Jill M. Hendon

Seasonal modulation in the secondary stress response of a carcharhinid shark, Rhizoprionodon terraenovae.

Some animals have the ability to modulate their stress response depending on the type and duration of the stressor. Modulations can initiate behavioral changes that increase fitness during the stressful period. The goal of this study was to determine if Atlantic sharpnose sharks, Rhizoprionodon terraenovae, exhibit seasonal modulations in their secondary stress parameters. Mature, male Atlantic sharpnose sharks were acutely stressed and serially sampled for one-hour, during spring, summer, and fall. An elevated stress response was observed for plasma glucose, lactate and osmolality during summer compared to spring and fall. Glucose also exhibited elevated initial concentrations, followed by a linear response during summer; varying from the asymptotic response during spring and fall. Hematocrit did not show differences over time or season; however, the power of the analysis was low due to the small sample size. When an additional 120 samples were included in the analysis, significantly higher initial hematocrit values were found during summer. Based on these results we suggest that summer is a demanding time for Atlantic sharpnose sharks.

Variability in the Reproductive Biology of the Atlantic Sharpnose Shark in the Gulf of Mexico

Abstract The reproductive biology of the Atlantic Sharpnose Shark Rhizoprionodon terraenovae in the Gulf of Mexico was investigated by examining 1,306 specimens (693 females, 613 males) collected from the Florida Keys to waters off Brownsville, Texas. The results of this study confirm the annual reproductive cycle established for this species; however, there was a significant amount of variability within the cycle. Ovulatory and postovulatory females were present from March to October, indicating that mating and ovulation were occurring over a more protracted period than previously described (e.g., May to July). The occurrence of postpartum females from April to September, the varying sizes of the embryos across several months, and the occurrence of mature spermatozoa in the testes of adults from March to November also corroborate the evidence of reproductive plasticity in this species. This observed variability in the reproductive cycle indicates that the Gulf of Mexico Atlantic Sharpnose Shark population is not completely synchronous in regards to mating, ovulation, and parturition, as a portion of the population is demonstrating reproductive asynchrony. Although the cause of this asynchrony remains unclear, it may be related to the environmental conditions of the Gulf of Mexico, which could provide water temperatures that are optimal for the reproduction of this species through much of the year (i.e., March to October), resulting in a protracted reproductive cycle. Given the results of the current study, the reproductive cycles of other carcharhinid species in this region should be examined in more detail to determine whether there is asynchrony in them as well, as this phenomenon could impact future management strategies.

Occurrence of an Intersexual Blacktip Shark in the Northern Gulf of Mexico, with Notes on the Standardization of Classifications for This Condition in Elasmobranchs

Abstract An intersexual Blacktip Shark Carcharhinus limbatus with a testis, immature female reproductive tracts (embedded), and claspers was caught in the Gulf of Mexico. Histology of the single gonad revealed that all stages of spermatogenesis were occurring; however, the absence of ovaries and a male duct system suggests that neither sex would have been functional in this individual. Intersexuality has been reported in 17 families and 36 species of elasmobranchs. The degree to which the different sexes are present in a given individual is often difficult to categorize by normal hermaphroditic standards, as this is typically an anomalous presentation in elasmobranchs. Therefore, this report provides three categories for classification (basic, incomplete, and complete intersexuality) to standardize terminology and allow for more precise comparisons to be made among elasmobranch examples. Basic intersexuals have gonadal tissue of only one sex and a combination of other male and female characters with neither or only one sex being complete. Incomplete intersexuals have gonadal tissue of both sexes and a combination of other male and female characters; however, neither or only one sex is complete. Complete intersexuals have claspers as well as gonadal tissue and tracts for both sexes. The majority of the reported intersexual elasmobranchs, including the shark described here, are basic intersexuals.

The influence of year, laying date, egg fertility and incubation, individual hen, hen age and mass and clutch size on maternal immunoglobulin Y concentration in captive Steller's and spectacled eider egg yolk

Stellers eiders and spectacled eiders are sea duck species whose populations have declined significantly and infectious diseases could influence offspring survival. Therefore, the maternal transfer of immunoglobulin Y (IgY) into yolk was investigated in captive Stellers and spectacled eiders during the 2007-2013 breeding seasons. This project had two objectives: establish baseline IgY levels in Stellers and spectacled eider yolk under controlled captive conditions and evaluate the effect of year, laying date, egg fertility, egg incubation duration, individual hen, hen age and mass, and laying order to determine which variables influenced IgY levels. Average IgY concentrations were 0.03-0.48 mg ml(-1) in Stellers eider yolk and 0.10-0.51 mg ml(-1) in spectacled eider yolk. The year and individual hen influenced IgY concentration in Stellers and spectacled eider yolk. The laying date was negatively correlated with egg IgY levels for most Stellers eider hens, but laying order was positively correlated with egg IgY concentration for spectacled eiders.

Monitoring programs of the U.S. Gulf of Mexico: inventory, development and use of a large monitoring database to map fish and invertebrate spatial distributions

Since the onset of fisheries science, monitoring programs have been implemented to support stock assessments and fisheries management. Here, we take inventory of the monitoring programs of the U.S. Gulf of Mexico (GOM) surveying fish and invertebrates and conduct a gap analysis of these programs. We also compile a large monitoring database encompassing much of the monitoring data collected in the U.S. GOM using random sampling schemes and employ this database to fit statistical models to then map the spatial distributions of 61 fish and invertebrate functional groups, species and life stages of the U.S. GOM. Finally, we provide recommendations for improving current monitoring programs and designing new programs, and guidance for more comprehensive use and sharing of monitoring data, with the ultimate goal of enhancing the inputs provided to stock assessments and ecosystem-based fisheries management (EBFM) projects in the U.S. GOM. Our inventory revealed that 73 fisheries-independent and fisheries-dependent programs have been conducted in the U.S. GOM, most of which (85%) are still active. One distinctive feature of monitoring programs of the U.S. GOM is that they include many fisheries-independent surveys conducted almost year-round, contrasting with most other marine regions. A major sampling recommendation is the development of a coordinated strategy for collecting diet information by existing U.S. GOM monitoring programs for advancing EBFM.