Recreational saltwater anglers from the mid-Atlantic through the Gulf of Mexico commonly target red drum. Due to concerns about overharvesting within South Carolina coupled with regional management actions, South Carolina explored the technical feasibility of stocking hatchery-produced juvenile red drum as a technique to augment the abundance of South Carolina stock. In order to assess a continued program, in 2005 a mail survey was used to collect data for estimating the economic benefits with the contingent valuation method. The theoretical validity of willingness to pay was assessed by comparison to the value of a change in red drum fishing trips that would result from the program. Benefits were compared to estimated, explicit stocking costs. We illustrate how a certainty recode approach can be used in sensitivity analysis. The net present values (NPVs) for the stocking program are positive suggesting that the program would have been economically efficient relative to no program.

The effects of four prebiotics (fructo-oligosaccharide, Bio-MOS®, transgalacto-oligosaccharide and GroBiotic®-A) on digestive enzymes and intestinal morphology were studied in juvenile hybrid striped bass (Morone chrysops×M. saxatilis) and red drum (Sciaenops ocellatus) using two separate 8-week feeding trials. Red drum were fed experimental diets with the four prebiotics each individually supplemented at 1 % and hybrid striped bass were fed diets supplemented with GroBiotic®-A at 1 and 2 %. Both trials were conducted with each diet fed to apparent satiation twice per d to three replicate groups of fifteen juvenile fish. For histomorphological analysis, gastrointestinal tract (GIT) samples from three randomly selected fish per tank were taken at 4 and 8 weeks for hybrid striped bass and at 8 weeks for red drum. For both trials, GIT samples from two randomly selected fish per tank were taken at 4 and 8 weeks and analysed for pepsin, trypsin, chymotrypsin, aminopeptidase, α-amylase, lipase, and both acid and alkaline phosphatase activities. The results of the histological evaluation indicated that the inclusion of prebiotics was adequate to elicit structural changes in the GIT of both species. On the other hand, no significant changes in the enzyme activities were detected at week 8 in both species. However, there was a transient effect of Bio-MOS® supplementation on the activities of aminopeptidase, α-amylase and alkaline phosphatase at week 4 in red drum only. Thus, previously observed improvements in nutrient digestibility by these fish in response to prebiotic supplementation appear to be mostly related to changes in GIT structure as opposed to the enhancement of digestive enzyme activity.

The present work examines the usefulness of the combination of multivariate analyses and further one-way analysis of variance in the search for links between causes and effects in heterologous stimulation of spawning in fish. Stimulations with both 20 and 50 μg.kg–1 doses of [D Trp6] luteinizing hormone-releasing hormone analogue (LH-RHa) were effective in inducing and synchronizing spawning of red drum, Sciaenops ocellatus. Oocyte development monitoring using ovarian biopsy allowed treatment injections at different stages of maturation. The influence at stimulation time of female oocyte development state upon further development was shown. An interesting potential of second stimulation, leading to high quality spawns, was established and factors of success were identified. The best conditions for stimulation success were simultaneously late stage of oocyte development characterized by the beginning of oil droplet coalescence, high ovarian homogeneity quoted by the proportion of most developed oocytes in the biopsy sample, and low dose of hormone (20 μg.kg–1) for both first and second stimulations.