Bait Type Research Articles

Bear baiting risks and mitigations: An assessment using expert opinion analyses.

Bear baiting is authorized in 12 states, 2 territories, and 8 provinces across North America. In Alaska, more than 70% of lands managed by the National Park Service (NPS) are open to some form of hunting including National Preserves where non-conflicting state wildlife hunting regulations apply. Alaska state regulations authorize bear baiting with few restrictions on the type or amount of bait that can be used to attract bears; although, restrictions related to bait station distance from roads and trails (¼ mile) and cabins/dwellings (1 mile) apply. However, National Preserves host diverse recreational activities in addition to hunting (e.g., hiking, camping, fishing). Because road and trail access to and within Alaska National Park and Preserve lands is limited, hunting and non-hunting-related activities often occur in the same areas-increasing potential for conflict between potentially non-compatible activities. We developed questionnaires about potential impacts on NPS lands, which were distributed to 14 NPS and 27 non-NPS bear research and management experts. We collated respondents' opinions regarding consistency of bear baiting practices with state and federal mandates for wildlife management. While minor differences in expert opinions were noted, findings from this study are unequivocal. Bear baiting is functionally equivalent to feeding bears, bears may defend a bait station similar to how they would defend a carcass, and bear baiting can lead to human food-conditioning in bears. Bear baiting also increases the likelihood bears will be killed in defense of life and property, and alters natural bear behaviors and ecological processes. Further, current mitigation strategies to minimize public safety risks and potential property damage are inadequate. For example, because bears are known to defend food resources, avoiding food conditioning of bears is central to the educational messaging of all entities that manage bears. In short, bear baiting is a harvest practice that challenges harmony between State mandates, which emphasize hunter opportunity, and NPS mandates that include public safety and natural processes.

Wild kea response to non-toxic baits with and without deer repellent – implications for management

ABSTRACT 1080 toxin (sodium fluoroacetate) is used in New Zealand for possum (Trichosurus vulpecula) and ship rat (Rattus rattus) control but can result in unintentional by-kill of native (e.g. kea Nestor notabilis) and non-native (e.g. deer) fauna. A newly developed deer repellent (Prodeer) in 1080 bait has proved highly effective in reducing deer by-kill while not impacting target pest efficacy. The ingredients in Prodeer bait are undisclosed due to commercial sensitivity, thus it is unknown whether this bait type increases acceptability and palatability to kea and increases risk over and above that posed by the standard (RS5) bait type normally used in aerial poisoning operations. During choice trials comparing kea responses to, and consumption of, non-toxic Prodeer and RS5 baits at alpine sites around Arthur’s Pass National Park and central Westland we found kea Prodeer and RS5 consumption (per interaction and total) were not significantly different. Most individuals consumed substantially less of both bait types than the estimated lower 1080 LD50 threshold for kea, and vastly less than captive kea consume. We conclude that 1080 operations using Prodeer are unlikely to pose a risk significantly over and above that already presented to kea in standard RS5 1080 operations.

Activity patterns of Octopus tetricus (Mollusca: Cephalopoda) and their behavioural responses to fisheries trap and bait combinations

An understanding of octopus behaviour and their capture by fishing gears is required to inform efficient, sustainable, and ethical octopus fisheries. Here, the behaviour of Octopus tetricus was assessed in response to different bait and trap combinations in an outdoor mesocosm experiment. Eight wild octopuses were collected, maintained in individual tanks with flow-through seawater and aeration, and monitored with a 24-h video surveillance system. Six different traps and four different baits were presented to each octopus in various combinations during four sequential trials. Fine-mesh crab traps were the most successful in capturing octopus, accounting for 23 of the total 30 captures across all trials. Whereas solid trigger traps produced the greatest number of other interactions (e.g., octopus sitting on trap/in the entrance), averaging 43 interactions per trial, but were rarely triggered. Bait type did not influence octopus capture, trap interaction frequency, or octopus activity; however, only artificial bait types were trialled, and fresh natural baits may elicit a stronger response and should be investigated in future research. Generally, octopus were inactive, dedicating only 9.5% of their total time to active behaviours. Octopus activity varied with time of day, with peak activity during morning daylight (0800–1200) and the lowest activity during the dark hours of the very early morning (0000–0400). Additionally, capture numbers, trap interactions, and activity varied among individuals, with bolder personalities in some octopus. This natural variation among individual octopuses may lead to fishery-induced selection associated with the elevated capture frequency of bold or more active individuals.

Feeding Behavior and Bait Selection Characteristics for the Portunidae Crabs Portunus sanguinolentus and Charybdis natator

Understanding the feeding behavior of Portunidae crabs with different baits can improve bait selection and is crucial for improving the effectiveness of crab fishing gear. This study, conducted in indoor experimental tanks, used trajectory tracking software and two types of natural baits (mackerel (Scomber australasicus) and squid (Uroteuthis chinensis)) to understand the behavior of Portunus sanguinolentus and Charybdis natator. Spatial distribution results showed that P. sanguinolentus was frequently present in the starting area (S1) and bait area (S3) in the control and treatment groups. However, C. natator was frequently present and concentrated in the S1 area compared to the middle areas S2 and S3, and only in the mackerel treatments were they observed to move to the S3 areas. The spatial distribution results indicate that P. sanguinolentus shows a stronger willingness to explore its surroundings, while C. natator is generally in a stationary, wait-and-see state. The swimming speeds of P. sanguinolentus and C. natator showed different trends. P. sanguinolentus showed continuous movement with no fixed speed when no bait was present in the control groups. However, when treated with mackerel and squid, the average swimming speed of P. sanguinolentus was faster (>5 cm/s) in the first 10 min and showed a more stable movement speed when searching for the baits. C. natator showed a stationary or low movement speed when no bait was present in the control groups. However, when C. natator perceived the presence of the baits in the treatment groups, their movement speed increased in the first 10 min. In addition, there was no significant difference between male and female crabs of P. sanguinolentus and C. natator in movement speed in the control and treatment groups. Compared to C. natator, P. sanguinolentus might be more sensitive to natural baits, as shown by its movement from S1 to S3. The results indicate that the species of Portunidae crabs show different bait selections. Natural baits (mackerel and squid) are recommended for catching P. sanguinolentus in crab fisheries.

Bait Biomass and Caloric Contribution From the Dungeness Crab (Cancer magister) Fishery in Oregon, USA

ABSTRACTFishery discards worldwide increase the availability of organic materials on the benthos, altering trophic relationships and potentially increasing the abundance of benthic consumers. Expert knowledge from fishers is a valuable yet often underutilized source of information to understand these dynamics. We interviewed Dungeness crab fishers (n = 24) to determine the most‐used bait types and to characterize regional and seasonal bait use strategies that drive inputs of organic matter into Oregon coastal waters during the commercial Dungeness crab fishery each year. Based on bomb calorimetry measurements of caloric densities of 12 commonly reported bait species, total energetic input was 12.99 × 109 kJ (3.10 B kcal) from bait in the 2019–2020 commercial ocean Dungeness season in Oregon, USA. Fishing effort and bait inputs were strongly seasonal, with 88% of effort concentrated in the first 60 days of the 9‐month‐long season but did not vary regionally. This large, temporally concentrated caloric input suggested that bait could contribute substantially to Dungeness crab productivity. Fisher respondents indicated that bait effectiveness was the most important motivating factor in choosing a bait type, more than availability or cost.

Evaluating the conservation benefit of circle hooks for the Atlantic Striped Bass recreational fishery

AbstractObjectiveThe Striped Bass Morone saxatilis is one of the most sought‐after recreational fish species along the US Atlantic coast. Regulations and a strong conservation ethic among anglers make Striped Bass among the most frequently released coastal marine fishes. A recent rule requires anglers to use circle hooks when targeting Striped Bass with natural baits, yet the conservation benefit of this action remains unclear.MethodsWe used acoustic telemetry to monitor the fate of Striped Bass that were recreationally caught with baited hooks (n = 349) and to estimate the influence of various biological (fish size), fishery (fight time, handling time, hook location, bait type, and hook type), and environmental (water temperature and air temperature) variables on postrelease survival.ResultA semi‐quantitative score of fish release condition was the single best predictor of mortality. A broader dataset that included untagged fish (n = 716) was used to identify the best predictors of fish release condition, which included hook location and handling time.ConclusionContrary to expectations, the circle hooks used in this study did not result in lower release mortality than conventional J‐hooks.

Temporal and trophic niche partitioning among arboreal ants in a Neotropical woodland savanna

Abstract Niche partitioning is a key mechanism for explaining species coexistence, including the coexistence of ants in trees of the Brazilian savanna (cerrado). However, we have limited information on the extent to which arboreal ant species exploit different food resources and/or have different daily foraging schedules. We tested these ideas through a baiting experiment, and by measuring the isotopic signature (δ15N) and the critical thermal maximum (CTmax) of the 14 most common species found in a typical cerrado tree species. Although most species foraged on all bait types offered, species‐specific preferences were noted for about one‐third of the species. We also found a wide variation in mean δ15N between species, reflecting interspecific differences in trophic position. Most (71.4%) species foraged predominantly on a given period of the day, ranging from strictly nocturnal species to those that foraged mainly in the afternoon. Species with a higher heat tolerance (higher CTmax) often foraged at warmer periods of the day than those with a lower tolerance. Despite the evidence of trophic and temporal niche partitioning, other mechanisms, such as nesting site specialization and behavioural trade‐offs, are required to explain species coexistence in this arboreal ant assemblage, as several species pairs largely overlapped both in their diet and time of foraging. Importantly, our results provide additional support for the idea that physiological restriction to high temperatures is important for understanding interspecific differences in foraging activity schedules.

Bait type affects the diversity assessment of cetoniid beetles in the Brazilian Cerrado

AbstractCetoniidae (Coleoptera), known as flower and fruit beetles, form a diverse group, feed on nectar, pollen, plant exudates, and are highly attracted to fermented fruits. To evaluate their diversity in natural and agricultural areas, traps baited with fermented fruits are used. The objective of this study was to compare the effectiveness of various types of fruit used as bait, with or without the addition of sugarcane juice to accelerate fruit fermentation, on the assessment of Cetoniidae diversity in the Brazilian Cerrado. The study was conducted in two conservation units in Brasília (DF, Brazil). Two experiments were conducted, the first aiming to select the most attractive fruits (banana, pineapple, mango, grape, or cagaita), and the second to verify whether there is interference of sugarcane juice in the fruit fermentation process and, consequently, in the attractiveness to Cetoniidae. The chemical profiles of the types of bait were evaluated by identifying and quantifying the main volatile organic compounds released by the fruit traps. Insect collections were conducted weekly using fruit‐baited traps for 1 month, without interruption. We found that the diversity estimate of Cetoniidae was higher for banana‐based baits relative to grape and cagaita fruit, but not relative to pineapple, mango, and sugarcane juice. Additionally, no increase in attractiveness was observed with the addition of sugarcane juice to banana, pineapple, and mango bait. Most compounds in the fruit extracts belong to alcohol, ester, and terpene functional groups. Our results suggest that banana, pineapple, mango, and sugarcane juice, used alone, may be used for Cetoniidae diversity studies, and that banana bait seems to be the most suitable for Cetoniidae collection in the Cerrado, because it enables the collection of a high diversity of species and also of species considered rare.

Evaluation of Bait Acceptance and Immune Response in Local Dogs during an Oral Rabies Vaccination Field Study in Morocco.

The objective of this study was to evaluate the bait preference of three selected bait types by local dogs and the induced immunogenicity of the oral rabies vaccine strain SPBN GASGAS in Morocco. The vaccine strain, combined with different bait types, has been tested in many different settings, but not yet in northern Africa. Overall, bait consumption and preference were similar in other studies using the same materials (bait type and sachet). The intestine bait had the highest acceptance rate (97.6%, 95%CI: 87.4-99.9), followed by the egg bait (83.0%, 95%CI: 69.2-92.4). Only 52% (95%CI: 37.4-66.3) of the dogs showed an interest in the fish meal bait. However, considering the successful release of the contents of the sachet (blue-dyed water) into the oral cavity, the egg bait (65.7%, 95%CI: 47.8-80.9) scored better than the intestine bait (51.7%, 95%CI: 32.5-70.6). The dogs selected for the immunogenicity study were offered the egg bait containing a sachet filled with SPBN GASGAS (3.0 mL, 107.5 FFU/mL) or were given the same dose by direct oral administration (d.o.a.). In addition, several dogs were vaccinated by the parenteral route (s.c.) using a commercially available inactivated rabies vaccine. Unfortunately, due to the COVID-19 pandemic and subsequent travel restrictions, it was not possible to collect blood samples directly after vaccination. The blood samples were collected pre-vaccination and on five occasions between 450 and 1088 days post vaccination. The seroconversion rate, as determined for rabies-virus-neutralizing antibodies by the FAVN test, was significantly lower than that found for binding antibodies, as determined by ELISA, for all blood samples collected post vaccination. No treatment effect (bait, d.o.a., s.c.) could be seen in the seroconversion rate. At 15 months post vaccination, 84.2% of the dogs offered vaccine bait still tested sero-positive in ELISA. Only after 3 years was a clear drop in the seroconversion rate observed in all three treatment groups. This study confirms the long-term immunogenicity of the oral rabies vaccine SPBN GASGAS in dogs under field conditions.

Leader material and bait effects on target and bycatch species caught in an Atlantic Ocean pelagic longline fishery

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.

Can hair snares provide a reliable method for estimating abundance of an exotic ungulate?

Mitigating exotic species invasions requires reliable information on abundance and source-sink dynamics to evaluate effectiveness of control efforts. Despite being present in the southeastern United States for centuries, wild pigs (Sus scrofa) continue to invade new areas, including the Sam D. Hamilton Noxubee National Wildlife Refuge (NNWR) in Mississippi, a forested landscape with an emerging wild pig population. Considering the early stage of invasion, we designed and implemented a non-invasive hair sampling technique to estimate abundance and relatedness of wild pigs within the NNWR. Following 8-week sampling periods in 2021 (n = 160 samples) and 2022 (n = 159 samples), we identified 38 and 26 unique individuals, respectively, although recapture rates were too low to yield precise abundance estimates. We also identified low heterozygosity indicating high relatedness among our population which likely reflected lack of barrier features to gene flow and/or a limited number of external source populations. Finally, we observed positive trends in viable samples collected relative to sampling week, suggesting more optimal sampling period(s) may exist (e.g., autumn). We also acknowledge that use of grain in more accessible areas rather than our remote approach using scent-only attractants may increase hair snare attractiveness and wild pig encounters, while permitting increased sampling frequency. Collectively, these modifications (i.e., altered season, bait type, and access) provide viable pathways to increase precision for abundance estimates. When used concomitantly with ongoing monitoring and control efforts, non-invasive hair sampling will contribute to a more holistic understanding of this exotic species and better inform management actions.

Effects of four types of natural bait on water quality, feeding, growth, and antioxidant enzyme activity of Monopterus albus in a recirculating aquaculture system

Monopterus albus is one of China’s renowned and superior aquaculture species, with its seedlings mainly sourced from wild capture. One of the bottlenecks in M. albus aquaculture is the high mortality rate and low feeding initiation rate from stocking wild fry to the initiation of feeding. In production, trash fish is commonly used to wean M. albus juveniles onto feeding. In this study, we introduced three other natural feeds, earthworms (EW), yellow mealworms (YMW), and fly maggots (FM), with frozen trash fish (TF) serving as the control group, to evaluate the effects of these four natural feeds on the survival rate, feeding initiation, antioxidant enzymes activity, and body composition of M. albus juveniles under recirculating water aquaculture conditions. The experiment comprised four treatments, each with three replicates. Each replicate consisted of stocking 150 M. albus juveniles weighing 10.02 ± 0.89 g in size, raised for 5 weeks. The survival rate of the YMW group was 73.33%–85.33%, which was significantly higher than that of the other three bait groups (p < 0.05). The four bait groups showed no significant differences in final body weight and specific growth rate (SGR) (p > 0.05). The EW group showed the highest final body weight, with an average SGR of 2.73, whereas the YMW group had an average SGR of 1.87. The average daily feeding amount was significantly higher in EW and YMW groups than in the other two groups (p < 0.05). The percentage of feeding amount to fish weight in the EW group reached 7.3% in the fifth week. After 5 weeks of cultivation, NO2−-N content was significantly higher in the waters of the TF and EW groups than in the waters of the FM and YMW groups (p < 0.05), there was no significant difference in TAN content among the treatment groups (p > 0.05). Liver malondialdehyde content was significantly higher in the TF group than in the other bait groups (p < 0.05). GSH-Px activity was significantly higher in the EW group than in the FM group and YMW group. No significant differences in SOD and CAT activity and T-AOC were observed among the bait groups (p > 0.05). The increase in crude protein content was significantly higher in the TF group than in the FM group, but the increase in crude ash content was significantly lower in the TFgroup. In conclusion, Tenebrio molitor could potentially serve as one of the alternative feeds during the initial stages of M. albus juveniles stocking.

Biodiversity and Altitudinal Variation of Dung Beetles (Scarabaeidae: Scarabaeinae) in the Oglán Alto Watershed, Ecuadorian Amazon

Dung beetles are considered a useful taxon to describe and to monitor spatial and temporal patterns of biodiversity. Tropical communities of dung beetles are usually diverse, abundant, and habitat specific; they respond quickly to many types of environmental changes. This study was carried out over 18 months, on an altitudinal gradient in the Oglán Alto watershed, located in Pastaza Province, Ecuador. A total of 10,227 individuals belonging to 59 species were collected. Food preference was analyzed and it was observed that species of coprophagous beetles are superior to necrophagous and generalists species. Tunnelers functional group was more abundant than rollers and dwellers groups, and only this group reduced its richness at higher altitudes. Six richness estimators were used for comparison between the two types of bait used (excrement and carrion). Correspondence Analysis was performed, according to the types of traps and species captured, with respect to the variation of altitudinal gradient. We concluded that the relation of altitudinal gradient and average of richness by traps is very similar among four transects sampled, showing a mixture of species of copro-necrophagous beetles associated to Amazon lowlands, with few species of foothill evergreen forest of the Ecuadorian east. It is recommended to continue studies in this type of vegetation, mainly in a higher altitudinal gradient.

Methodological factors affecting capture of juvenile salmon in baited “minnow” traps

AbstractObjectiveIn a southcentral Alaska stream system, we conducted a study to evaluate the effect of trap type (galvanized and nylon coated), bait type (salmon roe cured with and without sodium sulfite), and soak times (1 h and 24 h) on captures of juvenile salmon using Gee‐style minnow traps. This was undertaken due to the limited research on this topic, aiming to determine how variations in methodology affected captures in juvenile salmon.MethodsWe employed a three‐way fixed factorial design to sample 176 stream reaches (with a single trap in each each) from June 2021 to September 2021, capturing 296 Coho Salmon Oncorhynchus kisutch and 105 Chinook Salmon O. tshawytscha.ResultWe found an estimated 78% decrease in captures of Coho Salmon when nylon‐coated traps were used instead of galvanized traps, and we found that trap type showed no effect on number of captures for Chinook Salmon. Additionally, we did not detect effects of bait type and soak time on the number of captures for either species. Not surprisingly, there was a positive relationship between Julian date and temperature with captures for both species. Additionally, for Coho Salmon, we found a quadratic relationship between water velocity and captures.ConclusionUnderstanding and accounting for these factors will help researchers to maximize trapping efficiency, standardize protocols, and determine the extent to which results are comparable across studies employing different methods.

Functional compensation in a savanna scavenger community.

Functional redundancy, the potential for the functional role of one species to be fulfilled by another, is a key determinant of ecosystem viability. Scavenging transfers huge amount of energy through ecosystems and is, therefore, crucial for ecosystem viability and healthy ecosystem functioning. Despite this, relatively few studies have examined functional redundancy in scavenger communities. Moreover, the results of these studies are mixed and confined to a very limited range of habitat types and taxonomic groups. This study attempts to address this knowledge gap by conducting a field experiment in an undisturbed natural environment assessing functional roles and redundancy in vertebrate and invertebrate scavenging communities in a South African savanna. We used a large-scale field experiment to suppress ants in four 1 ha plots in a South African savanna and paired each with a control plot. We distributed three types of small food bait: carbohydrate, protein and seed, across the plots and excluded vertebrates from half the baits using cages. Using this combination of ant suppression and vertebrate exclusion, allowed us explore the contribution of non-ant invertebrates, ants and vertebrates in scavenging and also to determine whether either ants or vertebrates were able to compensate for the loss of one another. In this study, we found the invertebrate community carried out a larger proportion of overall scavenging services than vertebrates. Moreover, although scavenging was reduced when either invertebrates or vertebrates were absent, the presence of invertebrates better mitigated the functional loss of vertebrates than did the presence of vertebrates against the functional loss of invertebrates. There is a commonly held assumption that the functional role of vertebrate scavengers exceeds that of invertebrate scavengers; our results suggest that this is not true for small scavenging resources. Our study highlights the importance of invertebrates for securing healthy ecosystem functioning both now and into the future. We also build upon many previous studies which show that ants can have particularly large effects on ecosystem functioning. Importantly, our study suggests that scavenging in some ecosystems may be partly resilient to changes in the scavenging community, due to the potential for functional compensation by vertebrates and ants.

Baiting not-owned dogs against Echinococcus granulosus: innovative tools for integrated control.

Cystic echinococcosis (CE), caused by the larval stage of the cestode Echinococcus granulosus, is one of the most widespread zoonoses in Mediterranean countries. Baiting not-owned dogs with praziquantel (PZQ), due to their key role in the maintaining the transmission of CE, currently appears to be the most effective way to limit the transmission of CE, as well as an important aspect to introduce for the control of this parasitic disease. Therefore, this study aims to test 3 types of PZQ-based baits by evaluating different parameters (integrity over time, attractiveness and palatability for dogs, and mechanical resistance after release to different altitudes) and the bait acceptance in field by target animals, i.e. not-owned dogs, by using camera traps. The double PZQ-laced baits (with a double layer of highly palatable chews) showed the greatest resistance in the environment while also preserving the attractiveness and palatability up to 10 days, also withstood heights of 25 m, thus resulting as the most suitable also for drone delivery. The results on the field showed that most of the baits were consumed by not-owned dogs (82.2%), while the remaining were consumed by wild boars (8.9%), foxes (6.7%), badgers (1.1%) and hedgehogs (1.1%), confirming the specific and high attractiveness of the double PZQ-laced baits for the target population and highlights how an anthelmintic baiting programme may be a viable tool for the management of E. granulosus among free-ranging dog populations in endemic rural areas.

Anatomical hooking location and bleeding occurrence in northern pike (Esox lucius) caught in recreational catch-and-release angling in a lake with reduced prey fish availability

Catch-and-release (C&R) is a common practice in recreational angling for northern pike (Esox lucius), whereby the angler releases the fish back into the water after capture with the expectation that it will survive with negligible stress and physical injuries. This may not always be the case, as hooking in critical anatomical locations, such as gills, esophagus, and stomach, increases the frequency of bleeding at the hook wound and has been recognized as a key determinant of post-release mortality in pike. Several factors (e.g. bait type and size, hook characteristics, and fish length) can influence the risk of hooking in critical locations, and the fish’s willingness to strike the fishing lure/bait may largely depend on previous feeding history and associated motivation to feed. In this respect, food deprivation and greater feeding motivation can be expected to result in an intensified response and more forceful attacks on fishing lures/baits, which could increase the risk of hooking injuries in sensitive tissues, as the fish may ingest the hook more deeply. Here, we assess the hooking location and bleeding occurrence in pike caught on soft plastic shads and baitfish in a shallow eutrophic lake. The prey fish density of this lake, primarily common roach (Rutilus rutilus), has been substantially reduced by seining as part of a lake restoration project. Experimental angling sessions took place at the end of 2020 and 2022, approximately 1–2 months and 25–26 months after the initial reduction in prey fish density, respectively. Removal of roach from the lake was also done regularly by seining after the angling sessions in 2020. Pike angled in 2022 had significantly lower body condition than individuals caught in 2020, indicating that mass removal of roach from the lake resulted in food shortage. The risk of hooking in critical locations (herein defined as hooking in gills and back of mouth) was not associated to angling year, body condition, or length of the pike. However, across the two angling years, the incidence of hooking in critical locations was higher for soft plastic shads compared to baitfish (24.2% versus 7.4%). Pike caught on soft plastic shads also bled more frequently than individuals caught on baitfish (19.7% versus 6.2%), most likely due to the fact that hooking in the gills almost exclusively occurred with soft plastic shads. Bleeding propensity was also not related to angling year, body condition, or fish length. Hence, the present study found no evidence that long-term reductions in food availability and resulting declines in body condition influence how pike strike and ingest fishing lures/baits, at least not in a manner that increases the risk of hooking injuries in sensitive locations. Instead, bait type seems to play the largest role for the observed bleeding patterns. We recommend that future studies investigate the potential effects of C&R angling on the post-release survival of pike with reduced body condition due to limited food availability.

Optimizing the baiting strategy for oral vaccine delivery to wild boar

Baits are a means of orally delivering toxicants, medicaments, or chemical markers to wild boar and feral pigs (Sus scrofa). We tested three bait types, the paraffin-feed-sugar-based IREC bait (green and colorant-free versions), a puffed leguminous bait with the same flavoring as the IREC bait (Flavor), and a plain puffed leguminous bait without flavoring (Plain). Baits were deployed in a fenced hunting estate with year-round feeding to assess bait type preference and study the effect of bait flavoring and coloring, pre-feeding, baiting device, and habituation on bait consumption and bait selectivity. Baits were deployed under heavy pavel stones, targeting adult wild boar, or in piglet-selective feeders. The main bait consumer was the wild boar (IREC 54%; Flavor 15%; Plain 16%) followed by azure-winged magpies (Cyanopica cooki; IREC 11%; Flavor 8%; Plain 17%). The most consumed bait was IREC (n = 164; 71%, mean 4.1 baits per site/day), followed by Flavor (102; 40%; 2.5) and Plain (70; 29%; 1.7). Pre-feeding increased bait consumption of all bait types (IREC 92%; Flavor 63%; Plain 40%). IREC baits were more consumed when deployed under stones (86%) than when deployed in piglet feeders (57%), while no difference between baiting devices was observed for Flavor and Plain baits. Birds preferred color-free baits (consumption ratio of 10% for color-free baits and 0% for green baits), while no other animal showed color preference. We suggest using green IREC-type baits, deployed after pre-baiting using species- and age-specific baiting devices.ResumenLos cebos son un medio para administrar por vía oral tóxicos, medicamentos o marcadores a jabalíes y cerdos salvajes (Sus scrofa). Probamos tres tipos de cebo, el cebo IREC a base de parafina y azúcar (versiones verdes y sin colorantes), un cebo de leguminosas infladas con el mismo sabor que el cebo IREC (Flavor) y el mismo cebo de leguminosas sin sabor (Plain). Los cebos se colocaron en una finca de caza cercada con alimentación durante todo el año para evaluar la preferencia del tipo de cebo y estudiar el efecto del sabor y color del cebo, el precebado, el dispositivo de cebo y la habituación sobre el consumo y la selectividad. Los cebos se colocaron debajo de piedras, dirigidos a jabalíes adultos, o en comederos selectivos para rayones. El principal consumidor fue el jabalí (IREC 54%; Sabor 15%; Sencillo 16%) seguido del rabilargo (Cyanopica cooki; IREC 11%; Flavor 8%; Plain 17%). El cebo más consumido fue IREC (n = 164; 71%, media 4,1 cebos por sitio/día), seguido de Flavor (102; 40%; 2,5) y Plain (70; 29%; 1,7). El precebado aumentó el consumo de todos los tipos de cebo (IREC 92%; Flavor 63%; Plain 40%). Los cebos IREC se consumieron más cuando se colocaron bajo piedras (86%) que cuando se dispusieron en comederos para rayones (57%), mientras que no se observaron diferencias entre dispositivos para los demás cebos. Las aves prefirieron los cebos sin color (proporción de consumo del 10% para cebos sin color y 0% para cebos verdes), mientras que ningún otro animal mostró preferencia en función del color. Sugerimos utilizar cebos verdes tipo IREC, distribuidos tras un precebado y utilizando dispositivos específicos para cada especie y edad.

Kajian tentang jenis umpan buatan pancing tonda terhadap hasil tangkapan

The aim of this research is to determine the differences between two types of artificial bait on troll line on catches and to identify the composition of catch types based on bait type. This research was carried out in Tanawangko waters and was carried out from February to March 2023 using the experimental fishing method, where two pancing tonda each using silk fiber and chicken feather bait were operated simultaneously in one boat for 5 trips which were then analyzed using the t test. The catch during the research was 24 individuals with 3 species, namely with silk fiber bait, 20 individuals were caught consisting of 3 species and using chicken feather bait, 4 individuals were caught consisting of 2 species. The analysis results show that tcount = 1.684 < t table = 2.776; so it accepts H0 and rejects H1. This explains that the use of chicken feather bait is not significantly different from silk fiber as trolling bait for catch results. The conclusion of this research is that using silk fiber bait resulted in more catches than chicken feather bait, but the results of the t test analysis showed that the two were not significantly different and the three species of fish caught were 15 skipjack tuna (Katsuonus pelamis), 7 baby tuna (Thunnus sp.), and 2 lemadang (Coryphaena hippurus).

Limitations of invasive snake control tools in the context of a new invasion on an island with abundant prey

In October 2020, a new population of invasive brown treesnakes (Boiga irregularis) was discovered on the 33-ha Cocos Island, 2.5 km off the south coast of Guam. Cocos Island is a unique conservation resource, providing refuge for many lizards and birds, including endangered species, which were extirpated from mainland Guam by invasive predators including brown treesnakes. We sought to evaluate the usefulness of toxic baiting with acetaminophen-treated carrion baits and cage trapping, common tools for the control of brown treesnakes on mainland Guam, as potential eradication tools on Cocos Island. We evaluated multiple bait types and bait presentations: on the ground, suspended in the canopy emulating aerial bait applications and in four plastic-tube bait station configurations intended to exclude non-target species. We monitored all baits with time-lapse cameras. Despite improved exclusion of non-targets by bait station design, most baits were quickly removed by non-target species, particularly coconut crabs (Birgus latro) and Mariana monitors (Varanus tsukamotoi). Monitoring of 1,250 baits available for 2,427 bait nights resulted in no observations of brown treesnakes taking any bait. Subsequently, we tested two trap types commonly used on Guam and compared trapping success with live versus dead mouse lures. In 10,553 trap nights using live and dead mouse lures, we only captured one brown treesnake, in a trap with a live mouse lure. These baiting and trapping rates are so low as to be ineffectual for all practical purposes. Concurrent visual searching and hand capture of brown treesnakes during initial rapid response efforts demonstrates that these low baiting and trapping success rates are not a result of low snake density. We make a case for our assumption that the ineffectiveness of these tools on Cocos Island is due to the context of extremely high abundance of preferred live prey, primarily large geckos and birds. Our results have profound conservation ramifications, because any future island invasions by brown treesnakes are likely to occur within similarly prey-rich environments where these baiting and trapping methods might be similarly ineffective.