Increased connectivity and depth improve the effectiveness of marine reserves

Marine reserves are a key tool for the conservation of marine biodiversity, yet only ~2.5% of the world's oceans are protected. The integration of marine reserves into connected networks representing all habitats has been encouraged by international agreements, yet the benefits of this design has not been tested empirically. Australia has one of the largest systems of marine reserves, providing a rare opportunity to assess how connectivity influences conservation success. An Australia-wide dataset was collected using baited remote underwater video systems deployed across a depth range from 0 to 100 m to assess the effectiveness of marine reserves for protecting teleosts subject to commercial and recreational fishing. A meta-analytical comparison of 73 fished species within 91 marine reserves found that, on average, marine reserves had 28% greater abundance and 53% greater biomass of fished species compared to adjacent areas open to fishing. However, benefits of protection were not observed across all reserves (heterogeneity), so full subsets generalized additive modelling was used to consider factors that influence marine reserve effectiveness, including distance-based and ecological metrics of connectivity among reserves. Our results suggest that increased connectivity and depth improve the aforementioned marine reserve benefits and that these factors should be considered to optimize such benefits over time. We provide important guidance on factors to consider when implementing marine reserves for the purpose of increasing the abundance and size of fished species, given the expected increase in coverage globally. We show that marine reserves that are highly protected (no-take) and designed to optimize connectivity, size and depth range can provide an effective conservation strategy for fished species in temperate and tropical waters within an overarching marine biodiversity conservation framework.

Using tri-axial accelerometer loggers to identify spawning behaviours of large pelagic fish

BACKGROUND

Tri-axial accelerometers have been used to remotely describe and identify in situ behaviours of a range of animals without requiring direct observations. Datasets collected from these accelerometers (i.e. acceleration, body position) are often large, requiring development of semi-automated analyses to classify behaviours. Marine fishes exhibit many "burst" behaviours with high amplitude accelerations that are difficult to interpret and differentiate. This has constrained the development of accurate automated techniques to identify different "burst" behaviours occurring naturally, where direct observations are not possible.

METHODS

We trained a random forest machine learning algorithm based on 624 h of accelerometer data from six captive yellowtail kingfish during spawning periods. We identified five distinct behaviours (swim, feed, chafe, escape, and courtship), which were used to train the model based on 58 predictive variables.

RESULTS

Overall accuracy of the model was 94%. Classification of each behavioural class was variable; F₁ scores ranged from 0.48 (chafe) - 0.99 (swim). The model was subsequently applied to accelerometer data from eight free-ranging kingfish, and all behaviour classes described from captive fish were predicted by the model to occur, including 19 events of courtship behaviours ranging from 3 s to 108 min in duration.

CONCLUSION

Our findings provide a novel approach of applying a supervised machine learning model on free-ranging animals, which has previously been predominantly constrained to direct observations of behaviours and not predicted from an unseen dataset. Additionally, our findings identify typically ambiguous spawning and courtship behaviours of a large pelagic fish as they naturally occur.

Effectiveness of novel fabrics to resist punctures and lacerations from white shark (Carcharodon carcharias): Implications to reduce injuries from shark bites

Increases in the number of shark bites, along with increased media attention on shark-human interactions has led to growing interest in preventing injuries from shark bites through the use of personal mitigation measures. The leading cause of fatality from shark bite victims is blood loss; thus reducing haemorrhaging may provide additional time for a shark bite victim to be attended to by emergency services. Despite previous shark-proof suits being bulky and cumbersome, new technological advances in fabric has allowed the development of lightweight alternatives that can be incorporated onto traditional wetsuits. The ability for these fabrics to withstand shark bites has not been scientifically tested. In this report, we compared two types of recently developed protective fabrics that incorporated ultra-high molecular weight polyethylene (UHMWPE) fibre onto neoprene (SharkStop and ActionTX) and compared them to standard neoprene alternatives. We tested nine different fabric variants using three different tests, laboratory-based puncture and laceration tests, along with field-based trials involving white sharks Carcharodon carcharias. Field-based trials consisted of measuring C. carcharias bite force and quantifying damages to the new fabrics following a bite from 3–4 m total length C. carcharias. We found that SharkStop and ActionTX fabric variants were more resistant to puncture, laceration, and bites from C. carcharias. More force was required to puncture the new fabrics compared to control fabrics (laboratory-based tests), and cuts made to the new fabrics were smaller and shallower than those on standard neoprene for both types of test, i.e. laboratory and field tests. Our results showed that UHMWPE fibre increased the resistance of neoprene to shark bites. Although the use of UHMWPE fibre (e.g. SharkStop and ActionTX) may therefore reduce blood loss resulting from a shark bite, research is needed to assess if the reduction in damages to the fabrics extends to human tissues and decreased injuries.

Lack of light colour effects when sampling fish at night in low visibility environments

We compared night deployments of Baited Remote Underwater Video Stations (BRUVS) in South Australia, illuminated by either red or blue light and found similar species compositions and abundances with both colours. We observed c. 1800 individuals from 52 species across 107 night-time deployments, with only one site out of six showing differences in assemblages between the two colours. With five out of six sites showing similarities between light colours our results differ from previous results and more generally suggest that the most suitable colour can differ among studies.

What are we missing? Advantages of more than one viewpoint to estimate fish assemblages using baited video

Counting errors can bias assessments of species abundance and richness, which can affect assessments of stock structure, population structure and monitoring programmes. Many methods for studying ecology use fixed viewpoints (e.g. camera traps, underwater video), but there is little known about how this biases the data obtained. In the marine realm, most studies using baited underwater video, a common method for monitoring fish and nekton, have previously only assessed fishes using a single bait-facing viewpoint. To investigate the biases stemming from using fixed viewpoints, we added cameras to cover 360° views around the units. We found similar species richness for all observed viewpoints but the bait-facing viewpoint recorded the highest fish abundance. Sightings of infrequently seen and shy species increased with the additional cameras and the extra viewpoints allowed the abundance estimates of highly abundant schooling species to be up to 60% higher. We specifically recommend the use of additional cameras for studies focusing on shyer species or those particularly interested in increasing the sensitivity of the method by avoiding saturation in highly abundant species. Studies may also benefit from using additional cameras to focus observation on the downstream viewpoint.

Effects of prelay 6/85-strain Mycoplasma gallisepticum inoculation alone or in conjunction with the inoculation of F-strain Mycoplasma gallisepticum during lay on the blood characteristics of commercial egg-laying hens

The effects of 6/85-strain Mycoplasma gallisepticum (6/85MG) inoculation alone or in conjunction with F-strain M. gallisepticum (FMG) overlays and their timing on the blood characteristics of commercial egg-laying hens were investigated. Control birds received sham inoculations at 10 wk of age. Birds in a second treatment group were inoculated with 6/85MG at 10 wk of age, those in a third treatment group were inoculated with 6/85MG at 10 wk followed by an overlay inoculation of FMG at 22 wk, and those in a fourth treatment group were inoculated with 6/85MG at 10 wk followed by an overlay inoculation of FMG at 45 wk. Parameters investigated at 24, 32, 43, and 47 wk were hematocrit, plasma total protein, and serum calcium, triglycerides, and cholesterol. No significant treatment effects were noted for hematocrit, serum triglycerides, or serum cholesterol. However, at wk 32, plasma protein was greater in birds that received 6/85MG at 10 wk or 6/85MG at 10 wk and FMG at 22 wk in comparison to controls. Also, at wk 47, serum calcium concentration was greater in birds that received 6/85MG at 10 wk and FMG at 45 wk compared with controls and those that received 6/85MG at 10 wk and FMG at 22 wk. These results suggest that the prelay inoculation of pullets with 6/85MG may subsequently elevate plasma protein, and in conjunction with an FMG overlay at 45 wk, may increase serum calcium concentrations in laying hens.

Effects of supplemental dietary phytase and 25-hydroxycholecalciferol on the performance characteristics of commercial layers inoculated before or at the onset of lay with the F-strain of Mycoplasma gallisepticum

The effects of dietary supplementation with phytase and 25-hydroxycholecalciferol on the performance characteristics of commercial layers that were inoculated prelay (12 wk of age) or at the onset of lay (22 wk of age) with F-strain Mycoplasma gallisepticum were assessed. Experimental layer diets, which included a basal control diet or the same diet supplemented with 0.025% phytase and 25-hydroxycholecalciferol, were fed from 20 through 58 wk of age. Weekly and total egg production were determined from 22 through 58 wk, and egg weight and various internal egg and eggshell quality characteristics were examined at 34, 50, and 58 wk of age. F-strain M. gallisepticum inoculation decreased egg production at the beginning of lay (wk 22 and 23) but increased post-peak lay at wk 45. However, there were no treatment effects of any kind on total egg production, egg weight, or any of the internal egg and eggshell characteristics examined during lay. In conclusion, dietary supplementation with phytase and 25-hydroxycholecalciferol did not affect layer performance or interact with the effects of F-strain M. gallisepticum inoculation; however, F-strain M. gallisepticum inoculation resulted in a shift in egg production from wk 22 to 45 without having an overall effect on total egg production.

Effects of supplemental dietary phytase and 25-hydroxycholecalciferol on the blood characteristics of commercial layers inoculated before or at the onset of lay with the F-strain of Mycoplasma gallisepticum

In 3 trials, the effects of dietary supplementation with phytase (PHY) and 25-hydroxycholecalciferol on BW and the blood characteristics of commercial layers that were inoculated prelay (12 wk of age) or at the onset of lay (22 wk of age) with F-strain Mycoplasma gallisepticum were assessed at 34, 50, and 58 wk of age. Experimental layer diets, which included either a basal control diet or the same diet supplemented with 0.025% PHY and 25-hydroxycholecalciferol, were fed from 20 through 58 wk of age. The supplemented diet decreased blood hematocrit values across bird age, inoculation type (sham vs. F-strain M. gallisepticum), and age of inoculation (prelay vs. onset of lay). Phytase- and 25-hydroxycholecalciferol-supplemented diets reduced bird BW in sham-inoculated control birds across bird age and age of inoculation. This effect was not observed in F-strain M. gallisepticum-inoculated birds. Furthermore, across diet (control vs. supplemented) and inoculation type, total plasma protein concentration at 34 wk of age was higher in birds that were inoculated at the onset of lay compared with those inoculated prelay. Diet, inoculation type, and inoculation age had no effect on mortality, reproductive organ histopathological lesion scores, or serum cholesterol and Ca concentrations. In conclusion, throughout lay, the supplementation of commercial layer diets with PHY may lower hematocrit, and inoculation with F-strain M. gallisepticum prelay or at the onset of lay may ameliorate the depressing effects of dietary PHY and 25-hydroxycholecalciferol supplementation on hen BW.

Effects of Supplemental Dietary Phytase and 25-Hydroxycholecalciferol on the Digestive and Reproductive Organ Characteristics of Commercial Layers Inoculated Before or at the Onset of Lay with the F-Strain of Mycoplasma gallisepticum

In 3 trials, the effects of dietary supplementation with phytase (PHY) and 25-hydroxycholecalciferol (25-D3) on the digestive and reproductive organ characteristics of commercial layers that were inoculated prelay (12 wk of age) or at the onset of lay (22 wk of age) with F-strain Mycoplasma gallisepticum (FMG) were assessed at 58 wk of age. Experimental layer diets that included a basal control diet or a control diet supplemented with 0.025% PHY and 25-D3 were fed from 20 through 58 wk of age. As a percentage of total oviduct weight, magnum weight was lower in birds that were inoculated (sham or FMG) at lay onset compared with those that were inoculated prelay, and in FMG-inoculated birds, relative duodenum length was greater in those inoculated at 12 compared with 22 wk. Also, as percentages of organ weight or length, infundibulum length and isthmus weight were increased, whereas duodenum length was decreased by dietary supplementation with PHY and 25-D3. The overall timing (12 vs. 22 wk) of inoculation can affect the reproductive organ characteristics of layers, whereas, more specifically, the timing of an FMG inoculation may affect their digestive organ structure. Furthermore, independent of inoculation timing and type, the reproductive organ and digestive systems of laying hens may be influenced by dietary supplementation with PHY and 25-D3.

Effects of S6-strain Mycoplasma gallisepticum inoculation at ten, twenty-two, or forty-five weeks of age on the blood characteristics of commercial egg-laying hens

In 2 consecutive trials of the current study, the effect of the age of application of S6-strain Mycoplasma gallisepticum (S6MG) inoculation on the blood characteristics of commercial layers housed and maintained under controlled conditions was determined. The ages of inoculation compared were those before lay at 10 wk of age, during onset of lay at 22 wk of age, and during postpeak lay at 45 wk of age. In each trial, hematocrit, plasma protein, and serum cholesterol, triglycerides, and Ca were determined at 20, 24, 32, 43, 47, and 58 wk of age. The data from both trials were pooled then analyzed together, whereas, data from wk 20 (effect of 10-wk S6MG inoculation); data from wk 24, 32, and 43 (effects of 10- and 22-wk S6MG inoculations); and data from wk 47 and 58 (effects of 10-, 22-, and 45-wk S6MG inoculations) were analyzed separately. At wk 20, hematocrit was higher in birds inoculated with S6MG at 10 wk compared with sham-inoculated birds, and across wk 24, 32, and 43, serum Ca was higher in birds inoculated with S6MG at 10 or 22 wk compared with those that were sham-inoculated. Serum Ca level across wk 47 and 58 was higher in birds inoculated with S6MG at 10 wk compared with sham-inoculated controls and birds inoculated with S6MG at 22 wk, with 45-wk S6MG-inoculated birds being intermediate. The response of serum cholesterol level at 47 wk to S6MG inoculation at either 10, 22, or 45 wk compared with controls was nearly opposite to that of the response observed at 58 wk. However, serum triglycerides were depressed only at wk 47 due to the 45-wk S6MG inoculation compared with all other treatments. Variable post-peak alterations in serum Ca and lipids occur in response to the timing of S6MG inoculation in layers housed under controlled conditions.

Effects of S6-Strain Mycoplasma gallisepticum Inoculation at Ten, Twenty-Two, or Forty-Five Weeks of Age on the Egg Yolk Composition of Commercial Egg-Laying Hens

Commercial laying hens maintained under controlled conditions were experimentally inoculated with the S6 strain of Mycoplasma gallisepticum (S6MG) at 45 wk of age. This resulted in depressed liver lipid concentration, and inoculations at 20 and 45 wk affected the size of various portions of the reproductive tract. In 2 consecutive trials of the current study, the effect of age of application of S6MG inoculation on the egg yolk characteristics of commercial layers similarly housed and maintained under controlled conditions was determined. The ages of inoculation compared were prior to lay at 10 wk of age, during onset of lay at 22 wk of age, and during postpeak lay at 45 wk of age. In each trial, yolk moisture and total lipid content were determined at 24, 32, 43, 47, and 58 wk of age. Yolk cholesterol concentration and yolk fatty acid profiles at wk 47 and 58 were also examined. Data from wk 24, 32, and 43 (effects of S6MG inoculations at 10 and 22 wk) and data from wk 47 and 58 (effects of S6MG inoculations at 10, 22, and 45 wk) were analyzed separately. The data of both trials were pooled then analyzed together. Across wk 47 and 58, percentage yolk lipid was significantly lower in eggs laid by birds inoculated at 10 wk compared with those inoculated at 45 wk. Sham-inoculated control and 22-wk inoculated groups had intermediate percentage yolk lipids. Compared with sham-control and 10-wk S6MG inoculation groups across wk 47 and 58, yolk myristic, oleic, and linolenic acid concentrations were reduced, whereas yolk stearic and arachidonic acid levels were increased by either 22- or 45-wk S6MG inoculations. In comparison with all other treatment groups at wk 47, yolk linoleic acid concentration was reduced by S6MG inoculation at 45 wk. Variable postpeak alterations in yolk total lipid and fatty acid content occur in response to the timing of S6MG inoculation in layers housed under controlled conditions.

Effects of S6-strain Mycoplasma gallisepticum inoculation at 10, 22, or 45 weeks of age on the digestive and reproductive organ characteristics of commercial egg-laying hens

Experimental inoculation of commercial laying hens with the S6-strain of Mycoplasma gallisepticum (S6MG) at 20 wk of age, while being maintained under ideal conditions, has previously been shown to affect the lengths and weights of various portions of the reproductive tract. Two trials were conducted in the current study to compare the effects of S6MG inoculation prior to lay at 10 wk of age, during onset of lay at 22 wk of age, and during lay at 45 wk of age on the digestive and reproductive organs of commercial layers similarly housed and maintained under ideal conditions. In each trial, liver weight, liver moisture and lipid concentration, incidence of fatty liver hemorrhagic syndrome, ovary weight, ovarian mature follicle numbers, weights and lengths of the oviduct and oviductal regions, and weights and lengths of the small intestine and small intestinal regions were examined at 60 wk of hen age. At 60 wk, liver lipid concentration was depressed, and isthmus weight, as a percentage of total oviduct weight, was increased in birds that had been inoculated with S6MG at 45 wk. Alterations in liver lipid content and weight of the isthmal portion of the oviduct may occur in response to S6MG inoculation during the later stages of production in layers housed under ideal conditions.

Effects of S6-strain Mycoplasma gallisepticum inoculation at ten, twenty-two, or forty-five weeks of age on the performance characteristics of commercial egg laying hens

Experimental inoculation of commercial laying hens, maintained under controlled conditions, with the S6-strain of Mycoplasma gallisepticum (S6MG) at 10 wk of age has previously been shown to affect the lengths and weights of various portions of the reproductive tract without affecting subsequent performance. Two trials were conducted to compare the effects of S6MG inoculation at 10 wk of age (prior to lay), 22 wk of age (onset of lay), and 45 wk of age (during lay) on performance characteristics in commercial layers housed and maintained under controlled conditions, as in previous studies. In each trial, BW, mortality, egg production, egg weight, eggshell weight per unit of surface area, percentage eggshell weight, percentage albumen weight, percentage yolk weight, and yolk weight per albumen weight ratio were examined at various ages throughout an entire laying cycle. Across wk 47 and 58 (age periods after the last 45 wk inoculation), eggshell weight per unit of surface area and percentage eggshell weight were significantly reduced in birds that had received an S6MG inoculation at 45 wk of age when compared with birds that had not received an S6MG inoculation or had been inoculated with S6MG at either 10 or 22 wk of age. Alterations in eggshell quality in response to S6MG may become evident only in older birds that are experiencing declines in production when housed under controlled conditions.

Relationships among prehatch and posthatch physiological parameters in early nutrient restricted broilers hatched from eggs laid by young breeder hens

The objective of this study was to establish relationships among various physiological parameters in early (through 72 h posthatch) nutrient restricted broiler chicks from young breeder hens. Despite a 19% decrease in mean BW between 0 and 72 h posthatch, there were no chick mortalities. Liver glycogen peaked at 24 h, and peaks in rectal temperature, plasma glucose, and plasma refractive index occurred at 48 h. By 24 h, negative correlations were noted between BW and relative liver weight and between liver glycogen and both refractive index and rectal temperature. By 24 h, positive correlations were noted between relative liver weight and liver glycogen, BW and plasma glucose, rectal temperature and plasma glucose, and rectal temperature and body fat loss score. Mean daily relative egg weight loss between 0 and 19 d of incubation (RIEWL) was positively correlated with rectal temperature at 0 h but was negatively correlated with rectal temperature at 24 h and liver glycogen at 24 and 48 h. Furthermore, mean relative hatching chick weight (RHCW) had significantly positive correlations with plasma glucose at 6 h and rectal temperature at 48 and 72 h. Broilers having a greater RHCW after hatching from eggs with a lower RIEWL may maintain higher metabolic rates between 24 and 72 h posthatch despite nutrient deprivation. However, broiler chicks from eggs exhibiting a higher than optimal RIEWL may have greater dependence on gluconeogenesis, thus requiring stricter management during initial brooding.

In ovo peptide YY and epidermal growth factor administration and their effects on growth and yolk utilization in neonatal meat-type chickens (Gallus domesticus)

The effects of in ovo peptide YY (PYY) or epidermal growth factor (EGF) administration on chick growth, yolk absorption and yolk stalk function in posthatch (0-5 days) meat-type or broiler chicks were determined. At Day 18 of incubation, treated eggs were injected into the air cell with 100 microl of either PYY (Trial 1) or EGF (Trial 2) at a dosage of 600 microg/kg egg weight. Saline-treated control eggs were injected similarly with 0.9% saline. At hatch, 200 microl of (51)Cr-labeled microspheres were injected into chick yolk sacs. Epidermal growth factor increased ileal wet weight adjusted for body weight as well as ileal serosal dry matter. Body weight, feed consumption and excreta weight per bird, and relative weights of the yolk sac, intestine and liver were significantly affected by age of the chick in both trials. Relative radioactivity of the yolk sac, yolk stalk, blood, liver, and kidneys were affected by bird age in Trial 2; however, there were no significant effects due to PYY or EGF treatments on relative radioactivity of the tissues and organs examined. These data suggest that PYY and EGF had no effect on yolk absorption or yolk stalk function through 5 days in the posthatch chick.

Growth and immunity of broiler chicks as affected by dietary arginine

A dietary deficiency of Arg may suppress chick immune system functions; however, research evaluating immune function responsiveness of commercial broilers fed dietary Arg levels near NRC (1994) recommendations is sparse. Therefore, three experiments were conducted to evaluate growth and immunity of broilers fed varying Arg levels near NRC (1994) specifications. Because Arg and Lys are similar in structure and are known to compete in intestinal absorption, dietary Lys treatments [near NRC (1994) recommendations] were evaluated to determine if Arg and Lys interact to affect broiler immunity. There were four dietary treatments in Experiment 1 representing a 2 x 2 factorial design of additional Arg (120% of NRC) or additional Lys (120% of NRC) added to a control diet containing 100% of NRC Arg and Lys (six replications per treatment). Experiment 2 contained the following four treatments: the control diet; the control diet plus L-Arg (0.20% Arg of diet); the control diet plus L-Lys HCl (0.20% Lys of diet); and the control diet plus L-Arg-L-Glu (0.10% Arg of diet). Graduations of Arg were fed from 90 to 120% of NRC in 10% increments in Experiment 3. Also, half of the birds were exposed to vaccinations of Newcastle disease virus and infectious bronchitis virus in Experiment 3 to derive a 2 x 4 factorial design. Experiments 1 and 2 were conducted from Days 1 to 18 and Experiment 3 was conducted from Days 1 to 15 in Petersime battery brooders. No interactions occurred between dietary Lys and Arg in Experiment 1. Increasing dietary Arg, but not Lys, from 100 to 120% of the NRC recommendation increased (P < or = 0.05) Day 18 BW gain. Treatment differences in the cutaneous basophil hypersensitivity assay in Experiment 1 did not occur. In Experiment 2, treatment differences in growth responses, lymphoid organ development, and primary antibody titers to SRBC did not occur. Unvaccinated birds in Experiment 3 fed an Arg-deficient diet had lower (P < or = 0.05) feed conversion in comparison with vaccinated birds fed an Arg-deficient diet. Vaccinated birds had lower (P < or = 0.05) Day 15 BW than unvaccinated birds, but higher (P < or = 0.05) titers to Newcastle disease virus. Increasing dietary Arg in Experiment 3 increased plasma Arg (P < or = 0.05), but did not affect plasma Lys. Although increased dietary Arg improved BW gain in Experiment 1, minimal effects were noted in growth and immune system parameters throughtout this study. A dietary Arg level near the NRC (1994) recommendation should support proper immune system functions in healthy chicks.

The use of India ink and 51Cr-labeled microspheres in examining the function of the yolk stalk as a passageway between the yolk sac and intestine in posthatch broiler chicks

India ink and radioactive 51Cr-labeled microspheres were used in separate trials to examine the role of the yolk stalk lumen as a distinct pathway between the yolk sac and gut through the first 5 d of posthatch growth in broiler chicks. Throughout this period, India ink was able to pass from the yolk sac through the yolk stalk and into the intestine, but was not able to pass from the intestine into the yolk stalk or yolk sac. Furthermore, labeled microspheres moved from the yolk sac via the yolk stalk into the gut; which caused the total counts per minute of the intestine, yolk stalk, and excreta to progressively increase. It was concluded that India ink and 51Cr-labeled microspheres were useful materials in establishing that the yolk stalk provides a direct one-way passage by which material in the yolk sac may move into the intestine of broiler chicks during the first 5 d after hatching.