Post-release Mortality Research Articles

Vertical space use and thermal range of the great hammerhead (Sphyrna mokarran), (Rüppell, 1837) in the western North Atlantic.

The great hammerhead (Sphyrna mokarran) is a highly mobile, large-bodied shark primarily found in coastal-pelagic and semi-oceanic waters across a circumtropical range. It is a target or by-catch species in multiple fisheries, and as a result, rapid population declines have occurred in many regions. These declines have contributed to the species being assessed as globally critically endangered on the IUCN Red List. Although conservation and management measures have yielded promising results in some regions, such as the United States, high levels of at-vessel and post-release mortality remain a major concern to the species population recovery. This examined the vertical space use and thermal range of pop-off archival satellite-tagged S. mokarran in the western North Atlantic Ocean, expanding the understanding of the ecological niche of this species and providing insight into by-catch mitigation strategies for fisheries managers. The results showed that S. mokarran predominantly used shallow depths (75% of records <30 m) and had a narrow temperature range (89% of records between 23 and 28°C). Individual differences in depth use were apparent, and a strong diel cycle was observed, with sharks occupying significantly deeper depths during the daytime. Furthermore, two individuals were confirmed pregnant with one migrating from the Bahamas to South Carolina, U.S.A., providing further evidence of regional connectivity and parturition off the U.S. East Coast. The findings suggest that S. mokarran may be vulnerable to incidental capture in the western North Atlantic commercial longline fisheries due to substantial vertical overlap between the species and the gear. The results can be incorporated into conservation and management efforts to develop and/or refine mitigation measures focused on reducing the by-catch and associated mortality of this species, which can ultimately aide S. mokarran population recovery in areas with poor conservation status.

A project designed to examine, for the first time, the health records of adult prisoners in Northern Ireland and their linkage to other available health data: the test case of prisoner post-release mortality risk.

A project designed to examine, for the first time, the health records of adult prisoners in Northern Ireland and their linkage to other available health data: the test case of prisoner post-release mortality risk&#x0D; ObjectivesThe linkage of routinely collected administrative data for research purposes has the potential to improve knowledge and public benefit. We describe a novel data linkage study between the Northern Ireland (NI) Healthcare in Prisons and Business Services Organisation (BSO). This work is undertaken within the Administrative Data Research Centre-NI (ADRC-NI).&#x0D; ApproachThis joint project between ADRC-NI Queen’s University Belfast and NI Healthcare in Prisons (South Eastern Health and Social Care Trust) will test linkage of prisoner health records to health data held in the BSO and the potential to generate a population-based cohort for a retrospective analysis of prisoner health (2012-2021) that will attempt to characterise prisoners according to socio-demographic, health and committal factors, compare post-release mortality rates with a reference group from the NI population using indirect standardisation and estimate post-release mortality risk using Cox proportional hazards models.&#x0D; ResultsUsing novel data-linkages, a dataset will be created to examine the health of prisoners (and former prisoners) in NI. Ethics and governance approvals are in place for this data-linkage. The linkage will be undertaken via the Honest Broker Service (HBS) in NI and the dataset will be accessed in the safe setting at the BSO. The processes involved, experiences including significant delays or difficulties, and recommendations for future data-linkage studies will be discussed. In addition, a key deliverable of this project will be an assessment of access and linkage capabilities of the prisoner health data, with metadata created and made available to future researchers. In addition, we plan to present preliminary results relating to the test research question.&#x0D; ConclusionWe will describe the processes involved and first-hand research experience in the development of a novel data-linkage project, in addition we will detail access and linkage capabilities in relation to this new dataset to examine health in prisoners (and former prisoners) in NI.

The association of prison security level with mortality after release from prison: a retrospective national cohort study (2000–16)

Incarceration might contribute to increased mortality in an already marginalised population. A better understanding of the prison-related factors that are associated with mortality is important for preventing the negative health consequences of incarceration. We aimed to investigate all-cause and cause-specific mortality following release from high-security and low-security prisons. In this retrospective national cohort study, we used data from the Norwegian Prison Release study (nPRIS), which includes complete national register data for 96 859 individuals from the Norwegian Prison Register linked to the Norwegian Cause of Death Register from Jan 1, 2000, to Dec 31, 2016. The study cohort included all people in Norway released from a high-security or low-security prison unit. Cause of death was categorised into internal causes (infectious, cancerous, endocrine, circulatory, respiratory, digestive, nervous system diseases, and mental health disorders) and external causes (accidents, suicides, and homicides) according to the 10th revision of the International Classification of Diseases. We calculated crude mortality rates (CMR) and estimated Cox proportional-hazards models. There were 151 790 releases in the study period (68·4% from low-security and 31·6% from high-security prisons) from 91 963 individuals. The overall CMR was 854·4 [95% CI 834·7-874·2] per 100 000 person-years (436·2 [422·1-450·3] per 100 000 person-years for internal causes and 358·3 [345·5-371·1] per 100 000 person-years for external causes). The overall post-release mortality rate was higher in those released from high-security prisons (1142·5 [95% CI 1102·6-1182·5] per 100 000 person-years) than in those released from low-security prisons (714·6 [692·6-736·6] per 100 000 person-years). Our results suggest an association between release from high-security prisons and elevated mortality due to both external causes (adjusted hazard ratio [aHR] 1·75 [95% CI 1·60-1·91]) and internal causes (1·45 [1·33-1·59]), compared to release from low-security prisons. Imprisonment and the post-release period can be an important point for public health interventions. Particular attention to health is warranted for individuals incarcerated in and released from high-security prisons. The potential impact of both individual-level characteristics of people incarcerated in high-security facilities, and of the prison environment itself, on mortality outcomes, should be investigated further. The South-Eastern Norway Regional Health Authority and The Norwegian Research Council.

Post-release mortality, recovery, and stress physiology of blacknose sharks, Carcharhinus acronotus, in the Southeast U.S. recreational shark fishery

The post-release mortality (PRM) rate of sharks can be an important factor in estimating overall mortality in stock assessments. However, the accuracy of PRM rates is dependent on our ability to evaluate mortality under realistic fishing practices and conditions. In the Southeast U.S. recreational rod-and-reel fishery, we worked directly with recreational fishing captains to investigate the PRM of blacknose sharks, Carcharhinus acronotus. These sharks are primarily discarded alive in this fishery, but as PRM for this species has yet to be investigated, it is challenging to address the impact of recreational fishing on blacknose shark populations and assess the effectiveness of management measures. We examined PRM by first capturing blacknose sharks (n = 63) with South Carolina and Florida charter captains. Blood samples were taken immediately after capture to evaluate blood-based indicators of capture stress, and sharks were fit with acceleration data logger tags (measuring tri-axial acceleration, depth, and water temperature) to monitor fine-scale behavior and mortality for up to 136 h post-release. Sharks captured in warmer water temperatures displayed increased lactate and decreased pH, the latter of which was more pronounced in females. Fine-scale behavior profiles revealed survivorship for most animals and impaired swimming and mortality in others. All mortality events were attributed to predation events, as evidenced by marked changes in movement that deviated from recorded blacknose shark swimming behavior. Our estimated PRM rates ranged from 3.7% to 41.5%, depending on the release condition of the animal (i.e., increasing level of swimming impairment). Handling duration negatively influenced release condition, indicating extended handling durations increased the probability of a shark showing impaired swimming. Fishery-scale PRM was estimated as 8.5% when considering the distribution of release conditions observed throughout the study. Tag data showed that surviving sharks took an average of 11.7 h to recover and resume normal swimming behavior, with recovery taking longer in warmer water. The overall post-release mortality rate in this fishery is relatively low but may still impact the stock if the total catch is high enough throughout the fishery. Findings from our study will enhance estimates of fishing mortality in future stock assessments and help formulate best practices to reduce the overall fishing mortality of blacknose sharks.

Short-term response of giant trevally (Caranx ignobilis) to capture and handling in a catch-and-release fly fishing recreational fishery, Republic of the Seychelles, Western Indian Ocean.

Giant trevally (Caranx ignobilis, GT) are growing in popularity as a target for tourism-based recreational fisheries throughout their range in the Indo-Pacific. Although predominately catch-and-release (C&R), to date there is no species-specific scientific evidence to support capture and handling guidelines. As such, we examined how GT caught via fly fishing gear while in shallow water responded to capture and handling in the Alphonse Island Group, Republic of the Seychelles. Specifically, we evaluated the physical injury for GTs captured via fly fishing gear, as well as their reflex impairment and post-release activity (using tri-axial accelerometer biologgers) following three air exposure treatments (0 s, 15 s, 30 s). We also had a reference treatment where GTs were caught and landed quickly via a handline, and not exposed to air (0 s) prior to release. Hooking location for both gear types was predominately the jaw or corner of the mouth (fly fishing, n = 30; 83.3%; handline; n = 12, 85.7%), but one fish hooked in a critical location for each capture gear. Across all treatments, only one fish (2%) in the handline treatment was considered a potential short-term post-release mortality following being deeply hooked in the gills and subsequently losing equilibrium upon release. GT reflex impairment and overall post-release activity measured via overall dynamic body acceleration were not influenced by fight time and air exposure treatments used in our study. For GTs across all treatments, locomotor activity was lower in the initial minutes following release than during the second half of the ten minute monitoring period. Overall, our study suggests that GTs in the Alphonse Island Group are resilient to being caught via fly fishing, handled, and air exposed for up to 30 s. However, given the diversity of angling locations for GTs (e.g., shallow flats, deeper reefs) and gear types (e.g., conventional tackle, lures with several treble hooks), additional assessments are needed to help act as the foundation for more universal best practices that can inform management plans for GT recreational fisheries.

Influence of hook barbs on the “through-the-gill” hook removal method for deeply hooked Smallmouth Bass

Sustainable catch-and-release fisheries are based on the assumption that most fish survive an angling event. The adoption of best practices has become important to help mitigate post-release injury, behavioral impairment and mortality. However, in any catch-and-release fishery, a proportion of fish will become inadvertently deeply hooked (e.g., in the gullet) and numerous studies have shown this to be a major driver of mortality. Although available science suggests that cutting the line tends to yield better outcomes than removing hooks in the gullet, there has been interest within the angling community with removing hooks using the “through-the-gill” method where the hook shaft is turned outwards into the gill region and then the hook is removed by pulling anteriorly by gripping the outside bend of the hook. Here, we tested the efficacy of removing barbed and barbless hooks though the gill opening from experimentally deep-hooked Smallmouth Bass (Micropterus dolomieu) relative to leaving the hooks in place. Using a control group and four experimental treatment groups (barbed and removed through the gills; barbless and removed through gills; barbed and left in; barbless and left in), we evaluated handling time, presence of bleeding, incidence of gill or esophageal injury, reflex impairment, incidence of hook shedding (for the left in treatment groups), and survival across a 24-hour monitoring period. Collectively, our results suggested that when hooks were barbed and removed through the gills, fish condition and survival were lower. In addition, barbed hooks were more likely to cause bleeding, gill damage, esophageal tearing, and impair reflexes. When hook removal was done through the gills, the chances of all sublethal outcomes across all categories were more likely to occur. While short-term mortality was not statistically linked with any treatment group, the greatest percentage of mortality (24%) occurred for fish that had barbed hooks removed using the through-the-gill method. These data suggest that when anglers use barbed hooks and encounter a deeply hooked fish, cutting the line poses the least risk to the fish.

A systematic review of factors affecting wildlife survival during rehabilitation and release.

Millions of native animals around the world are rescued and rehabilitated each year by wildlife rehabilitators. Triage and rehabilitation protocols need to be robust and evidence-based, with outcomes consistently recorded, to promote animal welfare and better understand predictors of wildlife survival. We conducted a global systematic review and meta-analysis of 112 articles that reported survival rates of native mammals and birds during rehabilitation and after release to determine intrinsic and extrinsic factors associated with their survival. We assessed survival during rehabilitation and in the short- and long-term post-release, with the hypothesis that survival will vary as a function of species body size, diel activity pattern, trophic level and study location (region of the world). We aimed to determine the direction of effect of these factors on survival to assist in decision-making during triage and rehabilitation. Results showed that mammals and birds were equally likely to survive all stages of rehabilitation, and survival rates varied between locations. Birds in North America had the poorest survival rates post-release, particularly long-term, as did diurnal and carnivorous birds in the short-term post-release. Anthropogenic factors such as motor vehicle collisions and domestic or feral animal attack contributed to morbidity and post-release mortality in 45% (168 of 369) of instances. The reasons for rescue and associated severity of diagnosis were commonly reported to affect the likelihood of survival to release, but factors affecting survival were often species-specific, including bodyweight, age, and characteristics of the release location. Therefore, evidence-based, species-specific, and context-specific protocols need to be developed to ensure wildlife survival is maximised during rehabilitation and post-release. Such protocols are critical for enabling rapid, efficient rescue programs for wildlife following natural disasters and extreme weather events which are escalating globally, in part due to climate change.

Evaluation of post-stocking dispersal and mortality of juvenile lake trout Salvelinus namaycush in Lake Ontario using acoustic telemetry

Wild reproduction by stocked lake trout Salvelinus namaycush in Lake Ontario has yet to produce a self-sustaining population, requiring a reliance on stocking. Once released, age-1 juvenile lake trout are not typically surveyed until age-2, creating a gap in knowledge of fine-scale post-release behaviors. A method to track fine-scale movements and estimate mortality of juvenile lake trout could complement standard survey methods and benefit management decisions regarding stocking locations. We used acoustic telemetry to estimate post-stocking mortality and observe fine-scale spatial and temporal movements of 38 hatchery-reared, age-1 lake trout from an offshore stocking site in the eastern basin of Lake Ontario from 2017 to 2018. Cumulative post-stocking mortality was estimated at 5.3%, 10.5%, and 26.3% after one week, one month and one year, respectively. The majority of lake trout (68.4%) emigrated from the stocking location within two months and entered deep water (∼50 m) once warm-water incursions at the stocking site exceeded lake trout thermal preferences (15 °C). Lake trout made large movements (i.e., median 1.9 km, maximum 12.4 km straight-line distance) within the first hour post-release and had an average swimming speed of 1.64 km‧hr−1over the first day. There was no statistically significant relationship between total distance traveled and time of day, although distance traveled tended to be greater during crepuscular and dark periods compared to daylight. Our results provide a conservative estimate of post-release mortality and reveal behaviors of hatchery-reared juvenile lake trout that may be helpful when selecting stocking locations beneficial to restoration program goals.

Imprisonment, community sanctions and mortality by cause of death among patients with substance use disorder – a 28-year follow-up using Finnish register data

BackgroundThe first few weeks’ post-imprisonment are associated with high mortality, particularly among individuals with a history of substance use. Excess risk may vary by societal context due to a range of penal systems and substance use patterns. Using data on Finnish individuals who had sought treatment for substance use, we studied the association between criminal sanctions with cause-specific mortality. MethodsThe database contained 10887 individuals who had sought treatment between 1990 and 2009. Their treatment data were combined with register data on imprisonments and community sanctions and weekly mortality between 1992 and 2015. Mortality was analysed using discrete-time survival models. We controlled for age and sociodemographic factors, and analysed whether education, type of substance used and the type of latest sentence modified the associations. FindingsMortality was high in the first two weeks after sanctions (all-cause odds ratio [OR] 2.61, 95% confidence interval [CI] 1.67–4.07; drug-related deaths OR 8.52, 95% CI 4.64–15.7). Excess risk declined over time (OR after 12 weeks: 1.19, 95% CI 1.07–1.31). Most of the excess risk was attributable to external causes. Mortality was low during imprisonment, but not during community sanctions. The patterns were similar by level of education, substance use and the type of latest sentence. ConclusionsCommunity sanctions were not associated with mortality among people with substance use disorders. Mortality was low during imprisonment, but high post-release. Criminal sanctions should be better utilised as intervention touchpoints and follow-up resources should target prisoners with substance use treatment history to reduce post-release mortality.

Temporary Retention in Cold Water Reduces Postrelease Behavioral Impairment in Angled Rainbow Trout

AbstractThe effectiveness of catch and release as a conservation practice assumes minimal impacts to released fish. In most cases, angling‐related stressors can be mitigated via changes to angler behavior that reduce fight duration, handling, and air exposure. In some cases, stressors may significantly impact the ability of fish to engage in normal swimming behavior upon release. In these scenarios, it may be beneficial for anglers to assist recovery or retain fish until they are adequately recovered. We investigated the effectiveness of two assisted‐recovery devices at facilitating behavioral recovery in angled Rainbow Trout Oncorhynchus mykiss: (1) retention in a flow box, or (2) retention in a water‐filled cooler. Additionally, we compared the effects of assisted recovery in surface water (24–27°C) or cool water pumped from the hypolimnion (17–19°C). From July to mid‐September 2020, 169 fish were angled from five stocked lakes at Kenauk Nature (Montebello, Quebec). Fish were air exposed for 30 s, for 15 s, or not at all (0 s) and were held in a flow box or a water‐filled cooler for 3 min, while fish in a control group were immediately released. Triaxial acceleration and temperature biologgers were temporarily fixed around the trunk of the fish with Velcro to observe postrelease swimming behavior for 10 min. Rainbow Trout that were held in assisted‐recovery devices regained equilibrium significantly more quickly than those that were immediately released, and fish that were held in 17–19°C water regained equilibrium the most rapidly. In fish that were air exposed for 30 s, individuals that were held in recovery devices exhibited greater swimming activity compared to those that were immediately released. Our study demonstrates that for Rainbow Trout, assisted‐recovery devices can reduce equilibrium impairment, especially when water in the recovery devices is significantly cooler than the relatively warm surface water temperature. Global water temperatures are expected to rise as a result of anthropogenic climate change, and best practices for angling should be adapted to reflect increased thermal stressors for many game fish species. Ensuring that fish are vigorous upon release is imperative for reducing postrelease mortality caused by predation or thermal stress.

Estimating post-release mortality of long-line caught tropical tunas in the Pacific Ocean

Post-release mortality experiments were undertaken on bigeye (Thunnus obesus) and yellowfin (T. albacares) tuna to assess potential post-release survival probabilities of conventional tagging on such individuals during commercial longline operations. Survival was estimated from the release of 32 tuna tagged with pop-up, satellite survivorship tags (sPATs) during a commercial fishing trip aboard a Hawaii based tuna longline vessel. The tagged fish ranged in size from 103 to 145 cm fork length in size. Of the 32 sPATs released, 27 reported earlier than the pre-programmed 60 days, and five never reported. Of the 27 tags that reported data one tag appeared to shed early while the fish was still alive and swimming 32 days post-release while the remaining 26 tags deployed early due to mortality or other events, as observed through either sinking, ingestion by predators, or detached tags. Most mortalities occurred within four days post-release. The overall survival probability was estimated at around 10%, with some evidence that reduced time on the hook may increase this probability up to 50%. These results suggest that bigeye and yellowfin tuna caught during typical longline operations are unlikely to be suitable for electronic or conventional tagging experiments. Our study also suggests all discarded tuna should be treated as mortalities (including those discarded alive) for stock assessment purposes.

Analysis of Predator Avoidance Behavior in California Valley Quail

Quail populations have been in decline across the United States, primarily due to habitat loss and climate. For remedy, landowners and game managers have attempted to restore populations by releasing captive-reared quail. These releases were largely unsuccessful, presumably due to high predation losses. Recently, there has been an increased interest in quail translocations, which tend to have lower mortality rates than captive-reared bird releases. Translocations are expensive and unpredictable, and require many person-hours; releasing captive-reared quail would be more efficient if the practice were successful. We compared predator avoidance behavior between captive-reared and wild-translocated California quail (Callipepla californica) in an aviary using simulated predator attacks (raptorial and mammalian). We recorded predator detection time, antipredator response time, and antipredator response type. Antipredator response type (run, flush, or freeze) frequencies were different, where captive-reared quail ran more frequently than wild-translocated quail when encountering a simulated predator. Predator detection time between captive-reared and wild-translocated quail was not different. However, antipredator response time was quicker for captive-reared quail than wild-translocated quail when subjected to simulated raptorial and mammalian attacks. The differences in antipredator response time and response type may be due to the lack of predator interaction experience of captive-reared birds and offer insight into observed differences in postrelease mortality between captive-reared and wild-trapped quail.

Survival of translocated Columbian Sharp-tailed Grouse: recognizing trends in post-release mortality to improve reintroductions

Survival of translocated Columbian Sharp-tailed Grouse: recognizing trends in post-release mortality to improve reintroductions

Geostatistical tools to assess shifts in recreational fishing

The use of geostatistical indices to examine fishery-dependent data over time is novel. We assess the value of a range of these indices for describing trends in boat-based recreational fishing in Western Australia and areas of high effort and catches for two demersal species with varying biological characteristics, life histories and distributions. The number of blocks (10- × 10-nautical mile (~19- × 19-km) area) visited decreased by 40%, while the number of fishing trips with demersal species catch increased by 15%. Spatial indices showed a south-easterly shift in demersal catch per unit effort (CPUE) across survey years. The southerly shift of West Australian dhufish (Glaucosoma herbraicum) CPUE and subsequent return to the north likely to reflect the response of this temperate species to a marine heatwave. In comparison, CPUE of retained Baldchin groper (Choerodon rubescens) shifted north, whereas released catches shifted south with high probabilities of hotspots present associated with habitat structure. We identified hotspots of retained and released CPUE, highlighting potential areas where species experience high post-release mortality through barotrauma, and targeted spatial management strategies. Spatial indices allow quantitative definition of the structure of the fishery, identify high catch areas, and assess changes over time at a broader scale to sustainably manage multispecies fisheries.

Computed Tomographic Assessment of Hooking-Related Injuries in Recreationally Angled Blue Marlin.

Acute morbidity and mortality of marlins (family Istiophoridae) in hook-and-line fisheries have been studied; however, there has been little or no investigation of the skeletal injuries incurred from terminal tackles that could lead to decreased rates of postrelease survival. The objective of this study was to evaluate skeletal injuries in recreationally angled Atlantic Blue Marlin Makaira nigricans from the 2019 Big Rock Blue Marlin Tournament in Morehead City, North Carolina. We examined heads of six Blue Marlin that were angled using artificial lures rigged with J-hooks and harvested for weigh-in. The head of each Blue Marlin was scanned using computed tomography (CT) and examined with gross dissection. The CT interpretation revealed that two Blue Marlin had minimally displaced fractures of the maxilla, one of which also had a fracture to the lachrymal bone. These radiographic lesions were associated with penetrating hook injuries. The CT images also revealed degenerative changes within the quadrate-articular joint in four Blue Marlin, which was associated with fish weight; the causes and consequences of these degenerative changes are unknown. Although the hooking-related jaw fractures likely result in acute pain, their impact on postrelease morbidity is unknown and the impact on postrelease mortality is suspected to be small.

Connecting post-release mortality to the physiological stress response of large coastal sharks in a commercial longline fishery.

Bycatch mortality is a major factor contributing to shark population declines. Post-release mortality (PRM) is particularly difficult to quantify, limiting the accuracy of stock assessments. We paired blood-stress physiology with animal-borne accelerometers to quantify PRM rates of sharks caught in a commercial bottom longline fishery. Blood was sampled from the same individuals that were tagged, providing direct correlation between stress physiology and animal fate for sandbar (Carcharhinus plumbeus, N = 130), blacktip (C. limbatus, N = 105), tiger (Galeocerdo cuvier, N = 52), spinner (C. brevipinna, N = 14), and bull sharks (C. leucas, N = 14). PRM rates ranged from 2% and 3% PRM in tiger and sandbar sharks to 42% and 71% PRM in blacktip and spinner sharks, respectively. Decision trees based on blood values predicted mortality with >67% accuracy in blacktip and spinner sharks, and >99% accuracy in sandbar sharks. Ninety percent of PRM occurred within 5 h after release and 59% within 2 h. Blood physiology indicated that PRM was primarily associated with acidosis and increases in plasma potassium levels. Total fishing mortality reached 62% for blacktip and 89% for spinner sharks, which may be under-estimates given that some soak times were shortened to focus on PRM. Our findings suggest that no-take regulations may be beneficial for sandbar, tiger, and bull sharks, but less effective for more susceptible species such as blacktip and spinner sharks.

Horizontal and vertical movements of immature dusky sharks Carcharhinus obscurus in relation to commercial longline fisheries in the western North Atlantic Ocean

BackgroundMany species of sharks, including the dusky shark Carcharhinus obscurus, are often incidentally captured in commercial pelagic and bottom longline fisheries. Incidental capture can lead to at-vessel or post-release mortality and can be detrimental to populations of threatened, endangered, or prohibited species. The estimated at-vessel mortality for dusky sharks can be high in longline fisheries and, to minimize mortality, time–area closures have been designated in the western North Atlantic Ocean to mitigate interactions with longline fisheries, yet incidental capture of dusky sharks is still common. We compared the vertical and horizontal movements of dusky sharks to the overall fishing effort and depth fished of commercial pelagic and bottom longline fisheries to determine when and where overlap is present that could lead to incidental capture.ResultsTwenty-one (n = 21) dusky sharks were tagged with pop-up archival transmitting satellite tags and all were immature animals (123–200 cm FL) apart from two individuals (230 and 300 cm FL). Sharks were tagged off the coasts of North Carolina (71%) and Florida (29%). Twenty tags (95%) reported and provided tracks between 1 and 107 days (median 15 days) and 10 tags (50%) remained on sharks for > 4 days. Most individuals remained within the bottom longline closed area off the coast of North Carolina during their time at liberty. Dusky sharks primarily occupied the 20–40 m depth range 26% of the time, and overlapped with bottom and pelagic longline gears 41% and 59% of the time, respectively. Overlap was highest in the winter and spring for both commercial fisheries.ConclusionsThe use of archival satellite telemetry in this study has provided valuable preliminary information on vertical and horizontal movements of immature dusky sharks in western North Atlantic Ocean. Dusky sharks may be more vulnerable to incidental capture in the pelagic longline fishery due to the high fishing effort, larger areas of horizontal overlap, and greater percentage of vertical overlap. This information will inform mitigation measures of commercial longline fisheries, which can work toward population rebuilding of the species.

Spatially Targeted Biological Control of Mile-a-Minute Weed Using Rhinoncomimus latipes (Coleoptera: Curculionidae) and an Unmanned Aircraft System.

Rhinoncomimus latipes Korotyaev is a specialist biocontrol agent of mile-a-minute weed, Persicaria perfoliata (L.) H. Gross (Caryophyllales: Polygonaceae). Currently, R. latipes is released by hand where the presence of the weed is readily detected. However, the hand-release method is not applicable to weed patches spread in hard-to-access areas. This study was conducted to develop a spatially targeted biocontrol strategy by using an unmanned aircraft system (UAS, a.k.a. drone) for the detection of P. perfoliata and aerial release of R. latipes. A ground survey was performed to locate P. perfoliata patches and then a rotary-wing UAS was flown at 15 different altitudes to determine the detectability of P. perfoliata patches. We developed an insect-release system including a pod that housed R. latipes for aerial release. The pod was 3D printed with biodegradable polyvinyl alcohol (PVA), and field tests were conducted to determine the ability of R. latipes to escape the pod and assess their post-release mortality and feeding ability. The results of this study showed that P. perfoliata patches were readily detectable on the aerial images taken at ≤15 m above the ground. More than 98% of R. latipes (n = 118) successfully escaped from the pod within 24 h after aerial deployment. There were no significant (P > 0.05) effects of PVA exposure on the mortality and feeding ability of R. latipes. These results indicate that aerial detection of P. perfoliata and deployment of R. latipes for spatially targeted biological control in hard-to-access areas can be accomplished using a rotary-wing UAS.

Reconstructing historical baseline catches along Highway 101: U.S. West Coast marine fisheries, 1950–2017

The United States of America, as most other countries, emphasizes commercial fisheries when reporting statistics to the Food and Agriculture Organization of the United Nations (FAO), and excludes data from other sectors, such as recreational fisheries. Our study is a first attempt to account comprehensively for all sources of total U.S. marine catches from the Exclusive Economic Zone waters along the West Coast of the continental USA from 1950 to 2017 in one dataset, i.e., excluding the states of Alaska and Hawaii. Total reconstructed catches for 1950–2017 were 1.2 times higher than the data reported by the USA to the FAO. Commercial landings dominated catches, with 65% from large-scale, industrial fisheries and 31% from small-scale, commercial fisheries. Recreational fisheries accounted for 4% of the total catch, after accounting for post-release mortality. Total catches were highest in 1950 at around 750,000 t and declined to 570,000 t by 2017. Internationally unreported discards increased from 24,000 t in 1950 to 86,000 t in 1989, but declined after the introduction of bycatch reduction devices to around 10,000 t year−1 by the mid-2010s. Total catches by taxonomic category suggest a decline in the diversity in catches. Levels of reporting for total catches is excellent for recent decades, with around 95% of total catches accounted for by the mid-2010s, but around 40% of catches were missing from data reported to the FAO between the late 1960s and early 1990s. This discrepancy was largely driven by industrial catches of North Pacific hake (Merluccius productus) that were not in the officially reported data. Our results suggest that recreational fisheries and discards can make up a considerable component of total catches over time. We suggest that the USA include their recreational catch estimates in their annual data submission to the FAO, retroactively to 1950.

Hook retention but not hooking injury is associated with behavioral differences in Bluegill

Recreational catch-and-release angling (C&R) is prevalent and growing in popularity, along with concerns over the welfare of released fish. Although there have been many studies quantifying post-release mortality in fish exposed to C&R, there is growing interest in understanding and minimizing any sublethal consequences of recreational fisheries interactions with the aim of improving fish health and welfare. Short-term fish behavior has been explored as an endpoint for C&R, but effects of hooking injury have not been examined independently of other angling stressors. We used Bluegill (Lepomis macrochirus) as a model to assess whether immediate injuries from hooking or the retention of a hook influenced fish behavior compared to unhooked controls using Z-maze and flight initiation distance tests. Fish that retained a hook were less likely to leave a refuge-emergence chamber than fish that were hooked–unhooked or unhooked controls. Moreover, when fish with the hook retained did leave the refuge, they were less exploratory than fish in the other two treatments. Unhooked control fish and fish that were hooked-unhooked did not significantly differ in their overall behavioral patterns outside the refuge. This suggests that fish are resilient to the acute tissue damage associated with minor hooking injuries and that reported behavioral impairments in fish after release are driven more by hook retention, physiological exhaustion from the fight, landing, and/or subsequent handling and air exposure.