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.
This research was motivated by the desire to more efficiently estimate catch by recreational anglers than current methods do. The method illustrated here combines data from angler self-reports made by a smartphone app and dockside validation samples. The two data sources can be thought of as a capture and recapture, where the parameter of interest is the population total (catch) instead of the population size. We developed several estimators of the total and compared them to one that makes use only of catch observed in the validation sample but not self-reports of catch. All the proposed estimators allow measurement error in the self-reports and do not make any assumptions about their representativeness. The validation sample must be a probability sample for valid inference, and our estimators can accommodate a complex sample design. We provide recommendations about conditions under which one of the estimators discussed may be preferred to another. Finally, we illustrate the method with analysis of data from a pilot project to estimate recreational red snapper catch in the Gulf of Mexico off the coast of Texas.
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.
Fisheries managers often use regulations such as bag, size, and season limits to manage recreational anglers and prevent overharvest, and this has been the case for the Gulf of Mexico Red Snapper Lutjanus campechanus fishery, which has been highly regulated for over 20 years. During this period, the federal season for private recreational anglers has decreased from year‐round in 1996 to only 3 d in 2017. However, in 2017 the private recreational season was reopened for an additional 39 d. This scenario allowed us to examine a very short, derby‐style initial season with an unexpected extended season and make comparisons with longer‐term data sets from the Texas Parks and Wildlife Department's angler‐intercept program, where we hypothesized that harvest and effort may not be directly related to season length. Our data indicated that there were higher harvest and effort rates during the initial season than during the extended season, and these differences were a function of extended season length (i.e., future access) and weather. The harvest and effort rates of the extended season were not proportional to the initial season, suggesting that recreational anglers compensated for reductions in season length by compressing their effort into the shortened season. While our results suggest that an extended season results in a reduction of daily harvest and effort rates, it is important to have programs in place to closely monitor the total harvest in a timely manner to prevent overharvest.
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