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The non-destructive testing of adhesively bonded single lap joints can be conducted using either low-frequency Lamb waves in a pitch-catch mode or high-frequency bulk waves in a pulse-echo mode. Each method has its advantages and disadvantages over the other one. This paper presents a comparison between both techniques for damage imaging of adhesively bonded lap joints. The measurement method of high-frequency ultrasound is conducted in a pulse-echo approach using a delay line transducer. On the other hand, the low-frequency ultrasound measurement method is carried out in a pitch-catch configuration by using a PZT disk moved by a positioning system over the scan area. In both methods, the signals are acquired in a C-scan manner over the adhesive joint area. Applying signal processing techniques, including frequency-wavenumber filtering, bandpass filtering, and root-mean-square, images of the scan area are obtained. Finally, discussions on the results of using the two methods are presented.

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The purpose of this study to develop a framework for investigating the catch trend and estimation of optimized catch limit of the P. homarus stock by collecting catch data in the northern waters of the Oman Sea. In this research, the landing catch data of the northern waters of the Oman Sea (Sistan and Baluchistan province) for more than twenty years (based on tons) have been collected from the Iranian Fisheries Organization (1997-2019). The average catch for this study period is 33±6 tons with a 95% confidence interval of 27-39 tons, and the amount of catch increased during the study period (R = 0.37). The average (95% confidence interval) for the intrinsic growth rate (r), maximum sustainable yield (MSY), biomass of maximum sustainable yield (BMSY), and carrying capacity (K) were obtained 0.56 (0.4-0.78) annually, 140 (120-170) tons, 156 (95-255) tons, 313 (192-510) per year, respectively. Based on the trends of B/BMSY and F/FMSY ratios, it can be said that the increase in fishing mortality and the decrease in available biomass started in 2014 and continues. This research shows that the annual harvest of this species has reached its maximum amount and measures should be taken to reduce the amount of catch and fishing effort. [ABSTRACT FROM AUTHOR]

Eight oats catch crop trials were conducted over two years on winter forage paddocks on commercial dairy farms in Canterbury and Southland measuring the effect of tillage and timing-by-tillage, respectively, on dry-matter (DM) yields, N uptake and profitability (gross profit margin). The main objective was to successfully integrate catch crops into winter forage rotations over a critical period when the soil is normally bare and the potential for N drainage loss from urinary-N deposition is high. Oat harvest yields at green-chop silage maturity (∼50% panicle emergence) ranged from 8 to 10 t DM/ha when sown by the end of winter (4–5 months after drilling). Nitrogen uptakes ranged from 52 to 363 kg N/ha. Net gross profit typically ranged from NZ$1000 to NZ$1600/ha (assuming revenue of NZ$0.20/kg DM for standing feed). Minimum-till cultivation produced higher DM yields than direct-drill treatments in both years of the Canterbury trials (∼30% higher overall) but where N availability and good soil-seed contact were maintained, differences in yield were small (∼5%). Earlier sowing in Southland using a spader-drill combination increased DM yields and N uptake overall by 123% and 48%, respectively, over later sown conventional tillage options. [ABSTRACT FROM AUTHOR]

The growing popularity of digital catch logs may present a low‐cost opportunity to monitor climate change effects on the distribution and relative abundance of game fishes over large spatial scales. We analyzed data from a popular fishing app to identify spatiotemporal trends in freshwater game fish catches throughout the contiguous the United States during 2015–2021. Warm‐water species became more common than cool‐water species in many locations. Increases in relative abundance tended to occur in northern range boundaries or non‐native ranges, and declines tended to occur at southern range boundaries. Although catch log data can be biased and results may reflect alternative phenomena operating or interacting at similarly large spatial scales (e.g., cultural eutrophication, changes in game fish popularity), climate change remains a viable explanation. Future research should further explore app data as a potential tool for monitoring game fish responses to climate change and other stressors over longer time frames and at multiple spatial scales.

In autumn 2017, an unusual mortality event of Baltic grey seals (Halichoerus grypus grypus) occurred at the German Baltic coast. An alarming 23 carcasses of healthy, well‐fed, male large grey seals were found in a confined area in the Greifswald Bay (Mecklenburg‐Western Pomerania) in < 10 weeks from September to December. From 1997 to 2016, only a total of 30 grey seal carcasses were found along the entire coast of Mecklenburg‐Western Pomerania, with an annual maximum of eight seals in 2014. Pathological investigations were conducted on 19 seals, showing acute cardiac and circulatory failure of unknown origin. However, toxicological, virological, bacteriological and other presumed causes of acute death could be excluded. These findings in combination with inquiries about fishing permits in that region indicated that the seals likely died as by‐catch in a fyke net. A legal complaint was therefore filed because of the death of the legally protected grey seal. Although no offender was finally identified, this caused a series of consequences. Public prosecutors encouraged the fisheries authority to establish precautionary provisions. The use of scientific data and fishermen's expertise in by‐catch prevention techniques and regulations resulted in a new provision for fyke net permits in the Greifswald Bay. Since 2020, the entrance opening size for fyke nets must now not exceed 75‐cm circumference and no more comparable suspected by‐catch cases of grey seals were found in this area until 2022, emphasizing the potential of technical modifications of fishing gear to mitigate marine mammal by‐catch. This study shows how effective conservation measures established based on provisions, media attention, pathological assessments, scientific long‐term data sets and open‐minded efforts can protect a marine species from fisheries by‐catch.