratory through growth rate comparisons. Red snapper showed significantly faster growth rates in the absence of gray triggerfish, and suggested that competitive interactions between these two species do occur even when food was not limited. We used ultrasonic telemetry to estimate movements and mortality of red snapper. At six habitats we placed a VR2 remote receiver, each of which were encircled by four additional receivers evenly placed 1100 m from the reef. All receivers were retrieved, downloaded and replaced every few months. During receiver changes, we completed SCUBA visual surveys for tagged red snapper at the release sites. We have tagged and released a total of 100 red snapper with ultrasonic transmitters. All tagged fish ranged in size from 500-860 mm TL (mean=639 mm TL), and 1.9-13.0 kg (mean=4.6 kg). We manually tracked 7 red snapper at another reef site without remote receivers over a 24 h period (position fixes at 15 min intervals). Wide area surveys were completed around three reef sites. We compared fish recruitment to small "recruitment" reefs (n=10) that were 15 m from large cage reefs (n=10), to small reefs (n=10) that were 500 m from the large cage reefs. We completed 30 SCUBA fish surveys on all habitats. Age-0 red snapper were completely absent from the 15 m reefs and averaged 20 per reef on the 500 m reefs. These results clearly show that predators on the larger reefs affected recruitment of age-0 red snapper. The periodicity of otolith growth rings from adult red snapper was examined through a mark and recapture study. In 2005-2008, red snapper (n=251) were caught hook-and-line, injected with oxytetracycline, and released 15-40 km south of Dauphin Island, Alabama. Fish were recaptured up to 2.5 years after release (n=12). Sagittal otoliths were dissected, sectioned, and the number of growth rings past the OTC mark was compared to time at liberty of the fish. Results support an annual periodicity of growth ring formation, however, all recaptured fish were less than 10 years of age and validation of older red snapper (>10 years) is still needed. Otolith shape analysis was applied to otoliths taken from hatchery reared known-age red snapper. Shape analyses were able to distinguish among age-0, age-1 and age-2 otoliths. A discriminant function analysis showed an age classification success of 70% based on shape variables alone. The addition of otolith weight to the discriminant function increased classification success to 93%. Based on this data, otolith shape analysis is a potential new method for ageing young red snapper at least to age-2.
Publications
- Gallaway, B.J., S.T. Szedlmayer, and W.J. Gazey. 2009. A life history review for red snapper in the Gulf of Mexico with an evaluation of the importance of offshore petroleum platforms and other artificial reefs. Reviews in Fisheries Science. 17:48-67.
- Chapin, A.M., and S.T. Szedlmayer, R.P. Phelps. 2009. Survival and movement of hatchery-reared red snapper on artificial habitats in the northern Gulf of Mexico. Fisheries Management and Ecology. 16:28-36.
- Beyer S.A. 2008. Age determination through shape analysis and validation of otolith annular increments in red snapper, Lutjanus campechanus. Master's thesis, Auburn University, Auburn AL. 53 pp.
- Miller, D.A. 2008. A comparison of fish and epibenthic assemblages on artificial reefs with and without copper-based anti-fouling paint. Master's thesis, Auburn University, Auburn, AL. 82 pp.
- Simmons, C.M. 2008. Gray triggerfish, Balistes capriscus, reproductive behavior, early life history, and competitive interactions between red snapper, Lutjanus campechanus, in the northern Gulf of Mexico. Ph.D., dissertation, Auburn University, Auburn, AL. 105 pp.
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Progress 01/01/07 to 12/31/07
Outputs
The results for this project have been disseminated to communities of interest by presentations at two professional meeting in 2007: The annual meeting of the Alabama Fisheries Association, and the annual meeting of the American Society of Ichthyologists and Herpetologists. Information has also been disseminated through 6-month and 12-month grant report requirements of the MARFIN program of the National Marine Fisheries Service, NOAA, and the Mississippi-Alabama Sea Grant program, NOAA. Reports have also been provided to the Marine Resources Division, Alabama Department of Conservation and Natural Resources, and findings have been presented to the general public through presentations at the Mobile Boat Show, and The Saltwater Sportsmans Association, Mobile, Alabama.
Impacts
We examined recruitment periodicity through fish counts on experimental habitats in the northern Gulf of Mexico. Peak recruitment of age-0 gray triggerfish, Balistes capriscus, occurred from Sept. to Dec., with some recruiting as early as Aug. Significantly more age-0 gray triggerfish versus age-1 fish were found on reefs in the fall. In the laboratory, red snapper showed significantly faster growth rates in the absence of gray triggerfish, even when food was not limited. We used ultrasonic telemetry to estimate movement, mortality, and residency of red snapper Lutjanus campechanus. At five separate habitats we placed a center VR2 remote receiver, and encircled that with four additional receivers placed north, south, east, and west 1100 m from the center. All receivers have been retrieved, downloaded and replaced every few months. Thus far, 86 red snapper and been released with ultrasonic transmitters. Fish ranged in size from 407 to 720 mm SL
(mean = 517 mm SL), and 1.9 to 13.0 kg (mean = 4.6 kg). Many fish have shown residency for over 1 year. We have not confirmed any natural mortality, but fishing mortality was significant. We compared fish on artificial reefs with and without epibenthic communities. Artificial reefs (n = 60) were constructed in 20 m of water approximately 15 km south of Dauphin Island, Alabama. Half of the reefs (n = 30) were coated with copper-based anti-fouling paint and the other half were left unpainted. Fish and epibenthic communities were compared between reefs with and without the copper paint. We completed 6 SCUBA visual fish surveys on all of these artificial habitats. Overall, 35 different fish species were observed, with 25 species on unpainted reefs and 31 species on painted reefs. Red snapper, wrasse spp., gray triggerfish, pigfish, bank sea bass, rock sea bass, Blenniidae, and Atlantic spadefish showed significantly higher abundance on unpainted compared to painted reefs. These results
further support the contention that artificial reefs result in increased fish production not simply attraction. The periodicity of sagittal otolith growth rings from adult red snapper was examined through a mark and recapture study. In 2005-2007, red snapper (n=251) were captured and marked with oxytetracycline (OTC), then released 15-20 km south of Dauphin Island, Alabama. Four fish have been recaptured one year after release. Results supported annual ring formation. Otolith shape analysis was tested for possible age discrimination from hatchery reared known-age red snapper. Morphological shape indices of otoliths were able to distinguish among age-0, age-1 and age-2 red snapper. A discriminate function analysis and cross-validation showed an age classification success of 70% based on shape variables alone. The addition of otolith weight to the discriminate function increased age classification success to 93%.
Publications
- Piko, A.A. and S.T. Szedlmayer. 2007. Effects of habitat complexity and predator exclusion on the abundance of juvenile red snapper. Journal of Fish Biology. 70:758-769.
- Szedlmayer, S.T. 2007. An evaluation of the benefits of artifical habitats for red snapper, Lutjanus campechanus, in the northeast Gulf of Mexico. Proceedings of the Gulf and Caribbean Fisheries Institute. 59:223-230.
- MacKichan, C.A., and Szedlmayer, S.T. 2007. Reproductive behavior of the gray triggerfish, Balistes capriscus, in the northeastern Gulf of Mexico. Proceedings of the Gulf and Caribbean Fisheries Institute. 59:231-236.
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