First Record of a Nurse Shark, Ginglymostoma cirratum, within the Mississippi Sound

Of all the coastal shark species in the northern Gulf of Mexico, the nurse shark, Ginglymostoma cirratum, is one of the few species not documented in the Sound. Unlike most coastal sharks, nurse shark distribution is confined to a relatively specific suite of abiotic characteristics. Hannan et al. (2012) demonstrated that the distribution of nurse sharks in the northern GOM is primarily limited to hard bottom habitats with relatively high temperature, salinity, dissolved oxygen, and water clarity. Herein, we provide support for the findings of Hannan et al. (2012) and report the first documented occurrence of a nurse shark in the Sound

Notes on the Biology of an Adult Female Chimaera cubana Captured Off St. Croix, U.S. Virgin Islands

Within the western North Atlantic Ocean there are at least 4 genera and 5 species of chimaeroids occurring in deep waters generally associated with outer continental slopes or areas of high bathymetric relief (Didier 2002; Didier 2004). Two chimaeroids, Chimaera cubana and Hydrolagus alberti, are known to be indigenous to the Caribbean Sea in waters associated with the Greater and Lesser Antilles. While H. alberti occurs throughout the Gulf of Mexico and the Caribbean Sea, C. cubana is thought to be endemic to an area bounded by Cuba and Colombia (IUCN 2009). These two chimaeras are readily differentiated by the presence or absence of an anal fin and species–specific branching patterns of cranial lateral line canals (Didier 2004). Since the description of C. cubana by Howell–Rivero (1936), only 10 specimens have been reported in the primary literature with another 11 specimens located in museum collections (Bunkley–Williams and Williams 2004). The dearth of biological information on C. cubana led the International Union for the Conservation of Nature to recommend that “basic data be collected on all captures” (IUCN 2009)

Seasonal Occurrence, Horizontal Movements, and Habitat Use Patterns of Whale Sharks (\u3ci\u3eRhincodon typus\u3c/i\u3e) in the Gulf of Mexico

In the northern Gulf of Mexico (GOM), whale sharks (Rhincodon typus) form large aggregations at continental shelf-edge banks during summer; however, knowledge of movements once they leave aggregation sites is limited. Here we report on the seasonal occurrence of whale sharks in the northern GOM based on over 800 whale shark sightings from 1989 to 2016, as well as the movements of 42 whale sharks tagged with satellite-linked and popup satellite archival transmitting tags from 2008 to 2015. Sightings data were most numerous during summer and fall often with aggregations of individuals reported along the continental shelf break. Most sharks (66%) were tagged during this time at Ewing Bank, a known aggregation site off the coast of Louisiana. Whale shark track duration ranged from three to 366 days and all tagged individuals, which ranged from 4.5 to 12.0 m in total length, remained within the GOM. Sightings data revealed that whale sharks occurred primarily in continental shelf and shelf-edge waters (81%) whereas tag data revealed the sharks primarily inhabited continental slope and open ocean waters (91%) of the GOM. Much of their time spent in open ocean waters was associated with the edge of the Loop Current and associated mesoscale eddies. During cooler months, there was a net movement southward, corresponding with the time of reduced sighting reports. Several sharks migrated to the southwest GOM during fall and winter, suggesting this region could be important overwintering habitat and possibly represents another seasonal aggregation site. The three long-term tracked whale sharks exhibited interannual site fidelity, returning one year later to the vicinity where they were originally tagged. The increased habitat use of north central GOM waters by whale sharks as summer foraging grounds and potential interannual site fidelity to Ewing Bank demonstrate the importance of this region for this species

Population Connectivity of Pelagic Megafauna in the Cuba-Mexico-United States Triangle

The timing and extent of international crossings by billfishes, tunas, and sharks in the Cuba-Mexico-United States (U.S.) triangle was investigated using electronic tagging data from eight species that resulted in \u3e22,000 tracking days. Transnational movements of these highly mobile marine predators were pronounced with varying levels of bi- or tri-national population connectivity displayed by each species. Billfishes and tunas moved throughout the Gulf of Mexico and all species investigated (blue marlin, white marlin, Atlantic bluefin tuna, yellowfin tuna) frequently crossed international boundaries and entered the territorial waters of Cuba and/or Mexico. Certain sharks (tiger shark, scalloped hammerhead) displayed prolonged periods of residency in U.S. waters with more limited displacements, while whale sharks and to a lesser degree shortfin mako moved through multiple jurisdictions. The spatial extent of associated movements was generally associated with their differential use of coastal and open ocean pelagic ecosystems. Species with the majority of daily positions in oceanic waters off the continental shelf showed the greatest tendency for transnational movements and typically traveled farther from initial tagging locations. Several species converged on a common seasonal movement pattern between territorial waters of the U.S. (summer) and Mexico (winter)

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

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

Connecting Teenagers to Coastal Sciences through Research and Education: Shark Fest Program

In 2010, the Marine Education Center collaborated with the Center for Fisheries Research and Development\u27s Shark Research Program to design an educational program that combined research experiences and educational opportunities for teenage audiences. This program, Shark Fest, educates students about the sharks of the Mississippi Sound and engages them in scientific studies of shark populations and movements. This program has reached 398 participants in grades 7-12. During the program, students assist in conducting a population survey using a 152.4-m (500-ft) bottom longline with 50 hooks and fishing with a rod-and-reel. Students measure, weigh, determine sex, and identify to species all captured sharks, and tag those in good condition prior to release. Program participants also conduct water-quality sampling (salinity, temperature, dissolved oxygen, and water clarity) at each sample site for addition to the database. Students take a pre-test and post-test to assess the level of knowledge gained during the program. Results of a paired-sample t-test on 2015 pre-test and post-test data reflected a significant difference in pre-test (mean = 6.16, SD = 2.36) and post-test (mean = 8.54, SD = 1.93) scores (t([83]) = -9.172, P \u3c 0.0001), indicating an increase in content knowledge. Written and verbal post-participation assessments also highlighted a positive student experience. We conducted opportunistic interviews with several students 4 years after they were in the program and found evidence of retained knowledge along with positive overall impressions. Some participants stated that the experience influenced their career pursuits

Connecting Teenagers to Coastal Sciences Through Research and Education: Shark Fest Program

In 2010, the Marine Education Center collaborated with the Center for Fisheries Research and Development\u27s Shark Research Program to design an educational program that combined research experiences and educational opportunities for teenage audiences. This program, Shark Fest, educates students about the sharks of the Mississippi Sound and engages them in scientific studies of shark populations and movements. This program has reached 398 participants in grades 7-12. During the program, students assist in conducting a population survey using a 152.4-m (500-ft) bottom longline with 50 hooks and fishing with a rod-and-reel. Students measure, weigh, determine sex, and identify to species all captured sharks, and tag those in good condition prior to release. Program participants also conduct water-quality sampling (salinity, temperature, dissolved oxygen, and water clarity) at each sample site for addition to the database. Students take a pre-test and post-test to assess the level of knowledge gained during the program. Results of a paired-sample t-test on 2015 pre-test and post-test data reflected a significant difference in pre-test (mean = 6.16, SD = 2.36) and post-test (mean = 8.54, SD = 1.93) scores (t[83] = -9.172, P \u3c 0.0001), indicating an increase in content knowledge. Written and verbal post-participation assessments also highlighted a positive student experience. We conducted opportunistic interviews with several students 4 years after they were in the program and found evidence of retained knowledge along with positive overall impressions. Some participants stated that the experience influenced their career pursuits

Seasonal Modulation in the Secondary Stress Response of a Carcharhinid Shark, \u3ci\u3eRhizoprionodon terraenovae\u3c/i\u3e

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. Published by Elsevier Inc

Plasma Steroid Concentrations of Adult Male Atlantic Sharpnose Sharks, \u3ci\u3eRhizoprionodon terraenovae\u3c/i\u3e, in the Northern Gulf of Mexico, With Notes on Potential Long Term Shifts in Reproductive Timing

In previous literature it was proposed that Atlantic sharpnose sharks, Rhizoprionodon terraenovae, from the western Atlantic Ocean (WAO) population exhibited differences in their reproductive timing when compared to the northern Gulf of Mexico (GOM) population. The objective of the current study was to examine the reproductive cycle of mature male sharpnose sharks from the northern GOM population. Plasma testosterone (T) and estradiol (E(2)) were measured from 76 mature male sharpnose sharks sampled from 1999 to 2001, and the gonadosomatic index (GSI) was determined for 53 additional mature males sampled from 2007-2008. Plasma T, E(2), and GSI exhibited similar cycles with peak values occurring in late spring (April/May) and lowest values occurring during the summer. These results suggest that male sharpnose sharks in the northern GOM are reproductively active one to two months earlier than previously reported, which now brings them into synchrony with the WAO population. Interestingly, this shift in reproductive timing corresponds with a 3.0A degrees C (13.4%) increase in spring sea surface temperature (SST) from the Mississippi Sound over a 29 year period, which could translate into GOM male sharpnose sharks becoming reproductively active earlier in the year thus explaining the late spring peak in GSI