Combining sale records of landings and fishers knowledge for predicting métiers in a small-scale, multi-gear, multispecies fishery

Abstract

Stock management should be guided by assessment models that, among others, need to be fed by reliable data of catch and effort. However, precise data are difficult to obtain in heterogeneous fisheries. Specifically, small-scale, multi-gear, multispecies fisheries are dynamic systems where fishers may lively change fishing strategy (i.e., métier) conditioned by multiple drivers. Provided that some stocks can be shared by several métiers, a precise categorization of métiers should be the first step toward métier-specific estimates of catch and effort, which in turn would allow a better understanding of the system dynamics. Here we propose an approach for predicting the métier of any given fishing trip from its landing records. This approach combines the knowledge of expert fishers with the existing sales register of landings in Mallorca (Western Mediterranean). It successfully predicts métiers for all the 162,815 small-scale fishery fishing trips from Mallorca between 2004 and 2015. The largest effort is invested in the métiers Cuttlefish/Fish and Spiny lobster, landings peak for Cuttlefish/Fish and Dolphinfish and revenues for Spiny lobster and Dolphinfish. Métier predictions also allowed us to describe the temporal (seasonal and between-year) trends experienced by each métier and to characterize the species (commercial categories) that are specific to each métier. Seasonal variability is by far more relevant than betweenyear variability, which confirms that at least some fishers are adopting a rotation cycle of métiers along the year. Effort (fishing trips), landings and gross revenues decreased in the last 12 years (2004 to 2015). The approach proposed is also applicable to any other fishery for which the métier for a fishing trip sample is known (e.g., on-board observers or logbooks), but relying on fishers expertise points more directly to fishers' intention. Thus, métier predictions produced with the proposed approach are closer to the actual uses of fishers, providing better grounds for an improved management.

Net Fisheries’ Métiers in the Eastern Mediterranean: Insights for Small-Scale Fishery Management on Kalymnos Island

“…This activity raised the question of whether this métier is present throughout the Mediterranean. Sepia officinalis métier is also present in the Gulf of Patraikos, Greece [27], and in several areas of the Spanish coast with the trammel net in winter, spring, and summer [14,17,47].…”

Commercial catches and discards of a Mediterranean small-scale cuttlefish fishery: implications of the new EU discard policy

“…The cuttlefish trammel net fishery operates in Mallorca from January to July, with a clear spring (March and May) peak in catches (Quetglas et al 2015). The cuttlefish trammel nets are generally deployed at shallow depths of approximately 10 to 30 m, just at the lower boundary of the seagrass (Posidonia oceanica) meadows (Palmer et al 2017).…”

“…Small-scale fisheries are characterized by the use of small boats (less than 15 m long) and by being highly heterogeneous in terms of landings, fishing gear, fishing strategies and species targeted (Stergiou et al 2006, Palmer et al 2017. At the global scale, the importance of small-scale fisheries is based on the fact that they contribute half of the fish consumed by humans (FAO 2003, Stergiou et al 2006.…”

“…the fishing gear targeting a specific group of species in a fishing area during a specific season) use static nets (trammel net and gillnet), mainly targeting spiny lobster, cuttlefish and red mullet, but small seines targeting dolphinfish or transparent goby and small longlines are also commonly used métiers (Quetglas et al 2016, Palmer et al 2017. The cuttlefish trammel net fishery comprises 93 boats (29% of the small-scale fleet of the Balearic Islands), but this fishery is the most important in terms of fishing effort, with an average of 4964 fishing trips per year for the period 2004-2015 (33.9%), and in terms of landings, with an average of 123 t/year (29.1%; Palmer et al 2017). The gross revenues of the cuttlefish fishery are €959000 per year (24.6%), surpassed only by the spiny lobster trammel net fishery (Palmer et al 2017).…”

“…The cuttlefish trammel net fishery comprises 93 boats (29% of the small-scale fleet of the Balearic Islands), but this fishery is the most important in terms of fishing effort, with an average of 4964 fishing trips per year for the period 2004-2015 (33.9%), and in terms of landings, with an average of 123 t/year (29.1%; Palmer et al 2017). The gross revenues of the cuttlefish fishery are €959000 per year (24.6%), surpassed only by the spiny lobster trammel net fishery (Palmer et al 2017).…”