Effect of bait type on the octopus fishery in Algarve, Southern Portugal

Leitão, Francisco; Bueno-Pardo, Juan; Ovelheiro, Andreia; Monteiro, João N.; Nobre, Daniela; Teodósio, Alexandra

doi:10.1016/j.ocecoaman.2021.105587

Cited by 4 publications

(4 citation statements)

References 8 publications

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“…;Villanueva et al 2017) due to their particular nutrient requirements of lipids and copper(Villanueva et al 2017), and live crabs are often used as bait in octopus-targeted shing methods(Yarnall 1969; Arreguín-Sánchez et al 2000; Conners and Levine 2017;Sauer et al 2019). Despite this, we found no in uence of bait type on captures nor interactions with traps for O. tetricus (see alsoLeitão et al 2021). Bait also did not in uence octopuses' activity, with the highest amount of octopus activity occurring during the trap trial (12.4%; plain crab lures used only), and the lowest activity during the bait trial (7.5%).…”

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confidence: 55%

Behavioural patterns of Octopus tetricus (Mollusca: Cephalopoda) and their responses to fisheries trap and bait combinations

Vrandich,

Kelaher,

Hall

2024

Preprint

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Octopus fisheries are expanding globally. However, given their complex behavioural repertoires, cognitive capacities and individual personalities among octopuses, careful consideration of their interactions with and capture by fishing gears is required to inform efficient, sustainable, and ethical fisheries development. Here, the behaviour of Octopus tetricus was assessed in response to different bait and trap combinations in an outdoor mesocosm experiment. Eight wild octopuses were collected, maintained in individual tanks with flow-through seawater and aeration, and monitored with a 24-h video surveillance system. Six different trap types and four different baits were presented to each octopus in various combinations during four sequential trials. Fine-mesh crab traps were the most successful in capturing octopus, accounting for 23 of the total 30 captures across all trials. Whereas solid trigger traps produced the greatest number of other interactions (e.g., octopus sitting on trap or in the entrance), averaging 43 interactions per trial, but were rarely triggered. Bait type did not influence octopus capture, trap interaction frequency, or octopus activity. Octopus were generally inactive, dedicating only 9.5% of their total time to active behaviours. Octopus activity varied with time of day, with peak activity during morning daylight (0800–1200) and the lowest activity during the dark hours of the very early morning (0000–0400). Additionally, capture numbers, trap interactions, and activity varied among individuals, with bolder personalities in some octopus. This natural variation among individual octopuses may lead to fishery-induced selection associated with the elevated capture frequency of bold or more active individuals.

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confidence: 55%

Behavioural patterns of Octopus tetricus (Mollusca: Cephalopoda) and their responses to fisheries trap and bait combinations

Vrandich,

Kelaher,

Hall

2024

Preprint

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“…According to port landing data provided by the "Directorate-general for natural resources, safety and maritime services" (DGRM), this crab is fished along the entire Portuguese coast. C. maenas is sold as bait for octopus trap fishing, angling or sold fresh for human consumption in markets (Leitão et al 2021). Amid the 1980s and 1990s, it was also exported to Spain, potentially for seafood broth (Gomes 1991).…”

Section: Introductionmentioning

confidence: 99%

Variability in Carcinus maenas Fecundity Along Lagoons and Estuaries of the Portuguese Coast

Monteiro

Ovelheiro

Ventaneira

et al. 2022

Estuaries and Coasts

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Although Carcinus maenas as a species is widely studied, research focusing on fecundity is still scarce. The main objective of this study was to evaluate size-fecundity relationships across different lagoons and estuaries, along the Portuguese coast, to understand how the local environment affects reproductive patterns. Between 2019 and 2020, ovigerous females were collected from the Southern (Ria Formosa and Ria de Alvor), Central (Rio Sado) and Northern regions (Ria de Aveiro) of Portugal, and the fecundity of each female was estimated by counting and weighing eggs. Morphometric relationships (carapace width–egg counting; egg counting–egg weight; body wet weight–egg weight; carapace width–body wet weight) were inferred from 180 egg-bearing females with a carapace width between 26.96 and 61.25 mm. A positive correlation between fecundity and the morphological parameters was observed. Differences in fecundity were found among all systems, from northern to southern Portugal, varying between 22121 and 408538 eggs per female. Furthermore, a regional gradient was observed across regions, with lower temperature estuaries (Ria de Aveiro) displaying an increase in fecundity. The fecundity in Rio Sado was also affected by salinity. Fecundity differences across regions were associated with hydrodynamics, temperature, and salinity differences among systems. No statistically significant differences were observed between Carapace Width—Body Wet Weight regressions performed in each studied system, indicating that, contrary to fecundity, the somatic growth of C. maenas is not affected by latitudinal or environmental conditions.

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“…Live bait (green crab), prohibited in the Algarve region, was an alternative introduced in the 2000s that allows deployment of traps for longer periods of time (Sonderblohm et al 2017). Leitão et al (2021) have found no evidences to support the idea that crab bait result in higher octopus fishing effort or increased landings. Thus, more studies are needed to fully understand trade-offs of this measure as if it allows a reduction in fuel consumption and consequently in economic costs of operations.…”

Section: Major Contributions To Environmental Impacts Of Octopus's Fi...mentioning

confidence: 89%

“…Atlantic chub mackerel, sardine, or horse mackerel). The use of live bait (green crab) is prohibited since 2012 only in the Algarve, after the claim by some fishermen that it may allow for the handling of more traps during longer time periods, thereby increasing fishing effort, while also allows the expansion to fishing grounds at greater depths (Sonderblohm et al 2017;Leitão et al 2021). Other extra measures in place only in this region include the absence of fishing by the small-scale octopus' fishery during the weekend (only for the south coast of Algarve) (Pita et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Environmental assessment of common octopus (Octopus vulgaris) from a small-scale fishery in Algarve (Portugal)

Almeida

Loubet

Laso

et al. 2022

Int J Life Cycle Assess

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Purpose Common octopus is the fishing species with highest economic revenue in Portugal, and its consumption per capita is very high. The majority of catches come from the small-scale fleet with pots and traps. The aims were to assess main environmental impacts of common octopus’ fishery with traps and pots in the Algarve region, where the most important fleet size and landings volume occurs, and to find if there are significant differences between both fishing gears. Methods The assessment includes standard LCA impact categories, fishery-specific impact categories, and quantification of macroplastics and microplastics emitted to the environment. The functional unit selected was 1 kg of octopus and the study was a ‘cradle to gate’ system. The scope included fishing operations until the product is landed at the harbour. Primary data was obtained by face-to-face questionnaires from 22 vessels, with an average of 1005 pots and 1211 traps per vessel, and 372 pots and 234 traps lost annually to the environment. Plastic pots have a concrete block and traps are a metal framed covered by plastic netting. Each trap or pot is connected to the main line at regular intervals. Unlike traps, pots do not need bait. Results and discussion Fuel contribution to global warming is very high and where the highest potential exists to lower down the carbon footprint. The fuel use intensity resulted in 0.9 L/kg of octopus. The bait used in traps is significant and raises further environmental costs related with fuel consumption. The use of traps represents more than two times the impacts found for pots in all the categories studied except ecotoxicity categories. Zinc use was the main contributor to ecotoxicity categories, but it has not been included in other fishery LCA studies. It was estimated that 12.2 g of plastics is lost to the environment per kg of octopus. The loss of macroplastics from fishing gears was the highest contributor. Conclusions The carbon footprint obtained was 3.1 kg CO2 eq per kg of octopus, being lower compared to other seafood products, and less than half compared to octopus caught with trawling. Pots and traps are highly selective fishing gears, causing negligible disturbance to the seafloor. The stock is not assessed, but management measures exist and can be improved. A drawback exists related with gears lost to the environment.

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Effect of bait type on the octopus fishery in Algarve, Southern Portugal

Cited by 4 publications

References 8 publications

Behavioural patterns of Octopus tetricus (Mollusca: Cephalopoda) and their responses to fisheries trap and bait combinations

Behavioural patterns of Octopus tetricus (Mollusca: Cephalopoda) and their responses to fisheries trap and bait combinations

Variability in Carcinus maenas Fecundity Along Lagoons and Estuaries of the Portuguese Coast

Environmental assessment of common octopus (Octopus vulgaris) from a small-scale fishery in Algarve (Portugal)

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