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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]

Recreational angling for novel marine species and related tourism development can be important in a Blue Economy. The milkfish (Chanos chanos) is growing in popularity as a target of fly fishing‐based catch‐and‐release (C&R) recreational fisheries, largely because of their challenge to catch and powerful swimming abilities, resulting in fight times that can exceed 1 h. Anecdotal sentiments by anglers claim that milkfish can fight for long periods of time because they do not accumulate blood lactate. To test this hypothesis, we measured blood lactate and blood glucose for 21 milkfish caught by fly fishing in the remote Alphonse Group of islands, Republic of Seychelles. Fight times ranged 5–78.3 min. Blood lactate and blood glucose concentrations increased with fight times that did not exceed 60 min. Total length of milkfish was not correlated to blood lactate or blood glucose concentrations. Ours is the first study on C&R of milkfish that debunks the anecdote that milkfish can fight for long periods of time because they do not accumulate blood lactate. Our study also revealed that milkfish may begin to physiologically recover after fight times longer than 60 min. In the context of C&R, our study indicates that anglers should limit fight times to 20–30 min when possible to reduce angling‐induced physiological stress and other potential impacts (e.g., depredation) on milkfish in recreational fisheries.

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.

Fish populations in estuaries are declining due to the changes in environmental conditions and fishing pressures. The estuarine fish behaviour is highly variable, influenced by both upstream fluvial and downstream tidal conditions. This study aims to predict the catch per unit effort (CPUE) of the Japanese Grenadier Anchovy (Coilia nasus) in the Chikugo River estuary by analyzing an extensive dataset of hourly fish catches and environmental variables through Random Forest (RF) models. The fish catch data for C. nasus, collected at 14.6–16 km upstream from the river mouth during the spawning season of every year from 2009 to 2020 using traditional fishing methods, was used. Along with these catch records, hydro-environmental variables such as salinity, turbidity, and temperature were monitored during the same period. The longitudinal variation of these environmental variables along the estuary (0–16 km) was measured during a fortnightly tidal cycle in September 2010. A total of 32 models (M1-M32) were developed to identify the optimal set of environmental variables influencing CPUE. The analysis highlights the significant impact of variables such as salinity, suspended sediment concentration (SSC), temperature, river discharge, and mean tidal range on CPUE. The results revealed that model M19, which incorporated salinity, SSC, and discharge, achieved the highest predictive accuracy (R² = 0.89) and closely matched actual field conditions. Further, the results agree with previous research, as spatial distribution plots showed a preference for mature C. nasus habitats 15–16 km upstream from the river mouth. Additionally, the study found that temperature had a negligible effect on short-term CPUE predictions, likely due to its pronounced seasonal variability, suggesting that temperature may not be a critical factor for short-term CPUE predictions. This study highlights the significance of utilizing environmental variables to predict CPUE, emphasizing their role in understanding fish catch dynamics across spatiotemporal variations. The findings provide valuable insights for fisheries management, particularly in optimizing fishing zones based on environmental conditions to improve catch efficiency.

The fishing gear deployed by fishermen in seas and oceans throughout the world not only captures target species but also unintentionally ensnares non‐target species, a phenomenon known as ‘by‐catch’. This unintended capture of marine life can represent significant challenges for the fishing industry, with adverse impacts on both the environment and species such as sea turtles, marine mammals, seabirds and elasmobranchs, which may be injured or even killed. To address this problem, the fishing industry has implemented regulations and mitigation measures. In this literature review, we have examined 389 papers published between 2010 and 2022 that assess the effectiveness of these measures. Taking into account the fishing gear with which each group interacts the most, trawls for sea turtles, gillnets for marine mammals and longlines for seabirds and elasmobranchs, it has been demonstrated that ‘TEDs’ (Turtle Excluder Devices) are an effective measure for sea turtles, ‘pingers’ for marine mammals and ‘BSLs’ (Bird Scaring Lines), more commonly known as ‘tori lines’, for seabirds. The most complex case is that of elasmobranchs, and the most effective measure has yet to be discovered. This complexity arises from the ongoing targeted fishing of these species, resulting in less monitoring of their catches and, therefore, fewer surveys. Overall, we encourage the global implementation of these measures by the fishing industry in order to reduce by‐catch in an attempt to ensure the future of many endangered species.