Review: Fishes of the Gulf of Mexico, Texas, Louisiana and Adjacent Waters (2nd ed.) by H. Dickson Hoese and Richard H. Moore

Fishes of the Gulf of Mexico, Texas, Louisiana, and Adjacent Waters. 2nd ed. 1998. H. Dickson Hoese and Richard H. Moore, Texas A&M University Press, College Station, Texas 77843- 4354. 422 p

Modeling Wetland Loss in Coastal Louisiana: Geology, Geography, and Human Modifications

Habitat change in coastal Louisiana from 1955/6 to 1978 was analyzed to determine the influence of geological and man-made changes on landscape patterns within 7.5 min quadrangle maps. Three quantitative analyses were used: principal components analysis, multiple regression analysis, and cluster analysis. Regional differences in land loss rates reflect variations in geology and the deltaic growth/decay cycles, man-induced changes in hydrology (principally canal dredging and spoil banking), and land-use changes (principally urbanization and agricultural expansion). The coastal zone is not homogeneous with respect to these variables and the interaction between causal factors leading to wetland loss is therefore locally variable and complex. The relationship between wetland loss, hydrologic changes, and geology can be described with statistically meaningful results, even though these data are insufficient to precisely quantify the relationship. However, these data support the hypothesis that the indirect impacts of man-induced changes (hydrologic and land use) may be as influential as the direct impacts resulting in converting wetlands to open water (canals) or modified (impounded) habitat. Three regions within the Louisiana coastal zone can be defined, based on the potential causal factors used in the analyses. The moderate (mean = 22%) wetland loss rates in region 1 are a result of relatively high canal density and developed area in marshes which overlie sediments of moderate age and depth; local geology acts, in this case, to lessen indirect impacts. On the other hand, wetland loss rates in region 2 are high (mean = 36%), despite fewer man-induced impacts; the potential for increased wetland loss due to both direct and indirect effects of man\u27s activity in these areas is high. Conversely, wetland loss (mean = 20%) in region 3 is apparently least influenced by man\u27s activity in the coastal zone because of sedimentary geology (old, thin sediments), even though these areas have already experienced significant direct habitat alteration and wetland loss

Comparing the Applicability of Weight-Length Relationships, the Relative Condition Index and Morphometric Criteria to Assess Larval Condition: A Test Case with Striped Bass

We compared the applicability of using a weight-length relationship, the relative condition index (Kn) and morphometric criteria to provide insight on the nutritional condition and recruitment potential of larvae of the striped bass Morone saxatilis collected in the Potomac River, MD in 1980-1982 and 1986. Morphometric data indicate that relatively high numbers of larvae In poor condition were present In samples taken prior to mid-May In all years except 1986, but especially In 1980 and 1981. Results of ANCOVA on a subset of data from the first 2 weeks of May In each of the 4 years Indicated significant differences in weight-length regression equations. Larvae In the 1980 and 1981 samples were in poorer condition than in 1982 and 1986, based on regressions coefficients. Estimates of relative condition (Kn) were high in all years except 1986. The morphometric criteria and the regression parameter estimates concurred with an Index of striped bass year class strength, but only after a careful consideration of the assumptions of those condition indices, requiring a reduction in sample size that excluded larger larvae (\u3e 12 mm, morphometric criteria) or averaging data over several larval cohorts (regression parameters)

Experimental Evaluation of Potential Effects of Habitat Size and Presence of Conspecifics on Habitat Association by Young-of-the-Year Red Snapper

The potential effects of habitat size and the presence of larger conspecifics on habitat association by young-of-the-year (YOY) red snapper Lutjanus campechanus was evaluated in 2.2 m3 laboratory tanks. Our results indicate that YOY red snapper have a strong affinity for structure, which ranged in these experiments from open-sand bottom to concrete-block, artificial reef-like habitats. Mean distance of YOY red snapper from the blocks decreased significantly and the time spent near the structures increased significantly as the size of the habitat increased. However, when larger subadult snapper were present, both distances to the reefs and time that YOY spent near them was significantly reduced, as the larger conspecifics actively defended the structure from occupation by YOY. If similar interactions occur in situ, small snapper that attempt to move onto reefs from the shrimping grounds that serve as nursery areas for juveniles may be subject to predation pressures by piscivorous fishes inhabiting the reefs. Finally, in experiments that used both larger conspecifics and alternate prey similar in size to the YOY red snapper, results indicated that larger snapper preferentially consumed the alternate prey and did not cannibalize the YOY red snapper. Nevertheless, YOY still were not permitted to occupy the artificial reef habitats in any experiments when larger conspecifics were present in the tanks. If results of these experiments are exportable to the field, they may partially explain the observation that YOY red snapper in natural populations are more often found in shallower water on shrimping grounds, whereas larger juveniles begin to recruit to the offshore reefs once they have obtained a size refuge. If additional studies conclude that YOY red snapper are attracted to larger or more complex habitats but avoid these structures because of pressure from larger juveniles and/or adults, the strategy of continued placement of artificial reefs large enough to attract adult snapper and other piscivores in and near the inshore shrimping grounds should be reassessed

Regional differences in the age and growth of red snapper (Lutjanus campechanus) in the US Gulf of Mexico

In the U.S. Gulf of Mexico (GOM), red snapper (Lutjanus campechanus) are managed as a unit stock, although the stock is assessed as subunits east and west of the Mississippi River. Differences were examined between management subunits by comparison of the size and age structure and growth rates of red snapper among recreational catches from 6 regions of the GOM: South Texas, North Texas, Louisiana, Alabama, Northwest Florida, and Central Florida. In all of these regions, red snapper sampled in 2009 and 2010 were small and predominantly from age classes that represented the strong recruitment for the year classes of 2004-06. As such, our data indicate a highly truncated age structure with few fish older than 6 years. Demographic differences in size, age, and growth parameters were found. Small (550 ram in total length), fast-growing individuals dominated the catches in South Texas and the regions of Florida, whereas larger, slower-growing fish represented the majority of catches in Alabama and Louisiana. The potential mechanisms affecting observed demographic variation include environmental differences, fishing pressure, habitat preference, and management regimes; however, no definitive conclusion about cause and effect can be made. The combination of demographic differences between regions and consistent occurrence of the strong year classes GOM-wide supports recent conclusions that red snapper form a metapopulation of semi-isolated assemblages in the GOM

Marsh Management Plans in Practice: Do they work in coastal Louisiana, USA?

Louisiana\u27s coastal wetlands represent about 41% of the nation\u27s total and are extensively managed for fish, fur, and waterfowl. Marsh management plans (MMPs) are currently used to avoid potential user conflicts and are believed to be a best management practice for specific management goals. In this article, we define MMPs and examine their variety, history, impacts, and future. A MMP is an organized written plan submitted to state and federal permitting agencies for approval and whose purpose is to regulate wetland habitat quantity and quality (control land loss and enhance productivity). MMPs are usually implemented by making structural modifications in the marsh, primarily by using a variety of water control structures in levees to impound or semi-impound managed areas. It appears that MMPs using impoundments are only marginally successful in achieving and often contradict management goals. Although 20% of coastal Louisiana may be in MMPs by the year 2000, conflict resolution of public and private goals is compromised by a surfeit of opinion and dearth of data and experience. Based on interpretation of these results, we believe the next phase of management should include scientific studies of actual impacts, utilization of post-construction monitoring data, inventory of existing MMPs, development of new techniques, and determination of cumulative impacts

Feeding Periodicity and Prey Habitat Preference of Red Snapper, Lutjanus campechanus (Poey, 1860) on Alabama Artificial Reefs

Conclusive understanding of the role temperate artificial reefs play in the trophic dynamics of Lutjanus campechanus (Poey, 1860) is limited. Thus, diel feeding habits of red snapper on artificial reefs were examined using gut fullness, diet composition, and prey habitat preferences. Red snapper were collected by hook and line from artificial reefs off Alabama in July and Aug. 2000. Examination of stomach contents found red snapper feeding upon fish, demersal crustaceans, and pelagic zooplankton. Although other studies suggest that lutjanids primarily feed nocturnally, red snapper in this study fed throughout the day and night. Significant differences in gut fullness were found between 2-hr time intervals; however, no obvious pattern in feeding periodicity was evident. Although fish was the largest diet component by weight for both day and night during diel sampling, examination of prey habitat preferences indicate that red snapper fed on more water-column organisms during the day and more sand- or mud-associated organisms at night. Based on our interpretation of these results, we hypothesize that red snapper reside above the reefs during the day, opportunistically feeding mostly upon water-column-associated organisms and some benthic prey. At night they may move away from the reef to consume nocturnally active fishes and benthic crustaceans

Habitat and bycatch effects on population parameters of inshore lizardfish (Synodus foetens) in the north central Gulf of Mexico

We examined the effect of habitat and shrimp trawl bycatch on the density, size, growth, and mortality of inshore lizardfish (Synodus foetens), a nonexploited species that is among the most widespread and abundant benthic fishes in the north central Gulf of Mexico. Results of quarterly trawl sampling conducted from spring 2004 through spring 2005 revealed that inshore lizardfish are most abundant on sand habitat, but larger fish are more common on shell rubble habitat. There was no significant difference in fish density between habitats exposed to shrimp trawling on the open shelf versus those habitats within a permitted artificial reef zone that served as a de facto no-trawl area; this finding indicates that either inshore lizardfish experienced minimal effects from trawling or, more likely, that fish moved between trawled and nontrawled habitats. Exploitation ratio (bycatch mortality/total morality) estimates derived from catch curve analysis ranged from 0.43 inside the artificial reef zone to 0.55 outside the reef zone, thus indicating that inshore lizardfish are subject to significant fishing mortality in the north central Gulf of Mexico despite the lack of a directed fishery for the species. We infer from this result that effects of shrimp trawl bycatch may be significant at the population level for nonexploited species and that a broader ecosystem-scale examination of bycatch effects is warranted

Age, Growth, Diet, and Reproductive Biology of the Tripletail, Lobotes surinamensis, From the North-Central Gulf of Mexico

Tripletail, Lobotes surinamensis, are migratory fish that occur worldwide in warm seas, including the Gulf of Mexico and Caribbean. In the north-central Gulf of Mexico, tripletail support small recreational and commercial fisheries from April to Oct. and are commonly caught in bays and estuaries. Few studies have evaluated the life history and biological characteristics of tripletail; therefore, the objective of this study was to examine the age and growth, reproductive biology, and diet of tripletail caught off coastal Alabama. Our primary goal was to use life history information to determine. a minimum size limit for harvest. A secondary goal was to compare the results of our study with those of previous tripletail studies. A total of 119 specimens, ranging in size from 293- to 763-mm total length (TL), were collected from recreational anglers and from a wholesale seafood dealer between May 1998 and Aug. 2000. Female specimens were significantly longer and heavier than males. Total length varied greatly with age, although significant overlap in lengths was observed among ages. Age ranged from 0.87 to 4.09 yr. No male was older than 3.15 yr of age, whereas five females were estimated to be more than 4 yr old. Fifty percent of females reached sexual maturity by 494- to 594-mm TL and approximately 1 to 2 yr of age. All males greater than 380 mm were sexually mature. Diets were composed primarily of penaeid shrimps, various pelagic fish species, and portunid crabs, with the proportion of fish consumed increasing with tripletail length. On the basis of the results of this study as well as previous research on the life history and population dynamics of tripletail, the state of Alabama implemented a 406 mm (16 inch) minimum size limit for this species. This size limit is below the female size at 50% maturity (19.5-23.5 inch) and should be increased if large increases in fishing pressure occur