Red Snapper Abundance, Growth, and Movement at Different Structural Configurations in the Rio Grande Valley Artificial Reef

The Rio Grande Valley (RGV) artificial reef was built with the goal of providing habitat for reef fish at various life stages. This study used fish trapping to analyze red snapper and grey triggerfish size and abundance in the RGV reef. Mark-recapture of red snapper was utilized to determine growth, movement, and site fidelity within the reef. Nine configurations of patches consisting of varying combinations and densities of concrete pyramids and low-profile modules were surveyed, as well as additional sites of cinder block palettes and concrete railroad ties. Red snapper and triggerfish abundance per trap hour varied significantly by site type. Red snapper total length and triggerfish fork length were significantly smaller at low-profile cinder block platforms compared to mixed sites and pyramid sites. A recreational tagging study yielded a 9.7% return rate. Growth rates for recaptured red snapper within the RGV reef were 0.234 mm/day and 1.207 g/day

Occurrence and Behavior of Juvenile Red Snapper, Lutjanus campechanus, on Commercial Shrimp Fishing Grounds in the Northeastern Gulf of Mexico

Red snapper, Lutjanus campechanus, is subject to significant overfishing in U.S. Gulf of Mexico waters, and regulations are being implemented to reduce fishing mortality and restore them to a 20% spawning potential ratio by the year 2009. One source of mortality that must be reduced to achieve this goal is the incidental capture ofjuvenile red snappers in shrimp, Penaeus spp., trawls. NOAA's National Marine Fisheries Service is conducting research to develop shrimp trawl modifications to reduce the snapper bycatch. An important part of this research is the study of juvenile red snapper behavior on commercial shrimp grounds and in relation to trawling gear. An area of high juvenile red snapper abundance was identified off the coast of Mississippi. Most snappers were observed around structures or objects on the bottom which they appeared to use for refuge or orientation. Those ranging over barren bottom had no apparent point of orientation. When encountered by shrimp trawls, most juvenile snappers rose above the trawl footrope and fell back into the trawl. These observations have directed research toward modifying shrimp trawls to release juvenile red snappers after entry, rather than preventing them from entering a shrimp trawl

Red Snapper Distribution on Natural Habitats and Artificial Structures in the Northern Gulf of Mexico

In 2011, an intensive, multiple-gear, fishery-independent survey was carried out in the northern Gulf of Mexico (GOM) to collect comprehensive age and length information on Red Snapper Lutjanus campechanus. Based on this synoptic survey, we produced a spatial map of Red Snapper relative abundance that integrates both gear selectivity effects and ontogenetically varying habitat usage. Our methodology generated a spatial map of Red Snapper at a 10-km2 grid resolution that is consistent with existing knowledge of the species: Red Snapper occurred in relatively high abundances at depths of 50–90 m along the coasts of Texas and Louisiana and in smaller, patchy “hot spots” at a variety of depths along the Alabama coast and the west Florida shelf. Red Snapper biomass and fecundity estimates were higher for the northwestern GOM than for the northeastern GOM, as the latter area contained mostly smaller, younger individuals. The existence of similar surveys on petroleum platforms and artificial reefs also enabled us to calculate their relative contribution to Red Snapper distribution compared with that of natural habitats.We estimated that for the youngest ageclasses, catch rates were approximately 20 times higher on artificial structures than on natural reefs. Despite the high catch rates observed on artificial structures, they represent only a small fraction of the total area in the northern GOM; thus, we estimated that they held less than 14%of Red Snapper abundance. Because artificial structures—particularly petroleum platforms—attract mostly the youngest individuals, their contribution was even lower in terms of total population biomass (7.8%) or spawning potential (6.4%). Our estimates of Red Snapper relative abundance, biomass, and spawning potential can be used to design spatial management strategies or as inputs to spatial modeling techniques

Does Reproductive Potential of Red Snapper in the Northern Gulf of Mexico Differ Among Natural and Artificial Habitats?

This study compares the reproductive potential of red snapper (Lutjanus campechanus) at artificial and natural habitats. Natural habitats are areas of vertical relief created from biogenic/geologic processes that are thought to be the historical centers of abundance for red snapper in the northern Gulf of Mexico. Red snapper were collected from 2011 to 2013 at three natural habitat sites and two artificial habitat oil and gas platform sites. The mean gonadosomatic indices (GSI), maturity at size and age, spawning indicators, batch fecundity, spawning frequency, and annual fecundity for red snapper at each habitat were analyzed to examine reproductive potential among sites and habitats. Results indicate red snapper on natural habitats exhibited higher mean GSI than those on artificial habitats during peak spawning season. Female red snapper on natural habitats showed 98% maturity, compared to 52% maturity of females on artificial habitats. These data support previous observation of demographic differences in red snapper reproduction between natural and artificial habitats. The differences observed may be due to red snapper at natural habitats being in better nutritional condition than red snapper on artificial habitats, thus allowing red snapper on natural habitats to invest more energy in reproduction and less energy towards rapid growth early in life

Fish Community Analysis Using Multidirectional ROV Video Surveys in the Northwestern Gulf of Mexico

In this study, ROV surveys with multidirectional video were used to analyze the fish communities associated with artificial reef patches in the Rio Grande Valley artificial reef 13.7 km off the coast of South Padre Island, TX. Nine configurations of reef patches consisting of varying combinations and densities of concrete pyramid and low-profile modules were surveyed. The highest species diversity was found at patches with large deployments of both pyramids and low-profile modules. Total Red Snapper Lutjanus campechanus abundance did not differ between configurations, but the highest abundances of juvenile Red Snapper were found at configurations with one pyramid and one low-profile module and at the largest low-profile only sites. Negative correlations between juvenile Red Snapper and both Grey Triggerfish Balistes capriscus and adult Red Snapper were identified. The results of this study indicate that artificial reefs with separate habitat areas composed of 1) large deployments of mid-profile structures for older juvenile and adult Red Snapper and Grey Triggerfish and 2) isolated patches of low-profile habitat or a single mid-profile structure with associated low-profile habitat for small juvenile Red Snapper will be the most effective for fisheries enhancement and supporting diverse fish assemblages

A Management Strategy Evaluation of the Impacts of Interspecific Competition and Recreational Fishery Dynamics on Vermilion Snapper (Rhomboplites aurorubens) in the Gulf of Mexico

In the Gulf of Mexico (GOM), Vermilion Snapper (Rhomboplites auroruben), are believed to compete with Red Snapper directly for prey and habitat. The two species share similar diets and have significant spatial overlap in the Gulf. Red Snapper are thought to be the dominate competitor, forcing Vermilion Snapper to feed on less nutritious prey when local resources are depleted. In addition to ecological pressures, GOM Vermilion Snapper support substantial commercial and recreational fisheries. Over the past decade, recreational landings have steadily increased, reaching a historical high in 2018. One cause may be stricter regulations for similar target species such as Red Snapper and Gray Triggerfish. A better understanding of the impact of ecosystem and fishery dynamics is essential for successful, long-term management of the stock. In this study, I used management strategy evaluation to assess the effectiveness of current and alternative harvest control rules (HCR) for the stock when accounting for interspecific competition and increased recreational landings. I developed an operating model that simulates the underlying population and fishery dynamics of the Vermilion Snapper stock and includes an index of Red Snapper competition. The annual competition index values were the estimated annual abundance of Red Snapper relative to the total virgin or near-virgin abundances of Vermilion and Red Snapper combined. In the second chapter, I used a random utility model to estimate the probability of a recreational angler targeting Vermilion Snapper given past management for Red Snapper and Gray Triggerfish. I incorporated the predicted targeting probabilities into the operating model from chapter one and evaluated the outcomes of the simulation. In both simulations, catch limits were set using empirical or model-based approaches. I ran 100 trials for each scenario, projected over 50 years. I found that the GOM Vermilion Snapper stock is resilient to competition and increased recreational landings, and all HCR effectively managed the stock. This study provides a methodology to incorporate interspecific dynamics into a single-species assessment model

Kualitas Dan Daya Simpan Ikan Nila Dan Ikan Kakap Merah Dengan Menggunakan Daun Sirih Hijau Sebagai pengawet Alami

Tilapia and red snapper is a food that contains fairly high nutritional and beneficial for health, but the fish began to decline after two hours of quality physical death caused by microorganisms .Green betel leaf contains flavonoids , phenols , thiamine , and tannins that can inhibit microbial activity .The purpose of this study on the abundance of bacteria , moisture content , pH , organoleptic test, quality, and storability on tilapia and red snapper with green betel leaf extract concentration different. This research method using a completely randomized design (CRD) with two factors, first the type of fish (J1= tilapia, J2 = red snapper) and factor 2 is the concentration of betel leaf extract of green (K1 = 40 %, K2 = 50 %, K3= 60 % ) with 6 treatments .The results showed that the quality of the best fish preservation is in treatment J2K3 (120 g red snapper and green betel leaf extract 60 % ) , with a population of bacteria 43 x 105 cfu / g , the water content of 42.34 % and a pH of 6.6, with clear and bright appearance, aroma of fresh betel leaf green, dense and supple texture, color brownish red gills, eyes bulging and storability 18 hours and still be consume

Growth and Mortality of Fish Larvae in the Northcentral Gulf of Mexico and Implications to Recruitment.

Extensive plankton collections were taken during September for several years along the northcentral Gulf of Mexico\u27s inner continental shelf. Significant differences in growth rates were found for both vermilion snapper and Atlantic bumper larvae collected at stations where hydrographic conditions were similar, indicating the probable existence of small-scale patchily-distributed feeding conditions. Such variability in growth rates is probably inevitable given the high variability in the observed spatial and temporal distribution of surface chlorophyll a levels, macrozooplankton biomass, copepod abundance, and dispersion of fish larvae. Cruise estimates of mortality coefficients (Z) for larval vermilion snapper, red drum, and Atlantic bumper were derived from the descending limbs of age-frequency distributions (adjusted for stage duration). Estimates of Z for larval vermilion snapper (n = 2,581, 4 cruises) and Atlantic bumper (n = 39,247, 7 cruises) ranged from 0.18 to 0.29 and 0.20 to 0.39, respectively. Mortality coefficients for red drum larvae (n = 13,658, 15 cruises) were highly variable (Z = 0.17-1.62), which is most likely confounded by the aggregate, synchronous, batch-spawning behavior of red drum which would modulate the relative abundance of age classes. The overall estimate of Z for red drum larvae (0.31), obtained by pooling catch data, was very similar to values found for vermilion snapper and Atlantic bumper. Projections of juvenile recruitment based on these data show that even in a sub-tropical climate, where stage durations of larvae are short, changes in growth rates, particularly when combined with small changes in mortality rates, can cause large differences in cumulative larval survival. Even if the mortality rate is constant, twice as many vermilion snapper and Atlantic bumper larvae potentially survived to a length of 6 mm at stations with the fastest observed growth rates than at stations with the slowest observed growth rates. Accurately predicting recruitment variability may prove to be intractable because of the massive logistical task of adequately quantifying the spatial and temporal variability of the trophic relationships and physical dynamics involved

Environmental Relationships And Predator-Prey Interactions Within The Snapper-Grouper Complex In The Southeastern U.S. Atlantic – Implications For Fisheries Management

Stock assessments indicate many valuable fish species are declining, or are considered overfished and/or are undergoing overfishing. Fisheries scientists and managers in the southeastern U.S. typically have utilized a single-species approach, and relied on catch per unit effort data derived from fishery-independent surveys to determine indices of abundance for economically important reef fish. However, catchability for these surveys vary for many reasons including environmental and predator-prey relationships. This research was developed to elucidate environmental influences on reef fish assemblages and distribution of reef-associated marine predators, and examine predator-prey dynamics that may influence relative abundance of large predators based on chevron traps and video data from the southeastern U.S. Atlantic. The first part of this study focused on fish assemblage structure association with different environmental gradients such as distance to shelf edge, depth, substrate vertical relief, substrate size, biotic class and % biotic cover. The second part of the study further detailed the association of Scamp, Gag, Yellowmouth Grouper, Red Grouper, Snowy Grouper and Red Snapper with month, latitude, depth, temperature, surface geologic class, biotic class, and percent biotic cover and revealed Red Snapper had a wider niche breadth than the groupers, while alternatively, groupers exhibited greater habitat specificity. The final part of the study determined Gag, Red Grouper and Red Snapper showed a preference toward Tomtate and small Black Sea Bass when predation occurred within traps. However, statistical analyses determined selected prey species were not important drivers in the presence of the focal predator species within the traps or video observations. Based on observations during this study, predator-prey interactions may have more implications for indices based on video outside the traps for these focal predator species. Given environmental relationships and species interactions have implications for fisheries management, this study provides details that describe assemblage patterns across environmental gradients, determines habitat associations for economically and environmentally important groupers and Red Snapper, and determines the importance of predation regarding chevron traps. This information will be used to inform stock assessments and conservation management decisions to enhance fisheries sustainability

Fish assemblages and indicator species: reef fishes off the southeastern United States

For many fish stocks, resource management cannot be based on stock assessment because data are insufficient-a situation that requires alternative approaches to management. One possible approach is to manage data-limited stocks as part of an assemblage and to determine the status of the entire unit by a data-rich indicator species. The utility of this approach was evaluated in analyses of 15 years of commercial and 34 years of recreational logbook data from reef fisheries off the southeastern United States coast. Multivariate statistical analyses successfully revealed three primary assemblages. Within assemblages, however, there was little evidence of synchrony in population dynamics of member species, and thus, no support for the use of indicator species. Nonetheless, assemblages could prove useful as management units. Their identification offers opportunities for implementing management to address such ecological considerations as bycatch and species interrelations