Search Results (10)

Beyond continual reductions in catch, common octopus frequently suffer damage during pot fishing, which can reduce the quality of the product and consequently, its value. This study evaluated how pots with different mesh sizes affect the integrity of common octopuses captured by commercial fisheries. Experimental fishing was conducted in Taean-gun and Incheon-si using pots with different mesh sizes (16.3, 18.3, and 22.4 mm). Common octopuses were classified as either damaged or undamaged based on whether the number of injured arms exceeded a specific threshold value, and logistic regression was applied to estimate the probability of damage, based on the mesh size and region. Smaller mesh sizes significantly reduced the damage in common octopuses and increased the catch effectiveness; however, the degree of impact differed according to the region. This study provides quantitative estimates of the mesh sizes associated with specific damage probabilities, offering a scientific basis for refining regionally tailored management practices. By reducing the mesh size from the current legal standard of 22 mm to 16 mm, the probability of damage that leads to a decline in commercial value (i.e., threshold = 2) is projected to decrease from 77.8% to 46.5% in Taean-gun, and from 93.4% to 39.3% in Incheon-si. Full article

The contamination of soil with arsenic (As) and heavy metal is an increasing global environmental concern. The objective of this study was to rehabilitate soil contaminated with As, Pb, and Zn using fishery by-products as stabilizers to achieve both soil restoration and waste resource recycling. Cockle shells (CS) and manila clam shells (MC), selected as fishery by-product stabilizers, were processed into −#10-mesh and −#20-mesh materials. Additionally, a −#10-mesh material was calcined at a high temperature to produce calcined cockle shells (CCS) and calcined manila clam shells (CMC). Contaminated soil was treated with 2–10 wt% of these stabilizers and subjected to wet incubation for 1–4 weeks. Subsequently, the concentrations of As, Pb, and Zn eluted by 0.1 M HCl were evaluated. Additionally, lettuce was grown in stabilized soil to evaluate the reduction in contaminant mobility. The stabilization treatment results indicated that the concentrations of eluted As, Pb, and Zn were significantly reduced when treated with the −#10-mesh and −#20-mesh CS and MC, and they were rarely detected when treated with the calcined materials (CCS and CMC). The Pb concentration in lettuce grown in the contaminated soil pot exceeded the criterion for leafy vegetables (0.3 mg/kg); however, Pb was not detected in lettuce from the stabilized soil pot. An X-ray diffraction (XRD) analysis revealed that CaCO₃, the main component of CS and MC, was converted to CaO after calcination. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) and SEM elemental dot map analyses revealed that the immobilization of As was related to Ca–As precipitation and the immobilization of Pb and Zn to the pozzolanic reaction. Thus, recycling and processing CS and MC as stabilizers for contaminated soil can restore the agricultural value of the soil by immobilizing As, Pb, and Zn into safe forms, thus effectively preventing their uptake by crops. Full article

This study explores the visibility of phosphorescent-netting pots to snow crab (Chionoecetes opilio) using visual modeling techniques. Light emitted from such pots increases catch per unit effort, yet little is understood about the factors driving these higher catch rates. In this study, we measure pot light emission and snow crab visual acuity. Combining these data with estimates obtained in the literature for other biotic and abiotic factors, we model snow crab vision in relation to the pots. Utilizing these factors and environmental conditions, we derive a contrast ratio between the pot light and the ambient light. Findings reveal that the visibility of pot lights at 200-m depth depends primarily on solar angle (time of day) and time elapsed post-deployment. Additional factors influencing the vision of the pots include water column quality and benthic boundary layer turbidity. This study is the first to model the visual ecology of snow crab and the first to estimate snow crab visual acuity. These insights into snow crab visual ecology can potentially enhance fishing techniques, promote catch efficiency and sustainability, and help provide a path forward for visual ecology research in the fisheries science field. Full article

Fishery resources overexploitation, together with bycatch and discards, have an impact on marine ecosystems. The adoption of technologically innovative gears is a possible solution to reduce the discard and to enhance the sustainability of fishery, mainly in artisanal fisheries that represent about 80% of the EU Mediterranean fleet. In the perspective of fishery sustainability, it is necessary to study and test alternative gears to the traditional ones, also with collaboration of fishers. In the present study, results of experimental fishing activities carried out in two Mediterranean areas with traditional and innovative gears of small-scale fishing are reported. Thirty-four hauls were carried out to compare the catch of two types of trammel nets: a traditional one and experimental guarding net. Additionally, 12 hauls were carried out to compare collapsible pots and traditional pots. No significant differences were recorded between trammel nets in terms of commercial catch and discard. However, interesting differences in discard composition were recorded, with higher Elasmobranchs presence in trammel nets, including species assessed as critically endangered and vulnerable. The use of trapula pots in place of traditional ones showed a lower discard of specific resources and an advantage for fishers in terms of space occupied on board. Full article

Commercial harvesting of snow crabs (Chionoecetes opilio) began in Newfoundland and Labrador, Canada, in 1967. Today, the fishery consists of 2188 active fishing licenses and has grown into the province’s most economically valuable fishery. Snow crabs are captured using conical traps consisting of a mild carbon steel frame, hard plastic entry funnel and a jacket of polyethylene netting. The frames of these traps corrode over time, which is expedited by being deployed in marine environments and stored on land near the ocean when not in use. As a result, there is interest within the community to increase the longevity of crab traps. One solution is to galvanize the steel frames prior to installing the funnel and netting. However, before harvesters transition to galvanized traps, two questions must be answered. Will the use of galvanized steel negatively impact catch rates? Will the life cycle of a crab trap be extended sufficiently to justify the additional cost of galvanizing? This study employed a generalized linear mixed model to evaluate the catch of legal-sized male crabs (CPUE) during the commercial fishery as a function of three trap frame treatments (old traditional, new traditional and new galvanized). We also assessed the economic viability of galvanizing trap frames by evaluating the life cycle cost (LCC) of traditional and galvanized traps to the harvester. The LCC was calculated over a range of inflation (0–6%) and discount (3–20%) rates. Our results found no significant difference in CPUE between new traps (traditional vs. galvanized) and concluded that except during instances of very high discount rates (12.9–19.9%), it is economically favourable to galvanize crab trap frames. Full article

The longspined sea urchin, Centrostephanus rodgersii, is a climate-driven pest species in south-eastern Australia. The harvest of this species is highly encouraged and in Tasmania, the existing fishery is expanding resulting in a large amount of waste that needs disposal. Research into use of waste products as inputs for organic or biodynamic farming systems can help reduce costs of disposal and keep the industry profitable; by sustaining or incrementing sea urchin harvest the industry can assist in their control. In the current study, urchin waste was dried and finely ground to a powder and applied to tomato plants in a greenhouse to examine the effect on growth and productivity. Urchin waste powder (UWP) had a mineral composition of Ca (40 g 100 g⁻¹), Mg (1.7 g 100 g⁻¹), P (0.03 g 100 g⁻¹), Fe (19.34 mg kg⁻¹) and B (38 mg kg⁻¹), a pH 8.06 in water and an Electrical Conductivity (EC) value of 7.64 dSm⁻¹. Seven different treatment rates of UWP (0.3%; 0.5%; 0.8%; 1%; 2%; 3%; 5%), were added to 10 replicate pots containing 4 kg nutrient-poor potting mix planted with tomato (Variety K1) seedlings. Plant growth, yield, quality attributes and mineral content of tomato were measured under UWP treatments with comparison against a Hoagland solution control. UWP influenced tomato growth and productivity proportional to the quantity applied, however, the Hoagland solution control had a significantly greater yield. Potting mix pH increased from 6.8 to 7 and higher available P was detected in potting mix receiving higher rates of UWP. No phytotoxic effects were detected. The highest UWP treatment matched the Hoagland control in fruit quality and nutritional composition. Processing waste from the sea urchin fishery has potential as organic fertiliser or amendment providing plant-available Ca and some microelements such as Boron. Full article

The general picture of most harbours in the Basque region (eastern Cantabrian coast) has changed during the last few decades, suggesting a decline in small-scale fisheries (SSF) activity which is carried out by vessels with LOA < 15 m. However, little is known in detail about this change, i.e., the recent development of the different fleet segments, or temporal changes regarding landed species. The present study shows that during the last decade (2010–2020) trolling lines targeting albacore in summer and especially handline fishery targeting mackerel in spring was the most important seasonal SSF in the region. Moreover, these fisheries intensified the fishing effort and showed the highest landings, especially for mackerel. In contrast, a decline in vessel numbers as well as fishing efforts and therefore landings was observed for netters, i.e., gillnets and trammel nets. The use of longlines and pots did not show any time trend. Regarding targeted species, the mean fish length landed by both long-liners and netters decreased with time, and so did their fish length-based niche breadth, indicating a lower length range in landed fish. In contrast, while fish diversity landed by hand-liners decreased, probably due to the mackerel fishing intensification, netters targeted a wider variety of small fish species. Technical optimization, probably related to specific market demands, suggests that Basque SSF fleet are shifting to specialized hookers, i.e., seasonal mackerel and albacore fishing, while netters, which are declining in number, are landing a wider range of target species. Given that knowledge on SSF has been trapped in a data-poor cycle, due to the lower importance in data collection when compared to other commercial fleets, understanding such developments might contribute to future management plans on a regional scale. Full article

The bluefin sea robin (Chelidonichthys spinosus), hereafter BSR, is one of the most important fish species in the South Sea of Korea. The production value of BSR in 2020 was USD 4,733,057. The production volume in Korea has shown an annual mean increase of 8.9% since 2010, but the efficiency of the fishing gear decreased due to excessive use. This has led to a decrease in the profitability of fishery operators, and as compensation, the use of fishing gear has further increased through competitive operations. Alternative measures for improving catch performance and reducing the use of fishing gear are needed. As one such measure, LED (Light-Emitting Diode) lights were attached to the pot, and the effects were determined. The field experiment results showed that the catch of BSR was higher for the experimental groups (n = 10–273) using fishing gear with LED lights (red, green, blue, and white) than for the control group (n = 2) (Kruskal–Wallis test, p < 0.05). Among the experimental groups, the pot with green light achieved the largest catch (n = 273). The use of LED lights was found to enhance the catch efficiency of pot fishing gear for BSR. Full article

The European lobster, Homarus gammarus, was sampled from September 2016 to August 2017, using pots and gillnets in the Eastern Adriatic Sea. Official landings were also analyzed (2008–2020). The majority of landings were from the Northern Adriatic and showed an increase of 18.5% over the study period. Results revealed an extremely low catch rate that fluctuated significantly by season. Dominance by specimens in the size classes of 90–110 mm carapace length (CL) was observed. Experimental design revealed spatial heterogeneity, with larger individuals caught further from the coast (>3 nm) and undersized specimens caught near the coast (<3 nm). With increasing CL and total length (TL), an increase in weight was higher in males than females. TL and abdomen width (AW) increased linearly with CL and were more pronounced in females. At 80 mm CL, females started to develop secondary sex characteristics with wider AW than males. The results suggest that the modern legal framework is appropriate for lobster fisheries and a longer fishing season is not advisable, despite a positive catch trend in the northern part of the sea. Additional efforts are desirable to reduce fishing pressure in the coastal part. The morphometric relationships could reveal population characteristics required as inputs in stock assessment analysis for effective management. Full article

The European spiny lobster Palinurus elephas is a vulnerable species that inhabits and is harvested in the Mediterranean Sea and the adjacent Atlantic waters. The fisheries associated with the spiny lobster are mainly conducted with tangle nets, trammel nets, pots, and creels. The fishing pressure has greatly reduced their numbers, changing them from a common shallow coastal species to a largely remnant population. The relative research on the species’ biology and fisheries from the eastern Mediterranean Sea is almost absent. The fishery along the Chalkidiki Peninsula, Greece, is multispecies, and fishing is conducted by a small number of artisanal fishermen mainly using trammel nets. The lobster stock—both spiny and clawed lobsters—declined significantly during the late 1980s and early 1990s, later than most cases in the Mediterranean Sea. However, data regarding the nature and status of the fishery associated with the spiny lobster in Greece are lacking. Data regarding the characteristics of the spiny regional fishery were obtained by interviews and questionnaires. Additionally, fishery surveys were conducted during the main lobster fishing season from 1 May 2017 to 31 August 2017. Sixteen species were identified (15 finfish species and one invertebrate species) as targeted. In total, 79 spiny lobsters were sampled in this study; the population’s sex ratio significantly diverts from the theoretical 1:1 (χ² = 4.57; p < 0.05), and males were dominant. Both male and female individuals demonstrate negative allometric growth profiles. In addition, no significant differences were observed between sexes. In Greece, thus far, the knowledge and information are sporadic, limited, and/or species-specific, most of which regard finfish fisheries. Furthermore, the national legislation is rather complicated—or too generalized—thus creating great uncertainties. The in-depth knowledge and experience of fishermen should be further acknowledged and utilized, and wider collaborations among scientists, practitioners, and policy-makers should be established. The present study poses some thoughts on the effectiveness of the recent EU Landing Obligation and its contribution to the potential restoration of the species. Full article