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In the Great Plains region, the live bait industry relies on approved species of cultured and wild-harvested baitfish. The release of baitfish by anglers is prohibited in most locations, but angler compliance with these regulations can be low. Bait retailers can increase compliance with regulations by communicating with anglers about aquatic invasive species (AIS) risk and through their business practices. We conducted 66 telephone surveys with bait retailers in southeastern South Dakota from June to July 2023 to (1) characterize bait retailer practices that may influence AIS risk and (2) determine the extent and willingness of bait retailers to display educational materials to reduce AIS risk. Fathead minnows (Pimephales promelas) were the most sold species (96% of respondents), and most bait came from wholesale retailers (74%). However, 24% of bait retailers also occasionally bought from local bait harvesters. Non-advertised species were observed at least once in shipments by 35% of bait retailers, but retailers only encountered species they did not intend to order in 1% of their inspections. Regular inspections for non-advertised species in baitfish shipments were conducted by 74% of retailers. Most inspections occurred at the time of receiving a baitfish shipment (36%) or daily (36%). Bait retailers were interested in displaying provided AIS educational materials (80%), including posters and pamphlets (59%), stickers (41%), bait bags (39%), and keychains/boat key floats (36%). Displaying educational materials at bait retail locations may increase angler knowledge of AIS and compliance with bait disposal regulations. [ABSTRACT FROM AUTHOR]

Eel is a catadromous fish that is nocturnal. Demand for eels are increasing from year to year, resulting in increased cultivation and catching in the wild. Fishers use habits and their experience in catching eel both for bait and fishing time. The study was aimed at observing the biorhythm of the eel in the search for feeding and the response of the eel to different feeds. The feeds used are pasta, Sardinella lemuru, and soil worms. Biorhythm observation and response to feed were carried out using direct observation methods in the laboratory. The observations results showed that eel activities mostly occur in the afternoon to evening. At 16.30 PM and 01.00 PM many eels come out of the shelter and actively swimming. The time it takes for an eel to approach the paste bait at a distance of 50 cm is an average of 19.8 seconds. The time it takes for an eel to approach the worm bait at a distance of 100 cm is an average of 38.8 seconds. Eels respond to types of pasta bait and earthworms more quickly. [ABSTRACT FROM AUTHOR]

Orang Asli (OA) Seletar is one of indigenous group categorized under Proto-Malay group alongside with other tribes such as Temuan, Semelai, Jakun, Kanaq and Kuala. OA Seletar also has been recognized as one of sea gypsies group, alongside with OA Kuala because their entire livelihood depends on the sea. Besides that, their understanding of the marine world is different with common people as the sea is not just a source of sustenance but also means to provide to their families. Because of that, most of OA Seletar have taken up fishing as their main occupation to ensure their survival. This study aims to identify the socioeconomic activities carried out by the Seletar indigenous community in Kampung Bakar Batu, Johor Bahru. This study has used a qualitative approach such as in-depth interview methods, participant observation, and library methods. A total of five informants were interviewed to obtain the necessary information. Participatory observation was also done to obtain evidence to support the information obtained during the interview session. The results of the study found that the Seletar community in Kampung Bakar Batu has carried out two main socioeconomic activities, namely traditional fishing and the sale of fishing bait. However, these activities are creasingly challenged by development projects near their settlement areas. This study is indirectly important to document the persistence of the Seletar community in carrying out socioeconomic activities to improve their living standards and economic standards. [ABSTRACT FROM AUTHOR]

Human pressures are changing ocean environments, such as a shift from fish‐ to squid‐dominated ecosystems in overfished, poorly oxygenated environments. After death, carcasses of upper ocean fauna sink to the seafloor where they provide food for demersal scavengers. It is unclear how shifts in carcass type impact abyssal scavengers. We performed baited benthic camera lander deployments in the Cabo Verde Abyssal Basin to test how a shift from fish‐ to squid‐dominated carrion could modify abyssal scavenger ecology. At the fish bait, peak scavenger abundance was greater and occurred later for the majority of observed fauna. However, removal rates of squid bait were up to 10‐fold greater, and a significantly different community composition developed, favoring faster organisms with lower chemosensory thresholds. At the fish bait, slower organisms were less disadvantaged as the bait persisted for longer periods allowing the development of a more complex community and dense amphipod aggregations. The rapid squid consumption indicates that the accumulation of this type of food fall at the seafloor may not occur, preventing scientific observations necessary to estimate the importance of squid carrion to the biological C pump and deep‐sea food webs. As such, the flux of squid carrion to the seafloor is likely greater than currently recognized in this part of the Atlantic. The differences observed between bait types indicate how future changes in upper ocean ecosystems may impact abyssal scavengers and their ecosystem functions, including controlling seafloor biomass, regulating the behavior of benthic fauna, and contributing to nutrient cycling and energy transfer. [ABSTRACT FROM AUTHOR]

Low-impact fishing gear, such as fish pots, could help reduce human's impact on coastal marine ecosystems in fisheries but catch rates remain low and the harvest of resources used for baiting increases their environmental cost. Using black seabreams (Spondyliosoma cantharus) as target species in the Bay of Biscay, we developed and assessed the efficiency of biodegradable biopolymer-based baits (hereafter bio-baits) made of cockles (Cerastoderma edule) and different biopolymer concentrations. Through a suite of deep and machine learning models, we automatized both the tracking and behavior classification of seabreams based on quantitative metrics describing fish motion. The models were used to predict the interest behavior of seabream towards the bait over 127 h of video. All behavior predictions categorized as interested to the bait were validated, highlighting that bio-baits have a much weaker attractive power than natural bait yet with higher activity after 4 h once natural baits have been consumed. We also show that even with imperfect tracking models, fine behavioral information can be robustly extracted from video footage through classical machine learning methods, dramatically lifting the constraints related to monitoring fish behavior. This work therefore offers new perspectives both for the improvement of bio-baits and automatic fish behavior recognition. [ABSTRACT FROM AUTHOR]

Simple Summary: The overexploitation of the bristle worm Diopatra neapolitana in Ria de Aveiro, a coastal lagoon in mainland Portugal, has led to a generalized decline of its local populations, as it is commonly used as live bait for sports fishing. Several management actions have been put forward to reduce the impact of its harvesting, although illegal poaching still threatens the sustainable use of this marine resource. In an attempt to verify if D. neapolitana was sourced from no-take zones or if it was indeed collected from the place of origin claimed by live bait traders, this study evaluated if the geographic origin of D. neapolitana could be correctly assigned using a combination of fatty acid profiles and elemental fingerprints of its whole body and jaws, respectively. Results showed that both fatty acid profiles and elemental fingerprints differ significantly among locations, making it possible to discriminate the geographic origin of D. neapolitana. This discrimination achieves even higher accuracy when combining these two natural barcodes than when employing each one of them individually. The present work can, therefore, contribute to the enforcement of management plans for the sustainable use of this commercially important marine resource. Diopatra neapolitana Delle Chiaje, 1841 (Annelida, Onuphidae) is one of the most exploited polychaete species in European waters, particularly in Ria de Aveiro, a coastal lagoon in mainland Portugal, where the overexploitation of this resource has led to a generalized decline of local populations. In an attempt to reduce the impact of harvesting, several management actions were implemented, but illegal poaching still fuels a parallel economy that threatens the sustainable use of this marine resource. The present study evaluated the combination of fatty acid profiles and elemental fingerprints of the whole body and jaws, respectively, of D. neapolitana collected from four harvesting locations within Ria de Aveiro in order to determine if their geographic origin could be correctly assigned post-harvesting. Results showed that both fatty acid profiles and elemental fingerprints differ significantly among locations, discriminating the geographic origin with higher accuracy when combining these two natural barcodes than when employing each individually. The present work can, therefore, contribute to the implementation of an effective management plan for the sustainable use of this marine resource, making it possible to detect if D. neapolitana was sourced from no-take zones and if it was collected from the place of origin claimed by live bait traders. [ABSTRACT FROM AUTHOR]

Detection of animals is influenced by species traits, environment, season and the methods used. Analytical techniques can address imperfect detection, such as false absences, but data limitations hinder accurate density estimation. Identifying field survey methods that optimize detectability is therefore a high research priority, especially for species of conservation concern. We consider a model species, the sugar glider Petaurus notatus, to evaluate how optimizing detections can affect survey outcomes. A literature meta‐analysis found little innovation in baiting approaches for sugar gliders over four decades. Honey‐based baits prevailed, despite emerging evidence of opportunistic carnivory. We compared sugar glider detection probabilities using honey and fish‐based baits in a spatially explicit capture‐recapture study. Fish bait increased detections 33‐fold, and density estimation (0.12 ha−1) was only possible using the fish‐baited data – detections were too sparse using honey‐bait to facilitate analysis. Other factors that influence detectability include trap height and habitat connectivity, which were top moderators in our meta‐analysis, but these may be secondary to the bait or lure used. By using (i) species‐specific bait that accounts for the biology of the target species, and (ii) analytical tools to account for imperfect detection and heterogeneous movement of animals, we achieved good enough detection probabilities to undertake detailed analysis of the spatial ecology of sugar gliders. Compared to honey‐based baits (the prevailing approach of other studies on this species), the high detection probability attained with fish‐based baits provides an improvement on conventional practices. Our study is an important reminder that accounting for the biology of the target species during survey effort may mean the difference between collecting enough data for analysis or not. In the context of species conservation, optimizing detection likelihoods is critical for answering ecological questions about cryptic species, and our results demonstrate the need to reappraise generic approaches when better information is available. [ABSTRACT FROM AUTHOR]

Cheirodon interruptus is a small characid widely distributed in South America and frequently used as bait. The harvesting of wild fish to supply the market has a significant environmental impact. The effect of photoperiod and temperature on ovarian maturation is assessed to evaluate its potential to manipulate reproduction. Fish were exposed to three treatments (in triplicate): (light hours: L/temperature: °C) 12 L/20°C, 24 L/20-25°C, and 9.8–13.3 L/20-25°C. Gonadosomatic index (GSI), plasma estradiol (E2), oocyte diameter, and vitellogenic oocyte percentage were estimated. Mean GSI, E2 values, oocyte diameter, and percentage were significantly higher in 9.8–13.3 L/20-25°C than in the other treatments, indicating ovarian maturation. In turn, these values were minimal in the 24 L/20-25°C treatment, revealing ovarian regression. These results suggest that in C. interruptus, the photoperiod is the primary driver of gonadal maturation and the temperature plays a secondary role. This study demonstrated that manipulation of ovarian development is possible through the design of photothermal regimes based on the winter-spring transition. [ABSTRACT FROM AUTHOR]

The Length-Weight Relationships (LWRs) of seven live-bait fishes namely, Rhabdamia gracilis, Zoramia leptacantha, Verulux cypselurus, Gymnocaesio gymnoptera, Chromis viridis, Chrysiptera brownriggii and Lutjanus kasmira found in Lakshadweep waters were determined in the current study. The specimens were captured from Agatti Island lagoons, using lift nets and encircling nets at depths ranging from 2 to 10 m. This data collection spanned from January 2021 to March 2022. The estimated b values ranged from 3.09 to 3.38 for G. gymnoptera and Z. leptacantha, respectively. The coefficient of determination (r²) ranged from 0.99 (G. gymnoptera) to 0.89 (V. cypselurus). The study provides insight into the biological details of these live bait fishes, which support traditional tuna pole and line fishing in Lakshadweep waters. [ABSTRACT FROM AUTHOR]

This study detected two potential pathogens, Vibro parahaemolyticus, which causes acute hepatopancreatic necrosis disease (AHPND), and white spot syndrome virus (WSSV), in fishing bait in South Korea. However, their infectious nature was not confirmed, possibly due to the degradation caused by freezing/thawing or prolonged storage under frozen conditions. While infectivity was not confirmed in this study, there is still a significant risk of exposure to these aquatic products. Furthermore, fishing bait and feed should be handled with caution as they are directly exposed to water, increasing the risk of disease transmission. In Australia, cases of WSSV infection caused by imported shrimp intended for human consumption have occurred, highlighting the need for preventive measures. While freezing/thawing is a method for inactivating pathogens, there are still regulatory and realistic issues to be addressed. [ABSTRACT FROM AUTHOR]

During two campaigns, one in the Kattegat (Denmark) in 2018, and the other off Namibia in 2019, the same fish baited trap was applied to catch scavenging amphipods at two stations each. The water depths in both areas were between 50 and 130 m. In addition to very few individuals of other species (Isopoda and Amphipoda), the samples consisted mainly of Scopelocheirus sp. The species from the Kattegat was identified as S. hopei. The question arises as to whether it is possible that the same species could dominate scavenging communities in sea areas more than 10,000 km apart. At first glance, the scopelocheirid amphipods of the northern and southern hemispheres appear identical, but subtle morphological and large genetic differences led to the conclusion that we are dealing with a previously undescribed species off Namibia. We have named it Scopelocheirus sossi sp. nov. [ABSTRACT FROM AUTHOR]

Simple Summary: The genus Diopatra is a major driver in sedimentary systems, altering the structure of habitats and changing the frequency of refugia and predator access to prey. It is taken as prey by a variety of shorebirds, crustaceans, and fish and used worldwide as bait. Diopatra are quite charismatic, with iridescent colour patterns and a willingness to be fed by hand by entranced biologists, and their larvae can only be described as 'cute'. One might expect then that given their importance to sedimentary systems, the bait trade, etc. that we would know more than we do about their reproductive modes, physiological tolerances, etc. than we do. The recent discovery that the predominant onuphid of the very well-known Atlantic coast of Europe, D. neapolitana, is a protandric sequential hermaphrodite is startling. This special volume dedicated to Diopatra will hopefully stimulate more investigations and further insights. The annelid genus Diopatra occurs in all major oceans but is best represented in the shallow depths of warmer waters, where it lives in elaborately decorated tubes. This paper provides an introduction to the animals, discussing their history and diversity. We describe and illustrate its morphology and geographic distribution. While they were thought to be predominantly gonochoristic, recent reproductive studies show that several species are protandric simultaneous hermaphrodites. Development is by broadcast spawning with a brief pelagic stage or direct development in the parental tube or egg mass attached to it. Diopatra is a key ecosystem engineer, altering water flow and deposition and increasing the availability of refugia. We also discuss its harvesting as fishing bait, its role as an alien or introduced species, its capacity to regenerate, its therapeutic potential, and its applications as a bioindicator species for climate change, geographic distribution changes, and dispersal. [ABSTRACT FROM AUTHOR]

Diopatra claparedii Grube, 1878, is a common polychaete species that occurs in Southeast Asian countries, including Malaysia, Singapore, Thailand, and the Philippines. However, the occurrence of this species in Indonesia has never been recorded. In the present study, we identified the presence of D. claparedii in the eastern part of the Segara Anakan Lagoon in Cilacap, Central Java Province. The species is characterized as having distinct pectinate chaetae with funnel-like combs. The worms, like in some other Asian countries, are commercially exploited for use as fishing bait. The distributional map of this species is provided in this article. [ABSTRACT FROM AUTHOR]

Little attention has been directed toward the local use of seaweeds as fish baits despite their relevance to the success of fishing operations. Fish baits represent little more than a subset of the major local use of seaweeds in the Philippines. In Sorsogon, Bulusan has a history of smallscale fishing with three traditional fishing gears - namely, fish pot, hook and line, and long line. In this study, we provide traditional knowledge on the selection of seaweeds as fish baits among fishers in Bulusan. Currently, the traditional fishing practice in the area retains the use of nine seaweed fish bait taxa - namely, Acanthophora spicifera, Eucheuma denticulatum, Gracilaria gigas, Kappaphycus alvarezii, Sargassum polycystum, Ulva clathrata, Ulva flexuosa, Ulva lactuca, and Ulva reticulata. The last four species (collectively known as the ulvoids) were the most familiar seaweed fish baits. Eleven (11) target fish species were identified, being Naso and Siganus as the most dominant genera. Additional 22 species (17 fishes and five non-fishes) were recognized as incidental catch. We found that critical approaches take part in the continued construction of the contemporary Bulusanon fishing culture, particularly in knowledge about seaweed fish baits. The traditional fishing practice in Bulusan draws our attention to discuss caveats on its possible impact on marine environments, particularly in the light of overfishing and coral-algal phase shifts. Aspects of ethnobiological resources documented in this study may provide a framework for attaining sustainable fishery management, alongside preserving knowledge of the local old hands. [ABSTRACT FROM AUTHOR]

Apatinib is a tyrosine kinase inhibitor that cognately blocks the kinase activity of vascular endothelial growth factor receptor (VEGFR) signaling for the treatment of advanced gastric cancer (GC). However, the drug is also clinically found to reposition a significant suppressing potency on hepatocellular carcinoma (HCC). In this study, we reported the successful use of Apatinib as a bait to fish its potential kinase targets from the HCC druggable kinome pool. In the procedure, cell viability assays observed that the Apatinib has a potent cytotoxicity on human HCC cell lines. Dynamics simulations and affinity scoring systematically created an intermolecular interaction profile of Apatinib with ontologically enriched kinases in the HCC druggable kinome, from which the top-hit kinases were considered as potential candidates. It is revealed that the inhibitor has a weak potency on the well-established HCC target of ErbB pathway, but exhibits potent activity against some known targets or regulators of HCC. In particular, kinase assays substantiated that Apatinib can effectively inhibit four FGFR family members with moderate or high activity. In addition, the clinical FGFR1 gatekeeper mutation V561M was also observed to considerably impair the inhibitory activity, thus causing a drug resistance. Molecular modeling suggested that the Apatinib adopts two distinct binding modes to separately interact with wild-type and gatekeeper-mutant FGFR1 kinase domain. The Apatinib is used as a bait to fish its potential kinase targets from the HCC druggable kinome. A systematic interaction profile of Apatinib with ontologically enriched kinases in the HCC druggable kinome is created. Apatinib can inhibit its noncognate targets of FGFR family members in an unexpected manner. [ABSTRACT FROM AUTHOR]

The current study reports on the second record of a wild population of the invasive alien red swamp crayfish Procambarus clarkii in South Africa following a report from Mimosa Dam in the Free State Province. Sampling for crayfish was conducted over an 18 month period (June 2018 to November 2019) using various methods in order to determine the extent of the invasion as well as to obtain preliminary information on the population structure within Mimosa Dam. Additionally, a gear and bait comparison experiment was conducted to determine their efficiency in mechanical removal of the P. clarkii. Three sampling approaches were compared: promar collapsible traps baited with either dog food or fish; and rectangular traps baited with fish, all which have been historically used in crayfish surveys. A total of 1901 crayfish with a total biomass of 27.32 kg were caught during the study and 65% of those were juveniles. The female to male sex ratio (1:1.2) in Mimosa Dam was skewed towards males. Fish head bait provided a higher catch per unit effort (CPUE) (1.2 ± 0.57 and 0.71 ± 0.08 for rectangular and promar traps, respectively) which was significantly higher than that of the dog food bait (0.14 ± 0.04). The fish bait should hence be optimised for intensive population suppression. Complete eradication of P. clarkii is virtually impossible, as shown by this study, but population suppression can be concentrated on months of crayfish population surges to minimise associated impacts on native biota. [ABSTRACT FROM AUTHOR]

Coastal estuarine ecosystems serve as nursery habitats for many commercially and recreationally important fishes. Biodiversity is a structural indicator and has been used as a metric for conservation and management. In the hypersaline Lower Laguna Madre of Texas, a variety of organisms makes their living in and around the dominant seagrass vegetation. This study provides a general assessment of forage fishes biodiversity collected seasonally with bag seines in two sites: Holly Beach (HB) and South Bay (SB) within the most southern Texas bay system as part of a broader study on fish biology. A total of 15,880 fishes representing 32 species were collected during four quarterly samplings through a year (11,795 from HB and 4,085 from SB). Both sites are interconnected as no fishes similarities difference were found, nonetheless, the sites’ variable characteristics (i.e. basin area, seagrasses coverage, connection to the Gulf of Mexico) resulted in significant greater species richness, relative abundances, and diversity in HB than SB for most of the year, suggesting differences in habitat quality or at the very least variation in the availability of habitat types, which are known to contribute to differences in fish diversity attributes.

To investigate the influence of the number of inlet pipes on the characteristics of flow field and the discharge of solid particles such as bait residue and fish feces, STAR-CCM + was used to analyze the flow of field distribution in a ship-based aquaculture cabin under the conditions of two and four inlet pipes, thus optimizing the inlet pipes of the ship-based aquaculture cabin. Furthermore, a three-phase flow model (solid–liquid–gas) was established to determine the movement characteristics of similar solid particles of residual bait and fish manure in the cabin, while the emission performance of solid particles was analyzed. Finally, the formation of solid particles in the center of the aquaculture cabin was simulated. The simulation results show that the effect of flow field is better with two inlet pipes, and the discharge volume of the bottom outlet has little impact on the emission of solid particles. Findings from this study can serve as a reference and basis for the design and optimization of the aquaculture cabin of an aquaculture vessel. [ABSTRACT FROM AUTHOR]

The feeding characteristics of viscous miscellaneous fish bait were studied in order to place the bait into existing equipment. Through the feeding experiment and discrete element numerical simulation of miscellaneous fish pellet feed, the feeding characteristics of the sticky miscellaneous fish pellet feed in the silo were analyzed. The main factors affecting the uniform feeding of miscellaneous fish pellet bait were obtained, including the size of the feeding mouth of the silo, the size of the inclination angle of the silo, and the effect of external forces. According to the simulation and experiment results, the optimum design of the discharging device was carried out, including the optimization of the structure of the bin, the design of the agitation device and the optimization of the rotating parameters of the agitation device. The research and development of the stirred discharging device was completed, realizing the uniform, continuous and complete discharging of the mixed fish particle bait. Its feasibility was verified through the simulation and prototype experiment. [ABSTRACT FROM AUTHOR]

The influence of bait type and leader material on target and bycatch species was assessed through fishing experiments in the Portuguese shallow pelagic longline fishery in the Atlantic Ocean. Wire leaders were found to decrease catch rates of commercially valuable species such as bigeye tuna and yellowfin tuna, while increasing catch rates of elasmobranchs, including the blue shark and shortfin mako. The odds ratios of capture swordfish and tunas also decrease when using wire leaders, while elasmobranchs have higher odds ratios of capture and at-haulback mortality when using wire leaders. Squid bait led to higher catches of targeted tuna species, however it also resulted in higher catches of marine turtles. For most of the taxa caught at-haulback mortality risk was found to be higher on squid bait, which may be related with increased deep-hooking events. While bait type and leader material did not significantly affect size selectivity for most species, wire leaders were found to retain larger blue sharks and fish bait attracted smaller-sized swordfish. This study showed that banning wire leaders on pelagic longline fisheries is an effective measure for reducing the retention of pelagic shark species, particularly of large size blue sharks. • Wire leaders led to reduced catch rates of tuna species. The odds of capturing swordfish were also lower with wire leaders. • Wire leaders increased catch rates of elasmobranchs, including the blue shark and shortfin mako. • This study supports the exclusion of wire leaders in pelagic longline fisheries to reduce retention of pelagic shark species. • Squid bait increased tuna catches but resulted in higher marine turtle catches and higher risk of at-haulback mortality. [ABSTRACT FROM AUTHOR]

Some populations of marine mammals (particularly odontocete cetaceans, and pinnipeds) have responded to the expansion of fisheries by modifying their behaviour to take advantage of the foraging opportunities provided by fishing. This has led to interactions that include forms of "depredation", referring to the removal of, or damage to, marketable organisms as well as bait from fishing gear. The current scientific and technical usage of depredate or depredation appears inconsistent with some of the meanings found in dictionaries, such as to plunder (typically using force), pillage, ravage, lay waste, despoil, destroy, commit waste, or ransack. We suggest that the use of "depredation" when referring to marine mammal behaviour could strengthen misperception and misunderstanding, hardening notions that they are unfairly taking or destroying what is ours. Though most contemporary researchers do not mean to imply that predators are "stealing our fish", continued reference to the mammals' behaviour as depredation may reinforce, at least in some minds, the belief that fish and other marine resources "belong" only to humans. Alternative wording would help to prevent ambiguity in communications, especially outside the scientific community, and preserve recognition of the ecological roles that large marine predators play. [ABSTRACT FROM AUTHOR]

Riverine cetaceans are threatened globally by increasing anthropogenic impacts, and the Yangtze river dolphin Lipotes vexillifer is already extinct. The Amazon river dolphin Inia geoffrensis is widely distributed, but is categorized as Endangered on the IUCN Red List. Drowning in gillnets and being hunted for fish bait are probably the main causes of its decline. A long-term (25-year) study of the biology and ecology of I. geoffrensis in and near the Mamirauá Reserve in Amazonas state, Brazil, has produced estimates of survival and reproductive rates based on the individual recognition of > 650 animals. Concurrently, monthly standardized counts of dolphins along a fixed transect in the Reserve over 22 years demonstrated a sustained, profound decline. In this study we tested whether the measured rate of population decline is consistent with population parameters estimated from independent data, using population viability analysis. With the known parameters as input, programme Vortex predicted population extinction in all scenarios and a 95% loss of dolphins within 50 years. With default parameters, the model predicted a 5.5% annual decline, which is consistent with that observed. We conclude that the Amazon river dolphin population is in severe decline because of human pressures, even in one of the better protected parts of its range. Unless the accidental and deliberate killing of this species is rapidly reduced, it is highly likely that the Amazon river dolphin will follow its Yangtze counterpart to extinction. [ABSTRACT FROM AUTHOR]

Abstract Fish‐eating birds have been found to consume baitfish and sportfish raised on farms in the United States. Understanding the on‐farm economic effects of such wildlife conflicts is essential for wildlife management agencies to make informed decisions. Lesser scaup, while not widely considered a fish‐eating bird, will consume farmed fish. Baitfish and sportfish farms in Arkansas (the major baitfish and sportfish producing‐state in the U.S.) were surveyed to gather data on the cost of protecting farm crops from scaup. The values of lost sales revenue from the various species of baitfish and sportfish consumed by scaup were estimated based on a concomitant field study on the abundance, distribution, and dietary habits of scaup that visited Arkansas baitfish and sportfish farms during winters of 2016–2017 and 2017–2018. Economic effects were estimated for golden shiner, fathead minnow, sportfish, and goldfish farms. Total annual costs to scare birds from baitfish and sportfish farms were $622 ± 742 per ha. The greatest components of bird‐scaring costs were manpower (56%), truck usage (32%), levee upkeep for vehicle access to scare birds (9%), firearms and ammunition (2%), and pyrotechnic devices (1%). The combined annual economic losses, calculated as reduced revenue from fish losses to scaup plus expenditures to scare birds, averaged $683/ha for golden shiners, $695/ha for fathead minnows, $663/ha for sportfish, and $673/ha for goldfish across the two study years. The fish losses to scaup alone averaged $1.06 million per year ($0.09 million in Year 1 and $2.03 million in Year 2) for the Arkansas baitfish industry. Total direct negative economic effects on the Arkansas baitfish industry were estimated to be, on average, $5.5 million per year ($4.6 in Year 1 and $6.3 million in Year 2).

Split-pond systems (SPS) such as those used for catfish are being considered for raising baitfish. When using these systems for baitfish such as golden shiners Notemigonus crysoleucas , an important factor to be considered is how well the species can tolerate crowding, as the design mandates fish be confined to a smaller portion of the pond. Another aspect of the SPS design is the water flow between the two units for at least 10–14 h each day. SPS can be successfully implemented for other species if factors such as crowding, and water flow do not affect growth. Two laboratory studies were conducted each using 12, 40-L tank flow-through system to observe the growth and physiological performance of golden shiners held for 28 days at three crowding densities: 600; 1,200, and 2,400 fish/m3, keeping water flow at 1 cm/s (Experiment 1) and using three flow rates: 1, 2, and 4 cm/s at similar densities (600 fish/m3) (Experiment 2). At the end of the experiments, fish were subject to acute 1-min confinement stress and whole-body cortisol was measured at 30 min intervals for up to 2 h to monitor the secretion pattern and recovery. Results from experiments showed no difference in the final weight, length, feed conversion, and survival among treatment groups; survival rates were lower in the flow study because of columnaris Flavobacterium covae infections. Baseline cortisol was also not different among the treatments. Cortisol increased 30 min after the acute stress and returned to near baseline in 2 h in the crowding study suggesting acclimation to the chronic stressor. However, in the flow study, cortisol remained elevated even after 2 h, and hence a compromised pathophysiological response. Crowding and water flow do not impair feed intake, growth, or survival in golden shiners, and in these aspects may be a suitable species for SPS. [ABSTRACT FROM AUTHOR]

The release of live baitfish by anglers has been identified as a high‐risk pathway for the introduction of aquatic invasive species due to the potential for invasive fish, invertebrates, or pathogens to be released simultaneously with the baitfish. Consequently, the release of live baitfish is illegal in many jurisdictions, but little is known about compliance rates or angler motivations for illegal release. To assess the incidence of live baitfish release in Minnesota, a state with significant live baitfish use and substantial recreational fisheries, we administered a mail survey to a random sample of 4,000 anglers who held a 2018–2019 annual fishing license and received 671 completed responses. To mitigate potential recall bias, we also administered 345 intercept surveys at water body access sites around the state to ask anglers about their current day's behaviors. A total of 481 (72%) of the mail survey respondents reported that they used live baitfish, and of those, 98 (20%) reported that they release their leftover live baitfish into the water at least some of the time. Of the anglers surveyed at water body access sites, 59 (19%) were using live baitfish on the day they were surveyed, and of those, 11 (18%) released their leftover baitfish into the water. The reasons anglers provided for releasing their baitfish included convenience and their mistaken understanding that released baitfish benefit the recipient ecosystem. The potential for invasive species introductions through contaminated baitfish releases is high given the reported release rates. However, there is also significant opportunity for management interventions aimed at changing perceptions and providing convenient disposal alternatives to illegal release to reduce the risk presented by this pathway. [ABSTRACT FROM AUTHOR]

Clupeiformes are the most important food fish in the world, and provide a key trophic link in marine food chains. Here we describe broad scale patterns of clupeiform demographic characteristics of the delicate round herring sprat Spratelloides delicatulus on the Great Barrier Reef (GBR). Sampling was conducted over 10° of latitude and two seasons at multiple distances across the GBR shelf. The oldest S. delicatulus sampled was 152 days and the maximum standard length was 74 mm. Age and length maxima increased with latitude conforming with 'counter gradient theory' and these patterns were consistent between years. von Bertalanffy relationships showed that growth rates were highest at Northern GBR sites; growth coefficients ranged from 2–6 K year−1, and were lowest on southern reefs, i.e. 'tropical gradient of growth'. Daily survivorship ranged from 91–97% day−1 at all sites. Hatching dates estimated from counts of daily otolith increments indicated a prolonged spawning season of at least 9 months. Reproductive development indicated a size-based relationship. Males and females matured at similar sizes ranging from 36–38 mm, but fish from southern sites were 30–40 days older. Tropical clupeiforms live fast and die young, and patterns of abundance, composition and demography followed strong environmental gradients which conformed to some existing models. [ABSTRACT FROM AUTHOR]

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 m2 (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. [ABSTRACT FROM AUTHOR]

The current study reports on the second record of a wild population of the invasive alien red swamp crayfish Procambarus clarkii in South Africa following a report from Mimosa Dam in the Free State Province. Sampling for crayfish was conducted over an 18 month period (June 2018 to November 2019) using various methods in order to determine the extent of the invasion as well as to obtain preliminary information on the population structure within Mimosa Dam. Additionally, a gear and bait comparison experiment was conducted to determine their efficiency in mechanical removal of the P. clarkii. Three sampling approaches were compared: promar collapsible traps baited with either dog food or fish; and rectangular traps baited with fish, all which have been historically used in crayfish surveys. A total of 1901 crayfish with a total biomass of 27.32 kg were caught during the study and 65% of those were juveniles. The female to male sex ratio (1:1.2) in Mimosa Dam was skewed towards males. Fish head bait provided a higher catch per unit effort (CPUE) (1.2 ± 0.57 and 0.71 ± 0.08 for rectangular and promar traps, respectively) which was significantly higher than that of the dog food bait (0.14 ± 0.04). The fish bait should hence be optimised for intensive population suppression. Complete eradication of P. clarkii is virtually impossible, as shown by this study, but population suppression can be concentrated on months of crayfish population surges to minimise associated impacts on native biota. [ABSTRACT FROM AUTHOR]

The production, distribution, and sale of live baitfish represent a multimillion dollar industry in the United States. However, production is often limited by the feasibility of culture and few species are profitable. In turn, distribution often occurs well outside of a profitable species' natural range. Beyond the concern of nonnative species introductions, live baitfish can introduce or spread diseases, resulting in negative ecological consequences. As a result, Arizona Game and Fish Department (AZGFD) wanted to evaluate the feasibility of using a species native to Arizona and southwestern North America that is abundant with a wide regional distribution to meet current commercial needs for small‐bodied baitfish in Arizona. An internal AZGFD team had identified Longfin Dace Agosia chrysogaster as a potential candidate baitfish species due to its low conservation threat, wide distribution in Arizona, and optimal body size (i.e., similar to that of current nonnative baitfish). The goal of this study was to provide a proof‐of‐concept of Longfin Dace culture to meet current small‐bodied baitfish needs in Arizona. To meet this goal, we investigated the efficacy of extensive pond culture of Longfin Dace during 2017–2019 as an option for the replacement of nonnative baitfish. Extensive culture of Longfin Dace resulted in a 21–23‐fold population increase over the course of a year in 2018. Additionally, based on length‐frequency distributions, multiple generations were produced in one year. We conclude that the propagation of Longfin Dace via pond culture to replace nonnative, small‐bodied baitfish is potentially viable. However, the lack of information on carrying capacity and optimized pond characteristics for the pond culture of Longfin Dace should be addressed in the future. [ABSTRACT FROM AUTHOR]

Little is known about the behaviour of Common Loon (Gavia immer) during the critical overwintering period, let alone the behaviour of the small, but increasing number of loons that overwinter on freshwater lakes in North America. We examined the diurnal time-activity budgets of Common Loon overwintering on a large reservoir in northwest South Carolina between 2018 and 2020. Similar to previous studies of breeding individuals and individuals that overwinter in marine waters, loons (n = 132) overwintering on this reservoir spent most of their time (52%) foraging. However, we found distinct differences in the activity budgets of individuals associated with their degree of sociality. Solitary birds (individuals spending 0-20% of time within 20 m of conspecifics) spent significantly more time foraging than did those that were either loosely-social (>20-<70% of time within 20 m of conspecifics) or strongly-social (70-100% of time). Although solitary loons made as many foraging dives as social birds, their dives were much longer, likely reflecting dives for larger predatory fish. In contrast, social individuals made much shorter, shallower dives, often foraging on shallower baitfish that they appear to pursue to the water surface and consume collectively. Such findings add to our understanding of loon winter behaviour and raise interesting questions regarding social behaviour and the short- and long-term trade-offs associated with social foraging in this species. [ABSTRACT FROM AUTHOR]

The marine recreational fishing industry in Florida has an economic impact of $7.6 billion dollars, which includes the expenditures of its 2.4 million licensed anglers. Interest in developing aquaculture techniques for marine baitfish species have served as an impetus for recent research; however, market data in Florida has not been investigated and described in over two decades. The objectives of this survey were to evaluate and describe the live marine baitfish market for cultured pinfish (Lagodon rhomboides) and pigfish (Orthopristis chrysoptera) in Florida. A survey was designed and distributed to 280 bait retailers in 37 coastal counties of Florida. The survey was developed to gather information vital to market evaluation. Survey questions focused on baitfish species sold, shortcomings of wild baitfish, preferred baitfish characteristics, perception of aquaculture and cultured bait, and specific questions with an emphasis on quantities and purchasing habits for pinfish and pigfish. A total of 119 surveys representing 31 counties were returned for a 42.5% response rate. The results of this market survey will serve as a valuable resource for current and potential producers who market live marine baitfish to retailers throughout coastal Florida. [ABSTRACT FROM AUTHOR]

In the Western Indian Ocean (WIO), more than 76 records from peer-reviewed and grey literature identified approximately 60 invertebrate taxa harvested for bait and food. The most diverse phyla were Mollusca, followed by Arthropoda and Annelida, with few records of Porifera, Nemertea and Echinodermata. Importance of each phylum differs according to country, with arthropods (Upogebia africana and Kraussillichirus kraussi), and annelids (Marphysa mossambica) being most important in South Africa and Kenya, respectively. Of the taxa utilised, only 42 are reliably identified to species level, suggesting that the diversity of species utilised in the region is greatly underestimated. Most of the data on biology and exploitation were for species from South Africa. Less data were available from Kenya with minimal to none being available from the remaining WIO countries. This limits the understanding of biology and trends in exploitation of most bait taxa, and consequently information required for developing national and regional management policies. Bait management guidelines are available only for South Africa, but require updating in view of changes in use of bait resources. We recommend the development of coordinated multidisciplinary, multicountry research aimed at increasing data and information to feed into policy development and support national and regional bait resource management. [ABSTRACT FROM AUTHOR]

Fishing with circle hooks along with prescribed hook- setting methods can reduce deep- hooking rates in some fisheries, but baited circle hooks have not been evaluated in stillwater trout fisheries. Deep- hooking rates and catch probabilities were compared for cutthroat trout Oncorhynchus clarkii (Richardson), rainbow trout Oncorhyncus mykiss (Walbaum), cutthroat x rainbow trout hybrids, and brook trout Salvelinus fontinalis (MItchill) caught using three types of baited hooks (circle, intermediate circle and traditional J) and two hook- setting methods (active and passive) in several lakes containing naturally reared trout. Hook type had a negligible effect on deep- hooking rates, which averaged 20%. Actively setting the hook and fishing with a bobber both reduced deep- hooking rates, regardless of hook type. Larger fish were deeply hooked more frequently regardless of hook type. Catch probabilities were higher when active rather than passive hook- setting was used, particularly in combination with intermediate circle hooks. The present results, which indicate that circle hook use did not reduce deep hooking in lentic settings, contrast earlier studies done in lotic waters. Therefore, before proposing hook- type regulations intended to reduce deep hooking, fisheries managers should consider waterbody type in addition to fishing methods, fish size and species. [ABSTRACT FROM AUTHOR]

Between September and December, whale sharks (Rhincodon typus) aggregate in the coastal waters off Nosy Be, an island in north‐western Madagascar. Swimming with these sharks has become an important tourism activity, but no formal protection is in place in Madagascar to protect this endangered species from the potential negative effects of tourism or other human impacts.Boat‐based surveys (n = 405) were conducted from tourism vessels from September to December, 2015–2019. For most sightings (98%), whale sharks were sighted while foraging for bait fish at the surface, in association with mackerel tuna (Euthynnus affinis) and seabirds (Sternidae). A total of 408 individual whale sharks were individually photo‐identified over this period. All individuals were immature, and 82% of sexed sharks were male. Sharks ranged from 3.0 to 8.0 m in total length (TL), with a mean TL of 5.65 ± 0.94 m (n = 66) for females and 5.46 ± 1.09 m for males (n = 295).Most sharks (72% of the identified individuals) were only identified once within the study period. Movement modelling showed an open population with a short mean residence time of 7.2 days. Resightings were recorded from up to 12 years apart (2007–2019). Ten sharks were seen in all five seasons during 2015–2019. A basic POPAN mark–recapture model estimated a total population size of 681 (608–763) sharks over the 2015–2019 period.Nosy Be waters are an important foraging ground for juvenile whale sharks. Sighting data demonstrate that a high proportion of the sharks' preferred habitat lies outside existing protected areas, but within an identified Key Biodiversity Area. National species‐level protection and increased spatial management is warranted to secure the continued presence of whale sharks in this region. [ABSTRACT FROM AUTHOR]

As global trade of live animals expands, there is increasing need to assess the risks of invasive organisms, including pathogens, that can accompany these translocations. The movement and release of live baitfish by recreational anglers has been identified as a particularly high‐risk pathway for the spread of aquatic diseases in the United States. To provide risk‐based decision support for preventing and managing disease invasions from baitfish release, we developed a hazard identification and ranking tool to identify the pathogens that pose the highest risk to wild fish via this pathway. We created a screening protocol and semi‐quantitative stochastic risk ranking framework, combining published data with expert elicitation (n = 25) and applied the framework to identify high‐priority pathogens for the bait supply in Minnesota, USA. Normalized scores were developed for seven risk criteria (likelihood of transfer, prevalence in bait supply, likelihood of colonization, current distribution, economic impact if established, ecological impact if established and host species) to characterize a pathogen's ability to persist in the bait supply and cause impacts to wild fish species of concern. The generalist macroparasite Schizocotyle acheilognathi was identified as presenting highest overall threat, followed by the microsporidian Ovipleistophora ovariae, and viral haemorrhagic septicaemia virus. Our findings provide risk‐based decision support for managers charged with maintaining both the recreational fishing industry and sustainable, healthy natural resources. Particularly, the identification of several high‐risk but currently unregulated pathogens suggests that focusing risk management on pathogens of concern in all potential host species could reduce disease introduction risk. The ranking process, implemented here for a single state case study, provides a conceptual framework for integrating expert opinion and sparse available data that could be scaled up and applied across jurisdictions to inform risk‐based management of the live baitfish pathway. [ABSTRACT FROM AUTHOR]