Seventeen Gulf of Mexico sturgeons (Acipenser oxyrinchus desotoi) underwent endoscopic sex determination, gonadal biopsy, and various reproductive surgeries as part of a conservation development plan. The fish were anesthetized with tricaine methanesulfonate (MS-222) buffered with sodium bicarbonate and maintained on a recirculating water anesthesia circuit. A 6-mm Ternamian EndoTip Cannula, placed through the ventral midline, midway between pectoral and pelvic fins, permitted the introduction of a 5-mm telescope. Swim bladder aspiration and CO2 insufflation of the coelomic cavity provided excellent observation. Second and third cannulae were placed under direct visual control, lateral and cranial or caudal to the telescope cannula. Sex determination was successfully performed in all fish; however, five of 17 sturgeons (29%) required endoscopic gonadal biopsy to confirm sex. Bilateral ovariectomy or orchidectomy was successfully performed in three males and four females. Unilateral ovariectomy and bilateral ligation of the müllerian ducts using an extracorporeal suturing technique was accomplished in an additional three females. No apparent morbidity was associated with the anesthesia or endoscopic surgery in any fish. The ability to safely perform minimally invasive reproductive surgery in fish may have important management and conservation benefits.
The shortnose sturgeon Acipenser brevirostrum is a federally listed endangered fish species cultured for recovery efforts. Since high mortality and labor costs are associated with first-feeding sturgeon culture, particularly during the period of dietary conversion from live to formulated feed, we investigated the effects of six feeding regimens on the survival and growth of cultured shortnose sturgeon fry. During the 30d trial, five replicate groups (100 fish/replicate) of first-feeding shortnose sturgeon were fed according to six regimens: (1) live feed (live nauplii of brine shrimp Artemia spp.); (2) formulated (commercially formulated salmonid starter diet); (3) alternate (alternate feedings of the live and formulated feed); (4) transition (slow transition from the live to the formulated feed); (5) automatic (cofeeding the live and formulated feeds with the use of an automatic feeder); and (6) starvation (no feeding). Significantly greater survival rates were observed in the transition (97.4%), automatic (96.0%), alternate (93.8%), and live feed regimens (92.6%) than in the formulated (71.8%) and starvation regimens (31.6%). Length and weight of fish in the alternate (52.4 mm and 0.62 g), automatic (52.3 mm and 0.63 g), transition (46.9 mm and 0.48 g), and live feed regimens (46.4 mm and 0.43 g) were significantly greater than the length and weight of fish in the formulated (31.4 mm and 0.18 g) and starvation regimens (20.6 mm and 0.04 g). Fish weights in the alternate and automatic regimens were significantly greater than those in the live feed regimen. Based on the results of this study, we recommend the automatic regimen for first-feeding shortnose sturgeon culture. This feeding regimen produced heavier fish than the live feed regimen, appeared to reduce labor costs compared with the other feeding regimens, and alleviated possible complications associated with diet conversion.
Twenty 6-yr-old (1995-yr-class) Gulf of Mexico sturgeon (Acipenser oxyrinchus desotoi) were diagnosed as having bilateral cataracts. Histopathologic assessment of the lenses of two of the fish revealed the presence of a diplostomid trematode. Pharmacological treatment of the trematodes may be effective for killing the parasites, but the damage to the lenses and resulting cataracts are nonreversible. Because these animals were to be used in a subsequent study as sentinels in the natural environment, it was necessary to return the animals' vision to as close to normal as possible. Electroretinograms were performed on each fish's eyes to ensure that retinal function was present. Cataracts then were surgically removed by phacoemulsification and aspiration. The animals tolerated the surgical procedures well. This report is the first known report of surgical correction of cataracts in sturgeon species. It also is the first known attempt to correct vision problems in fish being returned to the wild.
p. 820) reflect the feelings of many engaged in neonatal care. However, I feel they have not carried their simplification quite far enough. At the moment I am undertaking a large series to compare the Apgar score with a score deduced from only the breathing and heart rate. This gives equally good correlation and, giving a score from 0 to 4, is also providing a valuable lead to correct ventilatory treatment.-I am, etc.
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