Involving citizen scientists in research has become increasingly popular in natural resource management and allows for an increased research effort at low cost, distribution of scientific information to relevant audiences, and meaningful public engagement. Scientists engaging fishing tournament participants as citizen scientists represent ideal scenarios for testing citizen science initiatives. For example, the Texas Shark Rodeo has begun shifting to conservation-oriented catch-and-release practices, which provides a unique opportunity to collect data on a large scale for extended periods of time, particularly through tagging large numbers of sharks for very little cost compared to a directed scientific study. However, critics are somewhat skeptical of citizen science due to the potential for lack of rigor in data collection and validation. A major management concern for shark fisheries is the ability of anglers to identify species. We tested some of the assumptions and value of citizen-collected data by cross-verifying species identification. Specifically, the purpose of this study was to evaluate the accuracy of shark species identifications made by anglers fishing in the Texas Shark Rodeo using photographs that were submitted as a requirement for tournament participation. Using a confusion matrix, we determined that anglers correctly identified 97.2% of all shark catches submitted during the Texas Shark Rodeo from 2014–2018; however, smaller sharks and certain species, including blacknose and spinner sharks, were more difficult to identify than others. Most commonly confused with blacktip sharks, spinner sharks were most commonly identified incorrectly (76.1% true positive rate [TPR]) followed by blacknose (86.8% TPR), finetooth (88.0% TPR), and Atlantic sharpnose sharks (93.8% TPR). This study demonstrated that citizen scientists have the ability to identify sharks with relatively low error. This is important for science and management, as these long-term datasets with relatively wide geographic scope could potentially be incorporated into future assessments of sharks in the Gulf of Mexico.
Highly mobile apex predators such as the shortfin mako shark (mako shark; Isurus oxyrinchus) serve an important role in the marine ecosystem, and despite their declining populations and vulnerability to overexploitation, this species is frequently harvested in high abundance in both commercial and recreational fisheries. In 2017, the North Atlantic stock was deemed overfished and to be undergoing overfishing and was recently listed in CITES Appendix II. Effective management of this species can benefit from detailed information on their movements and habitat use, which is lacking, especially in the Gulf of Mexico, a potential mating and parturition ground. In this study, we used satellite telemetry to track the movements of mako sharks in the western Gulf of Mexico between 2016 and 2020. In contrast to previous studies that have primarily tagged juvenile mako sharks (>80% juveniles), ∼80% of sharks tagged in this study (7 of 9) were presumed to be mature based on published size-at-maturity data. Sharks were tracked for durations ranging from 10 to 887 days (mean = 359 days; median = 239 days) with three mature individuals tracked for >2 years. Mako sharks tagged in this study used more of the northwestern Gulf of Mexico than reported in previous movement studies on juveniles, suggesting potential evidence of size segregation. While one mature female remained in the Gulf of Mexico over a >2-year period, predominantly on the continental shelf, two mature males demonstrated seasonal migrations ∼2,500 km from the tagging location off the Texas coast to the Caribbean Sea and northeastern United States Atlantic coast, respectively. During these migrations, mako sharks traversed at least 12 jurisdictional boundaries, which also exposed individuals to varying levels of fishing pressure and harvest regulations. Movement ecology of this species, especially for mature individuals in the western North Atlantic, has been largely unknown until recently. These data included here supplement existing information on mako shark movement ecology and potential stock structure that could help improve management of the species.
Anthropogenically caused physical and chemical habitat degradation, including water pollution, have caused dramatic declines in freshwater mollusk populations. Sodium dodecyl sulfate (SDS), a surfactant with no USEPA Water Quality Criteria (WQC), is commonly used in industrial applications, household cleaners, personal hygiene products, and herbicides. In aquatic habitats, previous SDS studies have associated deformities and death to mollusks found in these systems. The objective of this study was to determine EC 50 values for two freshwater juvenile unionids (Villosa nebulosa and Hamiota perovalis) and two freshwater caenogastropods (Leptoxis ampla and Somatogyrus sp.) endemic to the Mobile River Basin, USA, to SDS. Using the Trimmed Spearman-Karber method, EC 50 values were calculated. Results found that EC 50 values were:
Life-history studies have been published for only a small proportion of crayfish species native to the southeastern United States. The Southeastern Crayfish Biologist Working Group was formed to help meet this deficit by coordinating life-history research efforts. We used a combination of field sampling and computer modeling to evaluate a basic core sampling protocol and assess sample size issues. We focused on a locally abundant species, Procambarus versutus, and followed the protocol for 5 months at two sites in Alabama. Results showed a monthly sample size of 10 juvenile males plus 10 adult males could be met consistently and provided a = 85% probability of detecting seasonal shifts in proportion of Form I males under a range of scenarios. Weaknesses of the effort included inconsistent determination of sex in juveniles and form of adult males among sampling crews. More importantly, female life-history information was rarely obtainable due to an inability to collect sufficient numbers of glaired or berried adults. We suggest several priorities to address before implementation of coordinated, large-scale sampling efforts. These include development of sampling techniques to increase captures of glaired and berried females, and assessment of non-lethal gamete extraction techniques to track reproductive state of males and females.
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