Integrale notitie Fase 1 innovatief Praktijkproject Zelfsturing en Profit in de Noardlike Fryske Wâlden

Het TransForum innovatief praktijkproject Zelfsturing en profit Noardlike Fryske Wâlden richt zich op de verwaarding van het gebied met haar kwaliteiten en op het realiseren van een passend (zelf)sturingsarrangement. In fase 1 (januari t/m juni 2008) werd geconcentreerd op het vaststellen van de potenties voor regionale ontwikkeling en zelfsturing. Hiervoor zijn de volgende activiteiten uitgevoerd door Wageningen Universiteit (leerstoelgroepen Bestuurskunde en Rurale Sociologie), Rijksuniversiteit Groningen (Mansholt leerstoel) en Alterra, Wageningen UR: Een sociaal-economische schets van het gebied op basis van gedetailleerd secundair materiaal; Een uitwerking van voorbeelden van zelfsturing en regionale ontwikkeling; Een literatuurstudie naar vormen van zelfsturing en condities waaronder deze functioneren; Een interviewronde met betrokkenen uit en bij het gebied de Noardlike Fryske Wâlden (actoren- en netwerkanalyse); en een analyse van Europees plattelandsbeleid en het streekplan, voor zelfsturing en ontwikkeling van de Noardlike Fryske Wâlden. In deze notitie staan de overkoepelende conclusies

Methods to get more information from sparse vessel monitoring systems data

Vessel Monitoring Systems (VMS) and other vessel tracking data have been used for many years to map the distribution of fishing activities. Mapping areas with low levels of fishing activity can be of particular interest; for example to avoid conflicts between fishing and other ocean uses like offshore renewable energy or to protect relatively pristine ecosystems from increasing fishing pressure. A particular problem when trying to delineate areas that are lightly fished, is the relative sparsity of vessel monitoring data in these areas. This paper explores three novel methods for estimating the distribution of fishing activity from VMS data, with particular focus on lightly impacted areas. The first new method divides the area of interest into a nested grid with varying cell sizes (depending on the density of data at each location); the second new method uses Voronoi diagrams to define polygons around observations and the third method applies a local regression to generate a smooth map of fishing intensity. The new methods are compared with two established methods: applying spatial grids and interpolating fishing tracks. The track interpolation method generally performs better than any of the new methods, however it is not always possible or appropriate to apply track interpolation; in those cases the local regression method is the best alternative

Spatial overlap of grey seals and fisheries in Irish waters, some new insights using telemetry technology and VMS

Seals and humans often target the same food resource, leading to competition. This is of mounting concern with fish stocks in global decline. Grey seals were tracked from southeast Ireland, an area of mixed demersal and pelagic fisheries, and overlap with fisheries on the Celtic Shelf and Irish Sea was assessed. Overall, there was low overlap between the tagged seals and fisheries. However, when we separate active (e.g. trawls) and passive gear (e.g. nets, lines) fisheries, a different picture emerged. Overlap with active fisheries was no different from that expected under a random distribution, but overlap with passive fisheries was significantly higher. This suggests that grey seals may be targeting the same areas as passive fisheries and/or specifically targeting passive gear. There was variation in foraging areas between individual seals suggesting habitat partitioning to reduce intra-specific competition or potential individual specialisation in foraging behaviour. Our findings support other recent assertions that seal/fisheries interactions in Irish waters are an issue in inshore passive fisheries, most likely at the operational and individual level. This suggests that seal population management measures would be unjustifiable, and mitigation is best focused on minimizing interactions at nets

CE17003

The 2017 Irish Anglerfish and Megrim Survey (IAMS) took place from 14th February to 7th March (area 7bcjk) and 8-17th April 2017 (area 6a) on RV Celtic Explorer. The main objective of the survey is to obtain biomass estimates for anglerfish (Lophius piscatorius and L. budegassa) and establish an abundance index for megrim (Lepidorhombus whiffiaginis and L. boscii) in areas 6a (south of 58°N) and 7 (west of 8°W). Secondary objectives are to collect data on the distribution and relative abundance of anglerfish, megrim and other commercially exploited species. The survey also collects maturity and other biological information for commercial fish species. The IAMS survey is coordinated with the Scottish Anglerfish and Megrim Survey (SIAMISS) and uses the same gear and fishing practices

Searching speeds and the energetic feasibility of an obligate whale-scavenging fish

Two recently published models reach opposite conclusions on the energetic feasibility of a scavenging fish that specialises oil whale carcasses. We argue that the key difference between these models lies in their estimate of the likely searching speed of such a hypothetical scavenger. Neither of the previous models considers that although faster searching will allow food sites to be found more quickly, it will also reduce the time between meals that the fish can survive on its reserves. Hence, we present a novel model that encapsulates this trade-off, and use this model to predict the optimal searching speed for Such a hypothetical scavenger. The model predicts that the optimal speed should increase with mass and be in the range 0.1-0.2 m s(-1) for fish of the range of sizes found for the ubiquitous grenadier Coryphaenoides armatus. These values accord with most estimates of the swimming speeds for this species. Hence, we conclude that rejection of a whale-carcass feeding specialist fish on energetic grounds is premature. Although, we see no reason to dismiss Such a specialist oil energetic grounds, we argue that such a fish will be unlikely oil ecological grounds, although a deep-sea fish that gathered much of its energy from scavenging at relatively large food packages oil the ocean floor should be feasible

Monitoring the recovery of exploited deep-water species

Commercial fisheries for deep-water species off the Irish coast developed in the late 1990s and declined in the early 2000s. Many of the exploited stocks were depleted a result of commercial exploitation and ICES has advised a zero catch for Orange Roughy since 2004, and for Portuguese Dogfish and Leafscale Gulper shark since 2005. Since 2016, the deep water access regulation has effectively banned trawling in waters deeper than 800 m (EC, 2016) and fishing for deep-water sharks with static netting >600 m is also banned by the technical measures regulation (EC, 2019). However, some of these species continue to be caught, either by gears not covered by this regulation or in water <800 m deep. The Marine Institute carried out a survey programme to assess the distribution and abundance of these species between 1992 and 1999 and again between 2006 and 2009. Since 2019, 3 days of the Irish Anglerfish and Megrim Survey have been allocated to monitoring the recovery of commercial deep-water species. This work was funded under the European Maritime and Fisheries Fund (EMFF) from 2019 to 2021 and European Maritime, Fisheries and Aquaculture Fund (EMFAF) since 2022. The main objective of the current project is to assess the recovery of exploited deep-water species in Irish waters by comparing the results from 2019 to 2022 surveys with those from the previous period in 2006 to 2009 (methods used in the earlier period 1992 to 1999 were different, therefore a direct comparison with that period is not possible).EMFF, EMFAF, the project is co-funded by the Government of Ireland and the European Unio

The Baryonic Tully-Fisher Relation

We explore the Tully-Fisher relation over five decades in stellar mass in galaxies with circular velocities ranging over 30 < Vc < 300 km/s. We find a clear break in the optical Tully-Fisher relation: field galaxies with Vc < 90 km/s fall below the relation defined by brighter galaxies. These faint galaxies are however very gas rich; adding in the gas mass and plotting baryonic disk mass Md = M* + Mg in place of luminosity restores a single linear relation. The Tully-Fisher relation thus appears fundamentally to be a relation between rotation velocity and total baryonic mass of the form Md = A Vc^4.Comment: 10 pages including 1 color figure. Accepted for publication in ApJ Letter

Precision estimates and suggested sample sizes for length-frequency data

For most fisheries applications, the shape of a length-frequency distribution is much more important than its mean length or variance. This makes it difficult to evaluate at which point a sample size is adequate. By estimating the coefficient of variation of the counts in each length class and taking a weighted mean of these, a measure of precision was obtained that takes the precision in all length classes into account. The precision estimates were closely associated with the ratio of the sample size to the number of size classes in each sample. As a rule-of-thumb, a minimum sample size of 10 times the number of length classes in the sample is suggested because the precision deteriorates rapidly for smaller sample sizes. In absence of such a rule-of-thumb, samplers have previously under-estimated the required sample size for samples with large fish, while over-sampling small fish of the same species