From Trap to Nursery. Mitigating the Impact of an Artisanal Fishery on Cuttlefish Offspring

Abstract

BackgroundOverexploitation and the impact of several types of human activities have caused declines of marine resources. The direct and active involvement of fishermen in the management of marine resources is effective not only for resource conservation, but also for changing fishermen’s attitudes. In this study, we proposed and tested the efficacy and suitability of a measure for mitigating the impact of a trap fishery on cuttlefish eggs in the North Adriatic Sea. This measure directly involves fishermen in promoting the conservation of the early, and more vulnerable, stages of the cuttlefish life cycle.Methodology/Principal findingsThrough surveys on fishing boats and interviews with fishermen, we found that traps placed in coastal areas during the cuttlefish breeding season have a high impact on cuttlefish eggs, with over 3 million eggs likely being destroyed by 3750 traps of 15 fishermen in less than 3 miles of coast. The use of removable ropes attached inside traps as an additional substrate for egg deposition allowed the recovery of 23.7% of the eggs deposited on the traps on average, without affecting the catch rate of adults. Experiments examining hatching success in the field highlighted the need for a careful choice of hatching sites to maximise the efficacy of the mitigation measure.Conclusions/SignificanceThe proposed mitigation measure reduced the impact of fishing on cuttlefish eggs, with no significant effect on the commercial catch. Fishermen showed a positive attitude towards the application of this measure, which is inexpensive and easy to employ. The direct involvement of fishermen in the management of this resource and the maintenance of traditional fishing methods are a novel aspect of the proposed measure and represent the basis for its success.

Bycatch, discards and survival rates in the small‐scale cuttlefish trap fishery on sandy bottoms off the Algarve coast (southern Portugal)

“…Independent of their shape and structure, cuttlefish traps target essentially mature breeding individuals by exploiting the attraction of spawning females to deposition substrates (Melli, Riginella, Nalon & Mazzoldi, ; Pierce et al., ; Watanuki & Kawamura, ). In the present fishery, the eggs of S. officinalis laid inside the traps are kept untouched by fishermen and virtually intact throughout the fishing season, aiming to allow for the normal development of the eggs and hatching of the embryos.…”

The Clodia database: a long time series of fishery data from the Adriatic Sea

“…Up to now, the data included in the database have been used for scientific researches aimed to highlight temporal changes in the composition of the landings in response to fishery pressure and environmental factors 15 , the decline of exploited species, such as elasmobranchs 16 , the Atlantic mackerel Scomber scombrus 17 , and the common cuttlefish Sepia officinalis 18 , the response of single species ( Carcinus aestuarii ) to climate changes 19 .…”

Artificial spawning substrates and participatory research to foster cuttlefish stock recovery: A pilot study in the Adriatic Sea

“…According to a surplus production model applied in the framework of the General Fisheries Commission for the Mediterranean (GFCM) Working Group for Demersal Species, the current stock biomass is below the safe biological limit (B MSY ; [ 10 ]). The situation may be a direct result of the removal of adults and juveniles by fishing activities, the consequence of their interference with breeding events, and/or an indirect effect of the destruction of essential habitats and of resultant changes in trophic webs and community structures [ 11 ]. S .…”

“…Moreover, since egg masses are attached in clusters to seagrass, tube worms, drowned trees, ropes, and traps [ 13 ], recruitment strongly depends on the availability of spawning substrates. This may be a critical factor, especially in Adriatic coastal areas, where habitat loss and degradation are particularly severe due to human activities [ 11 ]. The choice of the spawning substrate has been reported to depend on the female’s preferences, which seem to favour tubular surfaces less than 10 mm in diameter [ 14 ].…”

“…Although egg removal and destruction from set gears is banned by a number of local regulations, in Italy removal with highly destructive devices (e.g. pressure washers) to ensure gear efficiency is quite frequent [ 11 , 16 , 17 ]. All the above factors, combined with natural predation [ 18 , 19 ], are likely to be involved in the decline of Adriatic cuttlefish stocks [ 9 ].…”