Fishing Areas Research Articles

Состояние запасов и перспективы промысла крабов в подрайоне Центральная часть Охотского моря

Based on the materials of research in 2015 and 2018, data on the spatial distribution and biological state of crabs in one of the new fishing areas for the Russian Federation are presented - subregion 61.52 Central part of the Sea of Okhotsk. In the area studied, the following commercial crab species were recorded in crab trap catches: Lithodes aequispinus, L. couesi, Paralomis multispina, P. verrilli, Chionoecetes opilio and Ch. angulatus. A single capture of 2 individuals of the sharp-winged crab Oregonia bifurca, which had not previously been encountered in the Sea of Okhotsk, was noted. The main clusters of commercial species of crabs were confined to the northern site at depths of 300-500 m. Of the entire variety of species, only the equidistant crab forms dense aggregations, the stocks of which have been exploited by industry since 2017. Chionoecetes opilio and Ch. angulatus stocks in the area of «polygon» can also recruit the resource base of commercial fishing.

Mapping fine-scale demersal trawl effort for application in ecosystem assessment and spatial planning

Fine-scale maps of fishing activity are valuable information layers for fisheries management, assessments of biodiversity impacts and marine spatial planning. Our aim was to develop an accurate map of demersal trawling intensity in South Africa and to demonstrate its utility at a national scale. We calculated a swept area ratio, representing demersal trawling effort for the entire study period (2005‒2018) and annually. We then plotted spatial and temporal patterns of trawling activity, identified core fishing areas, and examined spatial overlap between trawling, South Africa’s marine ecosystem types and the national network of marine protected areas. A high proportion of trawling effort (90%) was concentrated in 43% of the area exposed to trawling, with the remaining 10% spread across 57% of the fished areas. The fishery overlaps with 33 of 150 benthic and bentho-pelagic marine ecosystem types. Of those, 11 have more than 50% of their extent, and five have more than 80%, within the trawl ring-fence. Our analyses support a systematic prioritisation of ecosystem types for further management and protection. The new South African trawling-intensity map contributes an improved pressure layer for ecosystem assessments, can help identify priority fishing areas and has application in conservation, marine spatial planning and fisheries management.

Moving towards co-benefits of hydropower: Ecological efficiency evaluation based on LCA and DEA

China is ambitious to develop renewable energy for the commitment of carbon neutralization in 2060. Hydropower has been regarded as one important solution to mitigate greenhouse gas (GHG) emissions by replacing fossil fuels, while the related ecological impacts hinder its sustainable development. This study proposes a framework to integrate life cycle analysis and ecosystem service assessment by evaluating 43 case hydropower plants (HPs) in China. Combining with the super slacks-based measurement model, the ecological efficiency of HPs is evaluated to provide optimizing pathways. The results show most environmental impacts of the whole HP life cycle are from the preparation and construction stages of HPs. The ecosystem service losses (ESLs) are mainly from the losses of biodiversity and water supply. The first cascade HP generally has a smaller ecological efficiency than downstream HPs. Furthermore, the current pricing structure of the studied HPs does not adequately account for the associated ESLs. It suggests that consumers in transmission destinations should bear a higher cost to address the ecological impacts of HP operations. Consequently, there is a need to revise the pricing mechanisms to reflect and internalize the ecological costs more accurately. Finally, based on the results, policy implications for achieving “co-benefit” of hydropower development and ecosystem protection were raised: (a) conducting the comprehensive and systematic evaluation of HPs including LCA and ESL assessment before HP planning; (b) ensuring the connectivity of natural flow and the preservation of fish areas; (c) revising the pricing mechanisms of hydropower based on the fair price.

Biomass of key grazing fishes is an important determinant of coral growth and fouling control in coral nurseries

Restoration is an emerging tool for coral reef conservation, yet despite small‐scale successes there are concerns about high costs and ecological setbacks. Integration between reef ecology and restoration could help address such concerns. A prime example is the use of grazing by herbivores to reduce coral nursery cleaning costs. However, the relation between herbivore communities and cleaning benefits remains unquantified. This study aimed to measure links between herbivorous fish communities, grazing intensity and coral nursery performance. Six reefs were selected in southern Kenya, equally divided across three levels of fisheries management (fished < reserve < no‐take). Fish surveys determined herbivorous fish biomass and composition, and remote underwater videos recorded grazing intensity on coral nurseries. Accumulated fouling and coral growth were measured at the end of the 4‐month study. Grazing intensity was sixfold lower and fouling density fourfold higher in the fished areas compared to protected zones. Higher fouling strongly correlated with lower coral growth: exponential growth constants in fished areas were respectively twice and three times as low compared to marine reserves and no‐take zones. Across study sites grazing was dominated by bristletooth tangs (Ctenochaetus spp.), except where these were outcompeted by territorial damselfish. Thus, better coral nursery performance in protected areas can be partially linked to higher grazing intensity, which in turn is determined by both fish biomass and local species composition. We recommend protecting herbivorous fish species and placing coral nurseries in areas with high biomass of key grazers to improve coral nursery performance and reduce maintenance costs.

Recreational Fishing Effort and How Management Actions Can Affect It—Part 2: Literature and a Case Study.

Recreational fishing, crucially important to Florida’s economy and ecosystems, can be affected by management decisions. Decisions that change the allowable harvest or the type of access to certain fishing areas are often expected to have strong effects on fishing effort, but the outcome of these actions is not always obvious. To provide greater insight into what may happen to fishing effort after management decisions, we describe case studies from the North American fisheries literature, some Florida-specific. These illustrate that the same or similar management actions (e.g., a more restrictive harvest policy) can have opposite effects on total fishing effort depending on the specifics of the case. We use this information as well as additional fisheries theory to explore a specific case study—what might happen if special harvest or access regulations were applied to a popular but ecologically and environmentally sensitive habitat—the St. Martins Marsh Aquatic Preserve in Citrus County, Florida.

Fishing Area Prediction Using Scene-Based Ensemble Models

This study utilized Chlorophyll-a, sea surface temperature (SST), and sea surface height (SSH) as the environmental variables to identify skipjack tuna catch hotspots. This study conducted statistical methods (decision tree, DT, and generalized linear model, GLM) as ensemble models that were employed for predicting skipjack area for each time slice. Using spatial historical data, each model was trained for one of the ensemble model sets. For prediction, the correlations of historical and new inputs were applied to select the predictive model. Using the scene-based model with the highest input correlation, this study further identified the fishing area of skipjack tuna in every case whether the alterations in their environment affected their abundance or not. Overall, the performance achieved over 83% for correlation coefficients (CC) based on the accuracy assessment. This study concluded that DT appears to perform better than GLM in predicting skipjack tuna fishing areas. Moreover, the most influential environmental variable in model construction was sea surface temperature (SST), indicating that the presence of skipjack tuna was primarily influenced by regional temperature.

Population structure and reproductive dynamics of the ridged swimming crab Charybdis natator in the southern Taiwan Strait of China: significant changes within 25 years

The ridged swimming crab Charybdis natator (Portunidae) is a commercially important crustacean species in China. The purpose of this study is to compare its population structure and reproductive pattern within the same fishing area (the southern Taiwan Strait) from two datasets over 25 years; one from 1994−1996 (the early years of the C. natator fishery) and the other from 2019. The overall sex ratio (male:female) changed from a male bias (1:0.76, p < 0.01) in 1994−1996 to a female bias (1:1.38, p < 0.01) in 2019. Male body sizes (carapace width, CW) were significantly larger than those of females in both datasets (p < 0.05). The average CW and body weight (BW) of males and females in 2019 were significantly smaller (p < 0.01) and lighter (p < 0.01) than those in 1994−1996. The maximum body size and the proportion of large-sized individuals (CW > 10 cm) decreased dramatically over 25 years. One spawning peak season was identified from each dataset, i.e., March−August 1994−1996 and February−April 2019, revealing a 1-month shift. The minimum body sizes for female maturation (carrying eggs) were 6.9 cm CW in 1994−1996 and 6.1 cm CW in 2019, an 11.6% reduction over 25 years. For the first time, the CW at 50% female maturation, the relationship between female absolute fecundity and CW, and egg diameters were obtained from the 2019 dataset, which can be applied in the future comparisons. Recent studies have revealed a consistent spawning peak in February–April for several commercially important crabs in the southern Taiwan Strait. These findings should be considered in crab fishery management. Furthermore, both fishery- and environment-associated factors influencing crustacean population structure and reproductive dynamics merit further investigation.

Evaluating the use of side scan sonar for improved detection and targeted retrieval of abandoned, lost, or otherwise discarded fishing gear

Abandoned, lost, or otherwise discarded fishing gear (ALDFG) has surfaced as a significant conservation issue that continues to compromise the economic, social, and ecological aspects of the marine environment. To alleviate these concerns, methods of lost gear detection at the seabed can be applied to increase the precision of derelict gear retrieval and potentially improve the likelihood of success. Targeted in Canada's most productive American lobster (Homarus americanus) fishing area, a “hotspot” analysis was performed by mapping the density of reported lost gear at a 3 km × 3 km grid resolution. The hotspot analysis was used to target the collection of 27 side scan sonar (SSS) transects in Lobster Fishing Area (LFA) 34 over a 12-day survey period in Clark's Harbour, Nova Scotia, to evaluate the benefits of gear detection in large-scale retrieval missions. Following a comprehensive review of the SSS data post-processing, 114 potential ALDFG targets were visually identified, and only one item was confirmed retrieved. Despite this, a large volume of ALDFG was retrieved in areas where there was no SSS coverage based on fisher's local knowledge. The findings from this study demonstrate that retrieval of ALDFG based on SSS data can be difficult due to limitations of retrieval methods used, and that costs of SSS data acquisition may prohibit widescale use of this technology on an annual basis in spatially extensive fishing areas. Nonetheless, the use of SSS to identify ALDFG is recommended at smaller geographic scales in areas where the benthic environment may be sensitive. Although the use of fisher's local knowledge was not evaluated in this study, where the impacts of grappling for ALDFG are considered minimal, local knowledge can be extremely effective in the removal of lost fishing gear and other debris from the benthic environment.

Consistent edge effect patterns revealed using continuous surveys across an Eastern Mediterranean no-take marine protected area

AbstractBecause marine protected areas (MPAs) are not equally effective across their areas, monitoring should progress from dichotomic (within vs. outside) to a finer spatial resolution. Here, we examine the effect of an Eastern Mediterranean no-take MPA on fishes across the MPA and into fished areas, using three methods: underwater visual censuses, acoustic surveys, and towed-diver surveys. The Eastern Mediterranean includes non-indigenous species, so the effect of the MPA was also evaluated for its resistance to invasion. The fine-scale analysis revealed ecological phenomena that could not be captured by dichotomic sampling, such as the edge effect, a reduction of fish biomass along the MPA periphery. Despite their differences, all three methods revealed similar spatial patterns. The fine-scale analysis did not support a biotic resistance of the MPA to non-indigenous species. Our study supports the prevalence of edge effects even in well-enforced no-take MPAs and highlights the need for continuous monitoring to reveal these patterns.

Factors affecting condom use among fishers in Elmina fishing community in Ghana.

Although it is well known that low condom usage among fishers contributes to high HIV prevalence in fishing communities, little is known about the attitudes, beliefs, and behaviors of fishers when it comes to the use of condoms. This article is a follow-up to a cross-sectional study that used a mix-method design for data collection and analysis to examine the connection between mobility and the risk of contracting HIV among 385 fishers in the Elmina fishing community of Ghana. The Health Belief Model is utilized in the discussions to analyze attitudes and actions toward condom use among the fishers in Elmina. Over 40% of respondents who said they had intercourse in the previous year did not use condoms. The results show that male fishers are more likely than female fishers to use condoms during sexual activity, and younger fishers are more likely to use condoms than older fishers. More condoms were used by educated fishers than by less educated or uneducated fishers. According to the study, female fishers use less condoms than male fishers since they are unable to convince their partners to use them when they refuse to. Additionally, the findings show that slightly more than one in 10 respondents did not use condoms because they believed their sexual partner to be attractive and unlikely to carry any sexual infection. There is a general low perception of HIV susceptibility and severity resulting in the low condom usage among the fisherfolks according to the results. The article urges civil society organizations in the study area to investigate ways to incorporate the provision of free condoms to fishers and at the numerous fishing destination sites along the coast of Elmina. The regular use of condoms in Elmina and the nearby fishing areas should also be emphasised through this outreach or mobile HIV service outlets.

Fish Production and Evaluation of the Fishery Status for Shalateen Fishing Area, Red Sea, Egypt

Fish Production and Evaluation of the Fishery Status for Shalateen Fishing Area, Red Sea, Egypt

Using systematic conservation planning to inform restoration of freshwater habitat and connectivity for salmon

AbstractInstream barriers remain ubiquitous threats to freshwater species and their habitats. Decisions regarding barrier removal are often aimed at maximizing habitat area and connectivity for freshwater fish; yet can be challenging due to the sheer number of barriers, uncertainty in species presence, abundance, and habitat quality, as well as limited budgets alongside high costs of restoration. Here, we apply systematic conservation planning to prioritize in‐stream barrier removal aimed at restoring habitat connectivity for 14 populations of wild Pacific salmon in the lower Fraser River, Canada's most productive salmon‐bearing river. To understand how priorities change when stream quality is considered, we contrast scenarios that maximize habitat extent with scenarios that include four indicators of habitat quality. Region‐wide, approximately 64% of naturally accessible stream length is currently blocked by barriers. We estimate approximately 75% of this alienated habitat (over 1600 km of stream), could have full access restored with an investment of $200 million CAD, whereas 60% could be restored for half this amount. When stream quality was considered within the optimization, priorities for barriers removal shifted away from urbanized floodplain valleys towards less developed areas. The spatial shift in priorities meant that species like chum salmon (Oncorhynchus keta) would see less restored habitat. To inform barrier removal strategies using these model scenarios, an iterative and adaptive approach will be required that includes the values and priorities of rights and titleholders. Continuous improvement in data quality, accuracy, and feedback from monitoring as barriers are restored is also crucial.

TINGKAT PEMANFAATAN UDANG KARANG (Panulirus spp) BERDASARKAN PENDEKATAN MODEL PRODUKSI SURPLUS DI PERAIRAN KABUPATEN PANGKEP

Crayfish (Panulirus spp) is one type of Indonesian marine fishery resources that is very potential and has long been caught by fishermen in coral areas to find out the description of fishing gear, methods, and crayfish fishing areas (Panulirus spp) in the waters of Pangkep Regency and to find out the estimated utilization rate of crayfish using the MSY approach in Pangkep Regency. This research has been carried out by taking data in the form of primary data carried out from March 1, 2022 – April 30, 2022 and secondary data in the form of catch production data and fishing efforts (units) obtained from the Marine and Fisheries Service of Pangkep Regency for the 2016-2021 time period. The results of this study showed that the fishing gear used to catch crayfish (Panulirus spp) was a fixed gill net using a canoe boat as a tool. The process of catching crayfish includes setting, soaking and hauling. Coral fishing grounds are in rocky areas with the fishing season occurring from November to January. Based on the results of research using three surplus production models, it was concluded that the most suitable surplus production model for crayfish fisheries in Pangkep Regency is the Gulland model by showing a large (R2) and a small standard deviation. The maximum sustainable catch is 16,783.58 kg/year and the attempted catch is 12,496 units. The Utilization Rate (TP) and Capability Rate (TPU) have exceeded (yJTB) and (fJTB) with overexploited status.

Estimation Of Pelagic Fishing Area in Banten’s Southern Sea

The purpose of this research are to determine the average distribution of SST, chlorophyll-a, and see surface currents, and analyze the relationship between them with pelagic fish catches as an analysis material for determining pelagic fishing area in Banten’s Southern Sea. Data collected includes SST and chlorophyll-a using Aqua MODIS images data and and see surface currents data from Copernicus Marine Data for 6 years. The data was processed to produce the value of each parameter and then analyzed the parameters with the catches and determine the potential pelagic fishing area. The results showed that the SST throughout 2016 had a relatively high value allegedly due to the negative Indian Ocean Dipole (IOD). During the eastern until the end of second transitional season in 2019 there was a positive IOD which caused SST to decrease and chlorophyll-a to be larger than in other fishing seasons. See surface currents in the western season tend to be larger than in other fishing seasons. SST and chlorophyll-a have a stronger relationship with catches than see surface currents. The potential fishing area are around Tanjung Mantiyung, Muara Binuangeun, dan Tanjung Panto.

Modelling spatial variation in an exploited species across marine reserve boundaries

Abstract An increase in exploited species within marine reserves is often expected to benefit adjacent fished areas through the movement or ‘spill‐over’ of exploited species across reserve boundaries. However, harvest at and near reserve boundaries can also decrease abundances inside reserves, forming ‘edge‐effects’. Spatial analysis of gradients in abundance across reserve boundaries have been used to interpret the extents of edge‐effects and spill‐over. While the shape of these gradients will vary depending on species mobility and fishing intensity on reserve boundaries, they have largely been assumed to be gradual and quantified using continuous modelling strategies. This study shows that continuous modelling strategies can lead to overestimations of spill‐over and edge‐effects by underfitting the rapid transition in abundance that can occur from reserve to fished areas. The abundances of spiny lobster (Jasus edwardsii) across the boundaries of two north‐eastern New Zealand marine reserves were quantified using catch survey data collected over 2 years. Several modelling approaches were used, and the predictive performance of each approach was compared. Abrupt changes in lobster abundances were found across reserve boundaries and were best represented with models that incorporated a stepwise function across boundaries or where data from reserve and fished areas were modelled independently. Despite the mobile nature of this species, we found little evidence of edge‐effects and spill‐over within and adjacent to the surveyed marine reserves, which may reflect the low population status within these reserves. In contrast, standard continuous modelling approaches overestimated the extent of edge‐effects and spill‐over in both marine reserves. Policy implications. This study shows how accurate assessments of edge‐effects and spill‐over can be used to evaluate the effectiveness of existing marine reserves in protecting exploited species. These findings emphasise the importance comparing several different modelling strategies when evaluating edge‐effects and spill‐over to ensure appropriate model fits. Although modelling approaches such as generalised additive models present a simple solution to exploring spatial variation in ecological data, we emphasise the importance of questioning the applicability of such strategies when assessing variation across areas of rapid change such as protected area boundaries.

PENGEMBANGAN USAHA PERIKANAN SKALA KECIL MELALUI PENENTUAN DAERAH PENANGKAPAN IKAN POTENSIAL DAN MANAJEMEN USAHA

Determination of fishing ground by small-scale fisheries is still based on experience passed down from generation to generation. Fishermen do not yet have the knowledge and technology to make it easier for them to determine a good fishing ground, so it is inefficient in terms of time, cost and effort. In addition, business management that is not running properly has resulted in the business being run not developing. This training aims to increase fishermen's knowledge about determining potential fishing grounds, specifically for demersal fish species and management of small-scale fisheries. The training activities were carried out in Hukurila Village, South Leitimur District, Ambon City. The method of implementation is presentation of materials, discussions and than training in making bookkeeping simple. Participants were 31 fishers who were involved in this activity. Fishers felt that the material they received was very useful because it made it easier for them to determine demersal fishing areas that had important economic value. In addition, business bookkeeping through training has helped them manage the finances of the business they are running.

Identification of Surface Current Patterns in Small Pelagic Fishing Areas in the Western Season of the Spermonde Islands, Indonesia

Monsoonal wind commonly affects Indonesian waters, blowing in an adversative direction by turns in one year. These are well-known as west and east monsoonal winds. Spermonde Archipelago waters, located on the west coast of the southern part of South Sulawesi, is a water region comprising various islands with relatively shallow waters and situated in Makassar Strait. The study aimed to identify the pattern of current surface movement in each monsoon period, especially on the west monsoon on Small Pelagic Fish Catches Area. Data used in this study consisted of primary and secondary data. Primary data were obtained in the field for three months (April to Jun, second monsoonal transition monsoon into east monsoon). In December, the wind pattern was dominated from the northwest with a maximum speed of 8 knots. The surface current pattern offshore was from the south (0.16 m/s) to the north with decreasing speed (0.03 m/s). Meanwhile, in low tide, the current surface pattern offshore was from the north (speed may reach up to 0.04 m/s) to the south with an increasing speed of 0.20 m/s. The peak of the west monsoon occurs in January to February with high rainfall, and wind speed is dominated from south-west and west directions. Current pattern occurred in the offshore, either at high or low tide, showed similar pattern, which was divided into east and south directions.

Fish community dynamics in a coastal no-take marine protected area compared to a harvested area before and after protection from fishing

Abstract An ecosystem's ability to maintain key functions during environmental change is largely determined by its biodiversity. We compared fish species composition, richness, diversity, catch per unit effort (CPUE), and fish size between a 1.5 km2 no-take marine protected area (MPA) and a nearby fished area on the southern Norwegian coast annually for one decade (2011–2021), including before-protection status. In total, >26 thousand fish representing 31 species were sampled using a beach seine. No significant effect of protection was detected on either species richness, diversity, or evenness. For selected species of small-bodied intermediate predators, there was a significant decline in mean body size in the MPA area compared to the fished area, indicative of a response to protection involving trophic interactions. No significant effect of the MPA was detected on either CPUE or body size of Atlantic cod (Gadus morhua), a top predator mainly captured at the juvenile stage by our sampling. The limited responses seen in this study may be linked to the small size of the MPA compared to the dispersal and movement capabilities of species such as the cod.

Heterogeneity of adaptation strategies to climate shocks: Evidence from the Niger Delta region of Nigeria

There is overwhelming evidence to suggest that climate shocks undermine food security and livelihood well-being of the climate-impacted Niger Delta region of Nigeria. Employing survey data collected from farming and fishing households in the Niger Delta region of Nigeria, the study investigated the range of adaptation practices prevalent in the region, as well as factors influencing the adoption of these adaptation strategies. Five hundred and three (503) households (252 fishing households and 251 farming households) were selected using multi-stage sampling techniques. Multinomial logit model was used to determine factors affecting the household choice of adaptation strategies. The results show that adaptation strategies adopted by farming households were livelihood diversification (78.5%), crop management (77.7%), and soil and water management (64.5%). Factors influencing their choice of adaptation strategies were age, gender, household size, education, extension, and farm size. The adaptation strategies employed by the fishing households were livelihood diversification (83.61%) and intensification [which include the use of improved fishing gears (80.33%), varying fishing locations (67.21%), and expanding area of fishing (40.98%)]. Uncovering the heterogeneity in adaptation and resilience aspects to climate shocks has immense practical significance, particularly in providing targeted assistance for the two livelihood groups’ adoption.

Environmental and economic impacts of retrieved abandoned, lost, and discarded fishing gear in Southwest Nova Scotia, Canada

Abandoned, lost, and discarded fishing gear (ALDFG), negatively impacts marine environments. Managing ALDFG in Atlantic Canada is challenging due to knowledge gaps on loss rates, locations, data availability/accuracy, impacts, and regulatory barriers for retrieval. This study removed ALDFG in Southwest Nova Scotia in collaboration with local fishers (with local knowledge and practical ALDFG removal expertise), government, non-profit organizations, and academia. A total of 29,298 kg of ALDFG was retrieved, including 24,630 kg using towed grapples covering ~3986 km of seafloor and 4668 kg from shorelines (comprising, 68 % lobster traps and 12 % dragger cable by weight). Traps ranged from <1 to 37 years old (median, 10 years). Traps continued to catch target and non-target species with 25 species released, including 652 individual lobsters (82 % were market-sized) and 57 fish (42 were species-at-risk). Based on estimated 2 % trap losses, annual commercial losses from ALDFG were $155,836 CAD in Lobster Fishing Area 34.