We used 25 years of conventional tagging data (n=6173 recoveries) and 3 years of ultrasonic telemetry data (n=105 transmitters deployed) to examine movement rates and directional preferences of four ...age classes of red drum (Sciaenops ocellatus) in estuarine and coastal waters of North Carolina. Movement rates of conventionally tagged red drum were dependent on the age, region, and season of tagging. Age-1 and age-2 red drum tagged along the coast generally moved along the coast, whereas fish tagged in oligohaline waters far from the coast were primarily recovered in coastal regions infall months. Adult (age-4+) red drum moved from overwintering grounds on the continental shelf through inlets into Pamlico Sound in spring and summer months and departed in fall. Few tagged red drum were recovered in adjacent states (0.6% of all recoveries); however, some adult red drum migrated seasonally from overwintering grounds in coastal North Carolina northward to Virginia in spring, returning in fall. Age-2 transmitter-tracked red drum displayed seasonal emigration from a small tributary, but upstream and downstream movements within the tributary were correlated with fluctuating salinity regimes and not season. Large-scale conventional tagging and ultrasonic telemetry programs can provide valuable insights into the complex movement patterns of estuarine fish.
We compared numbers of strikes, proportions of fish that hooked up after strikes, proportions of fish that stayed on hook (retained) after hook up, and numbers of fish caught between circle and J ...hooks rigged with dead natural fish bait (ballyhoo) and trolled for three oceanic predator species: dolphinfish (Coryphaena hippurus), yellowfin tuna (Thunnus albacares), and wahoo (Acanthocybium solandri). Interactions were compared between circle and J hooks fished on 75 trips by two user groups (charter and recreational fishermen). Hooks were affixed to three species-specific leader types most commonly fished in this region: monofilament (dolphinfish), fluorocarbon (tuna), and wire (wahoo). Numbers of fish caught per trip and three potential mechanisms that might influence numbers caught (i.e., number of strikes, proportion of fish hooked, and proportion retained) were modeled with generalized linear models that considered hook type, leader type, species, user (fishing) group, and wave height as main effects. Hook type was a main effect at the catch level; generally, more fish were caught on J hooks than on circle hooks. The effect of hook type on strike rates was equivocal. However, J hooks had a greater proportion of hook-ups than did circle hooks. Finally, the proportion of fish retained once hooked was generally equal between hook types. We found similar results when data from additional species were pooled as a "tuna" group and a "mackerel" group. We conclude that J hooks are more effective than circle hooks at the hook-up level and result in greater numbers of troll-caught dolphinfish, tunas, and mackerels.
Members of the Epinephelinae subfamily of serranids (“grouper”) are heavily exploited by both recreational and commercial hook-and-line fishermen on the continental shelf of the southeastern United ...States. However, aspects of groupers’ biology and ecology render them extremely vulnerable to overexploitation, including slow growth, late reproduction, large size, and long life span. In addition to direct fishing mortality, hook and release mortalities likely occur when grouper are caught and released, due to injuries sustained from hooking as well as those associated with retrieval from deep waters. Here, we evaluated four hook sizes and styles (5/0 “J”, 7/0 “J”, 9/0 “J”, and 12/0 circle hooks) during the summer of 2003 by their ability to reduce catches of sublegal grouper and non-target species in Onslow Bay, North Carolina, USA. A total of 1249 fish representing 33 species were landed during 20 days of commercial fishing activities. The most common grouper landed were red grouper
Epinephelus morio (
n = 459), gag grouper
Mycteroperca microlepis (
n = 55), and scamp grouper
Mycteroperca phenax (
n = 50). Overall, 6.8% of grouper landed were below the minimum size limit, and the proportion of sublegal grouper caught per day decreased with depth. Catch rates for small grouper (i.e., <50.8
cm fork length), non-target individuals, and sharks varied across hook treatments, while catch rates for large grouper (i.e., ≥50.8
cm fork length) did not. Circle hooks significantly reduced gut hooking in all groupers as well as non-target species. The proportion of grouper and non-target fish that bled varied across hooking locations, with more fish bleeding from gut and gill hooking than jaw hooking. Finally, the proportion of red and gag grouper with distended stomachs was positively related to the water depth in which the fish were caught. These results suggest a tradeoff between fishing in shallow water to reduce depth-related injuries to grouper and fishing in deeper water to minimize the catch of sublegal grouper.
Abstract We report the case of a 43-year-old patient with HIV infection treated with antiretroviral therapy, which was complicated by immunoglobulin A (IgA) nephropathy and renal failure, who ...subsequently was transplanted using a deceased donor kidney transplant. During the late posttransplant period we detected specific anti-donor HLA antibodies showing a preserved alloantigen response. A renal biopsy showed no acute cellular or humoral rejection, an absence of pericapillary C4d deposits or SV40 infected cells, but demonstrated IgA mesangial deposits and mild interstitial fibrosis probably related to calcineurin inhibitor toxicity. This case shows that allo- and autoimmune responses are preserved despite immunosuppressive treatment and original HIV disease. It warns of the importance of maintaining optimal monitoring and immunosuppressive strategies among HIV-positive recipients who become solid organ transplant recipients.
Young-of-the-year (YOY) bluefish, Pomatomus saltatrix (L.) impose significant mortality on recently metamorphosed striped bass, Morone saxatilis (W.) in the Hudson River estuary. Field observations ...indicate that bluefish selectivity on striped bass increases with increasing striped bass density suggesting a density-dependent feeding response. Functional response and switching experiments were conducted to aid in determining the mechanism for this response. The type of functional response exhibited by bluefish under several prey treatments was examined. These were striped bass alone, Atlantic silversides, Menidia menidia (L.) alone, striped bass with a background density of alternative prey, and striped bass in the presence of eelgrass Zostera marina (L.). The functional response of bluefish to increasing prey density was more similar to a type I or II model than a type III model under all treatments. Switching was examined by providing bluefish both striped bass and silversides at five different ratios with and without a prey refuge, eelgrass. Bluefish did not exhibit a type III functional response or switching behavior suggesting that these mechanisms do not explain the observed density-dependent selectivity pattern in the field. Switching experiments did suggest that the presence of prey refuge can determine selectivity by YOY bluefish in the field. The abundance of submerged aquatic vegetation and other prey refuge may be important in controlling the predatory impact of bluefish on striped bass in the Hudson River.
The behavior of fish around bait is poorly understood despite it being important for the fish catching process and estimating relative abundance. We used a fine-scale acoustic positioning system to ...quantify the movements of 26 red snapper (Lutjanus campechanus) around 120 bait deployments in 2019 at a natural reef site (∼37-m deep) in North Carolina, USA. There were 39 instances of tagged red snapper approaching bait during four baiting days, some of which approached due to apparent sensory cues (28%), while most approached incidentally (72%). Tagged red snapper approached bait from initial distances of 1 to 1147 m (median = 27 m; mean = 86 m), and took 0–77 min (mean = 22 min) to approach. Fish were more likely to approach bait if they were located close to, and down-current of, the bait at deployment. Our estimated effective fishing area of 2290 m
2
(within which >50% of red snapper responded to bait) could be used along with video counts and other information to estimate densities of red snapper.
Minimum size limits may be ineffective for reef fishes because they often sustain barotrauma when caught from deep (>20 m) waters. A study was undertaken in conjunction with hook-and-line commercial ...fishermen to calculate discard percentages and evaluate potential release mortality of eight economically important species: black sea bass, Centropristis striata (Linnaeus), red grouper, Epinephelus morio (Valenciennes), snowy grouper, Epinephelus niveatus (Valenciennes), gag, Mycteroperca microlepis (Goode and Bean), scamp, Mycteroperca phenax (Jordan and Swain), vermilion snapper, Rhomboplites aurorubens (Cuvier), white grunt, Haemulon plumieri (Lacepède) and red porgy, Pagrus pagrus (Linnaeus). Fishing with baited hook and line occurred in 2004 and 2005 in Onslow Bay, NC, in waters 19-150 m deep. Sub-legal discard rates were 15% for vermilion snapper, 25% for red porgy, 7% for red grouper, 33% for gag, 35% for scamp and 12% for black sea bass. Although mortality based on post-release behaviour was relatively low, higher mortalities estimated from models incorporating hooking location and depth of capture suggest that minimum size limits may not provide the population benefits intended by management in the North Carolina reef fishery.
External attachment of electronic tags has been increasingly used in fish studies. Many researchers have used ad hoc attachment methods and provided little or no validation for the assumption that ...tagging itself does not bias animal behaviour or survival. The authors compared six previously published methods for externally attaching acoustic transmitters to fish in a tank holding experiment with black sea bass Centropristis striata (L.). They tracked tag retention, fish growth and external trauma (as a measure of fish welfare) for 60 days. For each of these metrics, the results showed a wide range of responses among tagging treatments. A simple attachment method using a spaghetti tag passed through the dorsal musculature of the fish and tied to the end cap of the transmitter emerged as the preferred option based on high retention, no impact on growth and relatively low detriment to fish welfare. Future field studies using external electronic tagging should consider tag‐related effects that could compromise results when selecting a method for tag attachment.
Climate change and the associated rise in air temperature have
affected the Tibetan Plateau to a significantly stronger degree than the
global average over the past decades. This has caused ...deglaciation,
increased precipitation and permafrost degradation. The latter in particular
is associated with increased slope instability and an increase in
mass-wasting processes, which pose a danger to infrastructure in the
vicinity. Interferometric synthetic aperture radar (InSAR) analysis is well
suited to study the displacement patterns driven by permafrost processes, as
they are on the order of millimeters to decimeters. The Nyainqêntanglha
range on the Tibetan Plateau lacks high vegetation and features relatively
thin snow cover in winter, allowing for continuous monitoring of those
displacements throughout the year. The short revisit time of the Sentinel-1
constellation further reduces the risk of temporal decorrelation, making it
possible to produce surface displacement models with good spatial coverage.
We created three different surface displacement models to study heave and
subsidence in the valleys, seasonally accelerated sliding and linear creep
on the slopes. Flat regions at Nam Co are mostly stable on a multiannual
scale but some experience subsidence. We observe a clear cycle of heave and
subsidence in the valleys, where freezing of the active layer followed by
subsequent thawing cause a vertical oscillation of the ground of up to a few
centimeters, especially near streams and other water bodies. Most slopes of
the area are unstable, with velocities of 8 to 17 mm yr−1. During the
summer months surface displacement velocities more than double on most
unstable slopes due to freeze–thaw processes driven by higher temperatures
and increased precipitation. Specific landforms, most of which have been
identified as rock glaciers, protalus ramparts or frozen moraines,
reach velocities of up to 18 cm yr−1. Their movement shows little
seasonal variation but a linear pattern indicating that their displacement
is predominantly gravity-driven.
Glacial lakes constitute a substantial part of the legacy of vanishing mountain glaciation and act as water storage, sediment traps and sources of both natural hazards and leisure activities. For ...these reasons, they receive growing attention by scientists and society. However, while the evolution of glacial lakes has been studied intensively over timescales tied to remote sensing-based approaches, the longer-term perspective has been omitted due a lack of suitable data sources. We mapped and analyzed the spatial distribution of glacial lakes in the Austrian Alps. We trace the development of number and area of glacial lakes in the Austrian Alps since the Little Ice Age (LIA) based on a unique combination of a lake inventory and an extensive record of glacier retreat.
We find that bedrock-dammed lakes are the dominant lake type in the inventory. Bedrock- and moraine-dammed lakes populate the highest landscape domains located in cirques and hanging valleys. We observe lakes embedded in glacial deposits at lower locations on average below 2000 m a.s.l. In general, the distribution of glacial lakes over elevation reflects glacier erosional and depositional dynamics rather than the distribution of total area. The rate of formation of new glacial lakes (number, area) has continuously accelerated over time with present rates showing an eight-fold increase since LIA. At the same time the total glacier area decreased by two-thirds. This development coincides with a long-term trend of rising temperatures and a significant stepping up of this trend within the last 20 years in the Austrian Alps.
•A detailed analysis is provided of glacial lake distribution and formation in the Austria Alps.•Glacial lake distribution of overelevation reflects erosional and depositional dynamics rather than total area.•We observed more than 260 new lakes that evolved since the Little Ice Age.•Glacial lake formation hascontinuously accelerated over time with present rates showing an eight-foldincrease since LIA.•This development coincides with long-term and short-term trends of rising temperatures in the Austrian Alps.
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