Stability in reproductive timing and habitat usage of Chinook salmon across six years of varying environmental conditions and abundance

The spatial and temporal distribution of spawning activity by autumn‐run Chinook salmon Oncorhynchus tshawytscha (Walbaum) was examined across multiple years. The study period included two years of extreme drought conditions when water temperatures in the spawning reach of the Stanislaus River were considered sub‐optimal for spawning and egg incubation. Despite varying levels of superimposition, redd counts and densities remained stable and positively associated with river location, indicating that superimposition may be driven by habitat preference rather than the absence of suitable spawning locations. Spawning occurred slightly later during drought years (6–10 days later compared with wetter years). This delay was attributable to deferred migration instead of deferred spawning, and the majority of redds were constructed at water temperatures exceeding the optimal temperature range. As a consequence, estimates of juvenile production during 2014 and 2015 were among the lowest on record. These findings may be related in part to the high hatchery contribution to the population, above‐average temperatures during spawning and incubation, and superimposition rates. Management recommendations include adequate cold‐water storage in the upstream reservoir, refined spawning habitat restoration techniques in the light of superimposition rates and, on a broader system scale, actions that reduce the amount of stray hatchery Chinook salmon.     

Impact of 24-h Cooling Prior to Freezing on the Survival of Domestic Cat (Felis catus) Epididymal Sperm

The aim of this study was to investigate the impact of a 24-h cooling period prior to freezing on domestic cat epididymal sperm viability. Fifteen tomcats were submitted to routine orchiectomy and sperm samples were retrieved from both epididymides in a Tris–glucose–20% egg yolk extender. For each tomcat, the diluted sperm was split into two equal volumes and cooled to 5°C at a rate of 0.5°C/min; one sample for 60 min (control) and the other for 24 h (cooled). After the cooling period, samples from both groups were frozen using an identical freezing protocol. Sperm samples were evaluated in three different periods: immediately after harvesting, after cooling at 5°C for 24 h (cooled group) and after freezing–thawing of control and cooled groups. Evaluations consisted of sperm motility and progressive status, sperm morphology and plasma membrane integrity (PMI) using two fluorescent probes. After cooling for 24 h, a decrease (p < 0.05) in sperm motility, progressive status and PMI was observed when compared to sperm samples immediately after collection. Comparing the results obtained after thawing, no difference (p < 0.05) was found regarding sperm motility, progressive status, PMI and sperm morphology between control and cooled groups. The results from the present study show that cooling cat epididymal spermatozoa at 5°C for 24 h prior to freezing does not lead to major damage of spermatozoa impairing the freeze–thaw process.     

Pelvic lymphoma as a cause of urethral compression in a mare

A 6-year-old mare was presented for evaluation of dysuria and pollakiuria. A pelvic mass, which caused obstruction of urinary outflow, was identified. Evidence of renal failure was also present. Due to poor prognosis the mare was euthanized. A postmortem examination revealed a pelvic lymphoma that surrounded and compressed the urethra.     

Are ovine fenugreek (Trigonella foenum‐graecum) staggers and kangaroo gait of lactating ewes two clinically and pathologically similar nervous disorders?

Fenugreek staggers has occurred in sheep in Victoria, as both an acute and a chronic syndrome. Signs included quadraparesis, a high stepping fore limb gait and a 'bunny-hopping' hind limb gait. Changes consistent with acute oedema were found in the brain and spinal cord of acute cases, and Wallerian degeneration in the peripheral nerves of chronic cases. Kangaroo gait occurred in ewes in New South Wales, and the clinical signs and microscopic changes were remarkably similar to those of fenugreek staggers. Although the diet associated with each is different the causal agent may be the same.     

Estimating rates of mortality in stocks of Metapenaeus macleayi in estuaries of eastern Australia

Estimating rates of mortality is important for assessing stocks and for effectively managing seafood resources. This study reports the first estimates of rates of instantaneous fishing mortality (F) and natural mortality (M) for the commercially important school prawn, Metapenaeus macleayi. Replicated tag-recapture experiments were conducted on two stocks (Clarence River and Wallis Lake) to estimate the catchability coefficient (q) and F, whilst M was estimated from meta-analyses. Experiments were conducted across spatial and temporal scales to consider variability between stocks and variability between fisheries targeting this resource. The catchability coefficient was fitted to tag-recapture data in a population model across a range of M values (0.001-0.025 per day) and average daily F values were calculated. Values of q ranged between 2.03E−04 and 5.43E−02 and, 1.29E−04 and 3.41E−03 for the Clarence River and Wallis Lake stocks, respectively. Average daily F ranged between 2.86E−03 and 1.69 for the Clarence stock and 1.71E−03 and 3.44E−02 for the Wallis stock. With one exception (the November 2004 experiment) there were no differences in q and F values between experiments conducted on the Wallis Lake stock. For the Clarence stock values of q and F varied between years and within years. Factors thought to contribute to this variability were changes in prawn behaviour, differences in sizes of prawns tagged between experiments and differences in the survival of tagged prawns. The catchability coefficient for the Clarence River stock was weakly correlated to greater rates of river discharge. Estimates of F for the Wallis stock, the Clarence stock in 2004-05 and estimates of M were comparable to those reported for other penaeid fisheries world wide. There was no consistent pattern in comparisons of q and F values between the predominantly trawling operation of the Clarence River fishery and the seine netting of the fishery in Wallis Lake.     

Examining the Effect of Billboards in Shaping the Great Wolf Debate of the American West

Large carnivore reintroductions have become commonplace in modern conservation. Despite the benefits of such initiatives, conflict with humans can jeopardize their success. Reintroductions of grey wolves (Canis lupus) in the American West are particularly polarizing, and opposing views are often popularized through visual media. We examined public billboards, both for and against wolves, in eastern Washington State. We used social science concepts—framing, affect, and the psychology of advertising—to assess the billboards’ role in the wolf debate. We analyzed visual imagery, traced frames in newspaper articles, and conducted interviews with local stakeholders. Our results showed that the billboards attracted attention to the issue and increased tension within the debate. However, they were limited in their ability to stimulate engagement due to a discrepancy between their structure and intended impacts. Results suggested the necessity for careful selection of campaign techniques and focused alignment of imagery and frames.     

Identification and characterization of a serine protease from wheat leaves

A putative serine protease with a potential role in the plant biotic and abiotic stress response was purified from wheat leaf apoplastic fluid and partially characterized. Following two-dimensional electrophoresis a protein of M_r = 75 k and a pI of 4.2 to 4.5 was observed. This protein displayed in-gel protease activity and was specifically inhibited by phenylmethanesulfonyl fluoride and partially inhibited by Ca²⁺ and Zn²⁺, but not by E-64 or leupeptin. An internal tryptic fragment of 13 amino acids was identified by MALDI QqTOF MS/MS, and this peptide showed a high level of homology (85–100 % identity) to a highly conserved region of known plant subtilisin-like proteases. We demonstrated that the protease activity increased until a late stage of wheat leaf development and increased in response to heat shock. In both cases Rubisco large subunit was degraded with time. Protease activity was also increased during biotic stress. Leaves challenged with leaf rust (Puccinia triticina), showed an approximately three fold increase in protease activity during an incompatible interaction, compared to activity in mock-inoculated leaves and to leaves in a compatible leaf rust interaction. These results suggest that the expression of this serine protease could be involved in the defense response against both abiotic and biotic stresses.