Preliminary Evaluation of Baits and Traps for Harvesting Orconectid Crayfish from Earthen Ponds

Four commercially available crayfish baits and two trap types were evaluated for efficiency in trapping Orconecres virilis and O. immunis from 13 unmanaged, contiguous earthen ponds in southern Illinois from May through October 1988. Specifically, this study compared three long-life baits and one one-day bait to gizzard shad, and four-funnel submerged pillow traps to three-funnel stand-up pyramid traps in matched-pair comparisons. Data from O. immunis harvest was not included in the final evaluation because of the relatively low numbers caught (343). The three long-life baits attracted significantly more O. virilis than did gizzard shad, but the attractability of the one-day bait was not significantly different from shad. There were no significant differences between four-funnel pillow traps and three-funnel pyramid traps or between catch per unit effort from deep or shallow ends of typical culture ponds. These data indicate that wild populations of O. virilis are susceptible to trapping with typical baits and traps used in the southern United States, and these methods may be more effective than those currently employed.     

Catch efficiency and retentive ability of commercial crawfish traps

The catch efficiency and retentive ability of 10 commercial crawfish traps were evaluated in commercial ponds. Trap designs with three entrance funnels caught significantly more crawfish than did trap designs with one or two funnels. Conversely, the retentive ability of the trap designs was inversely related to the number of entrance funnels.Traps constructed from PVC plastic-coated wire caught significantly more crawfish than identical trap designs made from galvanized wire; however, retentive ability of traps was not related to construction material. The posture (horizontal versus vertical) of identically designed traps when set in the pond did not affect the catch efficiency nor retentive ability of the traps. Traps with exposed bait caught 40–47% more crawfish than did traps with protected bait. An average of 84, 80 and 64% of marked crawfish were retained by traps after 12, 24 and 48 h, respectively.     

Evaluation of artificial and natural baits for the pot fishery of the sand crab Ovalipes punctatus (De Haan, 1833)

We compared the luring effectiveness of artificial bait made from fish waste with natural baits in pots targeting the sand crab Ovalipes punctatus in the East China Sea. Bait types used were fish (mackerel), minced fish (heads of greenling) and two artificial baits made mostly from fish waste and starch. The first two need frozen storage but artificial bait does not. Three fishing operations were conducted in May 2010 and in each forty pots (10/treatment) were fastened along a bottom line. Results for the three operations had catch data for 30 pots/treatment. The number of crabs captured was 496, of which 206 (41.5%) were caught in pots containing fish, 116 (23.4%) in those with minced bait, and 93 (18.8%) and 81(16.3%) in pots baited with the two artificial baits, respectively. Fish was significantly more attractive than minced bait and artificial baits, but no differences were detected between the other baits. Natural baits disappeared almost entirely by the time of hauling, with only 1% of the fish and 5.3% of the minced bait remaining; artificial bait remained almost intact (96.3–100%). The artificial bait catch was approximately half of that of fish bait, but it only contained 30% fish waste. Furthermore, if catch returns are calculated according to the bait's fish content their efficiency seemed higher, ranging from 88 to 100 crabs/kg of fish waste vs only 69 crabs/kg of fish.     

Development of Dry Artificial Fish Bait for Trap Fishing Using Tuna Red Meat and Shrimp Head Wastes

ABSTRACT

This study developed and evaluated dry artificial fish bait for trap fishing utilizing tuna red meat (TRM) and shrimp head powder (SHP), aiming to replace the usage of edible fishes, such as sardines and squids, as bait. A total of 23 dry baits were prepared and tested for stability in seawater and acceptance by tilapia. Based on the stability and acceptability test results, two baits were selected as ideal and were further tested for protein leaching and dry matter loss in seawater. The tests revealed that the stick-shaped bait containing 61% TRM and 15% SHP was the ideal bait, with a protein leaching rate of 24.82 mg/g/h and dry matter loss of 36.6 mg/g/h. The catch rate of the traps baited with the artificial fish bait was significantly higher (P < 0.05) than those baited with squid meat (17 Nos/trap) and sardines (23 Nos/trap). Further, the catch rate of traps baited with artificial bait (38 Nos/trap) was found to be comparable with those baited with raw shrimp head wastes (SHW) (40 Nos/trap). When the bait was concentrated with 0.1% sodium benzoate, shelf life was extended by up to 6 months.     

Temperature,plankton and conspecific density influence dynamics of age‐0 gizzard shad: implications for a gape‐limited piscivore

Age‐0 gizzard shad Dorosoma cepedianum are the main prey fish for white crappies Pomoxis annularis in many US reservoirs. However, these prey fish commonly outgrow their vulnerability to white crappie predation in some, but not all, northern Missouri reservoirs. Potential variables that could influence abundance, growth and mortality of age‐0 gizzard shad were examined in three reservoirs that differed with respect to age‐0 gizzard shad growth rates. Because of thermal effluent from a power plant, gizzard shad spawned earlier in Thomas Hill Lake and initial densities of larvae were greater than in the other reservoirs. Larval and juvenile gizzard shad grew slowest in Thomas Hill Lake, followed by Mark Twain Lake and Long Branch Lake. Growth rate of larvae increased with increasing water temperature and food abundance, but decreased with increasing conspecific density. Similar relationships were found for juvenile growth, except that growth declined with increasing temperature. The slower growth of larvae and juveniles in Thomas Hill Lake was probably a consequence of their greater densities relative to their food abundance and higher water temperatures during the juvenile stage. Conversely, both larvae and juvenile gizzard shad grew more rapidly and juveniles attained large sizes in Long Branch Lake owing to their lower densities relative to their available food. Mortality of larvae and juveniles was mostly similar among the reservoirs. Because of their greater abundance and slower growth, gizzard shad were available as prey for white crappies for a longer period in Thomas Hill Lake than in the other reservoirs.     

Influence of terminal rig configuration on the anatomical hooking location of line-caught yellowfin bream, Acanthopagrus australis

Abstract  Experiments were carried out to test the dependence of anatomical hooking location on terminal rig configuration, and identify strategies by which hook ingestion can be minimised to reduce post-release mortality of angled yellowfin bream, Acanthopagrus australis (Günther). Eighty-five anglers targeted yellowfin bream using different designs and sizes of circle and J hooks and recorded technical, environmental and biological data for each landed fish. Considerably fewer fish (16.6 and 8.5%, respectively) ingested hooks than those hooked in the mouth (82.1 and 88.6%), and a greater percentage of J hooks were ingested than circle hooks or a J hook modified with a 15-mm horizontal bar. Irrespective of hook type, the rate of ingestion also declined with increasing hook weight and decreasing fish size. In cage experiments, significantly more hooks baited with natural soft baits (e.g. intestines and cephalopods) were ingested than those baited with artificial baits, crustaceans or teleosts, while in the field fewer hooks were ingested using artificial bait (e.g. bread and pellets) than terrestrial animals, teleosts, crustaceans, teleost or terrestrial animal intestines, cephalopods or polychaetes. Similarly, rigs with floats, short traces or a sinker only on the hook, along with angling in environments with at least some current reduced ingestion. Based on this study, anglers targeting yellowfin bream should be encouraged to use circle or modified J hooks and, regardless of the hook design, the largest hook size possible attached to short traces or a sinker only and hard baits.     

Mesh selectivity of encircling gill net for gizzard shad Konosirus punctatus in the coastal sea of Korea

ABSTRACT:   Fishing experiments were carried out in Yeongil Bay, Korea using an encircling gill net with four different mesh sizes and two different hanging ratios to measure the mesh selectivity for gizzard shad Konosirus punctatus . Twenty-six trials were conducted giving a total catch of 485 gizzard shad. The 'share each length's catch total' (SELECT) analysis with maximum likelihood method was used to fit the different functional models, the normal, lognormal, and bi-normal model, for a selectivity curve to the catch data. In addition, two cases in which the relative fishing intensity was either estimated or fixed were compared. The bi-normal model with the fixed relative fishing intensity was found to fit the data best. For the selectivity curve on the bi-normal model, the relative length (the ratio of fish length to mesh size) with the maximum efficiency was obtained as 3.70. From this, the focal fish lengths in the commercial encircling gill net, with mesh size ranging from 5.0 to 6.0 cm, were inferred to be 18.5–22.2 cm.     

A test of crayfish predatory and nonpredatory fish species as bait in crayfish traps

The effectiveness of different crayfish: predatory (pike, Esox lucius L., perch, Perca fluviatilis L.) and nonpredatory [roach, Rutilus rutilus (L.) , and bream, Abramis brama (L.)] fish species as bait for noble crayfish, Astacus astacus L., was tested. Trapping was conducted in two lakes in Norway and Lithuania. Nonpredatory bream and roach were superior as noble crayfish bait compared with predatory perch and pike. In the Norwegian lake bream was also superior to roach. Pike- and perch-baited traps tended to catch larger crayfish than bream- and roach-baited traps. An alarm or avoidance response to different live or dead fish predators (e.g. pike or perch) might exist and could be more pronounced in smaller crayfish, thus explaining that pike and perch as bait catch fewer and larger crayfish. Another explanation could be that the odour of pike and perch flesh is simply less attractive or diffuses more slowly through the water. Selecting the most efficient bait will increase the catch per unit effort (CPUE); in this study there was a four-fold variation in CPUE between the best and worst bait type. In test-fishing/monitoring surveys it is important to standardize the bait type used.     

Variation in larval fish communities: implications for management and sampling designs in reservoir systems

Understanding spatial and temporal patterns in larval fish distributions is important for investigating factors related to recruitment variability and for developing sampling methodologies. Variation in species diversity (Shannon index) and density (number 100 m^?3) of larval fishes from nearshore and pelagic habitats in Glen Elder Reservoir, KS, USA, was assessed during 1999 and 2000. Species diversity and densities of individual taxa were significantly higher (P < 0.05) in nearshore habitats than pelagic habitats during both years. Larval fish densities were generally higher in the year 1999 with higher spring water levels. Gizzard shad Dorosoma cepedianum (Lesueur) was the most abundant taxon in nearshore and pelagic habitats during both years. In addition, larval gizzard shad was sampled for the longest duration in the upper water column and overlapped with all taxa collected. High densities of gizzard shad in both habitats suggested that the potential for competitive interactions was high, especially given the lack of aquatic vegetation and habitat heterogeneity in littoral habitats. Most of the variation in larval fish diversity and density was because of temporal variation. If sampling effort must be limited and the purpose of sampling is to monitor larval diversity or density, attention should focus on sampling the same location over long time periods rather than across a variety of sampling locations.     

Catches of swimming crabs using fish mince in “teabags” compared to conventional fish baits in collapsible pots

Fishing trials were conducted in a pond using collapsible pots containing fish mince inside a “teabag” or cut fish baits. Scomber japonicus was minced (100 g) and packed in a teabag or cut in half; non-baited pots served as controls. Baits were placed inside box-shaped pots (2.3 cm mesh size) with two slit entrances. Trials consisted of 100-pot hauls/bait type using a 1-day soaking time. The crab catches of Charybdis japonica and Portunus pelagicus from “fish” and “mince teabag” baits were not significantly different, but differences were found for total catch and damselfish Chromis notata. Trials using 80 g of mince and 20 g of sugar as the “teabag” bait lowered the catch of C. japonica, Thalamita sima and Thalamita prymna but not P. pelagicus when compared with fish bait. Results indicate that the mince in teabags is as suitable as fish bait, and that adding substances to the mince might be used to make selective crab baits.     

Substitution of Soybean Protein for Fish Protein in Formulated Diets for Red Swamp Crawfish Procambarus clarkii1

A 10 week laboratory growth trial was conducted with red swamp crawfish Procambarus clarkii to determine the amount of soybean protein that could be substituted for fish protein in formulated crawfish diets without reducing growth. Crawfish received 32% crude protein, isocaloric diets in which protein was supplied by soybean (soy) meal, menhaden fish meal or an isonitrogenous mixture of soybean and fish meal calculated to provide graded levels of each protein source. Dietary protein was provided as: 1) 100% soy protein; 2) 75% soy protein: 25% fish protein; 3) 50% soy protein: 50% fish protein; 4) 25% soy protein: 75% fish protein; and 5) 100% fish protein. Crawfish fed soy protein: fish protein (SP:FP) mixtures or fish protein alone exhibited better (P < 0.05) weight gain than crawfish fed a diet containing soy protein as the only protein source. Diets containing 25% soy protein: 75% fish protein (1:3 ratio) and 50% soy protein: 50% fish protein (1:1 ratio) produced greater (P < 0.05) weight gains than a diet in which fish protein was the sole protein source. Survival, feed efficiency ratio, maturation rate, net protein and energy retention, and body composition of crawfish did not differ (P > 0.05) among diets with SP:FP ratios of 1:3, 1:1 and 3:1. However, maximum (P < 0.05) weight gain occurred in crawfish fed the 1:3 SP:FP ratio. Although crawfish fed SP:FP ratios of 1:1 and 3:1 had lower weight gains in the laboratory than crawfish fed a 1:3 SP:FP ratio, SP:FP ratios of 1:1 and 3:1 might be adequate for supplemental diets fed to pond-reared crawfish that have access to natural sources of food.     

Short-term mortality of Australian bass, Macquaria novemaculeata, after catch-and-release angling

Abstract  Australian bass, Macquaria novemaculeata Steindachner, is angled in large numbers from coastal impoundments and rivers throughout south-eastern Australia. Many are released in the belief that most survive with few negative short-term impacts. This assumption was investigated in three experiments involving a range of conventional angling scenarios. A total of 313 Australian bass were angled and then released along with appropriate controls into either land-based tanks or floating cages, where they were monitored for up to 5 days. No controls died. Short-term mortalities of angled fish were low (0–6%) and attributed to the effects of bait type, hook location and fish size ( P  <   0.05). Specifically, fish that ingested hooks or were caught with natural baits were more likely to die than those that were mouth-hooked or caught on lures. Mortality negatively correlated with fish size. The results supported previous assertions that Australian bass is a resilient, hardy species that should tolerate short-term impacts associated with catch-and-release angling. However, other sublethal physiological impacts that could contribute towards delayed mortalities or reduced reproductive output warrant further investigation, particularly in relation to native populations in coastal rivers that form gauntlet fisheries during their annual spawning season.     

Variation in characteristics among gizzard shad populations: The role of impoundment size and productivity

Population characteristics of gizzard shad, Dorosoma cepedianum (Lesueur), an ecologically important fish species in Midwestern and southern USA impoundments, vary widely among water bodies. Impoundment productivity is known to influence population variables (e.g., recruitment, growth, mortality, size and age composition), but the role of impoundment morphometry (e.g., surface area, depth) is unknown. Differences in population characteristics of gizzard shad were compared between large and small impoundments across an impoundment–productivity gradient (indexed by total phosphorus [TP] concentration). Populations shifted from those comprised mostly of low abundances (indexed by catch per unit effort [CPUE], fish/hr of electric fishing) of long‐lived, large adults to those comprised of high abundances of short‐lived, small adults as TP increased. However, the trends in population variables across the TP gradient were less apparent in small impoundments than in large impoundments owing to considerable variation at a given TP level. Further analysis revealed that CPUE of gizzard shad was lowest in the smallest impoundments (<33 ha surface area) regardless of TP concentrations, probably because of more frequent winter kills. Overall, population characteristics were influenced by both density‐dependent effects and impoundment characteristics. Characteristics of gizzard shad were highly variable among populations, which have important consequences for ecosystem structure and function.     

Effect of type of bait on pelagic longline fishery–loggerhead turtle interactions in the Gulf of Gabes (Tunisia)

• 1. Sea turtles may migrate vast distances from their feeding areas to home rookeries where they nest. During these migrations sea turtles are subject to many threats, among which are interactions with pelagic longlines.
• 2. This gear is used frequently in the summer period in the Gulf of Gabes targeting mainly the sandbar shark (Carcharhinus plumbeus). Hooks are baited with mackerel (Scomber scombrus) or pieces of stingray (Dasyatis pastinaca).
• 3. Twenty‐one fishing trips (48 sets with a total of 35 950 hooks deployed) were conducted using onboard observers in the south of the Gulf of Gabes during the months of July, August and September in 2007 and 2008. Stingray and mackerel bait were used in 19 and 29 sets, respectively.
• 4. In total, 29 loggerhead sea turtles (Caretta caretta) were captured; the majority of them were juvenile and active. Turtles were caught at a statistically greater frequency on sets with hooks baited with mackerel than on sets with hooks baited with pieces of stingray.
• 5. The type of bait also affected the catch of the target species by increasing the efficiency when pieces of stingrays were used.
• 6. These results encourage further research into new baits to mitigate turtle catch by longline fisheries without affecting the catch of target species. Copyright © 2010 John Wiley & Sons, Ltd.

     

Effects of Supplemental Feeding on Harvest of Red Swamp Crawfish,Procambarus clarkii,in Forage‐based Ponds

Procambarid crawfish aquaculture in the USA relies on an established forage‐based system for providing sustenance for growing crawfish. These systems may become inadequate at times for providing sufficient nourishment to support maximum growth of the population. Supplemental feeding is not routinely used because management recommendations for the cost‐effective use of supplemental feeds in ponds are not available. Because crawfish under confinement readily consume and grow well when fed single feedstuffs, such as rough rice seed and whole, raw soybeans, this study was initiated to investigate the use of these readily available low‐cost feedstuffs as supplemental feeds in aquaculture ponds. Earthen ponds (0.2 ha), constructed and managed to simulate commercial crawfish ponds, were used over three consecutive production seasons to evaluate the effects of supplemental feeding on yields and size of crawfish. Treatments for Seasons 1 and 2 consisted of (a) hull‐on rough rice seed, (b) whole raw soybean, (c) formulated 25% crude protein pellet, and (d) no supplementation and were replicated in four and three ponds for Seasons 1 and 2, respectively. Treatments for Season 3 consisted of (a) whole raw soybean and (b) no feed, with 10 replicated ponds each. Feeding frequency was established each year, and feeding rates were adjusted according to predetermined guidelines and monitoring of feeding trays. Crawfish harvesting was conducted by baited wire‐mesh traps and all harvested crawfish were subjected to a mechanical grader and sorted into three size classes. Results show that supplemental feeding, while trap‐harvesting operations are underway, can reduce yields and generate a negative economic benefit, perhaps as a result of residual feed within the pond rendering the baited trap less effective.     

Association of Aeromonas sobria with mortalities of adult gizzard shad, Dorosoma cepedianum Lesueur

Abstract. This report describes an epizootic in a natural population of spawning females of gizzard shad, Dorosoma cepedianum Lesueur, which occurred in the Potomac River (Maryland, USA). Microbiological analysis of moribund shad revealed the presence in pure culture in all the organs examined of one bacterium which was identified as Aeromonas sobria by conventional tube and plate tests. The different API-systems used to attempt for a rapid diagnosis of the disease yielded false negative and positive reactions in important differential tests such as ornithine decarboxylase, arabinose fermentation, gelatinase, urease, indole and production of H₂S which gave an erroneous identification of the shad isolate. The virulence assays in rainbow trout revealed that A. sobria was pathogenic with a mean LD₅₀ of 2 × 10⁵. Bacterial extracellular products also displayed fish lethality and were cytotoxic for poikilothermic and homeothermic cell-lines. Although the source of shad infection is unknown, the physico-chemical conditions of the river, together with the stress associated with the spawning could have been contributing factors in the proliferation of A. sobria inducing this epizootic.     

Evaluation of Trap Density and Type for Harvesting Crawfish Procambarus spp. from Small Ponds

Harvested crawfish were stocked into 0.15-ha earthen ponds in March and May at rates of 114, 227, and 455 kg/ha to evaluate the effects of trap density, 27 and 54 traps/ha, on their recapture over 14 d following 3 d of acclimation. Two-funnel, stand-up pillow traps and three-funnel pyramid traps were compared. About 39% and 55% of stocked crawfish were recovered in March and May, respectively. There was considerable growth of those crawfish. Overall catch with both trap densities was equivalent in March but the higher trap density caught 1.3 times more crawfish in May. Pyramid traps caught 1.5–1.9 times more crawfish than pillow traps.     

Sampling fish assemblages in forested floodplain wetlands

Abstract– Four quantitative (area-standardized electrofishing, trap nets, small-mesh [1.3 and 2-cm bar mesh] gill nets, large-mesh [2.5 and 5-cm bar mesh] gill nets) and two qualitative (non-standardized electrofishing, dip netting) sampling techniques were concurrently used to capture larval to adult fish in forested wetland habitats on seasonally inundated floodplains of two Alabama (USA) streams. Standardized area electrofishing appeared to be the best sampling technique for collecting and quantifying species because of high catch rate, broad species and size coverage, and rapid sampling. Electrofishing accounted for most fish (47 and 57% of pooled catch), almost all taxa, and a broad range of fish sizes. Large-mesh gill nets captured few fish (2% and 8%), a distinct subset of the species present, and the largest fish. Light traps were the most efficient and taxa-comprehensive sampling technique for larval fish. Light traps captured the vast majority of the pooled larval fish catch, including 6 of 7 families recorded at the sites. Larval fish dip netting captured larval fish of most families known to be present but in low numbers. For surveys of species composition and rapid bioassessments, nonstandardized electrofishing and larval fish dip netting appear adequate. For intensive research studies, the combination of area electrofishing, large-mesh (and in some cases small-mesh) gill nets, and light traps provide thorough and comprehensive data on wetland fish assemblages.     

Evaluation of the Economics of Multi-Batch Channel Catfish Ictalurus punctatus Production Fed an Industry Standard and Three Alternative Diets

The purpose of this study was to determine the feasibility of growing marketable channel catfish, Ictalurus punctatus, from pond-run fingerlings (15.9 g/fish) using low stocking densities (7,413 or 14,826 fish/ha) and electrified bug lights to enhance natural forage available to fish. Even at low stocking densities, fish only averaged 0.2 kg at the end of the growing season. Because marketable sizes of fish were not reached over the growing season, stocking small fingerlings at these rates would not be practical under most commercial production scenarios. Nutritionally, captured insects from electrified bug lights were near a complete diet for catfish, but bug lights did not capture sufficient quantities of insects to affect fish production in either stocking density. Stocking small fingerlings at low stocking rates does not produce market‐sized catfish during one growing season; commercially available bug lights did not provide adequate amounts of natural forage to affect production variables.     

A study of delayed capture mortality syndrome in skipjack tuna, Katsuwonus pelamis (1).

Abstract. This study was initiated to determine the cause(s) of delayed mortality in newly captured skipjack tuna, Katsuwonus pelamis (L.), being held at the National Marine Fisheries Service Kewalo Research Facility. Sixty-four per cent of 244 skipjack tuna delivered to the facility died, usually on the second or third day after capture. The capture history, morphological data, serum chemistry (21 standard parameters), haematology, and histological samples of major organs, were obtained from 30 fish sampled at sea immediately after capture, or after approximately 4, 9, 24, 48 or 500+ h in captivity. The cause(s) of death in these fish could not be attributed to anoxia, disseminated intravascular coagulation, lactic acidosis, capture myopathy or infection. Post-capture haemodilution is hypothesized as a major factor of delayed capture mortality syndrome in skipjack tuna.