No abstract

Marchal, P., Andersen, B., Caillart, B., Eigaard, Guyader, O., Hovgaard, H., Iriondo, A., Le Fur, F., Sacchi, J., and Santurtún, M. 2007. Impact of technological creep on fishing effort and fishing mortality, for a selection of European fleets–ICES Journal of Marine Science, 64, 192–209. Face-to-face interviews were conducted to identify the main changes in gear and vessel technology that may have improved the fishing efficiency of a number of French, Danish, and Basque fleets over the past few decades. Important changes include the gradual appearance of twin trawls (Danish and French trawlers) and trammel-nets (French gillnetters), and the increased polyvalence of Basque bottom trawlers. The results suggest that fishing effort descriptors that are not traditionally measured (gear type, groundrope type, length of net used per day, headline length, crew size, number of winch or net drums) may have a substantial impact on catch rates. Adjusting fishing effort using such descriptors may generally improve the relationship between fishing effort and fishing mortality.

The scope of this paper is to quantify, for a wide selection of European fisheries, fishing tactics and strategies and to evaluate the benefits of adjusting the definition of fishing effort using these elements. Fishing tactics and strategies were identified by métiers choices and a series of indices. These indices have been derived to reflect shifts in tactics (within a fishing trip) and in strategies (within a year). The Shannon-Wiener spatial diversity indices of fishing tactics (FT_SW) and strategies (YE_SW) had the greatest impact on catch rates. In particular, FT_SW was always negatively correlated to catch rates. One may anticipate that during a fishing trip, vessels with high FT_SW have been searching fish aggregations for a long time, while vessels with low FT_SW have been more efficient in finding these aggregations. The linkage between YE_SW and catch rates was of a more complex nature. Adjusting fishing effort by means of (i) the métier effect and (ii) the indices of tactics and strategies generally led to a substantial gain in the precision of the relationship between fishing mortality and fishing effort. Résumé : L'objectif de cette étude est de quantifier, pour une large sélection de pêcheries européennes, les tactiques et stratégies de pêche, et d'évaluer dans quelle mesure ces éléments peuvent être utilisés pour mieux ajuster l'effort de pêche. Les tactiques et stratégies de pêche ont été identifiées par les choix de métiers et une série d'indices. Ces indices ont été calculés pour quantifier les changements de tactique (au cours d'une marée) et de stratégie (au cours d'une année). Les indices de Shannon-Wiener décrivant la distribution spatiale de l'effort de pêche au cours d'une marée (FT_SW) et d'une année (YE_SW) ont eu l'effet le plus important sur les taux de capture. En particulier, FT_SW était négativement corrélé aux taux de capture pour tous les cas d'étude. Ce résultat était prévisible. Au cours d'une marée, les bateaux caractérisés par un FT_SW élevé ont vraisemblablement cherché les agrégations de poisson pendant une longue période, tandis que les bateaux caractérisés par un faible FT_SW auront été plus efficaces pour localiser ces agrégations. Le lien entre YE_SW et les taux de capture était d'une nature plus complexe. L'ajustement de l'effort au moyen, (i) de l'effet métier et, (ii) des indices de tactique et de stratégie, conduit généralement à un gain substantiel de précision de la relation entre effort de pêche et mortalité par la pêche. Marchal et al. 533

Mahévas, S., Vermard, Y., Hutton, T., Iriondo, A., Jadaud, A., Maravelias, C. D., Punzón, A., Sacchi, J., Tidd, A., Tsitsika, E., Marchal, P., Goascoz, N., Mortreux, S., and Roos, D. 2011. An investigation of human vs. technology-induced variation in catchability for a selection of European fishing fleets. – ICES Journal of Marine Science, 68: 2252–2263. The impact of the fishing effort exerted by a vessel on a population depends on catchability, which depends on population accessibility and fishing power. The work investigated whether the variation in fishing power could be the result of the technical characteristics of a vessel and/or its gear or whether it is a reflection of inter-vessel differences not accounted for by the technical attributes. These inter-vessel differences could be indicative of a skipper/crew experience effect. To improve understanding of the relationships, landings per unit effort (lpue) from logbooks and technical information on vessels and gears (collected during interviews) were used to identify variables that explained variations in fishing power. The analysis was undertaken by applying a combination of generalized additive models and generalized linear models to data from several European fleets. The study highlights the fact that taking into account information that is not routinely collected, e.g. length of headline, weight of otter boards, or type of groundrope, will significantly improve the modelled relationships between lpue and the variables that measure relative fishing power. The magnitude of the skipper/crew experience effect was weaker than the technical effect of the vessel and/or its gear.

No abstract

No abstract

-Crew share remuneration systems are extensively used in fisheries as a way to tackle the moral hazard problem caused by asymmetric information distribution between the capital owner and the crew. To conduct a principalagent analysis of such a system, it is important to know how it deals with fuel costs. This paper is based on economic efficiency indicator calculations and a number of simulations for the Basque purse seiner-live bait fleet to shed light on the crew-capital owner relationship in this principal-agent problem. We conclude that the share remuneration system can protect crewmembers from variations in fuel prices, which might be one of the factors explaining its popularity. However, some profit indicators are affected by the remuneration system and, thus, cannot be used for the comparisons of economic efficiency of the fleets.

Advice for commercially exploited fish stocks is usually given on a stock-by-stock basis. In light of the ecosystem-based fisheries management, the need to move towards a holistic approach has been largely acknowledged. In addition, the discard bans in some countries requires consistent catch advice among stocks to mitigate choke species limiting fisheries activity. In this context, in 2015, the European Commission proposed the use of fishing mortality ranges around fishing mortality targets to give flexibility to the catch advice system and improve the use of fishing opportunities in mixed-fisheries. We present a multi-stock harvest control rule (HCR) that uses single stock assessment results and fishing mortality ranges to generate a consistent catch advice among stocks. We tested the performance of the HCR in two different case studies. An artificial case study with three stocks exploited simultaneously by a single fleet and the demersal mixed-fishery operating in Bay of Biscay and Celtic Sea. The HCR produced consistent catch advice among stocks when there was only a single fleet exploiting them. Even more, the HCR removed the impact of the discard ban. However, in a multi-fleet framework the performance of the HCR varied depending on the characteristics of the fleets.