Progress 03/25/14 to 02/28/19
Outputs
Target Audience:Fisheries Scientists and Fisheries Managers of NOAA's National Marine Fisheries Service and Florida's Fish and Wildlife Conservation Commission; representative of the Gulf States Marine Fisheries Commission and the Atlantic States Marine Fisheries Commission; state and local artificial reef program managers, in Florida, the southeastern US and nationally. Changes/Problems:As previously noted, low gag abundances followed major red tide events and required changes in sampling methods for Objective 2. However, this did not change the objective itself. What opportunities for training and professional development has the project provided?Graduate and undergraduate students participated in field work and data processing to gain practical experience in the execution of sampling protocols for fisheries research. How have the results been disseminated to communities of interest?Semi-annual progress reports and a final report have been submitted to and approved by NOAA Fisheries, while findings were shared with representatives of all target audiences at national symposia of the American Fisheries Society (AFS). What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
This project (1) contributes to the development of fishery-independent indices of gag abundance, and (2) examines a bottleneck hypothesis for juvenile gag on the shallow continental shelf of the northeastern Gulf of Mexico. With respect to (1), the SEDAR 33 - Gulf of Mexico Gag Stock Assessment Report (SEDAR 2014) included this recommendation from the Review Workshop: "Further investigation into the robustness of the design of the [FWRI/NMFS] video surveys should also be carried out in relation to coverage of the stock and density-dependent selection of habitats" (SEDAR 33 SAR Section V, p. 16; document p. 595). The MARFIN project reported here demonstrates why that recommendation is consequential and offers a complementary approach to fisheries-independent indices of abundance for some reef fishes, with gag as a model system. The strong expression of density-dependent habitat selection (DDHS) by gag (Lindberg et al. 2006) and MacCall's (1990) Basin Model (i.e. stock distribution changes as a function of stock size) together provide the basis for potentially accurate and sensitive fisheries-independent indices. This project advanced toward that potential by extending three data time-series to 15 and 10 years for juvenile gag, particularly ages 1-4, and demonstrating the utility of controlling habitat quality during fisheries independent sampling for this transitional life history stage. On the shallow continental shelf of the northeastern Gulf of Mexico, the intrinsic habitat quality sought by juvenile gag was controlled and contrasted in reef systems of replicate standardized habitat units (SHUs). Annually, scientific divers used a standardized underwater visual census (UVC) to count gag in size classes on the replicate SHUs. The data time-series were analyzed with Bayesian hierarchical negative binomial models to examine expectations derived from the logic of MacCall's Basin Model and knowledge of gag behavior. As expected, the observed trends in gag abundance from 2001 to 2016 depended on the intrinsic habitat qualities of the replicate sampling locations: (a) When the stock was declining, the decrease in observed abundance was greater in lower quality habitat than in higher quality habitat, and conversely (b) when the stock began recovering, the increase in observed abundance was slower in lower quality habitat than in higher quality habitat. Because of gag shoaling behavior, which presumably is an adaptation to manage predation risk along with shelter seeking, we also found that (c) the dispersion of gag among the higher quality reefs remained relatively low and stable during stock declines, while conversely the dispersion among lower quality reefs increased during stock declines (i.e., more lower quality reefs with zero or few gag and few such reefs with many gag). Two events of consequence, namely the "red tide" episodic natural mortality of 2005 and the exceptionally strong Age-0 year classes from 2007 to 2010, allowed us to establish (a), (b) and (c) with the fishery-independent surveys of SHUs. Consistent with the assumption of an ideal free distribution implicit in virtually all non-spatial population models, we also found that (d) geographically distinct reef systems of identical intrinsic habitat quality achieved equilibrium in the abundance of gag. A third event of consequence, namely the placement of 500 "conservation reefs" within the 100 sq. mi. Steinhatchee Fisheries Management Area (SFMA), allowed us to examine the assumption of stationarity in habitat availability that is implicit in most fisheries-independent sampling designs. We found that (e) regional increases in reef habitat availability (i.e. large-area artificial reef projects) could cause the observed abundance of gag at adjacent sampling sites to decline, despite increases in overall stock abundance. Lastly, a fourth event of consequence, the 2014 red tide in the northeastern Gulf of Mexico, allowed us to reconfirm (a), (b) and (c), as well as infer that stochastic strong year classes of gag are temporally lagged from red tide events. With respect to (2), artificial reefs remain very popular with anglers in the southeastern US because of their socio-economic benefits, yet artificial reefs are not used as tools in the direct management of targeted fishery stocks. One application of ecologically designed reef systems, like the SFMA, might be to alleviate life history bottlenecks due to habitat-mediated, density-dependent growth and mortality, particularly for juveniles of reef fishes like gag. This project attempted to test if that was plausible, but our results were inconclusive. The necessary conditions for a proper test unfortunately did not exist during the study period, owing to a 2014 red tide that directly affected the study region. Density-dependent processes require adequate densities to manifest measurable responses. Given the depressed gag densities and consequent low sample sizes, gag growth did not differ within and outside the SFMA; mortality was slightly higher within, yet so too were some measures of fish condition. These results were too equivocal to draw a credible conclusion. These findings advanced the science on which more precise fisheries independent indices of abundance can be based. In particular, the logic of MacCall's (1990) Basin Model applied to a gag was clearly corroborated over a period of changing stock abundance. The results of this project have important and obvious implications for the design and analyses of fisheries independent reef fish surveys, whether on natural hard-bottom habitats or SHUs. For example: Fisheries-independent sampling designs must be stratified on species-specific intrinsic habitat quality, either measured or controlled at appropriate spatial scales. Indices of abundance derived by comparing relatively lower quality to higher quality habitat might be highly sensitive to changes in overall stock abundance. The interaction of intrinsic habitat quality and shoaling behavior must be considered in the design and analyses of fisheries-independent reef fish surveys. The assumption of stationarity in habitat availability needs to be critically examined when analyzing fisheries-independent reef fish survey data. These findings, while inconclusive with respect to enhanced growth and survival of juvenile gag, also have implications for the application of ecologically designed artificial reefs as tools for fisheries management. Clearly, MacCall's Basin model applies to this study system. Therefore, one would expect the underlying density-dependent processes to be operating, even though conditions during this study were not favorable for clearly measuring those effects.
Publications
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Progress 10/01/17 to 09/30/18
Outputs
Target Audience:Fisheries Scientists and Fisheries Managers of NOAA's National Marine Fisheries Service and Florida's Fish and Wildlife Conservation Commission; representative of the Gulf States Marine Fisheries Commission and the Atlantic States Marine Fisheries Commission; state and local artificial reef program managers, in Florida, the southeastern US and nationally. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?Semi-annual progress reports and a final report have been submitted to and approved by NOAA Fisheries, while findings were shared with representatives of all target audiences at a national symposium of the American Fisheries Society (AFS) held in Atlantic City,NJ in August 2018. What do you plan to do during the next reporting period to accomplish the goals?One or two manuscripts will be drafted and submitted for publication in the peer-reviewed scientific literature.
Impacts
What was accomplished under these goals?
This project (1) contributes to the development of fishery-independent indices of gag abundance, and (2) examines a bottleneck hypothesis for juvenile gag on the shallow shelf of the northeastern Gulf of Mexico. For the first contribution, this project: (a) demonstrates the utility of controlling habitat quality at sampling sites, (b) fills-in a life history gap among fisheriesindependent surveys that existed when this effort began, (c) evaluates the effect of shoaling behavior on the dispersion of gag counts among sampling sites and (d) examines implicit assumptions of fisheries-independent reef fish surveys. Longestablished, standardized habitat units (SHUs) of two contrasting intrinsic habitat qualities were sampled annually (2001- 2016) by underwater visual census (UVC). As predicted from MacCall's (1990) Basin Model, the observed trends in gag abundance were functions of intrinsic habitat quality. Replicate SHUs of relatively lower quality showed changes in gag abundance as the Gulf of Mexico gag stock declined after a 2005 red tide event on the west-central Florida shelf (mean abundances = 21 gag/SHU in 2001, 20/SHU in 2005, 5/SHU in 2011 and 7/SHU in 2013; but then 16/SHU in 2016, all rounded to nearest integer). By comparison, SHUs of relatively higher quality were less sensitive to stock decline and more sensitive to stock recovery (mean abundances = 49 gag/SHU in 2001, 28/SHU in 2005, 32/SHU in 2010 and 27/SHU in 2013; but then a drop to 9/SHU in 2015 and recovery to 24/SHU in 2016). Notable changes in gag abundance in 2015 and 2016 are attributed to a regional red tide in 2014 that directly affected all of the reef systems in this project. Another system of SHUs placed in 2005 brackets the Florida Big Bend and was sampled by UVC for 10 years (2007-2016). By 2009, gag abundance on this reef system was the same as inshore SHUs of the same habitat quality (mean abundances = 11/SHU in 2009 and 6/SHU in 2011). That regional equilibrium persisted through 2011. A large-area artificial reef project altered the regional availability of juvenile gag habitat in 2011 and the reef systems previously in equilibrium diverged during 2012-2014. The regional red tide of 2014 caused the mean counts of gag to drop in all 3 reef systems and the frequencies of zero-gag-perreef to increase. An age-length key was applied to the UVC-generated annual size-frequency distributions for each monitored reef system. Recovery of gag abundances following each red tide was primarily attributed to Age-0 and Age-1 juveniles, rather than recolonization by older gag. Implications of these findings for fishery-independent reef fish surveys are briefly discussed, as are recommendations for next steps in this program. To examine the bottleneck hypothesis, gag were sampled within and outside the Steinhatchee Fisheries Management Area (SFMA), which was enhanced with 500 SHUs expected to improve juvenile gag growth and survival. Results were equivocal. No differences were found in measures of growth, though with some indication of better condition within the SFMA. Meanwhile, mortality was slightly higher within the SFMA. The bottleneck hypothesis was based on an expectation of habitat-mediated, density-dependent growth and mortality. Unfortunately, this project occurred while regional abundances of gag became depressed, so circumstances did not allow a definitive test.
Publications
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Progress 10/01/16 to 09/30/17
Outputs
Target Audience:Fisheries Scientists and Fisheries Managers of NOAA's National Marine Fisheries Service and Florida's Fish and Wildlife Conservation Commission; representative of the Gulf States Marine Fisheries Commission and the Atlantic States Marine Fisheries Commission; state and local artificial reef program managers, in Florida, the southeastern US and nationally. Changes/Problems:As previously noted, low gag abundances followed major red tide events and required changes in sampling methods for Objective 2. However, this did not change the objective itself. What opportunities for training and professional development has the project provided?Graduate and undergraduate students participating in field work and data processin gained practical experience in the execution of sampling protocols for fisheries research. How have the results been disseminated to communities of interest?Semi-annual progress reports and a final report have been submitted to and approved by NOAA Fisheries, while findings were shared with representatives of all target audiences at a national symposium of the American Fisheries Society (AFS) held in Tampa, FL in August 2017. What do you plan to do during the next reporting period to accomplish the goals?One or two manuscriptswill be drafted and submitted for publication in the peer-reviewed scientific literature.
Impacts
What was accomplished under these goals?
This project (1) contributes to the development of fishery-independent indices of gag abundance, and (2) examines a bottleneck hypothesis for juvenile gag on the shallow shelf of the northeastern Gulf of Mexico. For the first contribution, this project: (a) demonstrates the utility of controlling habitat quality at sampling sites, (b) fills-in a life history gap among fisheries-independent surveys that existed when this effort began, (c) evaluates the effect of shoaling behavior on the dispersion of gag counts among sampling sites and (d) examines implicit assumptions of fisheries-independent reef fish surveys. Long-established, standardized habitat units (SHUs) of two contrasting intrinsic habitat qualities were sampled annually (2001-2016) by underwater visual census (UVC). As predicted from MacCall's (1990) Basin Model, the observed trends in gag abundance were functions of intrinsic habitat quality. Replicate SHUs of relatively lower quality showed changes in gag abundance as the Gulf of Mexico gag stock declined after a 2005 red tide event on the west-central Florida shelf (mean abundances = 21 gag/SHU in 2001, 20/SHU in 2005, 5/SHU in 2011 and 7/SHU in 2013; but then 16/SHU in 2016, all rounded to nearest integer). By comparison, SHUs of relatively higher quality were less sensitive to stock decline and more sensitive to stock recovery (mean abundances = 49 gag/SHU in 2001, 28/SHU in 2005, 32/SHU in 2010 and 27/SHU in 2013; but then a drop to 9/SHU in 2015 and recovery to 24/SHU in 2016). Notable changes in gag abundance in 2015 and 2016 are attributed to a regional red tide in 2014 that directly affected all of the reef systems in this project. Another system of SHUs placed in 2005 brackets the Florida Big Bend and was sampled by UVC for 10 years (2007-2016). By 2009, gag abundance on this reef system was the same as inshore SHUs of the same habitat quality (mean abundances = 11/SHU in 2009 and 6/SHU in 2011). That regional equilibrium persisted through 2011. A large-area artificial reef project altered the regional availability of juvenile gag habitat in 2011 and the reef systems previously in equilibrium diverged during 2012-2014. The regional red tide of 2014 caused the mean counts of gag to drop in all 3 reef systems and the frequencies of zero-gag-per-reef to increase. An age-length key was applied to the UVC-generated annual size-frequency distributions for each monitored reef system. Recovery of gag abundances following each red tide was primarily attributed to Age-0 and Age-1 juveniles, rather than recolonization by older gag. Implications of these findings for fishery-independent reef fish surveys are briefly discussed, as are recommendations for next steps in this program. To examine the bottleneck hypothesis, gag were sampled within and outside the Steinhatchee Fisheries Management Area (SFMA), which was enhanced with 500 SHUs expected to improve juvenile gag growth and survival. Results were equivocal. No differences were found in measures of growth, though with some indication of better condition within the SFMA. Meanwhile, mortality was slightly higher within the SFMA. The bottleneck hypothesis was based on an expectation of habitat-mediated, density-dependent growth and mortality. Unfortunately, this project occurred while regional abundances of gag became depressed, so circumstances did not allow a definitive test.
Publications
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Progress 10/01/15 to 09/30/16
Outputs
Target Audience:Fisheries Scientists and Fisheries Managers of NOAA's National Marine Fisheries Service and Florida's Fish and Wildlife Conservation Commission; representative of the Gulf States Marine Fisheries Commission and the Atlantic States Marine Fisheries Commission; state and local artificial reef program managers, in Florida, the southeastern US and nationally. Changes/Problems:As noted in the Accomplishments section, low gag abundances following major red tide events required a change in sampling methods for Objective 2. However, this does not change the objective itself. What opportunities for training and professional development has the project provided?Graduate and undergraduate students participating in the field work and data processing gained practical experience in the execution of sampling protocols for fisheries research. How have the results been disseminated to communities of interest?Semi-annual progress reports have been submitted to NOAA Fisheries, while findings to date were shared with representatives of all target audiences at the National Artificial Reef Workshop held in Arlington VA in June 2016. What do you plan to do during the next reporting period to accomplish the goals?Data analyses should be completed and the final project report to NOAA Fisheries should be drafted.
Impacts
What was accomplished under these goals?
The 2016 sampling and data entry for Objective 1.1 was entirely completed within this reporting period, extending the time-series of data to 15 years. Likewise, the 2016 sampling and data entry for Objective 1.2 was entirely completed within this reporting period, extending this time-series of data to 10 years. Statistical analyses of the time-series of data from Objectives 1.1 and 1.2 have been updated annually using Bayesian hierarchical negative binomial models. Overall, that update analysis supported inferences about: (1) the effect of habitat quality on trends in abundance from fishery-independent monitoring, (2) exceptionally strong year classes in 2007-2010 likely buffering the higher quality reefs from a decline following the 2005 red tide mortality, (3) a regional equilibrium between inshore and offshore reefs of equal habitat quality during 2009-2011, when "all other things were equal", (4) an apparent shadow effect in the offshore reefs following the 2012 deployment of "conservation reefs" in the Steinhatchee Fisheries Management Area, and (5) an unequivocal regional decline in gag abundance following the 2014 red tide. The original statement of work for Objective 2outlined a tag and recapture methodology to sample the potential differential growth and mortality of gag in areas within the SFMA and in reference areas outside of the SFMA (Objectives 2.1 and 2.2, respectively). Based on sampling in the Summers of 2014 and 2015, however, tagging and recapturing gag in these areas has been extremely limited due to the low abundance of gag in the area. This decrease in abundance in the study area has been primarily due to the presence of a large, red tide in the area during 2014. Given this unexpected limitation, we changed the methodology associated with the growth and mortality portion of the study in order to accomplish the original objectives. We are now using primarily spearfishing, as well as traps and hook-and-line sampling, to sample gag within and outside of the SFMA. We are obtaining an overall count of gag on all sites sampled within and outside of the SFMA using either divers or submersible rotating video (SRV) systems.Data from sampling for Objectives 2.1 and 2.2 have not yet been analyzed for Objective 2.3.
Publications
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Progress 10/01/14 to 09/30/15
Outputs
Target Audience:Professional staff members of the Florida Fish and Wildlife Conservation Commission and NOAA Fisheries were apprised of the progress and results to date, as pertinent to State and Federal fisheries management. Changes/Problems:As noted above, an extensive red tide outbreak in the summer of 2014 resulted in fish kills within the study region and curtailed some sampling in 2014 and 2015. This natural event effectively reset the colonization clock for the reef community within the Steinhatchee Fisheries management area, thereby extending the time for expected effects to be manifested. What opportunities for training and professional development has the project provided?Graduate students participating in the field work and data processing gained practical experience in the execution of sampling protocols for fisheries research. How have the results been disseminated to communities of interest?In addition to progress reports submitted to NOAA Fisheries, progress and findings to date were also reported through presentations for state and federal agency staff at a Florida reef summit in January 2015 and a reef fish survey and habitat workshop in March 2015. What do you plan to do during the next reporting period to accomplish the goals?The sampling schedule for objectives 1 and 2 will continue through 2016, with analyses updated as warranted. In addition, findings and implications will be discussed with state and federal agency staff and other stakeholders at a regional symposium and national reef workshop.
Impacts
What was accomplished under these goals?
For objective 1.1, the standardized annual sampling was completed on all 48 replicate reefs on the 13-m depth contour. For objective 1.2, all 40 replicate reefs along the 20-m depth contour were sampled. Several sampling trips were also conducted toward objectives 2.1 and 2.2. However, sampling was curtailed because of very low grouper catches due to a persistent and widespread red tide outbreak in the northeastern Gulf of Mexico the prior year, which resulted in extensive fish kills in the study region. For objective 1.3, the time-series of data from 2001 through 2015 were analyzed by a Bayesian negative binomial hirearchical model, the results of which were subsequently reported to NOAA Fisheries.
Publications
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Progress 03/25/14 to 09/30/14
Outputs
Target Audience: Professional staff members of the Florida Fish and Wildlife Conservation Commission andNOAA Fisheries were apprised of the progress and results to date, as pertinent to State and Federal fisheries management. Changes/Problems: As noted above, an extensive red tide outbreak in the summer of 2014 resulted in fish kills within the study region and curtailed sampling because of hazardous conditions for the field crews. This natural event will effectively reset the colonization clock for the reef community within the Steinhatchee Fisheries management area, thereby extending the time for expected effects to be manifested. What opportunities for training and professional development has the project provided? Graduate students participating in the field work and data processing gained practical experience in the execution of sampling protocolsfor fisheries research. How have the results been disseminated to communities of interest? In addition to progress reports submitted to NOAA Fisheries, progress and findings to date were also reported through presentations at the Gulf and Carribean Fisheries Institute and the Florida Chapter American Fisheries Society meetings. What do you plan to do during the next reporting period to accomplish the goals? The sampling schedule for objectives 1 and 2 will continue through 2015, with analyses updated as warranted. In addition, findings and implications will be discussed with state and federal agency staff and other stakeholders at a Florida reef summit in January 2015 and a reef fish survey and habitat workshop in March 2015.
Impacts
What was accomplished under these goals?
For objective 1.1, the standardized annual sampling was completed on all 48 replicate reefs on the 13-m depth contour. For objective 1.2, 32 of 40 replicate reefs along the 20-m depth contour were sampled before conditions deteriorated. Several sampling trips were alsoconducted toward objectives 2.1 and 2.2.However, sampling was curtailed because of a persistent and widespread red tide outbreak in the northeastern Gulf of Mexico, which resulted in extensive fish kills and hazardous conditions for project personnel in the study region. For objective 1.3, the time-series of data from 2001 through 2013 were analyzed by a Bayesian negative binomial hirearchical model, the results of which were subsequently reported to NOAA Fisheries.
Publications
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