Stock assessment in brown shrimp (Crangon crangon) part 1: Investigation of possible methods

Het Ministerie van LNV, de gezamenlijke Producentenorganisaties voor de garnalenvisserij in Nederland, en de natuurorganisaties Stichting de Noordzee en de Waddenvereniging hebben het belang onderschreven van een gezamenlijk traject naar een verduurzaming van de garnalenvisserij en het verkrijgen van een MSC (Marine Stewardship Councel) certificering voor de garnalenvisserij. Om voor een MSC label in aanmerking te komen moet er aangetoond worden dat de gewone garnaal, Crangon crangon, niet overbevist wordt. Momenteel wordt de garnalen visserij niet beheerd en is er geen officiële bestandschatting. Wel worden er door de ICES crangon werkgroep (WGCRAN, ICES working Group on crangon fisheries and life history) op een beschrijvende manier de fluctuaties in dichtheden van de gewone garnaal bijgehouden. Het is echter wenselijk om tot een meer kwantitatieve bestandschatting te komen

Kennisvraag H-AKV-139: Fully documented fisheries Initial Advice

This document outlines some initial thoughts on what would be involved in setting up a pilot study for the use of a fully documented fishery (FDF) to allow for a system of catch quota management (CQM) in the North Sea flatfish fishery. Regulatory requirements, practical considerations and some analyses to determine the likely participation within the Dutch beam trawl fleet are also presented

The local governance of social security in rural Surkhondarya, Uzbekistan: Post-Soviet community, state and social order

Post-Soviet restructurings in the agricultural and social sectors exerted pressure on the livelihood situation of the Uzbek rural population. The sovkhoz/ kolkhoz had been an overarching organisation which locally organised not only agrarian production. It also served as a local administration, regulated the distribution of centrally provided social goods and services and thus guaranteed basic social security to its members. Its disintegration must have introduced dynamics of community change which go beyond the mere organisational aspects of production and social security. Together with political and economic frameworks the whole ensemble of local communities' imminent social structures is subject to change. But in this regard, village communities in the rural areas of Surkhondarya feature very distinct developments. They strongly differ in present local governance patterns and the role of the state as an actor holding a stake in these: In the cotton area where the state has strong interest in the maintenance of proven production patterns and thus an adherence to Soviet structural and institutional frameworks, the population in terms of social security still benefits from a collective-like and locally embedded agricultural production system. This bolstered the stability of social order shaped by a worldview based on a 'collective identity'. The mahalla as a newly introduced (self-)administration in the local arena could establish as a mediator between the state, the local farmers and the population and is of strong relevance in the governance of local affairs. Together with the new private agricultural producers it inherited the organisational and social functions of the kolkhoz. In contrast, the mountainous area - due to the absence of a highly state-regulated production system a politically and economically peripheral region - exhibits the emergence of a relatively liberal economic system under an environment of political self-regulation. A collective kolkhoz-identity has vanished. The mahalla plays only a marginal role in the local setting and did not find its standing in an adapting social order

Data availability for the evaluation of stock status of species without catch advice: Case study: turbot (Psetta maxima) and Brill (Scophthalmus rhombus)

Several commercially important demersal fish stocks for the North Sea fisheries are classified as “category 11” in the light of the EU policy paper on fisheries management (17 May 2010, COM(2010) 241). For stocks in this category, there is no STECF (Scientific, technical and economic committee for fisheries ) management advice, due to the unknown status of the stocks. The reason for this is that the data and information available to perform analytical stock assessments are highly uncertain or lacking. This document describes existing data and options for collecting new data for the evaluation of the state of category 11 stocks. We focus on turbot and brill in the North Sea. Existing data from logbooks and the market sampling program can be used to estimate LPUE series used in age-based stock assessment methods, similar to other commercially important flatfish species such as plaice and sole. Landings Per Unit of Effort (LPUE) data of the Dutch beam trawl fleet > 221 kW were standardised for engine power and corrected for targeting behaviour as described below and graphically shown in Figure 3.2.1. The methods are similar to those used to analyse commercial LPUE data for North Sea plaice, described in Quirijns and Poos (2010). Landing rates (LPUE) by market category were calculated for the period 2002-2010. The corrected LPUE series indicate an increase in commercial LPUE for both species during the period 2002-2006. For turbot, the LPUE stays stable in the first five years, increases between 2006 and 2008, and decreases afterwards. The increase in brill LPUE is larger, and occurs throughout the study period. Compared to other commercially important flatfish species relatively few brill and turbot market samples are taken. This reduces the ability to track the cohorts in the LPUE series of the older ages which is a prerequisite for reliable stock assessment estimates. Also, the time series currently spans only 9 years. Collection of additional data may therefore be desirable. Expanding the BTS survey will provide industry independent data and would therefore give easily interpretable results. The option of an industry survey is also a good option if the survey is already being executed for sole and plaice. However, both options are costly. Therefore, the option of increasing the samples of turbot and brill at the auction is relatively easy and relatively inexpensive and therefore at present the most promising. The methods used for this document will not per definition be applicable for all category 11 species. For dab, flounder, lemon sole and tub gurnard, samples at the auctions are taken to collect biological data. For these species it may be possible to raise the data in a similar way as was done in this report to estimate the age composition of the stock. For other species (witch flounder, horse mackerel, silver smelt, red mullet and squid) there is no market sampling. For these species, other methods will have to be developed

Effort allocation of the Dutch beam trawl fleet in response to a temporarily closed area in the North Sea

The spawning stock of North Sea cod is at a historic low level and immediate management measures are needed to improve this situation. As a first step, the European Commission in 2001 closed a large area in the North Sea between February 15 and April 30 to all cod related fishing fleets in order to protect the spawning population. The closed area comprised important fishing grounds of the beam trawl fleet fishing for flatfish. In this paper the response of the Dutch fleet (components 225-300hp and >300hp) is analysed using data from EU-logbooks and from position recordings from the Vessel Monitoring System. No change was observed in the fleet of small beam trawlers. The fleet of large vessels displaced its activity to fishing grounds in the North Sea outside the closed areas, and to fishing grounds outside the North Sea. In the North Sea, beam trawling concentrated along the borders of closed areas and the Plaice Box. In the first week after the closure the number of trips in the open area doubled. Coinciding with this increase, the catch rate, expressed as revenue per hp-day, decreased. After the area was re-opened, the catch rate was exceptionally high but decreased to the normal level in the 2nd - 3rd week. The change in catch rate in relation to the change in fishing effort indicated that competitive interactions (in particular interference interactions) occurred among vessels. The implication of the observed fleet response is discussed against the background of the objective of the management measure to protect cod and the broader objective of the Common Fisheries Policy of ecosystem management. It is concluded that it is unlikely that cod has benefited from the area closure. Furthermore, the closure may have had a negative impact on the rate of discarding of demersal species and a negative impact on vulnerable components of the ecosystem (e.g. skates, long lived benthic species) due to an increase in trawling activities in certain area

Market Sampling of Landings of Commercial Fish Species in the Netherlands in 2002

This report contains information on the biological sampling for the market sampling program: which species are sampled, how they were caught, when and where the samples are taken (date and position), how many fish have been measured, how many fish have been aged, etc. The report gives an overview of all the biological sampling activities in 2002 by RIVO on the landings of the commercial important species of herring, mackerel, horse mackerel, blue whiting, greater argentine, sole, plaice, turbot, brill, dab, lemon sole, cod, whiting, Norway lobster and four different species of rays from all ICES areas. This biological sampling took place on landings by both the Dutch fleet as well as foreign fleets landing in the Netherlands. In addition this report contains information on the biological samples collected during research vessel surveys and discard trips both on commercial and non-commercial species

Investigations of a stock assessment in brown shrimp (Crangon crangon) Part 2: Biomass model

The Ministry of Agriculture, Conservation and Food quality, Producer organisations of the Dutch shrimp fisheries and NGO’s (Stichting de Noordzee and Waddenvereniging) have underlined the importance of sustainable harvesting of brown shrimp in the North Sea and Wadden Sea. Also they would like the brown shrimp fishery to meet the conditions of an MSC (Marine Stewardship Council) certificate. The first principle that the shrimp fishery needs to fulfil in order to acquire an MSC-label states that the stock should not be overfished. The biomass dynamic model has been investigated. This model does not need demographic data and was used successfully in Northern shrimp (Pandalus borealis). The model only needs the total amount of shrimp landings and an index of catches per unit of effort (CPUE) to assess the stock. The main assumptions of the model are (1) the stock under study is a single stock and (2) the available index (CPUE, catch per unit of effort series) describes the trends in the population well. The main conclusion from the study is that the applicability of the biomass model for a reliable stock assessment of brown shrimp needs considerably more study and data collection