Bait Size Research Articles

Size Selectivity, Injury, Handling Time, and Determinants of Initial Hooking Mortality in Recreational Angling for Northern Pike: The Influence of Type and Size of Bait

AbstractWe examined the relationship between bait and lure size and type and body size, injury, and handling time for northern pike Esox lucius, an important recreational fisheries resource in much of North America and Europe. Bait type and size were significantly related to the size of fish captured and hooking location. Hooking in critical locations (i.e., gills, gullet) was more likely to occur with natural bait, soft plastic shads and jigs, and spoons than with spinners and wobblers (i.e., plugs). Small baits (<75 mm) were more likely to hook the fish in the gills and less likely to hook the fish in the upper jaw than larger baits. It took longer to remove hooks from gills than from other hooking locations. Frequency of bleeding was related to depth of hooking but was unrelated to fish size, bait type, bait size, or fishing method. Initial mortality of northern pike was low (mean ± 95% confidence interval = 2.4 ± 1.5%), and hooking mortality was significantly related to the level of bleeding as a proxy for severity of injury. Results of this study suggest that using large artificial lures and large natural baits can effectively reduce the incidence of hooking small northern pike (i.e., those that are sublegal in some jurisdictions). However, the use of natural bait can also result in a higher incidence of deep hooking, which in turn increases the likelihood of injury and bleeding. This study revealed the complexity associated with using bait and lure restrictions to complement standard harvest regulations in northern pike recreational fisheries.

Wistar rats with high versus low rearing activity differ in radial maze performance

Substantial work has shown that rats although identical in stock, sex, age, and housing conditions can differ considerably in terms of behavior and physiology. Such individual differences, which can be detected by specific behavioral screening tests, are rather stable, that is, they probably reflect a behavioral disposition or trait. Here, we asked whether and how such differences might affect performance in a task of spatial learning and memory, the radial maze. As in our previous work, we used the degree of rearing activity in a novel open field to assign male adult outbred Wistar rats into those with high versus low rearing activity (HRA/LRA rats). They were then tested in a plus-maze for possible differences in anxiety-related behavior. Finally, and most importantly, they were food deprived and underwent maze training using an 8-arm radial maze with four non-baited and four baited arms. One of these arms consistently contained a larger bait size than the other three. In the open field, HRA rats not only showed more rearing behavior, but also more locomotor activity than LRA rats. In the plus-maze, HRA rats again showed more locomotion, but did not differ in open arm time or percentage of open arm entries, that is, conventional measures of anxiety-related behavior. In the radial maze, HRA rats consistently needed less time to consume all pellets than LRA rats, which was due to faster locomotion on the arms and less time spent at the food pits (especially in baited arms) of HRA rats. During the initial days of training, they were also more efficient in obtaining all food pellets available. Furthermore, HRA rats visited more arms and made relatively less reference memory errors than LRA rats. This allowed them to forage food quickly, but was paralleled by more working memory errors than in LRA rats. In general, working memory errors were more frequent in the arm with the large bait size, but there were no indications that HRA and LRA rats responded differently dependent on reward size. Finally, LRA rats lost slightly more weight than HRA rats during the period of food deprivation. These results are discussed with respect to the role of cognitive and motivational mechanisms, which as subject-inherent factors can contribute substantially to inter-individual variability in the radial maze.

The effect of bait design on bait consumption in termites (Isoptera: Rhinotermitidae)

The efficacy of baiting as a pest control method relies on the bait appealing to the pest species. In the case of wood-eating termites, bait stations should be designed to encourage termite presence and to maximize their consumption of bait matrix in order to expedite control in minimal time. A field experiment examined the effect of bait size (one large bait or four small baits of equivalent total size, with commensurate inspection and replacement schedules), compaction (tightly rolled or loosely folded) and composition (paper only or paper plus wood) on termite presence and on untreated bait paper removal rates over four months. All three factors were significant, with bait size the most important factor, followed by compaction and then composition. The least effective baits were small, compacted (rolled) paper-only baits with monthly inspections; these had the highest abandonment rate (70%) and had the least paper removed (mean of 24 g). The most effective baits were large, folded paper-plus-wood baits with inspections at two months; these had the lowest abandonment rate (20%) and had the highest paper removal (mean of 112 g). The more than four-fold difference between these baits types demonstrates that bait efficacy can be altered considerably merely by changing bait design without adding new ingredients to the bait matrix.

Effect on the species selectivity of different bait and hook size in longline in Iskenderun Bay, eastern Mediterranean Sea.

Effect on the species selectivity of different bait and hook size in longline in Iskenderun Bay, eastern Mediterranean Sea.

플라스틱 붕장어 통발어업에 있어서 침지 시간과 어획과의 관계

Test fishing was carried out utilizing a coastal pot-fishing boat from IS March to 7 April 2002 and the results obtained are summarized as follows ; 1. Mean catches(Number of sea eels) according to the soak time of 3 hours, 6 hours and 12 hours were 44.6, 60.0 and 83.3, and CPUE(Number of catch / 10pots·hour) were 2.5, 1.7 and 1.1 respectively 2. Catch difference between over 24 hours and 48 hours was 11.3% and 3.3% between over 48 hours and 72 hours. 3. In the test fishing, by-catches were so low(1.5∼3%) until 12 hours of soaking time passed By-catches were increased according to the soaking time addition on the over 24 hours of soaking time. The bait effect for sea-eel seems to be diminished as soon as the casting started and there was big difference in proportion to bait size and freshness

Dung beetles in a Central Amazonian rainforest and their ecological role as secondary seed dispersers

Abstract1. The role of several factors that affect the composition of the dung beetle assemblages in an Amazonian rainforest was quantified, together with the effect of these factors on the role that dung beetles play as secondary seed dispersers.2. A total of 61 dung beetle species was captured during 3360 h of trapping. During nocturnal trapping periods, more dung beetles, of larger mean size, and more species were captured per trap than during diurnal trapping periods.3. During the rainy season, more dung beetle species were captured per trap than during the dry season, but the number of individuals and their mean size did not vary between seasons.4. Bait size had a significant effect on the mean number of beetles and mean number of species but not on mean beetle size. As bait size increased from 5, 10, 25, to 50 g, more beetles and more species were captured per trap.5. Between 6 and 73% of plastic beads, used as seed mimics, were buried by dung beetles at depths that ranged from 0.5 to 7 cm. Both the proportion of beads buried and burial depth decreased with increasing bead size, and increased with increasing amounts of dung surrounding each bead (5, 10, and 25 g).6. The proportion of buried seeds for three species varying in size between 5 and 27 mm, increased with increasing dung beetle size, using beetles of seven sizes, varying between 10 and 25 mm.7. Seeds surrounded by dung were buried more often and more deeply when placed on the forest floor during the late afternoon than when placed during the early morning. Seeds were also buried more often when placed on the forest floor during the rainy season than when placed during the dry season, but season had no effect on burial depth.8. Forests in Central Amazonia hold a rich dung beetle community that plays an active role in secondary seed dispersal, and consequently in plant regeneration. The interaction between seeds and beetles is complex because it is affected by many factors.

A comparison of size selection of Atlantic cod ( Gadus morhua) and haddock ( Melanogrammus aeglefinus) by bottom longlines and otter trawls

The size selection of Atlantic cod and haddock by bottom longlines was described in an experiment conducted off Nova Scotia, Canada, by comparing their catches at length with those from an otter trawl with a small mesh codend fished concurrently. Three longline configurations were tested that differed primarily in the size of circle hooks and baits used. Bait size was increased with increasing hook size. Size selection of diamond and square mesh otter trawl codends of 130 mm mesh size were tested in the same experiment. The size selection curves obtained for cod taken on longlines were asymptotic and selection parameters were calculated by fitting logistic curves to the data. For haddock, only the lower end of the selection curves could be described. Larger hooks/baits were less efficient at catching smaller cod, but more efficient at catching larger cod, than were smaller hooks/baits. The smallest hook/bait combination had a length at 50% selection for cod below that of the 130 mm diamond mesh trawl codend, the minimum mesh size allowed at the time of the experiment. This result was counter to expectations based on the observed length compositions of commercial landings. The largest hook/bait combination had a 50% selection above that of the 130 mm square mesh. Although cod up to 126 cm were caught during this experiment, few were larger than 90 cm, leaving unresolved the question of whether the selection curves described are applicable to the largest cod.

Unequal sex ratios in longline catches

There is sometimes a significant bias in the sex ratio of fish caught by longline. Usually, more females than males are caught. The possible reasons for unequal sex ratios in longline catches are listed and discussed. One sex could be more common in the area where the fishery takes place because there really is an unequal sex ratio in the population or because the other sex preferentially occurs in different places. Alternatively, longline fishery might preferentially catch one of the sexes. This could be a result of size difference between the sexes and thus a different response to the given hook size or bait size. Finally, sexes could differ in their feeding behaviour. There is growing evidence that females—not only of fish—are ‘energy maximizers’: they find food faster and spend more time feeding than do males. Thus, fishing methods using bait are likely to catch a higher proportion of females than fishing methods that do not use bait.

The expanding superfamily of serpins: searching for the real targets

The serpin superfamily of proteins has expanded rapidly in recent years as represented by the ovalbumin-type serpin subfamily. PCR methods have been used to identify new ovalbumin-type serpins, including leupin or SCCA-2, a close relative of SCCA. Although in vitro inhibition of proteases by these serpins has been shown, and we have evidence that leupin can protect cells against apoptosis, the exact role of these serpins is not well understood. Finding relevant targets is a major challenge in serpin biology, and we have investigated the yeast-2-hybrid trap for identification of new interactions. Preliminary studies suggest that serpins are at the upper limit for bait size, but this technique may be useful for identifying interactions where full-length serpin protein is not required.

Optimising bait size and 1080 concentration (sodium monofluoroacetate) for the control of brushtail possums Trichosurus vulpecula)

A method is presented for quantitatively assessing the likely effectiveness of specific bait size and 1080 concentration for controlling brushtail possums with a known weight distribution. Data from aerial 1080 operations for the control of brushtail possums in New Zealand show that estimates of the bait size and toxic concentration required derived from the mean parameters [pest weight, bait size, and lethal dose (LD 95)] will not be accurate. This inaccuracy is most likely to lead to an underestimate of the amount of toxin presented to each animal, so that many operations currently run the risk of sub-lethally dosing possums and thereby possibly inducing some degree of poison shyness. On the basis of more accurate quantitative assessments of bait effectiveness we recommend that the 1080 concentration be increased to 0.15% and that baits less than 5 g be excluded to ensure that when mean possum weights are less than 3 kg more than 95% of possums are lethally dosed by a single bait.

Management Strategies for Production of the Atlantic White Shrimp Penaeus setiferus as Bait Shrimp in Outdoor Ponds

Abstract The geographic distribution of the Atlantic white shrimp Penaeus setiferus is in coastal waters from New York to Florida and around the Gulf of Mexico. Beside its value to commercial fisheries, this shrimp is sold as bait for recreational fishing. Previous data suggest that demand for live bait shrimp cannot be satisfied by commercial fleets. A 120‐d trial was designed to study production of bait size P. setiferus at high densities in eight small outdoor ponds in south Texas. A 24–1 fractional factorial design was applied to study the effects of postlarval (PL) density (350 and 700 shrimp/m2), feed type (A and B), and water circulation methods (with and without airlift pumps or center pond dividers) on shrimp growth, survival and yield. No significant differences in survivals or yields were found between treatments (P = 0.2). Feed type (P = 0.011), airlift pumps (P = 0.021), and center dividers (P= 0.026), had significant impacts on shrimp growth rates. Density effect on growth was not statistically significant (P= 0.055). This study demonstrated that 6‐d‐old postlarvae can be stocked at 700 per square meter and reached a bait size (6.2 g) in 94 d with a 73.6% survival and a yield equivalent to 31,300 kg/ha when offered a commercial shrimp feed. A preliminary economic analysis based on this data suggests that operating a bait shrimp farm in Texas with two crops/yr will show profitability within 7 to 12 yr with an internal rate of return of 6.5 and 17.6%, respectively.

The design, management and production of a recirculating raceway system for the production of marine shrimp

Despite continuing problems with disease outbreaks and environmental concerns over effluent pollution and land usage, world shrimp farming continues to expand. Although traditional pond production systems will continue to be the dominant driving force in aquaculture expansion, there is continued interest in alternate production systems. The use of high density, water reuse systems is one alternative to conventional pond production systems which addresses restrictions associated with environmental regulations and user conflicts of coastal land and water usage. This paper reports on techniques which have been developed for the production of marine shrimp in recirculating raceway systems and typical results which have been observed over a 6-year production period. Both bait shrimp ( Penaeus setiferus) and food shrimp ( P. vannamei) have been produced with final biomass loads as high as 10 kg/m 3 utilizing 100–120-day and 160–175-day production cycles, respectively. Results from multi-phase growout are most promising and indicate that this may be a suitable mechanism to optimize biomass loading of the culture system. Although the economic viability of recirculating production systems for bait and food size shrimp have yet to be proven, the consistent results of production, low water usage and ease of waste management are encouraging and warrant further economic and marketing evaluations.

Effects of setting time, setting direction and soak time on longline catch rates

Most studies of factors affecting catch efficiency and selectivity in longlining have focused on various gear parameters (mainline and snood material, hook design and size, rigging) and on the bait (type and size). Few studies have investigated how catch rates are affected by the way the gear is operated during fishing. We carried out fishing experiments to study the effects of setting time, setting direction (relative to the current direction) and soak time on catch rates of cod ( Gadus morhua) and haddock ( Melanogrammus aeglefinus). Lines set before dawn and lines set across the current gave higher catch rates of haddock than lines set after dawn and in the same direction as the current, respectively. Such effects were not found for cod, and these differences between haddock and cod were explained by differences in behaviour and interspecific competition for the available baits. Soak time was not found to affect the catch rates of either species significantly, indicating that other factors have a more pronounced effect on longline catch rates and may therefore mask the effect of soak time.

Response of the Skink Oligosoma Maccanni (Reptilia: Lacertilia) to Two Vertebrate Pest-Control Baits.

The attractiveness of two vertebrate pest-control baits (non-toxic RS5 and Pindone-impregnated AgTech) to captive skinks (Oligosoma maccanni) was assessed with timelapse video and feeding trials in New Zealand. 0. maccanni were attracted to both bait types. When dry, pindone baits were more palatable than RS5 baits. However, when wet the palatability of both baits increased and was similar. Bait size had no significant effect on palatability. Lizards ate an average of 0.01 g of RS5 bait or 0.02 g of Agtech Pindone bait, over two days. On the basis of published susceptibility data, it is unlikely that this level of consumption would expose skinks to lethal doses of these vertebrate pest toxins. Potential sublethal effects of such doses require further study.

Size-selective effects of increasing bait size by using an inedible body on longline hooks

Larger minimum legal sizes and other regulations recently enforced in the Norwegian fisheries for gadoids have increased the need to improve the selectivity of fishing gear. In longlining, bait size is regarded as the most important factor affecting size selectivity, and the potential for improving the size selectivity of longlines by using a plastic body attached to the hook shank, causing the bait to appear larger, was therefore tested on pelagic longlines for haddock ( Melanogrammus aeglefinus), and on bottom longlines for torsk ( Brosme brosme) and ling ( Molva molva). The results showed that baited hooks with a plastic body attached to the shank caught a lower proportion of under-sized haddock (under 44 cm) than hooks with bait only. Catch rates and mean lengths of torsk and ling were similar for the two types of hook, indicating that an inedible body in combination with bait did not affect catching efficiency or size selectivity for these fish. In pelagic longlining, the baited hooks are more readily seen than hooks set on the seabed, and the differences observed may be explained by better visibility rather than in terms of species differences in behaviour.

Reduced Catch of Under-Sized Cod (Gadus morhua) in Longlining by Using Artificial Bait

Three sizes of artificial bait incorporating shrimp flavour into polyurethane foam were compared with natural shrimp bait of the size used in commercial longlining. Fishing trials were conducted during the spring fishery for Atlantic cod (Gadus morhua) off the coast of Northern Norway. The small artificial bait gave almost the same catch rate as natural shrimp bait, whereas artificial baits of larger sizes compared poorly. The length distribution of the catch was influenced by both bait type and bait size. Fewer small cod were caught on the artificial baits. There was no difference in the number of large cod. Mean cod length was therefore higher on the artificial baits and increasing the artificial bait size accentuated the difference. These effects are explained by different preferences with regard to prey species and size between small and large cod. The size selective effects of bait type and bait size are discussed in relation to conservation aspects.

Winter foraging at carcasses by three sympatric corvids, with emphasis on recruitment by the raven, Corvus corax

Large animal carcasses provide a highly clumped rich source of food for ravens that should be worth defending, yet in the forests of Maine and Vermont ravens commonly feed in groups. Ravens discover baits flying singly or in pairs, but after a bait is discovered they usually arrive in groups. In contrast, the maximum number of blue jays and crows eventually attending a bait is close to those discovering it. Unlike in crows and jays, two patterns of bait use are seen in ravens: baits are used by mated resident pairs or by large crowds (sometimes exceeding 40 individuals). This pattern is unrelated to bait size from at least 9 kg to 400 kg. Eightytwo of 91 individually marked ravens from 4 feeding crowds were juveniles and/or non-breeders. Observations of the marked ravens for parts of two winters indicate that the non-breeders are vagrant and/or they range over at least 1800 km2 in their foraging. Most of the over 135 baits (totalling nearly 8 t of meat) distributed over 50 km were discovered by ravens within a week, and most were consumed by crowds of ravens. The vagrants coming in crowds have (unlike the territorial adults) specific vocalizations in the bait vicinity that are a powerful recruitment stimulus in playback experiments. Vagrants sometimes feed alone, but in the presence of territorial adults they feed only in groups. Resident adults chase or attack vagrants, but mildly tolerate them (and even join them) when they come in large groups. I conclude from my observations that the feeding crowds of ravens consist primarily of juvenile non-breeding vagrants who (unlike some resident adults) roost communally and who vigorously recruit each other in part to neutralize the aggressiveness of resident adults defending prized food bonanzas. The ravens' recruitment results in a sharing that reduces the temporal patchiness of extremely rare food bonanzas, and it permits the non-territorial vagrants to specialize on carcasses in the winter.

An investigation of the parameters of anticoagulant treatment efficiency1

The traditional technique of applying anticoagulant rodenticides, as shaped by long experience in the use of low‐toxicity, first‐generation anticoagulants such as warfarin, aims to maximize treatment efficiency by maximizing the rate of bait consumption by the target rodents. This is done, somewhat laboriously, by laying surplus amounts of bait initially, and maintaining this surplus throughout the treatment by repeatedly replenishing the bait placements. The suggestion that the high toxicity of the second‐generation anticoagulants should enable a more efficient baiting system to be designed is examined experimentally in this field study of the control of Rattus norvegicus on British farms. Bait toxicity, infestation size and the incidence of complete takes of bait were found to be independent and highly significant determinants of treatment duration whilst, in comparison, the size and density of bait points and the frequency with which the bait was replenished were found to be relatively unimportant. However, bait size and, more especially, replenishment frequency had detectable secondary effects, apparently through partial relationships with the incidence of complete takes and infestation size. The results indicate, in relation to the control of commensal infestations of R. norvegicus on British farms, that the use of high‐toxicity bait formulations and frequent replenishment schedules increase the speed of control, whilst the number and size of bait placements are relatively unimportant; they also suggest that reductions in the frequency of bait replenishment made in order to save labour could be compensated for by increasing the toxicity of the bait and taking other steps to reduce the incidence of complete takes of bait. The results are discussed in relation to the concept of ‘pulsed baiting'.

Effect of bait size and sampling time on the attraction of the lysianassid amphipods Anonyx sarsi Steele & Brunel and Orchomenella pinguis (Boeck)

Traps were used to study the effect of bait size and sampling time on the attraction of Anonyx sarsi Steele & Brunei and Orchomenella pinguis (Boeck) in Baie des Rochers, Middle Saint Lawrence Estuary. Numbers of lysianassids attracted to traps increased with increasing bait size (1–700 g). However, traps with ⩾ 10 g bait yielded significantly more first (5–9 mm in length) and second (15–28 mm) cohort Anonyx sarsi per g fresh weight of bait than traps with 1g bait, while yield of Orchomenella pinguis did not differ significantly with l g bait compared with ⩾ 10 g bait. With large bait, catchability (i.e. ratio number in traps: endobenthic abundance) of second cohort Anonyx sarsi was greater than that of Orchomenella pinguis and first cohort Anonyx sarsi. Orchomenella pinguis and second cohort Anonyx sarsi were significantly less abundant in traps set for 30 min at high tide in the day compared with the night, demonstrating that darkness is an important modifying factor of their foraging behaviour. In contrast, first cohort A. sarsi were equally represented in traps deployed in the day and at night. The swift second cohort A. sarsi responded to bait faster than other lysianassids in laboratory and field experiments. These findings point to a distinct segregation of the foraging patterns of these lysianassid species and size classes, which is attributed to differences in activity rhythms and swimming speed and behaviour. Anonyx species are apparently better adapted to compete for large carrion than Orchomenella species.

THE EFFECT OF CLAM SIZE, NET SIZE, AND POISONED BAIT TREATMENTS ON SURVIVAL OF HARD CLAM, Mercenaria mercenaria, SEED IN FIELD PLOTS

ABSTRACTEconomics dictates that the seed of the hard clam, Mercenaria mercenaria, be grown only to moderate sizes before field planting. Survival in the field nursery area is a function of multiple interactions with size specific predation playing the dominant role in survival of planted seed clams. This investigation compares field survival of five sizes of clam seed (4 to 14 mm) with two protective mesh sizes (6.25 mm and 12.5 mm openings) and poisoned bait treatments (malathion injected fish). Baffle treatments for two seed sizes are included to relate these studies to those previously published. Analysis indicates significant increases in survival with the use of poisoned bait and mesh size treatments for small seed sizes. No effect of poisoned bait was found for large seed sizes. Statistically significant interactions occur between seed size and mesh combinations. Comparisons are made with other data to indicate the significance of these interactions.