Application of Métier-Based Approaches for Spatial Planning and Management: A Case Study on a Mixed Trawl Fishery in Taiwan

Mixed fisheries refer to fishing activities that catch more than one species simultaneously, and a species may be fished using different gear. A trawl fishery shares these features to exploit multiple species simultaneously, with diverse fishing gear and strategies. The situation becomes more complex when interactions among fleet dynamics, fishing activities, and fishery resources are involved and influence each other. Information regarding the operational patterns may be hidden in a set of long-term big data. This study aims to investigate the fishery structure and fleet dynamics of trawl fisheries in Taiwan for spatial planning and management, based on a long-term dataset from a management system that collects information by using voyage data recorders (VDR) and dockside observers. We applied a two-step data mining process with a clustering algorithm to classify the main groups of fishery resources and then identified 18 catch métiers based on catch composition. The target species, operation pattern, and fishing season were determined for each métier, and associated with the relevant fishery resources and the fishing gear used. Additionally, fishing effects on target species were estimated using information on fishing grounds and trajectories from VDR. The métier-based approach was successfully applied to define the six major fishery resources targeted by trawlers. We examined the key features of fishing activity associated with catch composition and spatial-temporal fishing metrics, which could be used to provide suggestions for the spatial planning and management of the mixed trawl fishery in the offshore waters of Taiwan.

Linking trawl fleet dynamics and the spatial distribution of exploited species can help to avoid unwanted catches: the case of the NW Mediterranean fishing grounds

With the full implementation of the landing obligation on 1 January 2019, In European waters it will become mandatory for the trawling fleet to land at port all catches of certain species because, according to Article 15 of the new European Common Fisheries Policy, the species subject to the minimum conservation reference size (MCRS) cannot be discarded. Additionally, since 2005, trawlers over 15 m in length are required to carry an onboard vessel monitoring system (VMS), which generates information on fleet dynamics. The objective of this work was to provide a tool for avoiding unwanted catches by integrating the catch study of trawlers operating in the port of Blanes together with VMS data. To achieve this objective, the catches of 40 hauls were monitored, sampled and analysed together with VMS data for the years 2012-2014 integrated in a geographical information system. The results show that specimens below the MCRS were often captured in crinoid aggregation habitats, bottoms with maërl and muddy bottoms that were identified as nursery habitats of commercial species, e.g. Merluccius merluccius, Pagellus spp. and Mullus spp. VMS data showed considerable fishing pressure on areas with maërl and muddy habitats during the recruitment periods of these and other commercially relevant species. Implementing spatial or seasonal closures in habitats where species regulated by the MCRS are subject to catches could be a useful tool for preventing unwanted catches.

Management strategy analysis for multispecies fisheries, including technical interactions and human behavior in modelling management decisions and fishing

A multispecies fishery management strategy evaluation (MSE) framework based on the example of the groundfish fishery in the Bering Sea and Aleutian Islands region of Alaska was used to examine the interplay between a bycatch species and three groundfish species. The study introduces a framework for a realistic multispecies fishery MSE by accounting for fleet dynamics, multispecies fishery quota allocation, and the temporal dynamics of technical interactions. The quota allocation and the fleet dynamics models were implemented using linear programming, and regression approaches were used to make a realistic projection of future users’ behavioral response to changes in the fishery. The models were calibrated and then validated using historical and out-of-sample data, respectively. The results highlight the importance of accounting for technical interactions and their interannual dynamics for both quota allocation and fleet dynamics to design a realistic multispecies fishery MSE (without them, the amount of lost yield increased). Therefore, particular attention should be paid to understanding human behavior as well as its uncertainty and to refining approaches to incorporate this information into a multispecies fishery management strategy analysis.

On the precision of predicting fishing location using data from the vessel monitoring system (VMS)

Defining fishing grounds based on data from vessel monitoring systems (VMS) has been a widely researched topic in recent years. Much of the research has focused on filtering algorithms for identifying fishing locations from VMS point data, most often supplemented with either imputed or reported vessel speed information. This study compared the precision of categorizing fishing locations from VMS data either by the most wide-spread “speed rule” approach or by a probability model. Using data from Northeast U.S. Fisheries for fishing years 2010–2014, we showed that the traditional representation of fishing activities as derived by speed rules leads to a severe misrepresentation of fishing grounds for gears other than bottom otter trawl. Predictions based on probability models outperformed gear-specific speed rules in classifying VMS polls for sink gillnet and scallop dredge trips, without adding substantial computational effort. The probability models thus provide the largest improvements in gears with complicated fishing patterns, while controlling for issues such as fleet dynamics that historically have not been dealt with in the static speed rules but which can have significant impacts on the quality of predictions.

A social–ecological study of stock structure and fleet dynamics in the Newfoundland herring fishery

Successful management of small pelagic fisheries is critical in integrated ecosystem based approaches and requires understanding of how the ecological dynamics of pelagic stocks mesh with the economic and social dynamics of commercial fisheries and the larger systems within which they operate. Combining insights from stock assessments with those from local fishers, scientists, and managers, can help identify knowledge gaps that could jeopardize stock resilience. This article presents results from a social-ecological, mixed-methods study that combines insights from science and from interviews with fishermen, scientists, and managers of small pelagic fisheries in western Newfoundland, Canada (NAFO division 4R) and in NAFO division 4X. Different approaches to herring management are used in the two areas. In area 4R fishing for herring (Clupea harengus) is part of a complex multi-species, multi-gear fishery; most harvesters who target herring also target Atlantic mackerel (Scomber scombrus). Harvester interviews indicate herring in 4R, like herring in 4X and elsewhere, have substantial within-species stock structure, but that it is not well-documented in science and not well protected under the current management system. Further, fishing strategies in the competitive mackerel fishery in which the herring vessels are involved may contribute to the risk of over-fishing on some herring populations.